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[ShrinkWrap] Add (a simplified version) of shrink-wrapping.

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This patch introduces a new pass that computes the safe point to insert the
prologue and epilogue of the function.
The interest is to find safe points that are cheaper than the entry and exits
blocks.

As an example and to avoid regressions to be introduce, this patch also
implements the required bits to enable the shrink-wrapping pass for AArch64.


** Context **

Currently we insert the prologue and epilogue of the method/function in the
entry and exits blocks. Although this is correct, we can do a better job when
those are not immediately required and insert them at less frequently executed
places.
The job of the shrink-wrapping pass is to identify such places.


** Motivating example **

Let us consider the following function that perform a call only in one branch of
a if:
define i32 @f(i32 %a, i32 %b)  {
 %tmp = alloca i32, align 4
 %tmp2 = icmp slt i32 %a, %b
 br i1 %tmp2, label %true, label %false

true:
 store i32 %a, i32* %tmp, align 4
 %tmp4 = call i32 @doSomething(i32 0, i32* %tmp)
 br label %false

false:
 %tmp.0 = phi i32 [ %tmp4, %true ], [ %a, %0 ]
 ret i32 %tmp.0
}

On AArch64 this code generates (removing the cfi directives to ease
readabilities):
_f:                                     ; @f
; BB#0:
  stp x29, x30, [sp, #-16]!
  mov  x29, sp
  sub sp, sp, #16             ; =16
  cmp  w0, w1
  b.ge  LBB0_2
; BB#1:                                 ; %true
  stur  w0, [x29, #-4]
  sub x1, x29, #4             ; =4
  mov  w0, wzr
  bl  _doSomething
LBB0_2:                                 ; %false
  mov  sp, x29
  ldp x29, x30, [sp], #16
  ret

With shrink-wrapping we could generate:
_f:                                     ; @f
; BB#0:
  cmp  w0, w1
  b.ge  LBB0_2
; BB#1:                                 ; %true
  stp x29, x30, [sp, #-16]!
  mov  x29, sp
  sub sp, sp, #16             ; =16
  stur  w0, [x29, #-4]
  sub x1, x29, #4             ; =4
  mov  w0, wzr
  bl  _doSomething
  add sp, x29, #16            ; =16
  ldp x29, x30, [sp], #16
LBB0_2:                                 ; %false
  ret

Therefore, we would pay the overhead of setting up/destroying the frame only if
we actually do the call.


** Proposed Solution **

This patch introduces a new machine pass that perform the shrink-wrapping
analysis (See the comments at the beginning of ShrinkWrap.cpp for more details).
It then stores the safe save and restore point into the MachineFrameInfo
attached to the MachineFunction.
This information is then used by the PrologEpilogInserter (PEI) to place the
related code at the right place. This pass runs right before the PEI.

Unlike the original paper of Chow from PLDI’88, this implementation of
shrink-wrapping does not use expensive data-flow analysis and does not need hack
to properly avoid frequently executed point. Instead, it relies on dominance and
loop properties.

The pass is off by default and each target can opt-in by setting the
EnableShrinkWrap boolean to true in their derived class of TargetPassConfig.
This setting can also be overwritten on the command line by using
-enable-shrink-wrap.

Before you try out the pass for your target, make sure you properly fix your
emitProlog/emitEpilog/adjustForXXX method to cope with basic blocks that are not
necessarily the entry block.


** Design Decisions **

1. ShrinkWrap is its own pass right now. It could frankly be merged into PEI but
for debugging and clarity I thought it was best to have its own file.
2. Right now, we only support one save point and one restore point. At some
point we can expand this to several save point and restore point, the impacted
component would then be:
- The pass itself: New algorithm needed.
- MachineFrameInfo: Hold a list or set of Save/Restore point instead of one
  pointer.
- PEI: Should loop over the save point and restore point.
Anyhow, at least for this first iteration, I do not believe this is interesting
to support the complex cases. We should revisit that when we motivating
examples.

Differential Revision: http://reviews.llvm.org/D9210

<rdar://problem/3201744>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236507 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Quentin Colombet 2015-05-05 17:38:16 +00:00
parent 1aeb111842
commit 2f7322b348
42 changed files with 1171 additions and 116 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
include/llvm/CodeGen/MachineFrameInfo.h
View File

@ -246,6 +246,16 @@ class MachineFrameInfo {
/// True if this is a varargs function that contains a musttail call.
bool HasMustTailInVarArgFunc;
/// Not null, if shrink-wrapping found a better place for the prologue.
MachineBasicBlock *Save;
/// Not null, if shrink-wrapping found a better place for the epilogue.
MachineBasicBlock *Restore;
/// Check if it exists a path from \p MBB leading to the basic
/// block with a SavePoint (a.k.a. prologue).
bool isBeforeSavePoint(const MachineFunction &MF,
const MachineBasicBlock &MBB) const;
public:
explicit MachineFrameInfo(unsigned StackAlign, bool isStackRealign,
bool RealignOpt)
@ -269,6 +279,8 @@ public:
HasInlineAsmWithSPAdjust = false;
HasVAStart = false;
HasMustTailInVarArgFunc = false;
Save = nullptr;
Restore = nullptr;
}
/// hasStackObjects - Return true if there are any stack objects in this
@ -597,6 +609,11 @@ public:
void setCalleeSavedInfoValid(bool v) { CSIValid = v; }
MachineBasicBlock *getSavePoint() const { return Save; }
void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; }
MachineBasicBlock *getRestorePoint() const { return Restore; }
void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; }
/// getPristineRegs - Return a set of physical registers that are pristine on
/// entry to the MBB.
///

10
include/llvm/CodeGen/Passes.h
View File

@ -120,6 +120,9 @@ protected:
/// Default setting for -enable-tail-merge on this target.
bool EnableTailMerge;
/// Default setting for -enable-shrink-wrap on this target.
bool EnableShrinkWrap;
public:
TargetPassConfig(TargetMachine *tm, PassManagerBase &pm);
// Dummy constructor.
@ -179,6 +182,9 @@ public:
/// Return true if the optimized regalloc pipeline is enabled.
bool getOptimizeRegAlloc() const;
/// Return true if shrink wrapping is enabled.
bool getEnableShrinkWrap() const;
/// Return true if the default global register allocator is in use and
/// has not be overriden on the command line with '-regalloc=...'
bool usingDefaultRegAlloc() const;
@ -426,6 +432,10 @@ namespace llvm {
/// basic blocks.
extern char &SpillPlacementID;
/// ShrinkWrap pass. Look for the best place to insert save and restore
// instruction and update the MachineFunctionInfo with that information.
extern char &ShrinkWrapID;
/// VirtRegRewriter pass. Rewrite virtual registers to physical registers as
/// assigned in VirtRegMap.
extern char &VirtRegRewriterID;

1
include/llvm/InitializePasses.h
View File

@ -247,6 +247,7 @@ void initializeSROA_DTPass(PassRegistry&);
void initializeSROA_SSAUpPass(PassRegistry&);
void initializeScalarEvolutionAliasAnalysisPass(PassRegistry&);
void initializeScalarEvolutionPass(PassRegistry&);
void initializeShrinkWrapPass(PassRegistry &);
void initializeSimpleInlinerPass(PassRegistry&);
void initializeShadowStackGCLoweringPass(PassRegistry&);
void initializeRegisterCoalescerPass(PassRegistry&);

13
include/llvm/Target/TargetFrameLowering.h
View File

@ -130,21 +130,26 @@ public:
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
virtual void emitPrologue(MachineFunction &MF) const = 0;
virtual void emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const = 0;
virtual void emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const = 0;
/// Adjust the prologue to have the function use segmented stacks. This works
/// by adding a check even before the "normal" function prologue.
virtual void adjustForSegmentedStacks(MachineFunction &MF) const { }
virtual void adjustForSegmentedStacks(MachineFunction &MF,
MachineBasicBlock &PrologueMBB) const {}
/// Adjust the prologue to add Erlang Run-Time System (ERTS) specific code in
/// the assembly prologue to explicitly handle the stack.
virtual void adjustForHiPEPrologue(MachineFunction &MF) const { }
virtual void adjustForHiPEPrologue(MachineFunction &MF,
MachineBasicBlock &PrologueMBB) const {}
/// Adjust the prologue to add an allocation at a fixed offset from the frame
/// pointer.
virtual void adjustForFrameAllocatePrologue(MachineFunction &MF) const { }
virtual void
adjustForFrameAllocatePrologue(MachineFunction &MF,
MachineBasicBlock &PrologueMBB) const {}
/// spillCalleeSavedRegisters - Issues instruction(s) to spill all callee
/// saved registers and returns true if it isn't possible / profitable to do

1
lib/CodeGen/CMakeLists.txt
View File

@ -93,6 +93,7 @@ add_llvm_library(LLVMCodeGen
ScheduleDAGInstrs.cpp
ScheduleDAGPrinter.cpp
ScoreboardHazardRecognizer.cpp
ShrinkWrap.cpp
ShadowStackGC.cpp
ShadowStackGCLowering.cpp
SjLjEHPrepare.cpp

1
lib/CodeGen/CodeGen.cpp
View File

@ -61,6 +61,7 @@ void llvm::initializeCodeGen(PassRegistry &Registry) {
initializePostRASchedulerPass(Registry);
initializeProcessImplicitDefsPass(Registry);
initializeRegisterCoalescerPass(Registry);
initializeShrinkWrapPass(Registry);
initializeSlotIndexesPass(Registry);
initializeStackColoringPass(Registry);
initializeStackMapLivenessPass(Registry);

38
lib/CodeGen/MachineFunction.cpp
View File

@ -600,8 +600,8 @@ MachineFrameInfo::getPristineRegs(const MachineBasicBlock *MBB) const {
for (const MCPhysReg *CSR = TRI->getCalleeSavedRegs(MF); CSR && *CSR; ++CSR)
BV.set(*CSR);
// The entry MBB always has all CSRs pristine.
if (MBB == &MF->front())
// Each MBB before the save point has all CSRs pristine.
if (isBeforeSavePoint(*MF, *MBB))
return BV;
// On other MBBs the saved CSRs are not pristine.
@ -613,6 +613,40 @@ MachineFrameInfo::getPristineRegs(const MachineBasicBlock *MBB) const {
return BV;
}
// Note: We could use some sort of caching mecanism, but we lack the ability
// to know when the cache is invalid, i.e., the CFG changed.
// Assuming we have that, we can simply compute all the set of MBBs
// that are before the save point.
bool MachineFrameInfo::isBeforeSavePoint(const MachineFunction &MF,
const MachineBasicBlock &MBB) const {
// Early exit if shrink-wrapping did not kick.
if (!Save)
return &MBB == &MF.front();
// Starting from MBB, check if there is a path leading to Save that do
// not cross Restore.
SmallPtrSet<const MachineBasicBlock *, 8> Visited;
SmallVector<const MachineBasicBlock *, 8> WorkList;
WorkList.push_back(&MBB);
Visited.insert(&MBB);
do {
const MachineBasicBlock *CurBB = WorkList.pop_back_val();
// By construction, the region that is after the save point is
// dominated by the Save and post-dominated by the Restore.
// If we do not reach Restore and still reach Save, this
// means MBB is before Save.
if (CurBB == Save)
return true;
if (CurBB == Restore)
continue;
// Enqueue all the successors not already visited.
for (MachineBasicBlock *SuccBB : CurBB->successors())
if (Visited.insert(SuccBB).second)
WorkList.push_back(SuccBB);
} while (!WorkList.empty());
return false;
}
unsigned MachineFrameInfo::estimateStackSize(const MachineFunction &MF) const {
const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();

30
lib/CodeGen/Passes.cpp
View File

@ -52,7 +52,10 @@ static cl::opt<bool> DisableMachineLICM("disable-machine-licm", cl::Hidden,
static cl::opt<bool> DisableMachineCSE("disable-machine-cse", cl::Hidden,
cl::desc("Disable Machine Common Subexpression Elimination"));
static cl::opt<cl::boolOrDefault>
OptimizeRegAlloc("optimize-regalloc", cl::Hidden,
EnableShrinkWrapOpt("enable-shrink-wrap", cl::Hidden,
cl::desc("enable the shrink-wrapping pass"));
static cl::opt<cl::boolOrDefault> OptimizeRegAlloc(
"optimize-regalloc", cl::Hidden,
cl::desc("Enable optimized register allocation compilation path."));
static cl::opt<bool> DisablePostRAMachineLICM("disable-postra-machine-licm",
cl::Hidden,
@ -206,10 +209,10 @@ TargetPassConfig::~TargetPassConfig() {
// Out of line constructor provides default values for pass options and
// registers all common codegen passes.
TargetPassConfig::TargetPassConfig(TargetMachine *tm, PassManagerBase &pm)
: ImmutablePass(ID), PM(&pm), StartAfter(nullptr), StopAfter(nullptr),
Started(true), Stopped(false), AddingMachinePasses(false), TM(tm),
Impl(nullptr), Initialized(false), DisableVerify(false),
EnableTailMerge(true) {
: ImmutablePass(ID), PM(&pm), StartAfter(nullptr), StopAfter(nullptr),
Started(true), Stopped(false), AddingMachinePasses(false), TM(tm),
Impl(nullptr), Initialized(false), DisableVerify(false),
EnableTailMerge(true), EnableShrinkWrap(false) {
Impl = new PassConfigImpl();
@ -524,6 +527,8 @@ void TargetPassConfig::addMachinePasses() {
addPostRegAlloc();
// Insert prolog/epilog code. Eliminate abstract frame index references...
if (getEnableShrinkWrap())
addPass(&ShrinkWrapID);
addPass(&PrologEpilogCodeInserterID);
/// Add passes that optimize machine instructions after register allocation.
@ -599,6 +604,21 @@ void TargetPassConfig::addMachineSSAOptimization() {
addPass(&DeadMachineInstructionElimID);
}
bool TargetPassConfig::getEnableShrinkWrap() const {
switch (EnableShrinkWrapOpt) {
case cl::BOU_UNSET:
return EnableShrinkWrap && getOptLevel() != CodeGenOpt::None;
// If EnableShrinkWrap is set, it takes precedence on whatever the
// target sets. The rational is that we assume we want to test
// something related to shrink-wrapping.
case cl::BOU_TRUE:
return true;
case cl::BOU_FALSE:
return false;
}
llvm_unreachable("Invalid shrink-wrapping state");
}
//===---------------------------------------------------------------------===//
/// Register Allocation Pass Configuration
//===---------------------------------------------------------------------===//

114
lib/CodeGen/PrologEpilogInserter.cpp
View File

@ -71,9 +71,9 @@ private:
// stack frame indexes.
unsigned MinCSFrameIndex, MaxCSFrameIndex;
// Entry and return blocks of the current function.
MachineBasicBlock *EntryBlock;
SmallVector<MachineBasicBlock *, 4> ReturnBlocks;
// Save and Restore blocks of the current function.
MachineBasicBlock *SaveBlock;
SmallVector<MachineBasicBlock *, 4> RestoreBlocks;
// Flag to control whether to use the register scavenger to resolve
// frame index materialization registers. Set according to
@ -133,20 +133,26 @@ bool PEI::isReturnBlock(MachineBasicBlock* MBB) {
/// Compute the set of return blocks
void PEI::calculateSets(MachineFunction &Fn) {
// Sets used to compute spill, restore placement sets.
const std::vector<CalleeSavedInfo> &CSI =
Fn.getFrameInfo()->getCalleeSavedInfo();
const MachineFrameInfo *MFI = Fn.getFrameInfo();
// If no CSRs used, we are done.
if (CSI.empty())
// Even when we do not change any CSR, we still want to insert the
// prologue and epilogue of the function.
// So set the save points for those.
// Use the points found by shrink-wrapping, if any.
if (MFI->getSavePoint()) {
SaveBlock = MFI->getSavePoint();
assert(MFI->getRestorePoint() && "Both restore and save must be set");
RestoreBlocks.push_back(MFI->getRestorePoint());
return;
}
// Save refs to entry and return blocks.
EntryBlock = Fn.begin();
SaveBlock = Fn.begin();
for (MachineFunction::iterator MBB = Fn.begin(), E = Fn.end();
MBB != E; ++MBB)
if (isReturnBlock(MBB))
ReturnBlocks.push_back(MBB);
RestoreBlocks.push_back(MBB);
return;
}
@ -226,7 +232,7 @@ bool PEI::runOnMachineFunction(MachineFunction &Fn) {
}
delete RS;
ReturnBlocks.clear();
RestoreBlocks.clear();
return true;
}
@ -372,6 +378,61 @@ void PEI::calculateCalleeSavedRegisters(MachineFunction &F) {
MFI->setCalleeSavedInfo(CSI);
}
/// Helper function to update the liveness information for the callee-saved
/// registers.
static void updateLiveness(MachineFunction &MF) {
MachineFrameInfo *MFI = MF.getFrameInfo();
// Visited will contain all the basic blocks that are in the region
// where the callee saved registers are alive:
// - Anything that is not Save or Restore -> LiveThrough.
// - Save -> LiveIn.
// - Restore -> LiveOut.
// The live-out is not attached to the block, so no need to keep
// Restore in this set.
SmallPtrSet<MachineBasicBlock *, 8> Visited;
SmallVector<MachineBasicBlock *, 8> WorkList;
MachineBasicBlock *Entry = &MF.front();
MachineBasicBlock *Save = MFI->getSavePoint();
if (!Save)
Save = Entry;
if (Entry != Save) {
WorkList.push_back(Entry);
Visited.insert(Entry);
}
Visited.insert(Save);
MachineBasicBlock *Restore = MFI->getRestorePoint();
if (Restore)
// By construction Restore cannot be visited, otherwise it
// means there exists a path to Restore that does not go
// through Save.
WorkList.push_back(Restore);
while (!WorkList.empty()) {
const MachineBasicBlock *CurBB = WorkList.pop_back_val();
// By construction, the region that is after the save point is
// dominated by the Save and post-dominated by the Restore.
if (CurBB == Save)
continue;
// Enqueue all the successors not already visited.
// Those are by construction either before Save or after Restore.
for (MachineBasicBlock *SuccBB : CurBB->successors())
if (Visited.insert(SuccBB).second)
WorkList.push_back(SuccBB);
}
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
for (MachineBasicBlock *MBB : Visited)
// Add the callee-saved register as live-in.
// It's killed at the spill.
MBB->addLiveIn(CSI[i].getReg());
}
}
/// insertCSRSpillsAndRestores - Insert spill and restore code for
/// callee saved registers used in the function.
///
@ -392,26 +453,22 @@ void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) {
MachineBasicBlock::iterator I;
// Spill using target interface.
I = EntryBlock->begin();
if (!TFI->spillCalleeSavedRegisters(*EntryBlock, I, CSI, TRI)) {
I = SaveBlock->begin();
if (!TFI->spillCalleeSavedRegisters(*SaveBlock, I, CSI, TRI)) {
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
// Add the callee-saved register as live-in.
// It's killed at the spill.
EntryBlock->addLiveIn(CSI[i].getReg());
// Insert the spill to the stack frame.
unsigned Reg = CSI[i].getReg();
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.storeRegToStackSlot(*EntryBlock, I, Reg, true, CSI[i].getFrameIdx(),
TII.storeRegToStackSlot(*SaveBlock, I, Reg, true, CSI[i].getFrameIdx(),
RC, TRI);
}
}
// Update the live-in information of all the blocks up to the save point.
updateLiveness(Fn);
// Restore using target interface.
for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri) {
MachineBasicBlock *MBB = ReturnBlocks[ri];
for (MachineBasicBlock *MBB : RestoreBlocks) {
I = MBB->end();
--I;
// Skip over all terminator instructions, which are part of the return
// sequence.
@ -721,21 +778,18 @@ void PEI::insertPrologEpilogCode(MachineFunction &Fn) {
const TargetFrameLowering &TFI = *Fn.getSubtarget().getFrameLowering();
// Add prologue to the function...
TFI.emitPrologue(Fn);
TFI.emitPrologue(Fn, *SaveBlock);
// Add epilogue to restore the callee-save registers in each exiting block
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
// If last instruction is a return instruction, add an epilogue
if (!I->empty() && I->back().isReturn())
TFI.emitEpilogue(Fn, *I);
}
// Add epilogue to restore the callee-save registers in each exiting block.
for (MachineBasicBlock *RestoreBlock : RestoreBlocks)
TFI.emitEpilogue(Fn, *RestoreBlock);
// Emit additional code that is required to support segmented stacks, if
// we've been asked for it. This, when linked with a runtime with support
// for segmented stacks (libgcc is one), will result in allocating stack
// space in small chunks instead of one large contiguous block.
if (Fn.shouldSplitStack())
TFI.adjustForSegmentedStacks(Fn);
TFI.adjustForSegmentedStacks(Fn, *SaveBlock);
// Emit additional code that is required to explicitly handle the stack in
// HiPE native code (if needed) when loaded in the Erlang/OTP runtime. The
@ -743,7 +797,7 @@ void PEI::insertPrologEpilogCode(MachineFunction &Fn) {
// different conditional check and another BIF for allocating more stack
// space.
if (Fn.getFunction()->getCallingConv() == CallingConv::HiPE)
TFI.adjustForHiPEPrologue(Fn);
TFI.adjustForHiPEPrologue(Fn, *SaveBlock);
}
/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical

383
lib/CodeGen/ShrinkWrap.cpp Normal file
View File

@ -0,0 +1,383 @@
//===-- ShrinkWrap.cpp - Compute safe point for prolog/epilog insertion ---===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass looks for safe point where the prologue and epilogue can be
// inserted.
// The safe point for the prologue (resp. epilogue) is called Save
// (resp. Restore).
// A point is safe for prologue (resp. epilogue) if and only if
// it 1) dominates (resp. post-dominates) all the frame related operations and
// between 2) two executions of the Save (resp. Restore) point there is an
// execution of the Restore (resp. Save) point.
//
// For instance, the following points are safe:
// for (int i = 0; i < 10; ++i) {
// Save
// ...
// Restore
// }
// Indeed, the execution looks like Save -> Restore -> Save -> Restore ...
// And the following points are not:
// for (int i = 0; i < 10; ++i) {
// Save
// ...
// }
// for (int i = 0; i < 10; ++i) {
// ...
// Restore
// }
// Indeed, the execution looks like Save -> Save -> ... -> Restore -> Restore.
//
// This pass also ensures that the safe points are 3) cheaper than the regular
// entry and exits blocks.
//
// Property #1 is ensured via the use of MachineDominatorTree and
// MachinePostDominatorTree.
// Property #2 is ensured via property #1 and MachineLoopInfo, i.e., both
// points must be in the same loop.
// Property #3 is ensured via the MachineBlockFrequencyInfo.
//
// If this pass found points matching all this properties, then
// MachineFrameInfo is updated this that information.
//===----------------------------------------------------------------------===//
#include "llvm/ADT/Statistic.h"
// To check for profitability.
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
// For property #1 for Save.
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
// To record the result of the analysis.
#include "llvm/CodeGen/MachineFrameInfo.h"
// For property #2.
#include "llvm/CodeGen/MachineLoopInfo.h"
// For property #1 for Restore.
#include "llvm/CodeGen/MachinePostDominators.h"
#include "llvm/CodeGen/Passes.h"
// To know about callee-saved.
#include "llvm/CodeGen/RegisterClassInfo.h"
#include "llvm/Support/Debug.h"
// To know about frame setup operation.
#include "llvm/Target/TargetInstrInfo.h"
// To access TargetInstrInfo.
#include "llvm/Target/TargetSubtargetInfo.h"
#define DEBUG_TYPE "shrink-wrap"
using namespace llvm;
STATISTIC(NumFunc, "Number of functions");
STATISTIC(NumCandidates, "Number of shrink-wrapping candidates");
STATISTIC(NumCandidatesDropped,
"Number of shrink-wrapping candidates dropped because of frequency");
namespace {
/// \brief Class to determine where the safe point to insert the
/// prologue and epilogue are.
/// Unlike the paper from Fred C. Chow, PLDI'88, that introduces the
/// shrink-wrapping term for prologue/epilogue placement, this pass
/// does not rely on expensive data-flow analysis. Instead we use the
/// dominance properties and loop information to decide which point
/// are safe for such insertion.
class ShrinkWrap : public MachineFunctionPass {
/// Hold callee-saved information.
RegisterClassInfo RCI;
MachineDominatorTree *MDT;
MachinePostDominatorTree *MPDT;
/// Current safe point found for the prologue.
/// The prologue will be inserted before the first instruction
/// in this basic block.
MachineBasicBlock *Save;
/// Current safe point found for the epilogue.
/// The epilogue will be inserted before the first terminator instruction
/// in this basic block.
MachineBasicBlock *Restore;
/// Hold the information of the basic block frequency.
/// Use to check the profitability of the new points.
MachineBlockFrequencyInfo *MBFI;
/// Hold the loop information. Used to determine if Save and Restore
/// are in the same loop.
MachineLoopInfo *MLI;
/// Frequency of the Entry block.
uint64_t EntryFreq;
/// Current opcode for frame setup.
int FrameSetupOpcode;
/// Current opcode for frame destroy.
int FrameDestroyOpcode;
/// Entry block.
const MachineBasicBlock *Entry;
/// \brief Check if \p MI uses or defines a callee-saved register or
/// a frame index. If this is the case, this means \p MI must happen
/// after Save and before Restore.
bool useOrDefCSROrFI(const MachineInstr &MI) const;
/// \brief Update the Save and Restore points such that \p MBB is in
/// the region that is dominated by Save and post-dominated by Restore
/// and Save and Restore still match the safe point definition.
/// Such point may not exist and Save and/or Restore may be null after
/// this call.
void updateSaveRestorePoints(MachineBasicBlock &MBB);
/// \brief Initialize the pass for \p MF.
void init(MachineFunction &MF) {
RCI.runOnMachineFunction(MF);
MDT = &getAnalysis<MachineDominatorTree>();
MPDT = &getAnalysis<MachinePostDominatorTree>();
Save = nullptr;
Restore = nullptr;
MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
MLI = &getAnalysis<MachineLoopInfo>();
EntryFreq = MBFI->getEntryFreq();
const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
FrameSetupOpcode = TII.getCallFrameSetupOpcode();
FrameDestroyOpcode = TII.getCallFrameDestroyOpcode();
Entry = &MF.front();
++NumFunc;
}
/// Check whether or not Save and Restore points are still interesting for
/// shrink-wrapping.
bool ArePointsInteresting() const { return Save != Entry && Save && Restore; }
public:
static char ID;
ShrinkWrap() : MachineFunctionPass(ID) {
initializeShrinkWrapPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesAll();
AU.addRequired<MachineBlockFrequencyInfo>();
AU.addRequired<MachineDominatorTree>();
AU.addRequired<MachinePostDominatorTree>();
AU.addRequired<MachineLoopInfo>();
MachineFunctionPass::getAnalysisUsage(AU);
}
const char *getPassName() const override {
return "Shrink Wrapping analysis";
}
/// \brief Perform the shrink-wrapping analysis and update
/// the MachineFrameInfo attached to \p MF with the results.
bool runOnMachineFunction(MachineFunction &MF) override;
};
} // End anonymous namespace.
char ShrinkWrap::ID = 0;
char &llvm::ShrinkWrapID = ShrinkWrap::ID;
INITIALIZE_PASS_BEGIN(ShrinkWrap, "shrink-wrap", "Shrink Wrap Pass", false,
false)
INITIALIZE_PASS_DEPENDENCY(MachineBlockFrequencyInfo)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_DEPENDENCY(MachinePostDominatorTree)
INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
INITIALIZE_PASS_END(ShrinkWrap, "shrink-wrap", "Shrink Wrap Pass", false, false)
bool ShrinkWrap::useOrDefCSROrFI(const MachineInstr &MI) const {
if (MI.getOpcode() == FrameSetupOpcode ||
MI.getOpcode() == FrameDestroyOpcode) {
DEBUG(dbgs() << "Frame instruction: " << MI << '\n');
return true;
}
for (const MachineOperand &MO : MI.operands()) {
bool UseCSR = false;
if (MO.isReg()) {
unsigned PhysReg = MO.getReg();
if (!PhysReg)
continue;
assert(TargetRegisterInfo::isPhysicalRegister(PhysReg) &&
"Unallocated register?!");
UseCSR = RCI.getLastCalleeSavedAlias(PhysReg);
}
// TODO: Handle regmask more accurately.
// For now, be conservative about them.
if (UseCSR || MO.isFI() || MO.isRegMask()) {
DEBUG(dbgs() << "Use or define CSR(" << UseCSR << ") or FI(" << MO.isFI()
<< "): " << MI << '\n');
return true;
}
}
return false;
}
/// \brief Helper function to find the immediate (post) dominator.
template <typename ListOfBBs, typename DominanceAnalysis>
MachineBasicBlock *FindIDom(MachineBasicBlock &Block, ListOfBBs BBs,
DominanceAnalysis &Dom) {
MachineBasicBlock *IDom = &Block;
for (MachineBasicBlock *BB : BBs) {
IDom = Dom.findNearestCommonDominator(IDom, BB);
if (!IDom)
break;
}
return IDom;
}
void ShrinkWrap::updateSaveRestorePoints(MachineBasicBlock &MBB) {
// Get rid of the easy cases first.
if (!Save)
Save = &MBB;
else
Save = MDT->findNearestCommonDominator(Save, &MBB);
if (!Save) {
DEBUG(dbgs() << "Found a block that is not reachable from Entry\n");
return;
}
if (!Restore)
Restore = &MBB;
else
Restore = MPDT->findNearestCommonDominator(Restore, &MBB);
// Make sure we would be able to insert the restore code before the
// terminator.
if (Restore == &MBB) {
for (const MachineInstr &Terminator : MBB.terminators()) {
if (!useOrDefCSROrFI(Terminator))
continue;
// One of the terminator needs to happen before the restore point.
if (MBB.succ_empty()) {
Restore = nullptr;
break;
}
// Look for a restore point that post-dominates all the successors.
// The immediate post-dominator is what we are looking for.
Restore = FindIDom<>(*Restore, Restore->successors(), *MPDT);
break;
}
}
if (!Restore) {
DEBUG(dbgs() << "Restore point needs to be spanned on several blocks\n");
return;
}
// Make sure Save and Restore are suitable for shrink-wrapping:
// 1. all path from Save needs to lead to Restore before exiting.
// 2. all path to Restore needs to go through Save from Entry.
// We achieve that by making sure that:
// A. Save dominates Restore.
// B. Restore post-dominates Save.
// C. Save and Restore are in the same loop.
bool SaveDominatesRestore = false;
bool RestorePostDominatesSave = false;
while (Save && Restore &&
(!(SaveDominatesRestore = MDT->dominates(Save, Restore)) ||
!(RestorePostDominatesSave = MPDT->dominates(Restore, Save)) ||
MLI->getLoopFor(Save) != MLI->getLoopFor(Restore))) {
// Fix (A).
if (!SaveDominatesRestore) {
Save = MDT->findNearestCommonDominator(Save, Restore);
continue;
}
// Fix (B).
if (!RestorePostDominatesSave)
Restore = MPDT->findNearestCommonDominator(Restore, Save);
// Fix (C).
if (Save && Restore && Save != Restore &&
MLI->getLoopFor(Save) != MLI->getLoopFor(Restore)) {
if (MLI->getLoopDepth(Save) > MLI->getLoopDepth(Restore))
// Push Save outside of this loop.
Save = FindIDom<>(*Save, Save->predecessors(), *MDT);
else
// Push Restore outside of this loop.
Restore = FindIDom<>(*Restore, Restore->successors(), *MPDT);
}
}
}
bool ShrinkWrap::runOnMachineFunction(MachineFunction &MF) {
if (MF.empty())
return false;
DEBUG(dbgs() << "**** Analysing " << MF.getName() << '\n');
init(MF);
for (MachineBasicBlock &MBB : MF) {
DEBUG(dbgs() << "Look into: " << MBB.getNumber() << ' ' << MBB.getName()
<< '\n');
for (const MachineInstr &MI : MBB) {
if (!useOrDefCSROrFI(MI))
continue;
// Save (resp. restore) point must dominate (resp. post dominate)
// MI. Look for the proper basic block for those.
updateSaveRestorePoints(MBB);
// If we are at a point where we cannot improve the placement of
// save/restore instructions, just give up.
if (!ArePointsInteresting()) {
DEBUG(dbgs() << "No Shrink wrap candidate found\n");
return false;
}
// No need to look for other instructions, this basic block
// will already be part of the handled region.
break;
}
}
if (!ArePointsInteresting()) {
// If the points are not interesting at this point, then they must be null
// because it means we did not encounter any frame/CSR related code.
// Otherwise, we would have returned from the previous loop.
assert(!Save && !Restore && "We miss a shrink-wrap opportunity?!");
DEBUG(dbgs() << "Nothing to shrink-wrap\n");
return false;
}
DEBUG(dbgs() << "\n ** Results **\nFrequency of the Entry: " << EntryFreq
<< '\n');
do {
DEBUG(dbgs() << "Shrink wrap candidates (#, Name, Freq):\nSave: "
<< Save->getNumber() << ' ' << Save->getName() << ' '
<< MBFI->getBlockFreq(Save).getFrequency() << "\nRestore: "
<< Restore->getNumber() << ' ' << Restore->getName() << ' '
<< MBFI->getBlockFreq(Restore).getFrequency() << '\n');
bool IsSaveCheap;
if ((IsSaveCheap = EntryFreq >= MBFI->getBlockFreq(Save).getFrequency()) &&
EntryFreq >= MBFI->getBlockFreq(Restore).getFrequency())
break;
DEBUG(dbgs() << "New points are too expensive\n");
MachineBasicBlock *NewBB;
if (!IsSaveCheap) {
Save = FindIDom<>(*Save, Save->predecessors(), *MDT);
if (!Save)
break;
NewBB = Save;
} else {
// Restore is expensive.
Restore = FindIDom<>(*Restore, Restore->successors(), *MPDT);
if (!Restore)
break;
NewBB = Restore;
}
updateSaveRestorePoints(*NewBB);
} while (Save && Restore);
if (!ArePointsInteresting()) {
++NumCandidatesDropped;
return false;
}
DEBUG(dbgs() << "Final shrink wrap candidates:\nSave: " << Save->getNumber()
<< ' ' << Save->getName() << "\nRestore: "
<< Restore->getNumber() << ' ' << Restore->getName() << '\n');
MachineFrameInfo *MFI = MF.getFrameInfo();
MFI->setSavePoint(Save);
MFI->setRestorePoint(Restore);
++NumCandidates;
return false;
}

20
lib/Target/AArch64/AArch64FrameLowering.cpp
View File

@ -275,8 +275,8 @@ static bool isCSSave(MachineInstr *MBBI) {
MBBI->getOpcode() == AArch64::STPDpre;
}
void AArch64FrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front(); // Prologue goes in entry BB.
void AArch64FrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.begin();
const MachineFrameInfo *MFI = MF.getFrameInfo();
const Function *Fn = MF.getFunction();
@ -539,15 +539,19 @@ static bool isCSRestore(MachineInstr *MI, const MCPhysReg *CSRegs) {
void AArch64FrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
assert(MBBI->isReturn() && "Can only insert epilog into returning blocks");
MachineFrameInfo *MFI = MF.getFrameInfo();
const AArch64InstrInfo *TII =
static_cast<const AArch64InstrInfo *>(MF.getSubtarget().getInstrInfo());
const AArch64RegisterInfo *RegInfo = static_cast<const AArch64RegisterInfo *>(
MF.getSubtarget().getRegisterInfo());
DebugLoc DL = MBBI->getDebugLoc();
unsigned RetOpcode = MBBI->getOpcode();
DebugLoc DL;
bool IsTailCallReturn = false;
if (MBB.end() != MBBI) {
DL = MBBI->getDebugLoc();
unsigned RetOpcode = MBBI->getOpcode();
IsTailCallReturn = RetOpcode == AArch64::TCRETURNdi ||
RetOpcode == AArch64::TCRETURNri;
}
int NumBytes = MFI->getStackSize();
const AArch64FunctionInfo *AFI = MF.getInfo<AArch64FunctionInfo>();
@ -559,7 +563,7 @@ void AArch64FrameLowering::emitEpilogue(MachineFunction &MF,
// Initial and residual are named for consistency with the prologue. Note that
// in the epilogue, the residual adjustment is executed first.
uint64_t ArgumentPopSize = 0;
if (RetOpcode == AArch64::TCRETURNdi || RetOpcode == AArch64::TCRETURNri) {
if (IsTailCallReturn) {
MachineOperand &StackAdjust = MBBI->getOperand(1);
// For a tail-call in a callee-pops-arguments environment, some or all of
@ -604,7 +608,7 @@ void AArch64FrameLowering::emitEpilogue(MachineFunction &MF,
unsigned NumRestores = 0;
// Move past the restores of the callee-saved registers.
MachineBasicBlock::iterator LastPopI = MBBI;
MachineBasicBlock::iterator LastPopI = MBB.getFirstTerminator();
const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&MF);
if (LastPopI != MBB.begin()) {
do {

2
lib/Target/AArch64/AArch64FrameLowering.h
View File

@ -34,7 +34,7 @@ public:
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
int getFrameIndexOffset(const MachineFunction &MF, int FI) const override;

16
lib/Target/ARM/ARMFrameLowering.cpp
View File

@ -278,8 +278,9 @@ static void emitAligningInstructions(MachineFunction &MF, ARMFunctionInfo *AFI,
}
}
void ARMFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
void ARMFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MBB == &MF.front() && "Shrink-wrapping not yet implemented");
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
@ -1861,7 +1862,8 @@ static const uint64_t kSplitStackAvailable = 256;
// ARM can be found at [1].
//
// [1] - https://github.com/mozilla/rust/blob/86efd9/src/rt/arch/arm/morestack.S
void ARMFrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const {
void ARMFrameLowering::adjustForSegmentedStacks(
MachineFunction &MF, MachineBasicBlock &PrologueMBB) const {
unsigned Opcode;
unsigned CFIIndex;
const ARMSubtarget *ST = &MF.getSubtarget<ARMSubtarget>();
@ -1874,7 +1876,7 @@ void ARMFrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const {
if (!ST->isTargetAndroid() && !ST->isTargetLinux())
report_fatal_error("Segmented stacks not supported on this platform.");
MachineBasicBlock &prologueMBB = MF.front();
assert(&PrologueMBB == &MF.front() && "Shrink-wrapping not yet implemented");
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineModuleInfo &MMI = MF.getMMI();
MCContext &Context = MMI.getContext();
@ -1902,8 +1904,8 @@ void ARMFrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const {
MachineBasicBlock *GetMBB = MF.CreateMachineBasicBlock();
MachineBasicBlock *McrMBB = MF.CreateMachineBasicBlock();
for (MachineBasicBlock::livein_iterator i = prologueMBB.livein_begin(),
e = prologueMBB.livein_end();
for (MachineBasicBlock::livein_iterator i = PrologueMBB.livein_begin(),
e = PrologueMBB.livein_end();
i != e; ++i) {
AllocMBB->addLiveIn(*i);
GetMBB->addLiveIn(*i);
@ -2156,7 +2158,7 @@ void ARMFrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const {
.addCFIIndex(CFIIndex);
// Organizing MBB lists
PostStackMBB->addSuccessor(&prologueMBB);
PostStackMBB->addSuccessor(&PrologueMBB);
AllocMBB->addSuccessor(PostStackMBB);

5
lib/Target/ARM/ARMFrameLowering.h
View File

@ -28,7 +28,7 @@ public:
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void fixTCReturn(MachineFunction &MF, MachineBasicBlock &MBB) const;
@ -55,7 +55,8 @@ public:
void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS) const override;
void adjustForSegmentedStacks(MachineFunction &MF) const override;
void adjustForSegmentedStacks(MachineFunction &MF,
MachineBasicBlock &MBB) const override;
private:
void emitPushInst(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,

5
lib/Target/ARM/Thumb1FrameLowering.cpp
View File

@ -82,8 +82,9 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MBB.erase(I);
}
void Thumb1FrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
void Thumb1FrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MBB == &MF.front() && "Shrink-wrapping not yet implemented");
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();

2
lib/Target/ARM/Thumb1FrameLowering.h
View File

@ -27,7 +27,7 @@ public:
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,

3
lib/Target/BPF/BPFFrameLowering.cpp
View File

@ -23,7 +23,8 @@ using namespace llvm;
bool BPFFrameLowering::hasFP(const MachineFunction &MF) const { return true; }
void BPFFrameLowering::emitPrologue(MachineFunction &MF) const {}
void BPFFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {}
void BPFFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {}

2
lib/Target/BPF/BPFFrameLowering.h
View File

@ -24,7 +24,7 @@ public:
explicit BPFFrameLowering(const BPFSubtarget &sti)
: TargetFrameLowering(TargetFrameLowering::StackGrowsDown, 8, 0) {}
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
bool hasFP(const MachineFunction &MF) const override;

5
lib/Target/Hexagon/HexagonFrameLowering.cpp
View File

@ -344,16 +344,17 @@ void HexagonFrameLowering::findShrunkPrologEpilog(MachineFunction &MF,
EpilogB = PDomB;
}
/// Perform most of the PEI work here:
/// - saving/restoring of the callee-saved registers,
/// - stack frame creation and destruction.
/// Normally, this work is distributed among various functions, but doing it
/// in one place allows shrink-wrapping of the stack frame.
void HexagonFrameLowering::emitPrologue(MachineFunction &MF) const {
void HexagonFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
auto &HST = static_cast<const HexagonSubtarget&>(MF.getSubtarget());
auto &HRI = *HST.getRegisterInfo();
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo *MFI = MF.getFrameInfo();
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();

3
lib/Target/Hexagon/HexagonFrameLowering.h
View File

@ -26,7 +26,8 @@ public:
// All of the prolog/epilog functionality, including saving and restoring
// callee-saved registers is handled in emitPrologue. This is to have the
// logic for shrink-wrapping in one place.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const
override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const
override {}
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,

5
lib/Target/MSP430/MSP430FrameLowering.cpp
View File

@ -39,8 +39,9 @@ bool MSP430FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const
return !MF.getFrameInfo()->hasVarSizedObjects();
}
void MSP430FrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
void MSP430FrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo *MFI = MF.getFrameInfo();
MSP430MachineFunctionInfo *MSP430FI = MF.getInfo<MSP430MachineFunctionInfo>();
const MSP430InstrInfo &TII =

2
lib/Target/MSP430/MSP430FrameLowering.h
View File

@ -27,7 +27,7 @@ public:
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void eliminateCallFramePseudoInstr(MachineFunction &MF,

5
lib/Target/Mips/Mips16FrameLowering.cpp
View File

@ -32,8 +32,9 @@ using namespace llvm;
Mips16FrameLowering::Mips16FrameLowering(const MipsSubtarget &STI)
: MipsFrameLowering(STI, STI.stackAlignment()) {}
void Mips16FrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
void Mips16FrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo *MFI = MF.getFrameInfo();
const Mips16InstrInfo &TII =
*static_cast<const Mips16InstrInfo *>(STI.getInstrInfo());

2
lib/Target/Mips/Mips16FrameLowering.h
View File

@ -23,7 +23,7 @@ public:
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,

5
lib/Target/Mips/MipsSEFrameLowering.cpp
View File

@ -364,8 +364,9 @@ bool ExpandPseudo::expandExtractElementF64(MachineBasicBlock &MBB,
MipsSEFrameLowering::MipsSEFrameLowering(const MipsSubtarget &STI)
: MipsFrameLowering(STI, STI.stackAlignment()) {}
void MipsSEFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
void MipsSEFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo *MFI = MF.getFrameInfo();
MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();

2
lib/Target/Mips/MipsSEFrameLowering.h
View File

@ -24,7 +24,7 @@ public:
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,

5
lib/Target/NVPTX/NVPTXFrameLowering.cpp
View File

@ -31,9 +31,10 @@ NVPTXFrameLowering::NVPTXFrameLowering()
bool NVPTXFrameLowering::hasFP(const MachineFunction &MF) const { return true; }
void NVPTXFrameLowering::emitPrologue(MachineFunction &MF) const {
void NVPTXFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
if (MF.getFrameInfo()->hasStackObjects()) {
MachineBasicBlock &MBB = MF.front();
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
// Insert "mov.u32 %SP, %Depot"
MachineBasicBlock::iterator MBBI = MBB.begin();
// This instruction really occurs before first instruction

2
lib/Target/NVPTX/NVPTXFrameLowering.h
View File

@ -23,7 +23,7 @@ public:
explicit NVPTXFrameLowering();
bool hasFP(const MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void

2
lib/Target/NVPTX/NVPTXPrologEpilogPass.cpp
View File

@ -68,7 +68,7 @@ bool NVPTXPrologEpilogPass::runOnMachineFunction(MachineFunction &MF) {
}
// Add function prolog/epilog
TFI.emitPrologue(MF);
TFI.emitPrologue(MF, MF.front());
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
// If last instruction is a return instruction, add an epilogue

5
lib/Target/PowerPC/PPCFrameLowering.cpp
View File

@ -555,8 +555,9 @@ void PPCFrameLowering::replaceFPWithRealFP(MachineFunction &MF) const {
}
}
void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
void PPCFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
const PPCInstrInfo &TII =

2
lib/Target/PowerPC/PPCFrameLowering.h
View File

@ -38,7 +38,7 @@ public:
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
bool hasFP(const MachineFunction &MF) const override;

5
lib/Target/R600/AMDGPUFrameLowering.cpp
View File

@ -99,9 +99,8 @@ AMDGPUFrameLowering::getCalleeSavedSpillSlots(unsigned &NumEntries) const {
NumEntries = 0;
return nullptr;
}
void
AMDGPUFrameLowering::emitPrologue(MachineFunction &MF) const {
}
void AMDGPUFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {}
void
AMDGPUFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {

2
lib/Target/R600/AMDGPUFrameLowering.h
View File

@ -37,7 +37,7 @@ public:
int getFrameIndexOffset(const MachineFunction &MF, int FI) const override;
const SpillSlot *
getCalleeSavedSpillSlots(unsigned &NumEntries) const override;
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
bool hasFP(const MachineFunction &MF) const override;
};

5
lib/Target/Sparc/SparcFrameLowering.cpp
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@ -82,10 +82,11 @@ void SparcFrameLowering::emitSPAdjustment(MachineFunction &MF,
.addReg(SP::O6).addReg(SP::G1);
}
void SparcFrameLowering::emitPrologue(MachineFunction &MF) const {
void SparcFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
SparcMachineFunctionInfo *FuncInfo = MF.getInfo<SparcMachineFunctionInfo>();
MachineBasicBlock &MBB = MF.front();
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo *MFI = MF.getFrameInfo();
const SparcInstrInfo &TII =
*static_cast<const SparcInstrInfo *>(MF.getSubtarget().getInstrInfo());

2
lib/Target/Sparc/SparcFrameLowering.h
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@ -26,7 +26,7 @@ public:
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void

5
lib/Target/SystemZ/SystemZFrameLowering.cpp
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@ -309,8 +309,9 @@ static void emitIncrement(MachineBasicBlock &MBB,
}
}
void SystemZFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front();
void SystemZFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineFrameInfo *MFFrame = MF.getFrameInfo();
auto *ZII =
static_cast<const SystemZInstrInfo *>(MF.getSubtarget().getInstrInfo());

2
lib/Target/SystemZ/SystemZFrameLowering.h
View File

@ -40,7 +40,7 @@ public:
override;
void processFunctionBeforeFrameFinalized(MachineFunction &MF,
RegScavenger *RS) const override;
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
bool hasFP(const MachineFunction &MF) const override;
int getFrameIndexOffset(const MachineFunction &MF, int FI) const override;

40
lib/Target/X86/X86FrameLowering.cpp
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@ -565,8 +565,9 @@ static uint64_t calculateMaxStackAlign(const MachineFunction &MF) {
- for 32-bit code, substitute %e?? registers for %r??
*/
void X86FrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front(); // Prologue goes in entry BB.
void X86FrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
const Function *Fn = MF.getFunction();
@ -1590,9 +1591,10 @@ GetScratchRegister(bool Is64Bit, bool IsLP64, const MachineFunction &MF, bool Pr
// limit.
static const uint64_t kSplitStackAvailable = 256;
void
X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const {
MachineBasicBlock &prologueMBB = MF.front();
void X86FrameLowering::adjustForSegmentedStacks(
MachineFunction &MF, MachineBasicBlock &PrologueMBB) const {
assert(&PrologueMBB == &MF.front() &&
"Shrink-wrapping is not implemented yet");
MachineFrameInfo *MFI = MF.getFrameInfo();
const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
const TargetInstrInfo &TII = *STI.getInstrInfo();
@ -1634,8 +1636,9 @@ X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const {
// The MOV R10, RAX needs to be in a different block, since the RET we emit in
// allocMBB needs to be last (terminating) instruction.
for (MachineBasicBlock::livein_iterator i = prologueMBB.livein_begin(),
e = prologueMBB.livein_end(); i != e; i++) {
for (MachineBasicBlock::livein_iterator i = PrologueMBB.livein_begin(),
e = PrologueMBB.livein_end();
i != e; i++) {
allocMBB->addLiveIn(*i);
checkMBB->addLiveIn(*i);
}
@ -1749,7 +1752,7 @@ X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const {
// This jump is taken if SP >= (Stacklet Limit + Stack Space required).
// It jumps to normal execution of the function body.
BuildMI(checkMBB, DL, TII.get(X86::JA_1)).addMBB(&prologueMBB);
BuildMI(checkMBB, DL, TII.get(X86::JA_1)).addMBB(&PrologueMBB);
// On 32 bit we first push the arguments size and then the frame size. On 64
// bit, we pass the stack frame size in r10 and the argument size in r11.
@ -1816,10 +1819,10 @@ X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const {
else
BuildMI(allocMBB, DL, TII.get(X86::MORESTACK_RET));
allocMBB->addSuccessor(&prologueMBB);
allocMBB->addSuccessor(&PrologueMBB);
checkMBB->addSuccessor(allocMBB);
checkMBB->addSuccessor(&prologueMBB);
checkMBB->addSuccessor(&PrologueMBB);
#ifdef XDEBUG
MF.verify();
@ -1841,7 +1844,8 @@ X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const {
/// call inc_stack # doubles the stack space
/// temp0 = sp - MaxStack
/// if( temp0 < SP_LIMIT(P) ) goto IncStack else goto OldStart
void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const {
void X86FrameLowering::adjustForHiPEPrologue(
MachineFunction &MF, MachineBasicBlock &PrologueMBB) const {
const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
const TargetInstrInfo &TII = *STI.getInstrInfo();
MachineFrameInfo *MFI = MF.getFrameInfo();
@ -1910,12 +1914,14 @@ void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const {
// If the stack frame needed is larger than the guaranteed then runtime checks
// and calls to "inc_stack_0" BIF should be inserted in the assembly prologue.
if (MaxStack > Guaranteed) {
MachineBasicBlock &prologueMBB = MF.front();
assert(&PrologueMBB == &MF.front() &&
"Shrink-wrapping is not implemented yet");
MachineBasicBlock *stackCheckMBB = MF.CreateMachineBasicBlock();
MachineBasicBlock *incStackMBB = MF.CreateMachineBasicBlock();
for (MachineBasicBlock::livein_iterator I = prologueMBB.livein_begin(),
E = prologueMBB.livein_end(); I != E; I++) {
for (MachineBasicBlock::livein_iterator I = PrologueMBB.livein_begin(),
E = PrologueMBB.livein_end();
I != E; I++) {
stackCheckMBB->addLiveIn(*I);
incStackMBB->addLiveIn(*I);
}
@ -1951,7 +1957,7 @@ void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const {
// SPLimitOffset is in a fixed heap location (pointed by BP).
addRegOffset(BuildMI(stackCheckMBB, DL, TII.get(CMPop))
.addReg(ScratchReg), PReg, false, SPLimitOffset);
BuildMI(stackCheckMBB, DL, TII.get(X86::JAE_1)).addMBB(&prologueMBB);
BuildMI(stackCheckMBB, DL, TII.get(X86::JAE_1)).addMBB(&PrologueMBB);
// Create new MBB for IncStack:
BuildMI(incStackMBB, DL, TII.get(CALLop)).
@ -1962,9 +1968,9 @@ void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const {
.addReg(ScratchReg), PReg, false, SPLimitOffset);
BuildMI(incStackMBB, DL, TII.get(X86::JLE_1)).addMBB(incStackMBB);
stackCheckMBB->addSuccessor(&prologueMBB, 99);
stackCheckMBB->addSuccessor(&PrologueMBB, 99);
stackCheckMBB->addSuccessor(incStackMBB, 1);
incStackMBB->addSuccessor(&prologueMBB, 99);
incStackMBB->addSuccessor(&PrologueMBB, 99);
incStackMBB->addSuccessor(incStackMBB, 1);
}
#ifdef XDEBUG

8
lib/Target/X86/X86FrameLowering.h
View File

@ -35,12 +35,14 @@ public:
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
void adjustForSegmentedStacks(MachineFunction &MF) const override;
void adjustForSegmentedStacks(MachineFunction &MF,
MachineBasicBlock &PrologueMBB) const override;
void adjustForHiPEPrologue(MachineFunction &MF) const override;
void adjustForHiPEPrologue(MachineFunction &MF,
MachineBasicBlock &PrologueMBB) const override;
void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS = nullptr) const override;

5
lib/Target/XCore/XCoreFrameLowering.cpp
View File

@ -220,8 +220,9 @@ bool XCoreFrameLowering::hasFP(const MachineFunction &MF) const {
MF.getFrameInfo()->hasVarSizedObjects();
}
void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
void XCoreFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineModuleInfo *MMI = &MF.getMMI();

3
lib/Target/XCore/XCoreFrameLowering.h
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@ -27,7 +27,8 @@ namespace llvm {
/// emitProlog/emitEpilog - These methods insert prolog and epilog code into
/// the function.
void emitPrologue(MachineFunction &MF) const override;
void emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const override;
void emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const override;

502
test/CodeGen/AArch64/arm64-shrink-wrapping.ll Normal file
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@ -0,0 +1,502 @@
; RUN: llc %s -o - -enable-shrink-wrap=true | FileCheck %s --check-prefix=CHECK --check-prefix=ENABLE
; RUN: llc %s -o - -enable-shrink-wrap=false | FileCheck %s --check-prefix=CHECK --check-prefix=DISABLE
target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128"
target triple = "arm64-apple-ios"
; Initial motivating example: Simple diamond with a call just on one side.
; CHECK-LABEL: foo:
;
; Compare the arguments and jump to exit.
; No prologue needed.
; ENABLE: cmp w0, w1
; ENABLE-NEXT: b.ge [[EXIT_LABEL:LBB[0-9_]+]]
;
; Prologue code.
; CHECK: stp [[SAVE_SP:x[0-9]+]], [[CSR:x[0-9]+]], [sp, #-16]!
; CHECK-NEXT: mov [[SAVE_SP]], sp
; CHECK-NEXT: sub sp, sp, #16
;
; Compare the arguments and jump to exit.
; After the prologue is set.
; DISABLE: cmp w0, w1
; DISABLE-NEXT: b.ge [[EXIT_LABEL:LBB[0-9_]+]]
;
; Store %a in the alloca.
; CHECK: stur w0, {{\[}}[[SAVE_SP]], #-4]
; Set the alloca address in the second argument.
; CHECK-NEXT: sub x1, [[SAVE_SP]], #4
; Set the first argument to zero.
; CHECK-NEXT: mov w0, wzr
; CHECK-NEXT: bl _doSomething
;
; Without shrink-wrapping, epilogue is in the exit block.
; DISABLE: [[EXIT_LABEL]]:
; Epilogue code.
; CHECK-NEXT: mov sp, [[SAVE_SP]]
; CHECK-NEXT: ldp [[SAVE_SP]], [[CSR]], [sp], #16
;
; With shrink-wrapping, exit block is a simple return.
; ENABLE: [[EXIT_LABEL]]:
; CHECK-NEXT: ret
define i32 @foo(i32 %a, i32 %b) {
%tmp = alloca i32, align 4
%tmp2 = icmp slt i32 %a, %b
br i1 %tmp2, label %true, label %false
true:
store i32 %a, i32* %tmp, align 4
%tmp4 = call i32 @doSomething(i32 0, i32* %tmp)
br label %false
false:
%tmp.0 = phi i32 [ %tmp4, %true ], [ %a, %0 ]
ret i32 %tmp.0
}
; Function Attrs: optsize
declare i32 @doSomething(i32, i32*)
; Check that we do not perform the restore inside the loop whereas the save
; is outside.
; CHECK-LABEL: freqSaveAndRestoreOutsideLoop:
;
; Shrink-wrapping allows to skip the prologue in the else case.
; ENABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; Prologue code.
; CHECK: stp [[CSR1:x[0-9]+]], [[CSR2:x[0-9]+]], [sp, #-32]!
; CHECK-NEXT: stp [[CSR3:x[0-9]+]], [[CSR4:x[0-9]+]], [sp, #16]
; CHECK-NEXT: add [[NEW_SP:x[0-9]+]], sp, #16
;
; DISABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; CHECK: mov [[SUM:w[0-9]+]], wzr
; CHECK-NEXT: movz [[IV:w[0-9]+]], #0xa
;
; Next BB.
; CHECK: [[LOOP:LBB[0-9_]+]]: ; %for.body
; CHECK: bl _something
; CHECK-NEXT: add [[SUM]], w0, [[SUM]]
; CHECK-NEXT: sub [[IV]], [[IV]], #1
; CHECK-NEXT: cbnz [[IV]], [[LOOP]]
;
; Next BB.
; Copy SUM into the returned register + << 3.
; CHECK: lsl w0, [[SUM]], #3
;
; Jump to epilogue.
; DISABLE: b [[EPILOG_BB:LBB[0-9_]+]]
;
; DISABLE: [[ELSE_LABEL]]: ; %if.else
; Shift second argument by one and store into returned register.
; DISABLE: lsl w0, w1, #1
; DISABLE: [[EPILOG_BB]]: ; %if.end
;
; Epilogue code.
; CHECK: ldp [[CSR3]], [[CSR4]], [sp, #16]
; CHECK-NEXT: ldp [[CSR1]], [[CSR2]], [sp], #32
; CHECK-NEXT: ret
;
; ENABLE: [[ELSE_LABEL]]: ; %if.else
; Shift second argument by one and store into returned register.
; ENABLE: lsl w0, w1, #1
; ENABLE: ret
define i32 @freqSaveAndRestoreOutsideLoop(i32 %cond, i32 %N) {
entry:
%tobool = icmp eq i32 %cond, 0
br i1 %tobool, label %if.else, label %for.body
for.body: ; preds = %entry, %for.body
%i.05 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
%sum.04 = phi i32 [ %add, %for.body ], [ 0, %entry ]
%call = tail call i32 bitcast (i32 (...)* @something to i32 ()*)()
%add = add nsw i32 %call, %sum.04
%inc = add nuw nsw i32 %i.05, 1
%exitcond = icmp eq i32 %inc, 10
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
%shl = shl i32 %add, 3
br label %if.end
if.else: ; preds = %entry
%mul = shl nsw i32 %N, 1
br label %if.end
if.end: ; preds = %if.else, %for.end
%sum.1 = phi i32 [ %shl, %for.end ], [ %mul, %if.else ]
ret i32 %sum.1
}
declare i32 @something(...)
; Check that we do not perform the shrink-wrapping inside the loop even
; though that would be legal. The cost model must prevent that.
; CHECK-LABEL: freqSaveAndRestoreOutsideLoop2:
; Prologue code.
; CHECK: stp [[CSR1:x[0-9]+]], [[CSR2:x[0-9]+]], [sp, #-32]!
; CHECK-NEXT: stp [[CSR3:x[0-9]+]], [[CSR4:x[0-9]+]], [sp, #16]
; CHECK-NEXT: add [[NEW_SP:x[0-9]+]], sp, #16
; CHECK: mov [[SUM:w[0-9]+]], wzr
; CHECK-NEXT: movz [[IV:w[0-9]+]], #0xa
; Next BB.
; CHECK: [[LOOP_LABEL:LBB[0-9_]+]]: ; %for.body
; CHECK: bl _something
; CHECK-NEXT: add [[SUM]], w0, [[SUM]]
; CHECK-NEXT: sub [[IV]], [[IV]], #1
; CHECK-NEXT: cbnz [[IV]], [[LOOP_LABEL]]
; Next BB.
; CHECK: ; %for.end
; CHECK: mov w0, [[SUM]]
; CHECK-NEXT: ldp [[CSR3]], [[CSR4]], [sp, #16]
; CHECK-NEXT: ldp [[CSR1]], [[CSR2]], [sp], #32
; CHECK-NEXT: ret
define i32 @freqSaveAndRestoreOutsideLoop2(i32 %cond) {
entry:
br label %for.body
for.body: ; preds = %for.body, %entry
%i.04 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
%sum.03 = phi i32 [ 0, %entry ], [ %add, %for.body ]
%call = tail call i32 bitcast (i32 (...)* @something to i32 ()*)()
%add = add nsw i32 %call, %sum.03
%inc = add nuw nsw i32 %i.04, 1
%exitcond = icmp eq i32 %inc, 10
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
ret i32 %add
}
; Check with a more complex case that we do not have save within the loop and
; restore outside.
; CHECK-LABEL: loopInfoSaveOutsideLoop:
;
; ENABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; Prologue code.
; CHECK: stp [[CSR1:x[0-9]+]], [[CSR2:x[0-9]+]], [sp, #-32]!
; CHECK-NEXT: stp [[CSR3:x[0-9]+]], [[CSR4:x[0-9]+]], [sp, #16]
; CHECK-NEXT: add [[NEW_SP:x[0-9]+]], sp, #16
;
; DISABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; CHECK: mov [[SUM:w[0-9]+]], wzr
; CHECK-NEXT: movz [[IV:w[0-9]+]], #0xa
;
; CHECK: [[LOOP_LABEL:LBB[0-9_]+]]: ; %for.body
; CHECK: bl _something
; CHECK-NEXT: add [[SUM]], w0, [[SUM]]
; CHECK-NEXT: sub [[IV]], [[IV]], #1
; CHECK-NEXT: cbnz [[IV]], [[LOOP_LABEL]]
; Next BB.
; CHECK: bl _somethingElse
; CHECK-NEXT: lsl w0, [[SUM]], #3
;
; Jump to epilogue.
; DISABLE: b [[EPILOG_BB:LBB[0-9_]+]]
;
; DISABLE: [[ELSE_LABEL]]: ; %if.else
; Shift second argument by one and store into returned register.
; DISABLE: lsl w0, w1, #1
; DISABLE: [[EPILOG_BB]]: ; %if.end
; Epilogue code.
; CHECK-NEXT: ldp [[CSR3]], [[CSR4]], [sp, #16]
; CHECK-NEXT: ldp [[CSR1]], [[CSR2]], [sp], #32
; CHECK-NEXT: ret
;
; ENABLE: [[ELSE_LABEL]]: ; %if.else
; Shift second argument by one and store into returned register.
; ENABLE: lsl w0, w1, #1
; ENABLE: ret
define i32 @loopInfoSaveOutsideLoop(i32 %cond, i32 %N) {
entry:
%tobool = icmp eq i32 %cond, 0
br i1 %tobool, label %if.else, label %for.body
for.body: ; preds = %entry, %for.body
%i.05 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
%sum.04 = phi i32 [ %add, %for.body ], [ 0, %entry ]
%call = tail call i32 bitcast (i32 (...)* @something to i32 ()*)()
%add = add nsw i32 %call, %sum.04
%inc = add nuw nsw i32 %i.05, 1
%exitcond = icmp eq i32 %inc, 10
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
tail call void bitcast (void (...)* @somethingElse to void ()*)()
%shl = shl i32 %add, 3
br label %if.end
if.else: ; preds = %entry
%mul = shl nsw i32 %N, 1
br label %if.end
if.end: ; preds = %if.else, %for.end
%sum.1 = phi i32 [ %shl, %for.end ], [ %mul, %if.else ]
ret i32 %sum.1
}
declare void @somethingElse(...)
; Check with a more complex case that we do not have restore within the loop and
; save outside.
; CHECK-LABEL: loopInfoRestoreOutsideLoop:
;
; ENABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; CHECK: stp [[CSR1:x[0-9]+]], [[CSR2:x[0-9]+]], [sp, #-32]!
; CHECK-NEXT: stp [[CSR3:x[0-9]+]], [[CSR4:x[0-9]+]], [sp, #16]
; CHECK-NEXT: add [[NEW_SP:x[0-9]+]], sp, #16
;
; DISABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; CHECK: bl _somethingElse
; CHECK-NEXT: mov [[SUM:w[0-9]+]], wzr
; CHECK-NEXT: movz [[IV:w[0-9]+]], #0xa
;
; CHECK: [[LOOP_LABEL:LBB[0-9_]+]]: ; %for.body
; CHECK: bl _something
; CHECK-NEXT: add [[SUM]], w0, [[SUM]]
; CHECK-NEXT: sub [[IV]], [[IV]], #1
; CHECK-NEXT: cbnz [[IV]], [[LOOP_LABEL]]
; Next BB.
; CHECK: lsl w0, [[SUM]], #3
;
; Jump to epilogue.
; DISABLE: b [[EPILOG_BB:LBB[0-9_]+]]
;
; DISABLE: [[ELSE_LABEL]]: ; %if.else
; Shift second argument by one and store into returned register.
; DISABLE: lsl w0, w1, #1
; DISABLE: [[EPILOG_BB]]: ; %if.end
; Epilogue code.
; CHECK: ldp [[CSR3]], [[CSR4]], [sp, #16]
; CHECK-NEXT: ldp [[CSR1]], [[CSR2]], [sp], #32
; CHECK-NEXT: ret
;
; ENABLE: [[ELSE_LABEL]]: ; %if.else
; Shift second argument by one and store into returned register.
; ENABLE: lsl w0, w1, #1
; ENABLE: ret
define i32 @loopInfoRestoreOutsideLoop(i32 %cond, i32 %N) #0 {
entry:
%tobool = icmp eq i32 %cond, 0
br i1 %tobool, label %if.else, label %if.then
if.then: ; preds = %entry
tail call void bitcast (void (...)* @somethingElse to void ()*)()
br label %for.body
for.body: ; preds = %for.body, %if.then
%i.05 = phi i32 [ 0, %if.then ], [ %inc, %for.body ]
%sum.04 = phi i32 [ 0, %if.then ], [ %add, %for.body ]
%call = tail call i32 bitcast (i32 (...)* @something to i32 ()*)()
%add = add nsw i32 %call, %sum.04
%inc = add nuw nsw i32 %i.05, 1
%exitcond = icmp eq i32 %inc, 10
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body
%shl = shl i32 %add, 3
br label %if.end
if.else: ; preds = %entry
%mul = shl nsw i32 %N, 1
br label %if.end
if.end: ; preds = %if.else, %for.end
%sum.1 = phi i32 [ %shl, %for.end ], [ %mul, %if.else ]
ret i32 %sum.1
}
; Check that we handle function with no frame information correctly.
; CHECK-LABEL: emptyFrame:
; CHECK: ; %entry
; CHECK-NEXT: mov w0, wzr
; CHECK-NEXT: ret
define i32 @emptyFrame() {
entry:
ret i32 0
}
; Check that we handle variadic function correctly.
; CHECK-LABEL: variadicFunc:
;
; ENABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; Prologue code.
; CHECK: sub sp, sp, #16
; DISABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; Sum is merged with the returned register.
; CHECK: mov [[SUM:w0]], wzr
; CHECK-NEXT: add [[VA_BASE:x[0-9]+]], sp, #16
; CHECK-NEXT: str [[VA_BASE]], [sp, #8]
; CHECK-NEXT: cmp w1, #1
; CHECK-NEXT: b.lt [[IFEND_LABEL:LBB[0-9_]+]]
;
; CHECK: [[LOOP_LABEL:LBB[0-9_]+]]: ; %for.body
; CHECK: ldr [[VA_ADDR:x[0-9]+]], [sp, #8]
; CHECK-NEXT: add [[NEXT_VA_ADDR:x[0-9]+]], [[VA_ADDR]], #8
; CHECK-NEXT: str [[NEXT_VA_ADDR]], [sp, #8]
; CHECK-NEXT: ldr [[VA_VAL:w[0-9]+]], {{\[}}[[VA_ADDR]]]
; CHECK-NEXT: add [[SUM]], [[SUM]], [[VA_VAL]]
; CHECK-NEXT: sub w1, w1, #1
; CHECK-NEXT: cbnz w1, [[LOOP_LABEL]]
;
; DISABLE-NEXT: b [[IFEND_LABEL]]
; DISABLE: [[ELSE_LABEL]]: ; %if.else
; DISABLE: lsl w0, w1, #1
;
; CHECK: [[IFEND_LABEL]]:
; Epilogue code.
; CHECK: add sp, sp, #16
; CHECK-NEXT: ret
;
; ENABLE: [[ELSE_LABEL]]: ; %if.else
; ENABLE: lsl w0, w1, #1
; ENABLE-NEXT: ret
define i32 @variadicFunc(i32 %cond, i32 %count, ...) #0 {
entry:
%ap = alloca i8*, align 8
%tobool = icmp eq i32 %cond, 0
br i1 %tobool, label %if.else, label %if.then
if.then: ; preds = %entry
%ap1 = bitcast i8** %ap to i8*
call void @llvm.va_start(i8* %ap1)
%cmp6 = icmp sgt i32 %count, 0
br i1 %cmp6, label %for.body, label %for.end
for.body: ; preds = %if.then, %for.body
%i.08 = phi i32 [ %inc, %for.body ], [ 0, %if.then ]
%sum.07 = phi i32 [ %add, %for.body ], [ 0, %if.then ]
%0 = va_arg i8** %ap, i32
%add = add nsw i32 %sum.07, %0
%inc = add nuw nsw i32 %i.08, 1
%exitcond = icmp eq i32 %inc, %count
br i1 %exitcond, label %for.end, label %for.body
for.end: ; preds = %for.body, %if.then
%sum.0.lcssa = phi i32 [ 0, %if.then ], [ %add, %for.body ]
call void @llvm.va_end(i8* %ap1)
br label %if.end
if.else: ; preds = %entry
%mul = shl nsw i32 %count, 1
br label %if.end
if.end: ; preds = %if.else, %for.end
%sum.1 = phi i32 [ %sum.0.lcssa, %for.end ], [ %mul, %if.else ]
ret i32 %sum.1
}
declare void @llvm.va_start(i8*)
declare void @llvm.va_end(i8*)
; Check that we handle inline asm correctly.
; CHECK-LABEL: inlineAsm:
;
; ENABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; Prologue code.
; Make sure we save the CSR used in the inline asm: x19.
; CHECK: stp [[CSR1:x[0-9]+]], [[CSR2:x19]], [sp, #-16]!
;
; DISABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; CHECK: movz [[IV:w[0-9]+]], #0xa
;
; CHECK: [[LOOP_LABEL:LBB[0-9_]+]]: ; %for.body
; Inline asm statement.
; CHECK: add x19, x19, #1
; CHECK: sub [[IV]], [[IV]], #1
; CHECK-NEXT: cbnz [[IV]], [[LOOP_LABEL]]
; Next BB.
; CHECK: mov w0, wzr
; Epilogue code.
; CHECK-NEXT: ldp [[CSR1]], [[CSR2]], [sp], #16
; CHECK-NEXT: ret
; Next BB.
; CHECK: [[ELSE_LABEL]]: ; %if.else
; CHECK-NEXT: lsl w0, w1, #1
; Epilogue code.
; DISABLE-NEXT: ldp [[CSR1]], [[CSR2]], [sp], #16
; CHECK-NEXT: ret
define i32 @inlineAsm(i32 %cond, i32 %N) {
entry:
%tobool = icmp eq i32 %cond, 0
br i1 %tobool, label %if.else, label %for.body
for.body: ; preds = %entry, %for.body
%i.03 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
tail call void asm sideeffect "add x19, x19, #1", "~{x19}"()
%inc = add nuw nsw i32 %i.03, 1
%exitcond = icmp eq i32 %inc, 10
br i1 %exitcond, label %if.end, label %for.body
if.else: ; preds = %entry
%mul = shl nsw i32 %N, 1
br label %if.end
if.end: ; preds = %for.body, %if.else
%sum.0 = phi i32 [ %mul, %if.else ], [ 0, %for.body ]
ret i32 %sum.0
}
; Check that we handle calls to variadic functions correctly.
; CHECK-LABEL: callVariadicFunc:
;
; ENABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
;
; Prologue code.
; CHECK: stp [[CSR1:x[0-9]+]], [[CSR2:x[0-9]+]], [sp, #-16]!
; CHECK-NEXT: mov [[NEW_SP:x[0-9]+]], sp
; CHECK-NEXT: sub sp, sp, #48
;
; DISABLE: cbz w0, [[ELSE_LABEL:LBB[0-9_]+]]
; Setup of the varags.
; CHECK: stp x1, x1, [sp, #32]
; CHECK-NEXT: stp x1, x1, [sp, #16]
; CHECK-NEXT: stp x1, x1, [sp]
; CHECK-NEXT: mov w0, w1
; CHECK-NEXT: bl _someVariadicFunc
; CHECK-NEXT: lsl w0, w0, #3
;
; DISABLE: b [[IFEND_LABEL:LBB[0-9_]+]]
; DISABLE: [[ELSE_LABEL]]: ; %if.else
; DISABLE-NEXT: lsl w0, w1, #1
; DISABLE: [[IFEND_LABEL]]: ; %if.end
;
; Epilogue code.
; CHECK: mov sp, [[NEW_SP]]
; CHECK-NEXT: ldp [[CSR1]], [[CSR2]], [sp], #16
; CHECK-NEXT: ret
;
; ENABLE: [[ELSE_LABEL]]: ; %if.else
; ENABLE-NEXT: lsl w0, w1, #1
; ENABLE-NEXT: ret
define i32 @callVariadicFunc(i32 %cond, i32 %N) {
entry:
%tobool = icmp eq i32 %cond, 0
br i1 %tobool, label %if.else, label %if.then
if.then: ; preds = %entry
%call = tail call i32 (i32, ...) @someVariadicFunc(i32 %N, i32 %N, i32 %N, i32 %N, i32 %N, i32 %N, i32 %N)
%shl = shl i32 %call, 3
br label %if.end
if.else: ; preds = %entry
%mul = shl nsw i32 %N, 1
br label %if.end
if.end: ; preds = %if.else, %if.then
%sum.0 = phi i32 [ %shl, %if.then ], [ %mul, %if.else ]
ret i32 %sum.0
}
declare i32 @someVariadicFunc(i32, ...)