mirror of
https://github.com/c64scene-ar/llvm-6502.git
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67828 91177308-0d34-0410-b5e6-96231b3b80d8
1454 lines
52 KiB
C++
1454 lines
52 KiB
C++
//===-- PrologEpilogInserter.cpp - Insert Prolog/Epilog code in function --===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass is responsible for finalizing the functions frame layout, saving
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// callee saved registers, and for emitting prolog & epilog code for the
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// function.
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//
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// This pass must be run after register allocation. After this pass is
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// executed, it is illegal to construct MO_FrameIndex operands.
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//
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// This pass implements a shrink wrapping variant of prolog/epilog insertion:
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// - Places callee saved register (CSR) spills and restores in the CFG to
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// tightly surround uses so that execution paths that do not use CSRs do not
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// pay the spill/restore penalty.
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//
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// - Avoiding placment of spills/restores in loops: if a CSR is used inside a
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// loop(nest), the spills are placed in the loop preheader, and restores are
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// placed in the loop exit nodes (the successors of the loop _exiting_ nodes).
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//
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// - Covering paths without CSR uses: e.g. if a restore is placed in a join
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// block, a matching spill is added to the end of all immediate predecessor
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// blocks that are not reached by a spill. Similarly for saves placed in
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// branch blocks.
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//
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// Shrink wrapping uses an analysis similar to the one in GVNPRE to determine
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// which basic blocks require callee-saved register save/restore code.
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//
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// This pass uses MachineDominators and MachineLoopInfo. Loop information
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// is used to prevent shrink wrapping of callee-saved register save/restore
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// code into loops.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "shrink-wrap"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/MachineDominators.h"
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#include "llvm/CodeGen/MachineLoopInfo.h"
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#include "llvm/CodeGen/MachineFunctionPass.h"
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#include "llvm/CodeGen/MachineInstr.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/RegisterScavenging.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Target/TargetRegisterInfo.h"
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#include "llvm/Target/TargetFrameInfo.h"
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#include "llvm/Target/TargetInstrInfo.h"
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#include "llvm/ADT/SparseBitVector.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/PostOrderIterator.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/ADT/STLExtras.h"
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#include <climits>
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#include <sstream>
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using namespace llvm;
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// Shrink Wrapping:
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static cl::opt<bool>
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ShrinkWrapping("shrink-wrap",
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cl::desc("Apply shrink wrapping to callee-saved register spills/restores"));
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namespace {
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struct VISIBILITY_HIDDEN PEI : public MachineFunctionPass {
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static char ID;
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PEI() : MachineFunctionPass(&ID) {}
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const char *getPassName() const {
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return "Prolog/Epilog Insertion & Frame Finalization";
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}
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesCFG();
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if (ShrinkWrapping) {
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AU.addRequired<MachineLoopInfo>();
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AU.addRequired<MachineDominatorTree>();
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}
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AU.addPreserved<MachineLoopInfo>();
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AU.addPreserved<MachineDominatorTree>();
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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/// runOnMachineFunction - Insert prolog/epilog code and replace abstract
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/// frame indexes with appropriate references.
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///
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bool runOnMachineFunction(MachineFunction &Fn) {
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const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
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RS = TRI->requiresRegisterScavenging(Fn) ? new RegScavenger() : NULL;
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// Get MachineModuleInfo so that we can track the construction of the
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// frame.
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if (MachineModuleInfo *MMI = getAnalysisIfAvailable<MachineModuleInfo>())
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Fn.getFrameInfo()->setMachineModuleInfo(MMI);
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// Allow the target machine to make some adjustments to the function
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// e.g. UsedPhysRegs before calculateCalleeSavedRegisters.
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TRI->processFunctionBeforeCalleeSavedScan(Fn, RS);
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// Scan the function for modified callee saved registers and insert spill
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// code for any callee saved registers that are modified. Also calculate
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// the MaxCallFrameSize and HasCalls variables for the function's frame
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// information and eliminates call frame pseudo instructions.
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calculateCalleeSavedRegisters(Fn);
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// Determine placement of CSR spill/restore code:
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// - with shrink wrapping, place spills and restores to tightly
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// enclose regions in the Machine CFG of the function where
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// they are used. Without shrink wrapping
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// - default (no shrink wrapping), place all spills in the
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// entry block, all restores in return blocks.
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placeCSRSpillsAndRestores(Fn);
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// Add the code to save and restore the callee saved registers
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insertCSRSpillsAndRestores(Fn);
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// Allow the target machine to make final modifications to the function
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// before the frame layout is finalized.
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TRI->processFunctionBeforeFrameFinalized(Fn);
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// Calculate actual frame offsets for all of the abstract stack objects...
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calculateFrameObjectOffsets(Fn);
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// Add prolog and epilog code to the function. This function is required
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// to align the stack frame as necessary for any stack variables or
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// called functions. Because of this, calculateCalleeSavedRegisters
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// must be called before this function in order to set the HasCalls
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// and MaxCallFrameSize variables.
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insertPrologEpilogCode(Fn);
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// Replace all MO_FrameIndex operands with physical register references
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// and actual offsets.
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//
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replaceFrameIndices(Fn);
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delete RS;
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return true;
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}
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private:
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RegScavenger *RS;
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// MinCSFrameIndex, MaxCSFrameIndex - Keeps the range of callee saved
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// stack frame indexes.
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unsigned MinCSFrameIndex, MaxCSFrameIndex;
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// Analysis info for spill/restore placement.
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// "CSR": "callee saved register".
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// CSRegSet contains indices into the Callee Saved Register Info
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// vector built by calculateCalleeSavedRegisters() and accessed
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// via MF.getFrameInfo()->getCalleeSavedInfo().
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typedef SparseBitVector<> CSRegSet;
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// CSRegBlockMap maps MachineBasicBlocks to sets of callee
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// saved register indices.
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typedef DenseMap<MachineBasicBlock*, CSRegSet> CSRegBlockMap;
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// Set and maps for computing CSR spill/restore placement:
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// used in function (UsedCSRegs)
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// used in a basic block (CSRUsed)
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// anticipatable in a basic block (Antic{In,Out})
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// available in a basic block (Avail{In,Out})
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// to be spilled at the entry to a basic block (CSRSave)
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// to be restored at the end of a basic block (CSRRestore)
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CSRegSet UsedCSRegs;
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CSRegBlockMap CSRUsed;
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CSRegBlockMap AnticIn, AnticOut;
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CSRegBlockMap AvailIn, AvailOut;
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CSRegBlockMap CSRSave;
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CSRegBlockMap CSRRestore;
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// Entry and return blocks of the current function.
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MachineBasicBlock* EntryBlock;
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SmallVector<MachineBasicBlock*, 4> ReturnBlocks;
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// Flag to control shrink wrapping per-function:
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// may choose to skip shrink wrapping for certain
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// functions.
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bool ShrinkWrapThisFunction;
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bool calculateSets(MachineFunction &Fn);
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void calculateAnticAvail(MachineFunction &Fn);
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MachineBasicBlock* moveSpillsOutOfLoops(MachineFunction &Fn,
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MachineBasicBlock* MBB);
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void addRestoresForSBranchBlock(MachineFunction &Fn,
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MachineBasicBlock* MBB);
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void moveRestoresOutOfLoops(MachineFunction& Fn,
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MachineBasicBlock* MBB,
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std::vector<MachineBasicBlock*>& SBLKS);
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void addSavesForRJoinBlocks(MachineFunction& Fn,
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std::vector<MachineBasicBlock*>& SBLKS);
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void placeSpillsAndRestores(MachineFunction &Fn);
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void placeCSRSpillsAndRestores(MachineFunction &Fn);
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void calculateCalleeSavedRegisters(MachineFunction &Fn);
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void insertCSRSpillsAndRestores(MachineFunction &Fn);
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void calculateFrameObjectOffsets(MachineFunction &Fn);
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void replaceFrameIndices(MachineFunction &Fn);
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void insertPrologEpilogCode(MachineFunction &Fn);
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// Initialize all shrink wrapping data.
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void initShrinkWrappingInfo() {
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UsedCSRegs.clear();
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CSRUsed.clear();
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AnticIn.clear();
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AnticOut.clear();
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AvailIn.clear();
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AvailOut.clear();
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CSRSave.clear();
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CSRRestore.clear();
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EntryBlock = 0;
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if (! ReturnBlocks.empty())
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ReturnBlocks.clear();
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ShrinkWrapThisFunction = ShrinkWrapping;
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}
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// Convienences for dealing with machine loops.
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MachineBasicBlock* getTopLevelLoopPreheader(MachineLoop* LP) {
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assert(LP && "Machine loop is NULL.");
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MachineBasicBlock* PHDR = LP->getLoopPreheader();
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MachineLoop* PLP = LP->getParentLoop();
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while (PLP) {
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PHDR = PLP->getLoopPreheader();
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PLP = PLP->getParentLoop();
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}
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return PHDR;
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}
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MachineLoop* getTopLevelLoopParent(MachineLoop *LP) {
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if (LP == 0)
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return 0;
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MachineLoop* PLP = LP->getParentLoop();
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while (PLP) {
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LP = PLP;
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PLP = PLP->getParentLoop();
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}
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return LP;
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}
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#ifndef NDEBUG
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// Debugging methods.
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static std::string getBasicBlockName(const MachineBasicBlock* MBB) {
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std::ostringstream name;
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if (MBB) {
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if (MBB->getBasicBlock())
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name << MBB->getBasicBlock()->getName();
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else
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name << "_MBB_" << MBB->getNumber();
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}
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return name.str();
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}
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static std::string stringifyCSRegSet(const CSRegSet& s,
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MachineFunction &Fn) {
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const TargetRegisterInfo* TRI = Fn.getTarget().getRegisterInfo();
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const std::vector<CalleeSavedInfo> CSI =
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Fn.getFrameInfo()->getCalleeSavedInfo();
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std::ostringstream srep;
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if (CSI.size() == 0) {
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srep << "[]";
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return srep.str();
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}
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srep << "[";
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CSRegSet::iterator I = s.begin(), E = s.end();
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if (I != E) {
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unsigned reg = CSI[*I].getReg();
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srep << TRI->getName(reg);
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for (++I; I != E; ++I) {
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reg = CSI[*I].getReg();
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srep << ",";
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srep << TRI->getName(reg);
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}
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}
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srep << "]";
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return srep.str();
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}
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static void dumpSet(const CSRegSet& s, MachineFunction &Fn) {
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DOUT << stringifyCSRegSet(s, Fn) << "\n";
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}
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#endif
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};
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char PEI::ID = 0;
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}
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/// createPrologEpilogCodeInserter - This function returns a pass that inserts
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/// prolog and epilog code, and eliminates abstract frame references.
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///
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FunctionPass *llvm::createPrologEpilogCodeInserter() { return new PEI(); }
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/// placeCSRSpillsAndRestores - determine which MBBs of the function
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/// need save, restore code for callee-saved registers by doing a DF analysis
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/// similar to the one used in code motion (GVNPRE). This produces maps of MBBs
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/// to sets of registers (CSRs) for saves and restores. MachineLoopInfo
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/// is used to ensure that CSR save/restore code is not placed inside loops.
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/// This function computes the maps of MBBs -> CSRs to spill and restore
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/// in CSRSave, CSRRestore.
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///
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/// If shrink wrapping is not being performed, place all spills in
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/// the entry block, all restores in return blocks. In this case,
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/// CSRSave has a single mapping, CSRRestore has mappings for each
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/// return block.
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///
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void PEI::placeCSRSpillsAndRestores(MachineFunction &Fn) {
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#ifndef NDEBUG
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DOUT << "Place CSR spills/restores for "
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<< Fn.getFunction()->getName() << "\n";
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#endif
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initShrinkWrappingInfo();
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if (calculateSets(Fn))
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placeSpillsAndRestores(Fn);
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}
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/// calculateAnticAvail - helper for computing the data flow
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/// sets required for determining spill/restore placements.
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///
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void PEI::calculateAnticAvail(MachineFunction &Fn) {
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// Calulate Antic{In,Out} and Avail{In,Out} iteratively on the MCFG.
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bool changed = true;
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unsigned iterations = 0;
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while (changed) {
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changed = false;
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for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
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MBBI != MBBE; ++MBBI) {
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MachineBasicBlock* MBB = MBBI;
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// AnticOut[MBB] = INTERSECT(AnticIn[S] for S in SUCC(MBB))
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MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
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SE = MBB->succ_end();
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if (SI != SE) {
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CSRegSet prevAnticOut = AnticOut[MBB];
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MachineBasicBlock* SUCC = *SI;
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AnticOut[MBB] = AnticIn[SUCC];
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for (++SI; SI != SE; ++SI) {
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SUCC = *SI;
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AnticOut[MBB] &= AnticIn[SUCC];
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}
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if (prevAnticOut != AnticOut[MBB])
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changed = true;
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}
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// AnticIn[MBB] = CSRUsed[MBB] | AnticOut[MBB];
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CSRegSet prevAnticIn = AnticIn[MBB];
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AnticIn[MBB] = CSRUsed[MBB] | AnticOut[MBB];
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if (prevAnticIn |= AnticIn[MBB])
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changed = true;
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// AvailIn[MBB] = INTERSECT(AvailOut[S] for S in PRED(MBB))
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MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
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PE = MBB->pred_end();
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if (PI != PE) {
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CSRegSet prevAvailIn = AvailIn[MBB];
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MachineBasicBlock* PRED = *PI;
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AvailIn[MBB] = AvailOut[PRED];
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for (++PI; PI != PE; ++PI) {
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PRED = *PI;
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AvailIn[MBB] &= AvailOut[PRED];
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}
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if (prevAvailIn != AvailIn[MBB])
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changed = true;
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}
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// AvailOut[MBB] = CSRUsed[MBB] | AvailIn[MBB];
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CSRegSet prevAvailOut = AvailOut[MBB];
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AvailOut[MBB] = CSRUsed[MBB] | AvailIn[MBB];
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if (prevAvailOut |= AvailOut[MBB])
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changed = true;
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}
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++iterations;
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}
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// EXP
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AnticIn[EntryBlock].clear();
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AnticOut[EntryBlock].clear();
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#ifndef NDEBUG
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DOUT << "-----------------------------------------------------------\n";
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DOUT << "iterations = " << iterations << "\n";
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DOUT << "-----------------------------------------------------------\n";
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DOUT << "MBB | ANTIC_IN | ANTIC_OUT | AVAIL_IN | AVAIL_OUT\n";
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DOUT << "-----------------------------------------------------------\n";
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for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
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MBBI != MBBE; ++MBBI) {
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MachineBasicBlock* MBB = MBBI;
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DOUT << getBasicBlockName(MBB) << " | "
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<< stringifyCSRegSet(AnticIn[MBB], Fn)
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<< " | "
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<< stringifyCSRegSet(AnticOut[MBB], Fn)
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<< " | "
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<< stringifyCSRegSet(AvailIn[MBB], Fn)
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<< " | "
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<< stringifyCSRegSet(AvailOut[MBB], Fn)
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<< "\n";
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}
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#endif
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}
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/// calculateSets - helper function for placeCSRSpillsAndRestores,
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/// collect the CSRs used in this function, develop the DF sets that
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/// describe the minimal regions in the Machine CFG around which spills,
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/// restores must be placed.
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///
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/// This function decides if shrink wrapping should actually be done:
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/// if all CSR uses are in the entry block, no shrink wrapping is possible,
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/// so ShrinkWrapping is turned off (for the current function) and the
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/// function returns false.
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///
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bool PEI::calculateSets(MachineFunction &Fn) {
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// Sets used to compute spill, restore placement sets.
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const std::vector<CalleeSavedInfo> CSI =
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Fn.getFrameInfo()->getCalleeSavedInfo();
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// If no CSRs used, we are done.
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if (CSI.empty()) {
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#ifndef NDEBUG
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DOUT << Fn.getFunction()->getName()
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<< " uses no callee-saved registers.\n";
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#endif
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return false;
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}
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#ifndef NDEBUG
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DOUT << "-----------------------------------------------------------\n";
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#endif
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const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
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bool allCSRUsesInEntryBlock = true;
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// Initialize UsedCSRegs set, CSRUsed map.
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// At the same time, put entry block directly into
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// CSRSave, CSRRestore sets if any CSRs are used.
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//
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// Quick exit option (not implemented):
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// Given N CSR uses in entry block,
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// revert to default behavior, skip the placement
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// step and put all saves in entry, restores in
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// return blocks.
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// Set up entry and return blocks.
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EntryBlock = Fn.begin();
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for (MachineFunction::iterator MBB = Fn.begin(), E = Fn.end();
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MBB != E; ++MBB)
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if (!MBB->empty() && MBB->back().getDesc().isReturn())
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ReturnBlocks.push_back(MBB);
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// TODO -- check for a use of a CSR in each imm. successor of EntryBlock,
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// do not shrink wrap this function if this is the case.
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// If not shrink wrapping (this function) at this point, set bits in
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// CSR{Save,Restore}[] and UsedCSRegs, then return.
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if (! ShrinkWrapThisFunction) {
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for (unsigned inx = 0, e = CSI.size(); inx != e; ++inx) {
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UsedCSRegs.set(inx);
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CSRSave[EntryBlock].set(inx);
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for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri)
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CSRRestore[ReturnBlocks[ri]].set(inx);
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}
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return false;
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}
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// Walk instructions in all MBBs, create basic sets, choose
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// whether or not to shrink wrap this function.
|
|
for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
|
|
MBBI != MBBE; ++MBBI) {
|
|
MachineBasicBlock* MBB = MBBI;
|
|
for (MachineBasicBlock::iterator I = MBB->begin(); I != MBB->end(); ++I) {
|
|
for (unsigned inx = 0, e = CSI.size(); inx != e; ++inx) {
|
|
unsigned Reg = CSI[inx].getReg();
|
|
// If instruction I reads or modifies Reg, add it to UsedCSRegs,
|
|
// CSRUsed map for the current block.
|
|
for (unsigned opInx = 0, opEnd = I->getNumOperands();
|
|
opInx != opEnd; ++opInx) {
|
|
const MachineOperand &MO = I->getOperand(opInx);
|
|
if (! (MO.isReg() && (MO.isUse() || MO.isDef())))
|
|
continue;
|
|
unsigned MOReg = MO.getReg();
|
|
if (!MOReg)
|
|
continue;
|
|
if (MOReg == Reg ||
|
|
(TargetRegisterInfo::isPhysicalRegister(MOReg) &&
|
|
TargetRegisterInfo::isPhysicalRegister(Reg) &&
|
|
TRI->isSubRegister(MOReg, Reg))) {
|
|
// CSR Reg is defined/used in block MBB.
|
|
UsedCSRegs.set(inx);
|
|
CSRUsed[MBB].set(inx);
|
|
// Short-circuit analysis for entry, return blocks:
|
|
// if a CSR is used in the entry block, add it directly
|
|
// to CSRSave[EntryBlock] and to CSRRestore[R] for R
|
|
// in ReturnBlocks. Note CSR uses in non-entry blocks.
|
|
if (ShrinkWrapThisFunction) {
|
|
if (MBB == EntryBlock) {
|
|
CSRSave[MBB].set(inx);
|
|
for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri)
|
|
CSRRestore[ReturnBlocks[ri]].set(inx);
|
|
} else
|
|
allCSRUsesInEntryBlock = false;
|
|
} else {
|
|
// Not shrink wrapping => ensure saves/restores are correctly
|
|
// added for entry, return blocks.
|
|
CSRSave[EntryBlock].set(inx);
|
|
for (unsigned ri = 0, re = ReturnBlocks.size(); ri != re; ++ri)
|
|
CSRRestore[ReturnBlocks[ri]].set(inx);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
#ifndef NDEBUG
|
|
DOUT << "CSRUsed[" << getBasicBlockName(MBB) << "] = "
|
|
<< stringifyCSRegSet(CSRUsed[MBB], Fn) << "\n";
|
|
#endif
|
|
}
|
|
|
|
#ifndef NDEBUG
|
|
DOUT << "UsedCSRegs = " << stringifyCSRegSet(UsedCSRegs, Fn) << "\n";
|
|
#endif
|
|
|
|
// Early exit:
|
|
// 1. Not asked to do shrink wrapping => just "place" all spills(restores)
|
|
// in the entry(return) block(s), already done above.
|
|
// 2. All CSR uses in entry block => same as case 1, but say we will
|
|
// not shrink wrap the current function.
|
|
ShrinkWrapThisFunction = (ShrinkWrapping &&
|
|
ShrinkWrapThisFunction &&
|
|
! allCSRUsesInEntryBlock);
|
|
if (! ShrinkWrapThisFunction) {
|
|
return false;
|
|
}
|
|
|
|
calculateAnticAvail(Fn);
|
|
|
|
return true;
|
|
}
|
|
|
|
/// moveSpillsOutOfLoops - helper for placeSpillsAndRestores() which
|
|
/// relocates a spill from a subgraph in a loop to the loop preheader.
|
|
/// Returns the MBB to which saves have been moved, or the given MBB
|
|
/// if it is a branch point.
|
|
///
|
|
MachineBasicBlock* PEI::moveSpillsOutOfLoops(MachineFunction &Fn,
|
|
MachineBasicBlock* MBB) {
|
|
if (MBB == 0 || CSRSave[MBB].empty())
|
|
return 0;
|
|
|
|
// Block to which saves are moved.
|
|
MachineBasicBlock* DEST = 0;
|
|
MachineLoopInfo &LI = getAnalysis<MachineLoopInfo>();
|
|
|
|
if (MachineLoop* LP = LI.getLoopFor(MBB)) {
|
|
MachineBasicBlock* LPH = getTopLevelLoopPreheader(LP);
|
|
assert(LPH && "Loop has no top level preheader?");
|
|
|
|
#ifndef NDEBUG
|
|
DOUT << "Moving saves of "
|
|
<< stringifyCSRegSet(CSRSave[MBB], Fn)
|
|
<< " from " << getBasicBlockName(MBB)
|
|
<< " to " << getBasicBlockName(LPH) << "\n";
|
|
#endif
|
|
// Add CSRegSet from MBB to LPH, empty out MBB's CSRegSet.
|
|
CSRSave[LPH] |= CSRSave[MBB];
|
|
// If saves moved to entry block, add restores to returns.
|
|
if (LPH == EntryBlock) {
|
|
for (unsigned i = 0, e = ReturnBlocks.size(); i != e; ++i)
|
|
CSRRestore[ReturnBlocks[i]] |= CSRSave[MBB];
|
|
} else {
|
|
// Remember where we moved the save so we can add
|
|
// restores on successor paths if necessary.
|
|
if (LPH->succ_size() > 1)
|
|
DEST = LPH;
|
|
}
|
|
CSRSave[MBB].clear();
|
|
} else if (MBB->succ_size() > 1)
|
|
DEST = MBB;
|
|
return DEST;
|
|
}
|
|
|
|
/// addRestoresForSBranchBlock - helper for placeSpillsAndRestores() which
|
|
/// adds restores of CSRs saved in branch point MBBs to the front of any
|
|
/// successor blocks connected to regions with no uses of the saved CSRs.
|
|
///
|
|
void PEI::addRestoresForSBranchBlock(MachineFunction &Fn,
|
|
MachineBasicBlock* MBB) {
|
|
|
|
if (MBB == 0 || CSRSave[MBB].empty() || MBB->succ_size() < 2)
|
|
return;
|
|
|
|
// Add restores of CSRs saved in branch point MBBs to the
|
|
// front of any succ blocks flowing into regions that
|
|
// have no uses of MBB's CSRs.
|
|
bool hasCSRUses = false;
|
|
for (MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
|
|
SE = MBB->succ_end(); SI != SE; ++SI) {
|
|
MachineBasicBlock* SUCC = *SI;
|
|
bool needsRestore = false;
|
|
if (CSRUsed[SUCC].intersects(CSRSave[MBB])) {
|
|
hasCSRUses = true;
|
|
continue;
|
|
}
|
|
needsRestore = true;
|
|
for (df_iterator<MachineBasicBlock*> BI = df_begin(SUCC),
|
|
BE = df_end(SUCC); BI != BE; ++BI) {
|
|
MachineBasicBlock* SBB = *BI;
|
|
if (CSRUsed[SBB].intersects(CSRSave[MBB])) {
|
|
hasCSRUses = true;
|
|
needsRestore = false;
|
|
break;
|
|
}
|
|
}
|
|
// Additional restores are needed for SUCC iff there is at least
|
|
// one CSR use reachable from the successors of MBB and there
|
|
// are no uses in or below SUCC.
|
|
if (needsRestore && hasCSRUses) {
|
|
#ifndef NDEBUG
|
|
DOUT << "MBB " << getBasicBlockName(MBB)
|
|
<< " needs a restore on path to successor "
|
|
<< getBasicBlockName(SUCC) << "\n";
|
|
#endif
|
|
// Add restores to SUCC for all CSRs saved in MBB...
|
|
CSRRestore[SUCC] = CSRSave[MBB];
|
|
}
|
|
}
|
|
}
|
|
|
|
/// moveRestoresOutOfLoops - helper for placeSpillsAndRestores() which
|
|
/// relocates restores from a subgraph in a loop to the loop exit blocks.
|
|
/// This function records the MBBs to which restores have been moved in
|
|
/// SBLKS. If no restores are moved, SBLKS contains the input MBB if it
|
|
/// is a join point in the Machine CFG.
|
|
///
|
|
void PEI::moveRestoresOutOfLoops(MachineFunction& Fn,
|
|
MachineBasicBlock* MBB,
|
|
std::vector<MachineBasicBlock*>& SBLKS) {
|
|
|
|
SBLKS.clear();
|
|
if (MBB == 0 || CSRRestore[MBB].empty())
|
|
return;
|
|
|
|
MachineLoopInfo &LI = getAnalysis<MachineLoopInfo>();
|
|
|
|
if (MachineLoop* LP = LI.getLoopFor(MBB)) {
|
|
LP = getTopLevelLoopParent(LP);
|
|
assert(LP && "Loop with no top level parent?");
|
|
|
|
SmallVector<MachineBasicBlock*, 4> exitBlocks;
|
|
|
|
LP->getExitBlocks(exitBlocks);
|
|
assert(exitBlocks.size() > 0 &&
|
|
"Loop has no top level exit blocks?");
|
|
for (unsigned i = 0, e = exitBlocks.size(); i != e; ++i) {
|
|
MachineBasicBlock* EXB = exitBlocks[i];
|
|
|
|
#ifndef NDEBUG
|
|
DOUT << "Moving restores of "
|
|
<< stringifyCSRegSet(CSRRestore[MBB], Fn)
|
|
<< " from " << getBasicBlockName(MBB)
|
|
<< " to " << getBasicBlockName(EXB) << "\n";
|
|
#endif
|
|
|
|
// Add CSRegSet from MBB to LPE, empty out MBB's CSRegSet.
|
|
CSRRestore[EXB] |= CSRRestore[MBB];
|
|
if (EXB->pred_size() > 1)
|
|
SBLKS.push_back(EXB);
|
|
}
|
|
CSRRestore[MBB].clear();
|
|
} else if (MBB->pred_size() > 1)
|
|
SBLKS.push_back(MBB);
|
|
}
|
|
|
|
/// addSavesForRJoinBlocks - Add saves of CSRs restored in join point MBBs
|
|
/// to the ends of any pred blocks that flow into MBB from regions that
|
|
/// have no uses of MBB's CSRs.
|
|
///
|
|
void PEI::addSavesForRJoinBlocks(MachineFunction& Fn,
|
|
std::vector<MachineBasicBlock*>& SBLKS) {
|
|
|
|
if (SBLKS.empty())
|
|
return;
|
|
|
|
for (unsigned i = 0, e = SBLKS.size(); i != e; ++i) {
|
|
MachineBasicBlock* MBB = SBLKS[i];
|
|
if (MBB->pred_size() > 1) {
|
|
bool needsSave = false;
|
|
for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
|
|
PE = MBB->pred_end(); PI != PE; ++PI) {
|
|
MachineBasicBlock* PRED = *PI;
|
|
|
|
// Walk back up in the CFG from the preds of MBB, look for
|
|
// a block that uses any CSR that is restored in MBB.
|
|
if (CSRUsed[PRED].intersects(CSRRestore[MBB]))
|
|
continue;
|
|
needsSave = true;
|
|
for (idf_iterator<MachineBasicBlock*> PPI = idf_begin(PRED),
|
|
PPE = idf_end(PRED); PPI != PPE; ++PPI) {
|
|
MachineBasicBlock* PBB = *PPI;
|
|
if (CSRUsed[PBB].intersects(CSRRestore[MBB])) {
|
|
needsSave = false;
|
|
break;
|
|
}
|
|
}
|
|
if (needsSave) {
|
|
// Add saves to PRED for all CSRs restored in MBB...
|
|
#ifndef NDEBUG
|
|
DOUT << "MBB " << getBasicBlockName(MBB)
|
|
<< " needs a save on path from predecessor "
|
|
<< getBasicBlockName(PRED) << "\n";
|
|
#endif
|
|
CSRSave[PRED] = CSRRestore[MBB];
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// placeSpillsAndRestores - decide which MBBs need spills, restores
|
|
/// of CSRs.
|
|
///
|
|
void PEI::placeSpillsAndRestores(MachineFunction &Fn) {
|
|
|
|
#ifndef NDEBUG
|
|
DOUT << "-----------------------------------------------------------\n";
|
|
#endif
|
|
|
|
// Calculate CSR{Save,Restore} using Antic, Avail on the Machine-CFG.
|
|
for (MachineFunction::iterator MBBI = Fn.begin(), MBBE = Fn.end();
|
|
MBBI != MBBE; ++MBBI) {
|
|
MachineBasicBlock* MBB = MBBI;
|
|
// Entry block saves are recorded in UsedCSRegs pass above.
|
|
if (MBB != EntryBlock) {
|
|
// Intersect (CSRegs - AnticIn[P]) for all predecessors P of MBB
|
|
CSRegSet anticInPreds;
|
|
MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
|
|
PE = MBB->pred_end();
|
|
if (PI != PE) {
|
|
MachineBasicBlock* PRED = *PI;
|
|
anticInPreds = UsedCSRegs - AnticIn[PRED];
|
|
for (++PI; PI != PE; ++PI) {
|
|
PRED = *PI;
|
|
// Handle self loop.
|
|
if (PRED != MBB)
|
|
anticInPreds &= (UsedCSRegs - AnticIn[PRED]);
|
|
}
|
|
}
|
|
// CSRSave[MBB] = (AnticIn[MBB] - AvailIn[MBB]) & anticInPreds
|
|
CSRSave[MBB] = (AnticIn[MBB] - AvailIn[MBB]) & anticInPreds;
|
|
|
|
// Remove the CSRs that are saved in the entry block
|
|
if (! CSRSave[MBB].empty() && ! CSRSave[EntryBlock].empty())
|
|
CSRSave[MBB] = CSRSave[MBB] - CSRSave[EntryBlock];
|
|
|
|
// Move saves inside loops to the preheaders of the outermost
|
|
// containing loops, add restores to blocks reached by saves
|
|
// placed at branch points where necessary.
|
|
if (MachineBasicBlock* DESTBB = moveSpillsOutOfLoops(Fn, MBB)) {
|
|
// Add restores to blocks reached by saves placed at branch
|
|
// points where necessary.
|
|
addRestoresForSBranchBlock(Fn, DESTBB);
|
|
}
|
|
}
|
|
|
|
#ifndef NDEBUG
|
|
if (! CSRSave[MBB].empty())
|
|
DOUT << "SAVE[" << getBasicBlockName(MBB) << "] = "
|
|
<< stringifyCSRegSet(CSRSave[MBB], Fn) << "\n";
|
|
#endif
|
|
|
|
// Compute CSRRestore, which may already be set for return blocks.
|
|
if (! CSRRestore[MBB].empty() || MBB->pred_size() == 0)
|
|
continue;
|
|
|
|
// Intersect (CSRegs - AvailOut[S]) for all successors S of MBB
|
|
CSRegSet availOutSucc;
|
|
MachineBasicBlock::succ_iterator SI = MBB->succ_begin(),
|
|
SE = MBB->succ_end();
|
|
if (SI != SE) {
|
|
MachineBasicBlock* SUCC = *SI;
|
|
availOutSucc = UsedCSRegs - AvailOut[SUCC];
|
|
for (++SI; SI != SE; ++SI) {
|
|
SUCC = *SI;
|
|
// Handle self loop.
|
|
if (SUCC != MBB)
|
|
availOutSucc &= (UsedCSRegs - AvailOut[SUCC]);
|
|
}
|
|
} else if (! CSRUsed[MBB].empty()) {
|
|
// Take care of uses in return blocks (which have no successors).
|
|
availOutSucc = UsedCSRegs;
|
|
}
|
|
// CSRRestore[MBB] = (AvailOut[MBB] - AnticOut[MBB]) & availOutSucc
|
|
CSRRestore[MBB] = (AvailOut[MBB] - AnticOut[MBB]) & availOutSucc;
|
|
|
|
// Remove the CSRs that are restored in the return blocks.
|
|
// Lest this be confusing, note that:
|
|
// CSRSave[EntryBlock] == CSRRestore[B] for all B in ReturnBlocks.
|
|
if (! CSRRestore[MBB].empty() && ! CSRSave[EntryBlock].empty())
|
|
CSRRestore[MBB] = CSRRestore[MBB] - CSRSave[EntryBlock];
|
|
|
|
// Move restores inside loops to the exits of the outermost (top level)
|
|
// containing loops.
|
|
std::vector<MachineBasicBlock*> saveBlocks;
|
|
moveRestoresOutOfLoops(Fn, MBB, saveBlocks);
|
|
|
|
// Add saves of CSRs restored in join point MBBs to the ends
|
|
// of any pred blocks that flow into MBB from regions that
|
|
// have no uses of MBB's CSRs.
|
|
addSavesForRJoinBlocks(Fn, saveBlocks);
|
|
|
|
#ifndef NDEBUG
|
|
if (! CSRRestore[MBB].empty())
|
|
DOUT << "RESTORE[" << getBasicBlockName(MBB) << "] = "
|
|
<< stringifyCSRegSet(CSRRestore[MBB], Fn) << "\n";
|
|
#endif
|
|
}
|
|
|
|
#ifndef NDEBUG
|
|
DOUT << "-----------------------------------------------------------\n";
|
|
DOUT << "Final SAVE, RESTORE:\n";
|
|
DOUT << "-----------------------------------------------------------\n";
|
|
for (MachineFunction::iterator MBB = Fn.begin(), E = Fn.end();
|
|
MBB != E; ++MBB) {
|
|
if (! CSRSave[MBB].empty()) {
|
|
DOUT << "SAVE[" << getBasicBlockName(MBB) << "] = "
|
|
<< stringifyCSRegSet(CSRSave[MBB], Fn);
|
|
if (CSRRestore[MBB].empty())
|
|
DOUT << "\n";
|
|
}
|
|
if (! CSRRestore[MBB].empty()) {
|
|
if (! CSRSave[MBB].empty())
|
|
DOUT << " ";
|
|
DOUT << "RESTORE[" << getBasicBlockName(MBB) << "] = "
|
|
<< stringifyCSRegSet(CSRRestore[MBB], Fn) << "\n";
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/// calculateCalleeSavedRegisters - Scan the function for modified callee saved
|
|
/// registers. Also calculate the MaxCallFrameSize and HasCalls variables for
|
|
/// the function's frame information and eliminates call frame pseudo
|
|
/// instructions.
|
|
///
|
|
void PEI::calculateCalleeSavedRegisters(MachineFunction &Fn) {
|
|
const TargetRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
|
|
const TargetFrameInfo *TFI = Fn.getTarget().getFrameInfo();
|
|
|
|
// Get the callee saved register list...
|
|
const unsigned *CSRegs = RegInfo->getCalleeSavedRegs(&Fn);
|
|
|
|
// Get the function call frame set-up and tear-down instruction opcode
|
|
int FrameSetupOpcode = RegInfo->getCallFrameSetupOpcode();
|
|
int FrameDestroyOpcode = RegInfo->getCallFrameDestroyOpcode();
|
|
|
|
// These are used to keep track the callee-save area. Initialize them.
|
|
MinCSFrameIndex = INT_MAX;
|
|
MaxCSFrameIndex = 0;
|
|
|
|
// Early exit for targets which have no callee saved registers and no call
|
|
// frame setup/destroy pseudo instructions.
|
|
if ((CSRegs == 0 || CSRegs[0] == 0) &&
|
|
FrameSetupOpcode == -1 && FrameDestroyOpcode == -1)
|
|
return;
|
|
|
|
unsigned MaxCallFrameSize = 0;
|
|
bool HasCalls = false;
|
|
|
|
std::vector<MachineBasicBlock::iterator> FrameSDOps;
|
|
for (MachineFunction::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB)
|
|
for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I)
|
|
if (I->getOpcode() == FrameSetupOpcode ||
|
|
I->getOpcode() == FrameDestroyOpcode) {
|
|
assert(I->getNumOperands() >= 1 && "Call Frame Setup/Destroy Pseudo"
|
|
" instructions should have a single immediate argument!");
|
|
unsigned Size = I->getOperand(0).getImm();
|
|
if (Size > MaxCallFrameSize) MaxCallFrameSize = Size;
|
|
HasCalls = true;
|
|
FrameSDOps.push_back(I);
|
|
}
|
|
|
|
MachineFrameInfo *FFI = Fn.getFrameInfo();
|
|
FFI->setHasCalls(HasCalls);
|
|
FFI->setMaxCallFrameSize(MaxCallFrameSize);
|
|
|
|
for (unsigned i = 0, e = FrameSDOps.size(); i != e; ++i) {
|
|
MachineBasicBlock::iterator I = FrameSDOps[i];
|
|
// If call frames are not being included as part of the stack frame,
|
|
// and there is no dynamic allocation (therefore referencing frame slots
|
|
// off sp), leave the pseudo ops alone. We'll eliminate them later.
|
|
if (RegInfo->hasReservedCallFrame(Fn) || RegInfo->hasFP(Fn))
|
|
RegInfo->eliminateCallFramePseudoInstr(Fn, *I->getParent(), I);
|
|
}
|
|
|
|
// Now figure out which *callee saved* registers are modified by the current
|
|
// function, thus needing to be saved and restored in the prolog/epilog.
|
|
//
|
|
const TargetRegisterClass* const *CSRegClasses =
|
|
RegInfo->getCalleeSavedRegClasses(&Fn);
|
|
std::vector<CalleeSavedInfo> CSI;
|
|
for (unsigned i = 0; CSRegs[i]; ++i) {
|
|
unsigned Reg = CSRegs[i];
|
|
if (Fn.getRegInfo().isPhysRegUsed(Reg)) {
|
|
// If the reg is modified, save it!
|
|
CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i]));
|
|
} else {
|
|
for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
|
|
*AliasSet; ++AliasSet) { // Check alias registers too.
|
|
if (Fn.getRegInfo().isPhysRegUsed(*AliasSet)) {
|
|
CSI.push_back(CalleeSavedInfo(Reg, CSRegClasses[i]));
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (CSI.empty())
|
|
return; // Early exit if no callee saved registers are modified!
|
|
|
|
unsigned NumFixedSpillSlots;
|
|
const std::pair<unsigned,int> *FixedSpillSlots =
|
|
TFI->getCalleeSavedSpillSlots(NumFixedSpillSlots);
|
|
|
|
// Now that we know which registers need to be saved and restored, allocate
|
|
// stack slots for them.
|
|
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
|
|
unsigned Reg = CSI[i].getReg();
|
|
const TargetRegisterClass *RC = CSI[i].getRegClass();
|
|
|
|
// Check to see if this physreg must be spilled to a particular stack slot
|
|
// on this target.
|
|
const std::pair<unsigned,int> *FixedSlot = FixedSpillSlots;
|
|
while (FixedSlot != FixedSpillSlots+NumFixedSpillSlots &&
|
|
FixedSlot->first != Reg)
|
|
++FixedSlot;
|
|
|
|
int FrameIdx;
|
|
if (FixedSlot == FixedSpillSlots+NumFixedSpillSlots) {
|
|
// Nope, just spill it anywhere convenient.
|
|
unsigned Align = RC->getAlignment();
|
|
unsigned StackAlign = TFI->getStackAlignment();
|
|
// We may not be able to sastify the desired alignment specification of
|
|
// the TargetRegisterClass if the stack alignment is smaller.
|
|
// Use the min.
|
|
Align = std::min(Align, StackAlign);
|
|
FrameIdx = FFI->CreateStackObject(RC->getSize(), Align);
|
|
if ((unsigned)FrameIdx < MinCSFrameIndex) MinCSFrameIndex = FrameIdx;
|
|
if ((unsigned)FrameIdx > MaxCSFrameIndex) MaxCSFrameIndex = FrameIdx;
|
|
} else {
|
|
// Spill it to the stack where we must.
|
|
FrameIdx = FFI->CreateFixedObject(RC->getSize(), FixedSlot->second);
|
|
}
|
|
CSI[i].setFrameIdx(FrameIdx);
|
|
}
|
|
|
|
FFI->setCalleeSavedInfo(CSI);
|
|
}
|
|
|
|
/// insertCSRSpillsAndRestores - Insert spill and restore code for
|
|
/// callee saved registers used in the function, handling shrink wrapping.
|
|
///
|
|
void PEI::insertCSRSpillsAndRestores(MachineFunction &Fn) {
|
|
// Get callee saved register information.
|
|
MachineFrameInfo *FFI = Fn.getFrameInfo();
|
|
const std::vector<CalleeSavedInfo> &CSI = FFI->getCalleeSavedInfo();
|
|
|
|
// Early exit if no callee saved registers are modified!
|
|
if (CSI.empty())
|
|
return;
|
|
|
|
const TargetInstrInfo &TII = *Fn.getTarget().getInstrInfo();
|
|
MachineBasicBlock::iterator I;
|
|
std::vector<CalleeSavedInfo> blockCSI;
|
|
|
|
#ifndef NDEBUG
|
|
DOUT << "Inserting spill/restore code for CSRs in function "
|
|
<< Fn.getFunction()->getName() << "\n";
|
|
#endif
|
|
|
|
// Insert spills.
|
|
for (CSRegBlockMap::iterator
|
|
BI = CSRSave.begin(), BE = CSRSave.end(); BI != BE; ++BI) {
|
|
MachineBasicBlock* MBB = BI->first;
|
|
CSRegSet save = BI->second;
|
|
|
|
if (save.empty())
|
|
continue;
|
|
|
|
if (! ShrinkWrapThisFunction) {
|
|
// Spill using target interface.
|
|
I = MBB->begin();
|
|
if (!TII.spillCalleeSavedRegisters(*MBB, I, CSI)) {
|
|
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
|
|
// Add the callee-saved register as live-in. It's killed at the spill.
|
|
MBB->addLiveIn(CSI[i].getReg());
|
|
|
|
// Insert the spill to the stack frame.
|
|
TII.storeRegToStackSlot(*MBB, I, CSI[i].getReg(), true,
|
|
CSI[i].getFrameIdx(), CSI[i].getRegClass());
|
|
}
|
|
}
|
|
} else {
|
|
#ifndef NDEBUG
|
|
DOUT << "CSRSave[" << getBasicBlockName(MBB) << "] = "
|
|
<< stringifyCSRegSet(save, Fn) << "\n";
|
|
#endif
|
|
|
|
blockCSI.clear();
|
|
for (CSRegSet::iterator RI = save.begin(),
|
|
RE = save.end(); RI != RE; ++RI) {
|
|
blockCSI.push_back(CSI[*RI]);
|
|
}
|
|
assert(blockCSI.size() > 0 &&
|
|
"Could not collect callee saved register info");
|
|
|
|
// If MBB has no uses of CSRs being saved, this means saves
|
|
// must be inserted at the _end_.
|
|
if (! MBB->empty() && ! CSRUsed[MBB].intersects(save)) {
|
|
I = MBB->end();
|
|
--I;
|
|
if (I->getDesc().isCall()) {
|
|
++I;
|
|
} else {
|
|
MachineBasicBlock::iterator I2 = I;
|
|
while (I2 != MBB->begin() && (--I2)->getDesc().isTerminator())
|
|
I = I2;
|
|
}
|
|
} else {
|
|
I = MBB->begin();
|
|
}
|
|
|
|
// When shrink wrapping, use stack slot stores/loads.
|
|
for (unsigned i = 0, e = blockCSI.size(); i != e; ++i) {
|
|
// Add the callee-saved register as live-in.
|
|
// It's killed at the spill.
|
|
MBB->addLiveIn(blockCSI[i].getReg());
|
|
|
|
// Insert the spill to the stack frame.
|
|
TII.storeRegToStackSlot(*MBB, I, blockCSI[i].getReg(),
|
|
true,
|
|
blockCSI[i].getFrameIdx(),
|
|
blockCSI[i].getRegClass());
|
|
}
|
|
}
|
|
}
|
|
// Use CSRRestore to add code to restore the callee-saved registers in
|
|
// each block.
|
|
for (CSRegBlockMap::iterator
|
|
BI = CSRRestore.begin(), BE = CSRRestore.end(); BI != BE; ++BI) {
|
|
MachineBasicBlock* MBB = BI->first;
|
|
CSRegSet restore = BI->second;
|
|
|
|
if (restore.empty())
|
|
continue;
|
|
if (! ShrinkWrapThisFunction) {
|
|
// Restore using target interface.
|
|
I = MBB->end(); --I;
|
|
|
|
// Skip over all terminator instructions, which are part of the return
|
|
// sequence.
|
|
MachineBasicBlock::iterator I2 = I;
|
|
while (I2 != MBB->begin() && (--I2)->getDesc().isTerminator())
|
|
I = I2;
|
|
|
|
bool AtStart = I == MBB->begin();
|
|
MachineBasicBlock::iterator BeforeI = I;
|
|
if (!AtStart)
|
|
--BeforeI;
|
|
|
|
// Restore all registers immediately before the return and any
|
|
// terminators that preceed it.
|
|
if (!TII.restoreCalleeSavedRegisters(*MBB, I, CSI)) {
|
|
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
|
|
TII.loadRegFromStackSlot(*MBB, I, CSI[i].getReg(),
|
|
CSI[i].getFrameIdx(),
|
|
CSI[i].getRegClass());
|
|
assert(I != MBB->begin() &&
|
|
"loadRegFromStackSlot didn't insert any code!");
|
|
// Insert in reverse order. loadRegFromStackSlot can insert
|
|
// multiple instructions.
|
|
if (AtStart)
|
|
I = MBB->begin();
|
|
else {
|
|
I = BeforeI;
|
|
++I;
|
|
}
|
|
}
|
|
}
|
|
} else {
|
|
#ifndef NDEBUG
|
|
DOUT << "CSRRestore[" << getBasicBlockName(MBB) << "] = "
|
|
<< stringifyCSRegSet(restore, Fn) << "\n";
|
|
#endif
|
|
|
|
blockCSI.clear();
|
|
for (CSRegSet::iterator RI = restore.begin(),
|
|
RE = restore.end(); RI != RE; ++RI) {
|
|
blockCSI.push_back(CSI[*RI]);
|
|
}
|
|
assert(blockCSI.size() > 0 &&
|
|
"Could not find callee saved register info");
|
|
|
|
// If MBB uses no CSRs but has restores, this means
|
|
// it must have restores inserted at the _beginning_.
|
|
// N.B. -- not necessary if edge splitting done.
|
|
if (MBB->empty() || ! CSRUsed[MBB].intersects(restore)) {
|
|
I = MBB->begin();
|
|
} else {
|
|
I = MBB->end();
|
|
--I;
|
|
|
|
// EXP iff spill/restore implemented with push/pop:
|
|
// append restore to block unless it ends in a
|
|
// barrier terminator instruction.
|
|
|
|
// Skip over all terminator instructions, which are part of the
|
|
// return sequence.
|
|
if (I->getDesc().isCall()) {
|
|
++I;
|
|
} else {
|
|
MachineBasicBlock::iterator I2 = I;
|
|
while (I2 != MBB->begin() && (--I2)->getDesc().isTerminator())
|
|
I = I2;
|
|
}
|
|
}
|
|
|
|
bool AtStart = I == MBB->begin();
|
|
MachineBasicBlock::iterator BeforeI = I;
|
|
if (!AtStart)
|
|
--BeforeI;
|
|
|
|
#ifndef NDEBUG
|
|
if (! MBB->empty() && ! CSRUsed[MBB].intersects(restore)) {
|
|
MachineInstr* MI = BeforeI;
|
|
DOUT << "adding restore after ";
|
|
DEBUG(MI->dump());
|
|
} else {
|
|
DOUT << "adding restore to beginning of "
|
|
<< getBasicBlockName(MBB) << "\n";
|
|
}
|
|
#endif
|
|
|
|
// Restore all registers immediately before the return and any
|
|
// terminators that preceed it.
|
|
for (unsigned i = 0, e = blockCSI.size(); i != e; ++i) {
|
|
TII.loadRegFromStackSlot(*MBB, I, blockCSI[i].getReg(),
|
|
blockCSI[i].getFrameIdx(),
|
|
blockCSI[i].getRegClass());
|
|
assert(I != MBB->begin() &&
|
|
"loadRegFromStackSlot didn't insert any code!");
|
|
// Insert in reverse order. loadRegFromStackSlot can insert
|
|
// multiple instructions.
|
|
if (AtStart)
|
|
I = MBB->begin();
|
|
else {
|
|
I = BeforeI;
|
|
++I;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// AdjustStackOffset - Helper function used to adjust the stack frame offset.
|
|
static inline void
|
|
AdjustStackOffset(MachineFrameInfo *FFI, int FrameIdx,
|
|
bool StackGrowsDown, int64_t &Offset,
|
|
unsigned &MaxAlign) {
|
|
// If stack grows down, we need to add size of find the lowest address of the
|
|
// object.
|
|
if (StackGrowsDown)
|
|
Offset += FFI->getObjectSize(FrameIdx);
|
|
|
|
unsigned Align = FFI->getObjectAlignment(FrameIdx);
|
|
|
|
// If the alignment of this object is greater than that of the stack, then
|
|
// increase the stack alignment to match.
|
|
MaxAlign = std::max(MaxAlign, Align);
|
|
|
|
// Adjust to alignment boundary.
|
|
Offset = (Offset + Align - 1) / Align * Align;
|
|
|
|
if (StackGrowsDown) {
|
|
FFI->setObjectOffset(FrameIdx, -Offset); // Set the computed offset
|
|
} else {
|
|
FFI->setObjectOffset(FrameIdx, Offset);
|
|
Offset += FFI->getObjectSize(FrameIdx);
|
|
}
|
|
}
|
|
|
|
/// calculateFrameObjectOffsets - Calculate actual frame offsets for all of the
|
|
/// abstract stack objects.
|
|
///
|
|
void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
|
|
const TargetFrameInfo &TFI = *Fn.getTarget().getFrameInfo();
|
|
|
|
bool StackGrowsDown =
|
|
TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
|
|
|
|
// Loop over all of the stack objects, assigning sequential addresses...
|
|
MachineFrameInfo *FFI = Fn.getFrameInfo();
|
|
|
|
unsigned MaxAlign = FFI->getMaxAlignment();
|
|
|
|
// Start at the beginning of the local area.
|
|
// The Offset is the distance from the stack top in the direction
|
|
// of stack growth -- so it's always nonnegative.
|
|
int64_t Offset = TFI.getOffsetOfLocalArea();
|
|
if (StackGrowsDown)
|
|
Offset = -Offset;
|
|
assert(Offset >= 0
|
|
&& "Local area offset should be in direction of stack growth");
|
|
|
|
// If there are fixed sized objects that are preallocated in the local area,
|
|
// non-fixed objects can't be allocated right at the start of local area.
|
|
// We currently don't support filling in holes in between fixed sized
|
|
// objects, so we adjust 'Offset' to point to the end of last fixed sized
|
|
// preallocated object.
|
|
for (int i = FFI->getObjectIndexBegin(); i != 0; ++i) {
|
|
int64_t FixedOff;
|
|
if (StackGrowsDown) {
|
|
// The maximum distance from the stack pointer is at lower address of
|
|
// the object -- which is given by offset. For down growing stack
|
|
// the offset is negative, so we negate the offset to get the distance.
|
|
FixedOff = -FFI->getObjectOffset(i);
|
|
} else {
|
|
// The maximum distance from the start pointer is at the upper
|
|
// address of the object.
|
|
FixedOff = FFI->getObjectOffset(i) + FFI->getObjectSize(i);
|
|
}
|
|
if (FixedOff > Offset) Offset = FixedOff;
|
|
}
|
|
|
|
// First assign frame offsets to stack objects that are used to spill
|
|
// callee saved registers.
|
|
if (StackGrowsDown) {
|
|
for (unsigned i = MinCSFrameIndex; i <= MaxCSFrameIndex; ++i) {
|
|
// If stack grows down, we need to add size of find the lowest
|
|
// address of the object.
|
|
Offset += FFI->getObjectSize(i);
|
|
|
|
unsigned Align = FFI->getObjectAlignment(i);
|
|
// If the alignment of this object is greater than that of the stack,
|
|
// then increase the stack alignment to match.
|
|
MaxAlign = std::max(MaxAlign, Align);
|
|
// Adjust to alignment boundary
|
|
Offset = (Offset+Align-1)/Align*Align;
|
|
|
|
FFI->setObjectOffset(i, -Offset); // Set the computed offset
|
|
}
|
|
} else {
|
|
int MaxCSFI = MaxCSFrameIndex, MinCSFI = MinCSFrameIndex;
|
|
for (int i = MaxCSFI; i >= MinCSFI ; --i) {
|
|
unsigned Align = FFI->getObjectAlignment(i);
|
|
// If the alignment of this object is greater than that of the stack,
|
|
// then increase the stack alignment to match.
|
|
MaxAlign = std::max(MaxAlign, Align);
|
|
// Adjust to alignment boundary
|
|
Offset = (Offset+Align-1)/Align*Align;
|
|
|
|
FFI->setObjectOffset(i, Offset);
|
|
Offset += FFI->getObjectSize(i);
|
|
}
|
|
}
|
|
|
|
// Make sure the special register scavenging spill slot is closest to the
|
|
// frame pointer if a frame pointer is required.
|
|
const TargetRegisterInfo *RegInfo = Fn.getTarget().getRegisterInfo();
|
|
if (RS && RegInfo->hasFP(Fn)) {
|
|
int SFI = RS->getScavengingFrameIndex();
|
|
if (SFI >= 0)
|
|
AdjustStackOffset(FFI, SFI, StackGrowsDown, Offset, MaxAlign);
|
|
}
|
|
|
|
// Make sure that the stack protector comes before the local variables on the
|
|
// stack.
|
|
if (FFI->getStackProtectorIndex() >= 0)
|
|
AdjustStackOffset(FFI, FFI->getStackProtectorIndex(), StackGrowsDown,
|
|
Offset, MaxAlign);
|
|
|
|
// Then assign frame offsets to stack objects that are not used to spill
|
|
// callee saved registers.
|
|
for (unsigned i = 0, e = FFI->getObjectIndexEnd(); i != e; ++i) {
|
|
if (i >= MinCSFrameIndex && i <= MaxCSFrameIndex)
|
|
continue;
|
|
if (RS && (int)i == RS->getScavengingFrameIndex())
|
|
continue;
|
|
if (FFI->isDeadObjectIndex(i))
|
|
continue;
|
|
if (FFI->getStackProtectorIndex() == (int)i)
|
|
continue;
|
|
|
|
AdjustStackOffset(FFI, i, StackGrowsDown, Offset, MaxAlign);
|
|
}
|
|
|
|
// Make sure the special register scavenging spill slot is closest to the
|
|
// stack pointer.
|
|
if (RS && !RegInfo->hasFP(Fn)) {
|
|
int SFI = RS->getScavengingFrameIndex();
|
|
if (SFI >= 0)
|
|
AdjustStackOffset(FFI, SFI, StackGrowsDown, Offset, MaxAlign);
|
|
}
|
|
|
|
// Round up the size to a multiple of the alignment, but only if there are
|
|
// calls or alloca's in the function. This ensures that any calls to
|
|
// subroutines have their stack frames suitable aligned.
|
|
// Also do this if we need runtime alignment of the stack. In this case
|
|
// offsets will be relative to SP not FP; round up the stack size so this
|
|
// works.
|
|
if (!RegInfo->targetHandlesStackFrameRounding() &&
|
|
(FFI->hasCalls() || FFI->hasVarSizedObjects() ||
|
|
(RegInfo->needsStackRealignment(Fn) &&
|
|
FFI->getObjectIndexEnd() != 0))) {
|
|
// If we have reserved argument space for call sites in the function
|
|
// immediately on entry to the current function, count it as part of the
|
|
// overall stack size.
|
|
if (RegInfo->hasReservedCallFrame(Fn))
|
|
Offset += FFI->getMaxCallFrameSize();
|
|
|
|
unsigned AlignMask = std::max(TFI.getStackAlignment(),MaxAlign) - 1;
|
|
Offset = (Offset + AlignMask) & ~uint64_t(AlignMask);
|
|
}
|
|
|
|
// Update frame info to pretend that this is part of the stack...
|
|
FFI->setStackSize(Offset+TFI.getOffsetOfLocalArea());
|
|
|
|
// Remember the required stack alignment in case targets need it to perform
|
|
// dynamic stack alignment.
|
|
FFI->setMaxAlignment(MaxAlign);
|
|
}
|
|
|
|
|
|
/// insertPrologEpilogCode - Scan the function for modified callee saved
|
|
/// registers, insert spill code for these callee saved registers, then add
|
|
/// prolog and epilog code to the function.
|
|
///
|
|
void PEI::insertPrologEpilogCode(MachineFunction &Fn) {
|
|
const TargetRegisterInfo *TRI = Fn.getTarget().getRegisterInfo();
|
|
|
|
// Add prologue to the function...
|
|
TRI->emitPrologue(Fn);
|
|
|
|
// 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().getDesc().isReturn())
|
|
TRI->emitEpilogue(Fn, *I);
|
|
}
|
|
}
|
|
|
|
|
|
/// replaceFrameIndices - Replace all MO_FrameIndex operands with physical
|
|
/// register references and actual offsets.
|
|
///
|
|
void PEI::replaceFrameIndices(MachineFunction &Fn) {
|
|
if (!Fn.getFrameInfo()->hasStackObjects()) return; // Nothing to do?
|
|
|
|
const TargetMachine &TM = Fn.getTarget();
|
|
assert(TM.getRegisterInfo() && "TM::getRegisterInfo() must be implemented!");
|
|
const TargetRegisterInfo &TRI = *TM.getRegisterInfo();
|
|
const TargetFrameInfo *TFI = TM.getFrameInfo();
|
|
bool StackGrowsDown =
|
|
TFI->getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
|
|
int FrameSetupOpcode = TRI.getCallFrameSetupOpcode();
|
|
int FrameDestroyOpcode = TRI.getCallFrameDestroyOpcode();
|
|
|
|
for (MachineFunction::iterator BB = Fn.begin(),
|
|
E = Fn.end(); BB != E; ++BB) {
|
|
int SPAdj = 0; // SP offset due to call frame setup / destroy.
|
|
if (RS) RS->enterBasicBlock(BB);
|
|
|
|
for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ) {
|
|
if (I->getOpcode() == TargetInstrInfo::DECLARE) {
|
|
// Ignore it.
|
|
++I;
|
|
continue;
|
|
}
|
|
|
|
if (I->getOpcode() == FrameSetupOpcode ||
|
|
I->getOpcode() == FrameDestroyOpcode) {
|
|
// Remember how much SP has been adjusted to create the call
|
|
// frame.
|
|
int Size = I->getOperand(0).getImm();
|
|
|
|
if ((!StackGrowsDown && I->getOpcode() == FrameSetupOpcode) ||
|
|
(StackGrowsDown && I->getOpcode() == FrameDestroyOpcode))
|
|
Size = -Size;
|
|
|
|
SPAdj += Size;
|
|
|
|
MachineBasicBlock::iterator PrevI = BB->end();
|
|
if (I != BB->begin()) PrevI = prior(I);
|
|
TRI.eliminateCallFramePseudoInstr(Fn, *BB, I);
|
|
|
|
// Visit the instructions created by eliminateCallFramePseudoInstr().
|
|
if (PrevI == BB->end())
|
|
I = BB->begin(); // The replaced instr was the first in the block.
|
|
else
|
|
I = next(PrevI);
|
|
continue;
|
|
}
|
|
|
|
MachineInstr *MI = I;
|
|
bool DoIncr = true;
|
|
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i)
|
|
if (MI->getOperand(i).isFI()) {
|
|
// Some instructions (e.g. inline asm instructions) can have
|
|
// multiple frame indices and/or cause eliminateFrameIndex
|
|
// to insert more than one instruction. We need the register
|
|
// scavenger to go through all of these instructions so that
|
|
// it can update its register information. We keep the
|
|
// iterator at the point before insertion so that we can
|
|
// revisit them in full.
|
|
bool AtBeginning = (I == BB->begin());
|
|
if (!AtBeginning) --I;
|
|
|
|
// If this instruction has a FrameIndex operand, we need to
|
|
// use that target machine register info object to eliminate
|
|
// it.
|
|
|
|
TRI.eliminateFrameIndex(MI, SPAdj, RS);
|
|
|
|
// Reset the iterator if we were at the beginning of the BB.
|
|
if (AtBeginning) {
|
|
I = BB->begin();
|
|
DoIncr = false;
|
|
}
|
|
|
|
MI = 0;
|
|
break;
|
|
}
|
|
|
|
if (DoIncr && I != BB->end()) ++I;
|
|
|
|
// Update register states.
|
|
if (RS && MI) RS->forward(MI);
|
|
}
|
|
|
|
assert(SPAdj == 0 && "Unbalanced call frame setup / destroy pairs?");
|
|
}
|
|
}
|