mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-25 00:29:20 +00:00
Rewrite LoopRotation's SSA updating code using SSAUpdater.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85016 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
parent
a3f85d206a
commit
e6e37b94e8
@ -21,6 +21,7 @@
|
||||
#include "llvm/Analysis/ScalarEvolution.h"
|
||||
#include "llvm/Transforms/Utils/Local.h"
|
||||
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
|
||||
#include "llvm/Transforms/Utils/SSAUpdater.h"
|
||||
#include "llvm/Support/CommandLine.h"
|
||||
#include "llvm/Support/Debug.h"
|
||||
#include "llvm/ADT/Statistic.h"
|
||||
@ -32,16 +33,6 @@ using namespace llvm;
|
||||
STATISTIC(NumRotated, "Number of loops rotated");
|
||||
namespace {
|
||||
|
||||
class RenameData {
|
||||
public:
|
||||
RenameData(Instruction *O, Value *P, Instruction *H)
|
||||
: Original(O), PreHeader(P), Header(H) { }
|
||||
public:
|
||||
Instruction *Original; // Original instruction
|
||||
Value *PreHeader; // Original pre-header replacement
|
||||
Instruction *Header; // New header replacement
|
||||
};
|
||||
|
||||
class LoopRotate : public LoopPass {
|
||||
public:
|
||||
static char ID; // Pass ID, replacement for typeid
|
||||
@ -71,25 +62,12 @@ namespace {
|
||||
/// Initialize local data
|
||||
void initialize();
|
||||
|
||||
/// Make sure all Exit block PHINodes have required incoming values.
|
||||
/// If incoming value is constant or defined outside the loop then
|
||||
/// PHINode may not have an entry for original pre-header.
|
||||
void updateExitBlock();
|
||||
|
||||
/// Return true if this instruction is used outside original header.
|
||||
bool usedOutsideOriginalHeader(Instruction *In);
|
||||
|
||||
/// Find Replacement information for instruction. Return NULL if it is
|
||||
/// not available.
|
||||
const RenameData *findReplacementData(Instruction *I);
|
||||
|
||||
/// After loop rotation, loop pre-header has multiple sucessors.
|
||||
/// Insert one forwarding basic block to ensure that loop pre-header
|
||||
/// has only one successor.
|
||||
void preserveCanonicalLoopForm(LPPassManager &LPM);
|
||||
|
||||
private:
|
||||
|
||||
Loop *L;
|
||||
BasicBlock *OrigHeader;
|
||||
BasicBlock *OrigPreHeader;
|
||||
@ -97,7 +75,6 @@ namespace {
|
||||
BasicBlock *NewHeader;
|
||||
BasicBlock *Exit;
|
||||
LPPassManager *LPM_Ptr;
|
||||
SmallVector<RenameData, MAX_HEADER_SIZE> LoopHeaderInfo;
|
||||
};
|
||||
}
|
||||
|
||||
@ -199,168 +176,88 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
|
||||
"New header doesn't have one pred!");
|
||||
FoldSingleEntryPHINodes(NewHeader);
|
||||
|
||||
// Copy PHI nodes and other instructions from the original header
|
||||
// into the original pre-header. Unlike the original header, the original
|
||||
// pre-header is not a member of the loop.
|
||||
//
|
||||
// The new loop header is the one and only successor of original header that
|
||||
// is inside the loop. All other original header successors are outside
|
||||
// the loop. Copy PHI Nodes from the original header into the new loop header.
|
||||
// Add second incoming value, from original loop pre-header into these phi
|
||||
// nodes. If a value defined in original header is used outside original
|
||||
// header then new loop header will need new phi nodes with two incoming
|
||||
// values, one definition from original header and second definition is
|
||||
// from original loop pre-header.
|
||||
|
||||
// Remove terminator from Original pre-header. Original pre-header will
|
||||
// receive a clone of original header terminator as a new terminator.
|
||||
OrigPreHeader->getInstList().pop_back();
|
||||
// Begin by walking OrigHeader and populating ValueMap with an entry for
|
||||
// each Instruction.
|
||||
BasicBlock::iterator I = OrigHeader->begin(), E = OrigHeader->end();
|
||||
PHINode *PN = 0;
|
||||
for (; (PN = dyn_cast<PHINode>(I)); ++I) {
|
||||
// PHI nodes are not copied into original pre-header. Instead their values
|
||||
// are directly propagated.
|
||||
Value *NPV = PN->getIncomingValueForBlock(OrigPreHeader);
|
||||
DenseMap<const Value *, Value *> ValueMap;
|
||||
|
||||
// Create a new PHI node with two incoming values for NewHeader.
|
||||
// One incoming value is from OrigLatch (through OrigHeader) and the
|
||||
// second incoming value is from original pre-header.
|
||||
PHINode *NH = PHINode::Create(PN->getType(), PN->getName(),
|
||||
NewHeader->begin());
|
||||
NH->addIncoming(PN->getIncomingValueForBlock(OrigLatch), OrigHeader);
|
||||
NH->addIncoming(NPV, OrigPreHeader);
|
||||
|
||||
// "In" can be replaced by NH at various places.
|
||||
LoopHeaderInfo.push_back(RenameData(PN, NPV, NH));
|
||||
}
|
||||
// For PHI nodes, the value available in OldPreHeader is just the
|
||||
// incoming value from OldPreHeader.
|
||||
for (; PHINode *PN = dyn_cast<PHINode>(I); ++I)
|
||||
ValueMap[PN] = PN->getIncomingValue(PN->getBasicBlockIndex(OrigPreHeader));
|
||||
|
||||
// Now, handle non-phi instructions.
|
||||
// For the rest of the instructions, create a clone in the OldPreHeader.
|
||||
TerminatorInst *LoopEntryBranch = OrigPreHeader->getTerminator();
|
||||
for (; I != E; ++I) {
|
||||
Instruction *In = I;
|
||||
assert(!isa<PHINode>(In) && "PHINode is not expected here");
|
||||
|
||||
// This is not a PHI instruction. Insert its clone into original pre-header.
|
||||
// If this instruction is using a value from same basic block then
|
||||
// update it to use value from cloned instruction.
|
||||
Instruction *C = In->clone();
|
||||
C->setName(In->getName());
|
||||
OrigPreHeader->getInstList().push_back(C);
|
||||
|
||||
for (unsigned opi = 0, e = In->getNumOperands(); opi != e; ++opi) {
|
||||
Instruction *OpInsn = dyn_cast<Instruction>(In->getOperand(opi));
|
||||
if (!OpInsn) continue; // Ignore non-instruction values.
|
||||
if (const RenameData *D = findReplacementData(OpInsn))
|
||||
C->setOperand(opi, D->PreHeader);
|
||||
}
|
||||
|
||||
// If this instruction is used outside this basic block then
|
||||
// create new PHINode for this instruction.
|
||||
Instruction *NewHeaderReplacement = NULL;
|
||||
if (usedOutsideOriginalHeader(In)) {
|
||||
PHINode *PN = PHINode::Create(In->getType(), In->getName(),
|
||||
NewHeader->begin());
|
||||
PN->addIncoming(In, OrigHeader);
|
||||
PN->addIncoming(C, OrigPreHeader);
|
||||
NewHeaderReplacement = PN;
|
||||
}
|
||||
LoopHeaderInfo.push_back(RenameData(In, C, NewHeaderReplacement));
|
||||
Instruction *C = I->clone();
|
||||
C->setName(I->getName());
|
||||
C->insertBefore(LoopEntryBranch);
|
||||
ValueMap[I] = C;
|
||||
}
|
||||
|
||||
// Rename uses of original header instructions to reflect their new
|
||||
// definitions (either from original pre-header node or from newly created
|
||||
// new header PHINodes.
|
||||
//
|
||||
// Original header instructions are used in
|
||||
// 1) Original header:
|
||||
//
|
||||
// If instruction is used in non-phi instructions then it is using
|
||||
// defintion from original heder iteself. Do not replace this use
|
||||
// with definition from new header or original pre-header.
|
||||
//
|
||||
// If instruction is used in phi node then it is an incoming
|
||||
// value. Rename its use to reflect new definition from new-preheader
|
||||
// or new header.
|
||||
//
|
||||
// 2) Inside loop but not in original header
|
||||
//
|
||||
// Replace this use to reflect definition from new header.
|
||||
for (unsigned LHI = 0, LHI_E = LoopHeaderInfo.size(); LHI != LHI_E; ++LHI) {
|
||||
const RenameData &ILoopHeaderInfo = LoopHeaderInfo[LHI];
|
||||
// Along with all the other instructions, we just cloned OrigHeader's
|
||||
// terminator into OrigPreHeader. Fix up the PHI nodes in each of OrigHeader's
|
||||
// successors by duplicating their incoming values for OrigHeader.
|
||||
TerminatorInst *TI = OrigHeader->getTerminator();
|
||||
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
|
||||
for (BasicBlock::iterator BI = TI->getSuccessor(i)->begin();
|
||||
PHINode *PN = dyn_cast<PHINode>(BI); ++BI)
|
||||
PN->addIncoming(PN->getIncomingValueForBlock(OrigHeader), OrigPreHeader);
|
||||
|
||||
if (!ILoopHeaderInfo.Header)
|
||||
continue;
|
||||
// Now that OrigPreHeader has a clone of OrigHeader's terminator, remove
|
||||
// OrigPreHeader's old terminator (the original branch into the loop), and
|
||||
// remove the corresponding incoming values from the PHI nodes in OrigHeader.
|
||||
LoopEntryBranch->eraseFromParent();
|
||||
for (I = OrigHeader->begin(); PHINode *PN = dyn_cast<PHINode>(I); ++I)
|
||||
PN->removeIncomingValue(PN->getBasicBlockIndex(OrigPreHeader));
|
||||
|
||||
Instruction *OldPhi = ILoopHeaderInfo.Original;
|
||||
Instruction *NewPhi = ILoopHeaderInfo.Header;
|
||||
// Now fix up users of the instructions in OrigHeader, insertting PHI nodes
|
||||
// as necessary.
|
||||
SSAUpdater SSA;
|
||||
for (I = OrigHeader->begin(); I != E; ++I) {
|
||||
Value *OrigHeaderVal = I;
|
||||
Value *OrigPreHeaderVal = ValueMap[OrigHeaderVal];
|
||||
|
||||
// Before replacing uses, collect them first, so that iterator is
|
||||
// not invalidated.
|
||||
SmallVector<Instruction *, 16> AllUses;
|
||||
for (Value::use_iterator UI = OldPhi->use_begin(), UE = OldPhi->use_end();
|
||||
UI != UE; ++UI)
|
||||
AllUses.push_back(cast<Instruction>(UI));
|
||||
// The value now exits in two versions: the initial value in the preheader
|
||||
// and the loop "next" value in the original header.
|
||||
SSA.Initialize(OrigHeaderVal);
|
||||
SSA.AddAvailableValue(OrigHeader, OrigHeaderVal);
|
||||
SSA.AddAvailableValue(OrigPreHeader, OrigPreHeaderVal);
|
||||
|
||||
for (SmallVector<Instruction *, 16>::iterator UI = AllUses.begin(),
|
||||
UE = AllUses.end(); UI != UE; ++UI) {
|
||||
Instruction *U = *UI;
|
||||
BasicBlock *Parent = U->getParent();
|
||||
// Visit each use of the OrigHeader instruction.
|
||||
for (Value::use_iterator UI = OrigHeaderVal->use_begin(),
|
||||
UE = OrigHeaderVal->use_end(); UI != UE; ) {
|
||||
// Grab the use before incrementing the iterator.
|
||||
Use &U = UI.getUse();
|
||||
|
||||
// Used inside original header
|
||||
if (Parent == OrigHeader) {
|
||||
// Do not rename uses inside original header non-phi instructions.
|
||||
PHINode *PU = dyn_cast<PHINode>(U);
|
||||
if (!PU)
|
||||
// Increment the iterator before removing the use from the list.
|
||||
++UI;
|
||||
|
||||
// SSAUpdater can't handle a non-PHI use in the same block as an
|
||||
// earlier def. We can easily handle those cases manually.
|
||||
Instruction *UserInst = cast<Instruction>(U.getUser());
|
||||
if (!isa<PHINode>(UserInst)) {
|
||||
BasicBlock *UserBB = UserInst->getParent();
|
||||
|
||||
// The original users in the OrigHeader are already using the
|
||||
// original definitions.
|
||||
if (UserBB == OrigHeader)
|
||||
continue;
|
||||
|
||||
// Do not rename uses inside original header phi nodes, if the
|
||||
// incoming value is for new header.
|
||||
if (PU->getBasicBlockIndex(NewHeader) != -1
|
||||
&& PU->getIncomingValueForBlock(NewHeader) == U)
|
||||
// Users in the OrigPreHeader need to use the value to which the
|
||||
// original definitions are mapped.
|
||||
if (UserBB == OrigPreHeader) {
|
||||
U = OrigPreHeaderVal;
|
||||
continue;
|
||||
|
||||
U->replaceUsesOfWith(OldPhi, NewPhi);
|
||||
continue;
|
||||
}
|
||||
}
|
||||
|
||||
// Used inside loop, but not in original header.
|
||||
if (L->contains(U->getParent())) {
|
||||
if (U != NewPhi)
|
||||
U->replaceUsesOfWith(OldPhi, NewPhi);
|
||||
continue;
|
||||
}
|
||||
|
||||
// Used inside Exit Block. Since we are in LCSSA form, U must be PHINode.
|
||||
if (U->getParent() == Exit) {
|
||||
assert(isa<PHINode>(U) && "Use in Exit Block that is not PHINode");
|
||||
|
||||
PHINode *UPhi = cast<PHINode>(U);
|
||||
// UPhi already has one incoming argument from original header.
|
||||
// Add second incoming argument from new Pre header.
|
||||
UPhi->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
|
||||
} else {
|
||||
// Used outside Exit block. Create a new PHI node in the exit block
|
||||
// to receive the value from the new header and pre-header.
|
||||
PHINode *PN = PHINode::Create(U->getType(), U->getName(),
|
||||
Exit->begin());
|
||||
PN->addIncoming(ILoopHeaderInfo.PreHeader, OrigPreHeader);
|
||||
PN->addIncoming(OldPhi, OrigHeader);
|
||||
U->replaceUsesOfWith(OldPhi, PN);
|
||||
}
|
||||
// Anything else can be handled by SSAUpdater.
|
||||
SSA.RewriteUse(U);
|
||||
}
|
||||
}
|
||||
|
||||
/// Make sure all Exit block PHINodes have required incoming values.
|
||||
updateExitBlock();
|
||||
|
||||
// Update CFG
|
||||
|
||||
// Removing incoming branch from loop preheader to original header.
|
||||
// Now original header is inside the loop.
|
||||
for (BasicBlock::iterator I = OrigHeader->begin();
|
||||
(PN = dyn_cast<PHINode>(I)); ++I)
|
||||
PN->removeIncomingValue(OrigPreHeader);
|
||||
|
||||
// Make NewHeader as the new header for the loop.
|
||||
// NewHeader is now the header of the loop.
|
||||
L->moveToHeader(NewHeader);
|
||||
|
||||
preserveCanonicalLoopForm(LPM);
|
||||
@ -369,31 +266,6 @@ bool LoopRotate::rotateLoop(Loop *Lp, LPPassManager &LPM) {
|
||||
return true;
|
||||
}
|
||||
|
||||
/// Make sure all Exit block PHINodes have required incoming values.
|
||||
/// If an incoming value is constant or defined outside the loop then
|
||||
/// PHINode may not have an entry for the original pre-header.
|
||||
void LoopRotate::updateExitBlock() {
|
||||
|
||||
PHINode *PN;
|
||||
for (BasicBlock::iterator I = Exit->begin();
|
||||
(PN = dyn_cast<PHINode>(I)); ++I) {
|
||||
|
||||
// There is already one incoming value from original pre-header block.
|
||||
if (PN->getBasicBlockIndex(OrigPreHeader) != -1)
|
||||
continue;
|
||||
|
||||
const RenameData *ILoopHeaderInfo;
|
||||
Value *V = PN->getIncomingValueForBlock(OrigHeader);
|
||||
if (isa<Instruction>(V) &&
|
||||
(ILoopHeaderInfo = findReplacementData(cast<Instruction>(V)))) {
|
||||
assert(ILoopHeaderInfo->PreHeader && "Missing New Preheader Instruction");
|
||||
PN->addIncoming(ILoopHeaderInfo->PreHeader, OrigPreHeader);
|
||||
} else {
|
||||
PN->addIncoming(V, OrigPreHeader);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Initialize local data
|
||||
void LoopRotate::initialize() {
|
||||
L = NULL;
|
||||
@ -401,34 +273,6 @@ void LoopRotate::initialize() {
|
||||
OrigPreHeader = NULL;
|
||||
NewHeader = NULL;
|
||||
Exit = NULL;
|
||||
|
||||
LoopHeaderInfo.clear();
|
||||
}
|
||||
|
||||
/// Return true if this instruction is used by any instructions in the loop that
|
||||
/// aren't in original header.
|
||||
bool LoopRotate::usedOutsideOriginalHeader(Instruction *In) {
|
||||
for (Value::use_iterator UI = In->use_begin(), UE = In->use_end();
|
||||
UI != UE; ++UI) {
|
||||
BasicBlock *UserBB = cast<Instruction>(UI)->getParent();
|
||||
if (UserBB != OrigHeader && L->contains(UserBB))
|
||||
return true;
|
||||
}
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
/// Find Replacement information for instruction. Return NULL if it is
|
||||
/// not available.
|
||||
const RenameData *LoopRotate::findReplacementData(Instruction *In) {
|
||||
|
||||
// Since LoopHeaderInfo is small, linear walk is OK.
|
||||
for (unsigned LHI = 0, LHI_E = LoopHeaderInfo.size(); LHI != LHI_E; ++LHI) {
|
||||
const RenameData &ILoopHeaderInfo = LoopHeaderInfo[LHI];
|
||||
if (ILoopHeaderInfo.Original == In)
|
||||
return &ILoopHeaderInfo;
|
||||
}
|
||||
return NULL;
|
||||
}
|
||||
|
||||
/// After loop rotation, loop pre-header has multiple sucessors.
|
||||
|
Loading…
Reference in New Issue
Block a user