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Diffstat (limited to 'lib/Target/PowerPC/PPCCTRLoops.cpp')
-rw-r--r--lib/Target/PowerPC/PPCCTRLoops.cpp86
1 files changed, 64 insertions, 22 deletions
diff --git a/lib/Target/PowerPC/PPCCTRLoops.cpp b/lib/Target/PowerPC/PPCCTRLoops.cpp
index fc638829378a..6b9e2383e36f 100644
--- a/lib/Target/PowerPC/PPCCTRLoops.cpp
+++ b/lib/Target/PowerPC/PPCCTRLoops.cpp
@@ -30,11 +30,14 @@
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/CodeMetrics.h"
#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/LoopIterator.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/Transforms/Utils/Local.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/CodeGen/TargetSchedule.h"
#include "llvm/IR/Constants.h"
@@ -50,8 +53,8 @@
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/LoopUtils.h"
#ifndef NDEBUG
@@ -403,15 +406,16 @@ bool PPCCTRLoops::mightUseCTR(BasicBlock *BB) {
}
if (Opcode) {
- MVT VTy = TLI->getSimpleValueType(
- *DL, CI->getArgOperand(0)->getType(), true);
- if (VTy == MVT::Other)
+ EVT EVTy =
+ TLI->getValueType(*DL, CI->getArgOperand(0)->getType(), true);
+
+ if (EVTy == MVT::Other)
return true;
- if (TLI->isOperationLegalOrCustom(Opcode, VTy))
+ if (TLI->isOperationLegalOrCustom(Opcode, EVTy))
continue;
- else if (VTy.isVector() &&
- TLI->isOperationLegalOrCustom(Opcode, VTy.getScalarType()))
+ else if (EVTy.isVector() &&
+ TLI->isOperationLegalOrCustom(Opcode, EVTy.getScalarType()))
continue;
return true;
@@ -454,13 +458,16 @@ bool PPCCTRLoops::mightUseCTR(BasicBlock *BB) {
return true;
}
+ // FREM is always a call.
+ if (J->getOpcode() == Instruction::FRem)
+ return true;
+
if (STI->useSoftFloat()) {
switch(J->getOpcode()) {
case Instruction::FAdd:
case Instruction::FSub:
case Instruction::FMul:
case Instruction::FDiv:
- case Instruction::FRem:
case Instruction::FPTrunc:
case Instruction::FPExt:
case Instruction::FPToUI:
@@ -500,13 +507,19 @@ bool PPCCTRLoops::convertToCTRLoop(Loop *L) {
// Process nested loops first.
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) {
MadeChange |= convertToCTRLoop(*I);
- DEBUG(dbgs() << "Nested loop converted\n");
+ LLVM_DEBUG(dbgs() << "Nested loop converted\n");
}
// If a nested loop has been converted, then we can't convert this loop.
if (MadeChange)
return MadeChange;
+ // Bail out if the loop has irreducible control flow.
+ LoopBlocksRPO RPOT(L);
+ RPOT.perform(LI);
+ if (containsIrreducibleCFG<const BasicBlock *>(RPOT, *LI))
+ return false;
+
#ifndef NDEBUG
// Stop trying after reaching the limit (if any).
int Limit = CTRLoopLimit;
@@ -527,14 +540,35 @@ bool PPCCTRLoops::convertToCTRLoop(Loop *L) {
SmallVector<BasicBlock*, 4> ExitingBlocks;
L->getExitingBlocks(ExitingBlocks);
+ // If there is an exit edge known to be frequently taken,
+ // we should not transform this loop.
+ for (auto &BB : ExitingBlocks) {
+ Instruction *TI = BB->getTerminator();
+ if (!TI) continue;
+
+ if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
+ uint64_t TrueWeight = 0, FalseWeight = 0;
+ if (!BI->isConditional() ||
+ !BI->extractProfMetadata(TrueWeight, FalseWeight))
+ continue;
+
+ // If the exit path is more frequent than the loop path,
+ // we return here without further analysis for this loop.
+ bool TrueIsExit = !L->contains(BI->getSuccessor(0));
+ if (( TrueIsExit && FalseWeight < TrueWeight) ||
+ (!TrueIsExit && FalseWeight > TrueWeight))
+ return MadeChange;
+ }
+ }
+
BasicBlock *CountedExitBlock = nullptr;
const SCEV *ExitCount = nullptr;
BranchInst *CountedExitBranch = nullptr;
for (SmallVectorImpl<BasicBlock *>::iterator I = ExitingBlocks.begin(),
IE = ExitingBlocks.end(); I != IE; ++I) {
const SCEV *EC = SE->getExitCount(L, *I);
- DEBUG(dbgs() << "Exit Count for " << *L << " from block " <<
- (*I)->getName() << ": " << *EC << "\n");
+ LLVM_DEBUG(dbgs() << "Exit Count for " << *L << " from block "
+ << (*I)->getName() << ": " << *EC << "\n");
if (isa<SCEVCouldNotCompute>(EC))
continue;
if (const SCEVConstant *ConstEC = dyn_cast<SCEVConstant>(EC)) {
@@ -546,9 +580,15 @@ bool PPCCTRLoops::convertToCTRLoop(Loop *L) {
if (SE->getTypeSizeInBits(EC->getType()) > (TM->isPPC64() ? 64 : 32))
continue;
+ // If this exiting block is contained in a nested loop, it is not eligible
+ // for insertion of the branch-and-decrement since the inner loop would
+ // end up messing up the value in the CTR.
+ if (LI->getLoopFor(*I) != L)
+ continue;
+
// We now have a loop-invariant count of loop iterations (which is not the
// constant zero) for which we know that this loop will not exit via this
- // exisiting block.
+ // existing block.
// We need to make sure that this block will run on every loop iteration.
// For this to be true, we must dominate all blocks with backedges. Such
@@ -602,7 +642,8 @@ bool PPCCTRLoops::convertToCTRLoop(Loop *L) {
if (!Preheader)
return MadeChange;
- DEBUG(dbgs() << "Preheader for exit count: " << Preheader->getName() << "\n");
+ LLVM_DEBUG(dbgs() << "Preheader for exit count: " << Preheader->getName()
+ << "\n");
// Insert the count into the preheader and replace the condition used by the
// selected branch.
@@ -690,11 +731,12 @@ check_block:
}
if (I != BI && clobbersCTR(*I)) {
- DEBUG(dbgs() << printMBBReference(*MBB) << " (" << MBB->getFullName()
- << ") instruction " << *I << " clobbers CTR, invalidating "
- << printMBBReference(*BI->getParent()) << " ("
- << BI->getParent()->getFullName() << ") instruction " << *BI
- << "\n");
+ LLVM_DEBUG(dbgs() << printMBBReference(*MBB) << " (" << MBB->getFullName()
+ << ") instruction " << *I
+ << " clobbers CTR, invalidating "
+ << printMBBReference(*BI->getParent()) << " ("
+ << BI->getParent()->getFullName() << ") instruction "
+ << *BI << "\n");
return false;
}
@@ -708,10 +750,10 @@ check_block:
if (CheckPreds) {
queue_preds:
if (MachineFunction::iterator(MBB) == MBB->getParent()->begin()) {
- DEBUG(dbgs() << "Unable to find a MTCTR instruction for "
- << printMBBReference(*BI->getParent()) << " ("
- << BI->getParent()->getFullName() << ") instruction " << *BI
- << "\n");
+ LLVM_DEBUG(dbgs() << "Unable to find a MTCTR instruction for "
+ << printMBBReference(*BI->getParent()) << " ("
+ << BI->getParent()->getFullName() << ") instruction "
+ << *BI << "\n");
return false;
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-09 22:29:29 +0000