[CodeGenPrepare] Fix ModifiedDT flag in optimizeSelectInst
r44412 fixed a huge compile time regression but it needed ModifiedDT flag to be
maintained correctly in optimizations in optimizeBlock() and optimizeInst().
Function optimizeSelectInst() does not update the flag.
This patch propagates the flag in optimizeSelectInst() back to
optimizeBlock().
This patch also removes ModifiedDT in CodeGenPrepare class (which is not used).
The property of ModifiedDT is now recorded in a ref parameter.
Differential Revision: https://reviews.llvm.org/D59139
llvm-svn: 355751
diff --git a/llvm/lib/CodeGen/CodeGenPrepare.cpp b/llvm/lib/CodeGen/CodeGenPrepare.cpp
index ab11df2..57182f6 100644
--- a/llvm/lib/CodeGen/CodeGenPrepare.cpp
+++ b/llvm/lib/CodeGen/CodeGenPrepare.cpp
@@ -291,9 +291,6 @@
/// Keep track of SExt promoted.
ValueToSExts ValToSExtendedUses;
- /// True if CFG is modified in any way.
- bool ModifiedDT;
-
/// True if optimizing for size.
bool OptSize;
@@ -354,11 +351,11 @@
bool optimizeExt(Instruction *&I);
bool optimizeExtUses(Instruction *I);
bool optimizeLoadExt(LoadInst *Load);
- bool optimizeSelectInst(SelectInst *SI);
+ bool optimizeSelectInst(SelectInst *SI, bool &ModifiedDT);
bool optimizeShuffleVectorInst(ShuffleVectorInst *SVI);
bool optimizeSwitchInst(SwitchInst *SI);
bool optimizeExtractElementInst(Instruction *Inst);
- bool dupRetToEnableTailCallOpts(BasicBlock *BB);
+ bool dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT);
bool placeDbgValues(Function &F);
bool canFormExtLd(const SmallVectorImpl<Instruction *> &MovedExts,
LoadInst *&LI, Instruction *&Inst, bool HasPromoted);
@@ -373,7 +370,7 @@
bool AllowPromotionWithoutCommonHeader,
bool HasPromoted, TypePromotionTransaction &TPT,
SmallVectorImpl<Instruction *> &SpeculativelyMovedExts);
- bool splitBranchCondition(Function &F);
+ bool splitBranchCondition(Function &F, bool &ModifiedDT);
bool simplifyOffsetableRelocate(Instruction &I);
bool tryToSinkFreeOperands(Instruction *I);
@@ -402,7 +399,6 @@
InsertedInsts.clear();
PromotedInsts.clear();
- ModifiedDT = false;
if (auto *TPC = getAnalysisIfAvailable<TargetPassConfig>()) {
TM = &TPC->getTM<TargetMachine>();
SubtargetInfo = TM->getSubtargetImpl(F);
@@ -445,8 +441,9 @@
// unconditional branch.
EverMadeChange |= eliminateMostlyEmptyBlocks(F);
+ bool ModifiedDT = false;
if (!DisableBranchOpts)
- EverMadeChange |= splitBranchCondition(F);
+ EverMadeChange |= splitBranchCondition(F, ModifiedDT);
// Split some critical edges where one of the sources is an indirect branch,
// to help generate sane code for PHIs involving such edges.
@@ -1956,7 +1953,7 @@
/// %tmp2 = tail call i32 @f2()
/// ret i32 %tmp2
/// @endcode
-bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB) {
+bool CodeGenPrepare::dupRetToEnableTailCallOpts(BasicBlock *BB, bool &ModifiedDT) {
if (!TLI)
return false;
@@ -5863,7 +5860,7 @@
/// If we have a SelectInst that will likely profit from branch prediction,
/// turn it into a branch.
-bool CodeGenPrepare::optimizeSelectInst(SelectInst *SI) {
+bool CodeGenPrepare::optimizeSelectInst(SelectInst *SI, bool &ModifiedDT) {
// If branch conversion isn't desirable, exit early.
if (DisableSelectToBranch || OptSize || !TLI)
return false;
@@ -6957,7 +6954,7 @@
return optimizeCallInst(CI, ModifiedDT);
if (SelectInst *SI = dyn_cast<SelectInst>(I))
- return optimizeSelectInst(SI);
+ return optimizeSelectInst(SI, ModifiedDT);
if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(I))
return optimizeShuffleVectorInst(SVI);
@@ -7015,7 +7012,7 @@
}
}
}
- MadeChange |= dupRetToEnableTailCallOpts(&BB);
+ MadeChange |= dupRetToEnableTailCallOpts(&BB, ModifiedDT);
return MadeChange;
}
@@ -7091,7 +7088,7 @@
///
/// FIXME: Remove the (equivalent?) implementation in SelectionDAG.
///
-bool CodeGenPrepare::splitBranchCondition(Function &F) {
+bool CodeGenPrepare::splitBranchCondition(Function &F, bool &ModifiedDT) {
if (!TM || !TM->Options.EnableFastISel || !TLI || TLI->isJumpExpensive())
return false;
@@ -7248,10 +7245,7 @@
}
}
- // Note: No point in getting fancy here, since the DT info is never
- // available to CodeGenPrepare.
ModifiedDT = true;
-
MadeChange = true;
LLVM_DEBUG(dbgs() << "After branch condition splitting\n"; BB.dump();