Extended replaceCongruentPhis to handle mixed phi types.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147707 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index a82ac47..0c4bb82 100644
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -19,6 +19,7 @@
#include "llvm/LLVMContext.h"
#include "llvm/Support/Debug.h"
#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLowering.h"
#include "llvm/ADT/STLExtras.h"
using namespace llvm;
@@ -1557,6 +1558,15 @@
return true;
}
+/// Sort Phis by integer width for replaceCongruentIVs.
+static bool width_descending(PHINode *lhs, PHINode *rhs) {
+ // Put pointers at the back and make sure pointer < pointer = false.
+ if (!lhs->getType()->isIntegerTy() || !rhs->getType()->isIntegerTy())
+ return rhs->getType()->isIntegerTy() && !lhs->getType()->isIntegerTy();
+ return rhs->getType()->getPrimitiveSizeInBits()
+ < lhs->getType()->getPrimitiveSizeInBits();
+}
+
/// replaceCongruentIVs - Check for congruent phis in this loop header and
/// replace them with their most canonical representative. Return the number of
/// phis eliminated.
@@ -1564,23 +1574,45 @@
/// This does not depend on any SCEVExpander state but should be used in
/// the same context that SCEVExpander is used.
unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
- SmallVectorImpl<WeakVH> &DeadInsts) {
+ SmallVectorImpl<WeakVH> &DeadInsts,
+ const TargetLowering *TLI) {
+ // Find integer phis in order of increasing width.
+ SmallVector<PHINode*, 8> Phis;
+ for (BasicBlock::iterator I = L->getHeader()->begin();
+ PHINode *Phi = dyn_cast<PHINode>(I); ++I) {
+ Phis.push_back(Phi);
+ }
+ if (TLI)
+ std::sort(Phis.begin(), Phis.end(), width_descending);
+
unsigned NumElim = 0;
DenseMap<const SCEV *, PHINode *> ExprToIVMap;
- for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I) {
- PHINode *Phi = cast<PHINode>(I);
+ // Process phis from wide to narrow. Mapping wide phis to the their truncation
+ // so narrow phis can reuse them.
+ for (SmallVectorImpl<PHINode*>::const_iterator PIter = Phis.begin(),
+ PEnd = Phis.end(); PIter != PEnd; ++PIter) {
+ PHINode *Phi = *PIter;
+
if (!SE.isSCEVable(Phi->getType()))
continue;
PHINode *&OrigPhiRef = ExprToIVMap[SE.getSCEV(Phi)];
if (!OrigPhiRef) {
OrigPhiRef = Phi;
+ if (Phi->getType()->isIntegerTy() && TLI
+ && TLI->isTruncateFree(Phi->getType(), Phis.back()->getType())) {
+ // This phi can be freely truncated to the narrowest phi type. Map the
+ // truncated expression to it so it will be reused for narrow types.
+ const SCEV *TruncExpr =
+ SE.getTruncateExpr(SE.getSCEV(Phi), Phis.back()->getType());
+ ExprToIVMap[TruncExpr] = Phi;
+ }
continue;
}
- // If one phi derives from the other via GEPs, types may differ.
- // We could consider adding a bitcast here to handle it.
- if (OrigPhiRef->getType() != Phi->getType())
+ // Replacing a pointer phi with an integer phi or vice-versa doesn't make
+ // sense.
+ if (OrigPhiRef->getType()->isPointerTy() != Phi->getType()->isPointerTy())
continue;
if (BasicBlock *LatchBlock = L->getLoopLatch()) {
@@ -1589,8 +1621,10 @@
Instruction *IsomorphicInc =
cast<Instruction>(Phi->getIncomingValueForBlock(LatchBlock));
- // If this phi is more canonical, swap it with the original.
- if (!isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L)
+ // If this phi has the same width but is more canonical, replace the
+ // original with it.
+ if (OrigPhiRef->getType() == Phi->getType()
+ && !isExpandedAddRecExprPHI(OrigPhiRef, OrigInc, L)
&& isExpandedAddRecExprPHI(Phi, IsomorphicInc, L)) {
std::swap(OrigPhiRef, Phi);
std::swap(OrigInc, IsomorphicInc);
@@ -1600,21 +1634,35 @@
// that a phi is congruent, it's often the head of an IV user cycle that
// is isomorphic with the original phi. So it's worth eagerly cleaning up
// the common case of a single IV increment.
- if (OrigInc != IsomorphicInc &&
- OrigInc->getType() == IsomorphicInc->getType() &&
- SE.getSCEV(OrigInc) == SE.getSCEV(IsomorphicInc) &&
+ const SCEV *TruncExpr = SE.getTruncateOrNoop(SE.getSCEV(OrigInc),
+ IsomorphicInc->getType());
+ if (OrigInc != IsomorphicInc
+ && TruncExpr == SE.getSCEV(IsomorphicInc) &&
hoistStep(OrigInc, IsomorphicInc, DT)) {
DEBUG_WITH_TYPE(DebugType, dbgs()
<< "INDVARS: Eliminated congruent iv.inc: "
<< *IsomorphicInc << '\n');
- IsomorphicInc->replaceAllUsesWith(OrigInc);
+ Value *NewInc = OrigInc;
+ if (OrigInc->getType() != IsomorphicInc->getType()) {
+ IRBuilder<> Builder(OrigInc->getNextNode());
+ Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
+ NewInc = Builder.
+ CreateTruncOrBitCast(OrigInc, IsomorphicInc->getType(), IVName);
+ }
+ IsomorphicInc->replaceAllUsesWith(NewInc);
DeadInsts.push_back(IsomorphicInc);
}
}
DEBUG_WITH_TYPE(DebugType, dbgs()
<< "INDVARS: Eliminated congruent iv: " << *Phi << '\n');
++NumElim;
- Phi->replaceAllUsesWith(OrigPhiRef);
+ Value *NewIV = OrigPhiRef;
+ if (OrigPhiRef->getType() != Phi->getType()) {
+ IRBuilder<> Builder(L->getHeader()->getFirstInsertionPt());
+ Builder.SetCurrentDebugLocation(Phi->getDebugLoc());
+ NewIV = Builder.CreateTruncOrBitCast(OrigPhiRef, Phi->getType(), IVName);
+ }
+ Phi->replaceAllUsesWith(NewIV);
DeadInsts.push_back(Phi);
}
return NumElim;