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Revert "indvars: sink truncates outside the loop." 

This reverts commit r198654.

One of the bots reported a SciMark failure.

llvm-svn: 198659
This commit is contained in:
Andrew Trick 2014-01-07 01:50:58 +00:00
parent 0458b599f8
commit 3c0ed08996
2 changed files with 7 additions and 27 deletions
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27
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -883,8 +883,6 @@ const SCEVAddRecExpr *WidenIV::GetWideRecurrence(Instruction *NarrowUse) {
/// This IV user cannot be widen. Replace this use of the original narrow IV
/// with a truncation of the new wide IV to isolate and eliminate the narrow IV.
static void truncateIVUse(NarrowIVDefUse DU, DominatorTree *DT) {
DEBUG(dbgs() << "INDVARS: Truncate IV " << *DU.WideDef
<< " for user " << *DU.NarrowUse << "\n");
IRBuilder<> Builder(getInsertPointForUses(DU.NarrowUse, DU.NarrowDef, DT));
Value *Trunc = Builder.CreateTrunc(DU.WideDef, DU.NarrowDef->getType());
DU.NarrowUse->replaceUsesOfWith(DU.NarrowDef, Trunc);
@ -895,27 +893,10 @@ static void truncateIVUse(NarrowIVDefUse DU, DominatorTree *DT) {
Instruction *WidenIV::WidenIVUse(NarrowIVDefUse DU, SCEVExpander &Rewriter) {
// Stop traversing the def-use chain at inner-loop phis or post-loop phis.
if (PHINode *UsePhi = dyn_cast<PHINode>(DU.NarrowUse)) {
if (LI->getLoopFor(UsePhi->getParent()) != L) {
// For LCSSA phis, sink the truncate outside the loop.
// After SimplifyCFG most loop exit targets have a single predecessor.
// Otherwise fall back to a truncate within the loop.
if (UsePhi->getNumOperands() != 1)
truncateIVUse(DU, DT);
else {
PHINode *WidePhi =
PHINode::Create(DU.WideDef->getType(), 1, UsePhi->getName() + ".wide",
UsePhi);
WidePhi->addIncoming(DU.WideDef, UsePhi->getIncomingBlock(0));
IRBuilder<> Builder(WidePhi->getParent()->getFirstInsertionPt());
Value *Trunc = Builder.CreateTrunc(WidePhi, DU.NarrowDef->getType());
UsePhi->replaceAllUsesWith(Trunc);
DeadInsts.push_back(UsePhi);
DEBUG(dbgs() << "INDVARS: Widen lcssa phi " << *UsePhi
<< " to " << *WidePhi << "\n");
}
return 0;
}
if (isa<PHINode>(DU.NarrowUse) &&
LI->getLoopFor(DU.NarrowUse->getParent()) != L) {
truncateIVUse(DU, DT);
return 0;
}
// Our raison d'etre! Eliminate sign and zero extension.
if (IsSigned ? isa<SExtInst>(DU.NarrowUse) : isa<ZExtInst>(DU.NarrowUse)) {

7
llvm/test/Transforms/IndVarSimplify/iv-widen.ll
View File

@ -7,11 +7,10 @@ target triple = "x86_64-apple-darwin"
; Only one phi now.
; CHECK: phi
; CHECK-NOT: phi
; One trunc for the gep.
; We now get 2 trunc, one for the gep and one for the lcssa phi.
; CHECK: trunc i64 %indvars.iv to i32
; One trunc for the dummy() call.
; CHECK-LABEL: exit24:
; CHECK: trunc i64 {{.*}}lcssa.wide to i32
; CHECK: trunc i64 %indvars.iv to i32
; CHECK-LABEL: B24:
define void @sloop(i32* %a) {
Prologue:
br i1 undef, label %B18, label %B6