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[GVN] Make GVN aware of aligned_alloc

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Make the GVN pass aware of aligned_alloc.

Depends on D76974.

Differential Revision: https://reviews.llvm.org/D76975
This commit is contained in:
Uday Bondhugula 2020-03-28 12:57:35 +05:30
parent 8dca3bb9a7
commit 386b6fa7b3
2 changed files with 33 additions and 7 deletions
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15
lib/Transforms/Scalar/GVN.cpp
View File

@ -947,6 +947,7 @@ bool GVN::AnalyzeLoadAvailability(LoadInst *LI, MemDepResult DepInfo,
// Loading the allocation -> undef.
if (isa<AllocaInst>(DepInst) || isMallocLikeFn(DepInst, TLI) ||
isAlignedAllocLikeFn(DepInst, TLI) ||
// Loading immediately after lifetime begin -> undef.
isLifetimeStart(DepInst)) {
Res = AvailableValue::get(UndefValue::get(LI->getType()));
@ -1451,7 +1452,7 @@ static bool impliesEquivalanceIfFalse(CmpInst* Cmp) {
Value *LHS = Cmp->getOperand(0);
Value *RHS = Cmp->getOperand(1);
// If we can prove either side non-zero, then equality must imply
// equivalence.
// equivalence.
// FIXME: We should do this optimization if 'no signed zeros' is
// applicable via an instruction-level fast-math-flag or some other
// indicator that relaxed FP semantics are being used.
@ -1516,10 +1517,10 @@ bool GVN::processAssumeIntrinsic(IntrinsicInst *IntrinsicI) {
// If we find an equality fact, canonicalize all dominated uses in this block
// to one of the two values. We heuristically choice the "oldest" of the
// two where age is determined by value number. (Note that propagateEquality
// above handles the cross block case.)
//
// above handles the cross block case.)
//
// Key case to cover are:
// 1)
// 1)
// %cmp = fcmp oeq float 3.000000e+00, %0 ; const on lhs could happen
// call void @llvm.assume(i1 %cmp)
// ret float %0 ; will change it to ret float 3.000000e+00
@ -1560,7 +1561,7 @@ bool GVN::processAssumeIntrinsic(IntrinsicInst *IntrinsicI) {
<< *CmpLHS << " with "
<< *CmpRHS << " in block "
<< IntrinsicI->getParent()->getName() << "\n");
// Setup the replacement map - this handles uses within the same block
if (hasUsersIn(CmpLHS, IntrinsicI->getParent()))
@ -1826,7 +1827,7 @@ void GVN::assignBlockRPONumber(Function &F) {
bool GVN::replaceOperandsForInBlockEquality(Instruction *Instr) const {
bool Changed = false;
for (unsigned OpNum = 0; OpNum < Instr->getNumOperands(); ++OpNum) {
Value *Operand = Instr->getOperand(OpNum);
Value *Operand = Instr->getOperand(OpNum);
auto it = ReplaceOperandsWithMap.find(Operand);
if (it != ReplaceOperandsWithMap.end()) {
LLVM_DEBUG(dbgs() << "GVN replacing: " << *Operand << " with "
@ -1946,7 +1947,7 @@ bool GVN::propagateEquality(Value *LHS, Value *RHS, const BasicBlockEdge &Root,
// If "A == B" is known true, or "A != B" is known false, then replace
// A with B everywhere in the scope. For floating point operations, we
// have to be careful since equality does not always imply equivalance.
// have to be careful since equality does not always imply equivalance.
if ((isKnownTrue && impliesEquivalanceIfTrue(Cmp)) ||
(isKnownFalse && impliesEquivalanceIfFalse(Cmp)))
Worklist.push_back(std::make_pair(Op0, Op1));

25
test/Transforms/GVN/malloc-load-removal.ll
View File

@ -54,3 +54,28 @@ if.end: ; preds = %if.then, %entry
; CHECK_NO_LIBCALLS: load
; CHECK_NO_LIBCALLS: icmp
}
declare i8* @aligned_alloc(i64, i64) nounwind
define noalias i8* @test3() nounwind uwtable ssp {
entry:
%call = tail call i8* @aligned_alloc(i64 256, i64 32) nounwind
%0 = load i8, i8* %call, align 32
%tobool = icmp eq i8 %0, 0
br i1 %tobool, label %if.end, label %if.then
if.then: ; preds = %entry
store i8 0, i8* %call, align 1
br label %if.end
if.end: ; preds = %if.then, %entry
ret i8* %call
; CHECK-LABEL: @test3(
; CHECK-NOT: load
; CHECK-NOT: icmp
; CHECK_NO_LIBCALLS-LABEL: @test3(
; CHECK_NO_LIBCALLS: load
; CHECK_NO_LIBCALLS: icmp
}