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[MemorySSA] Don't hoist stores if interfering uses (as calls) exist.

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llvm-svn: 373674
This commit is contained in:
Alina Sbirlea 2019-10-03 22:20:04 +00:00
parent 47a80aaad6
commit e0abdc6f76
3 changed files with 46 additions and 2 deletions
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12
lib/Transforms/Scalar/LICM.cpp
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@ -1248,12 +1248,22 @@ bool llvm::canSinkOrHoistInst(Instruction &I, AAResults *AA, DominatorTree *DT,
// FIXME: More precise: no Uses that alias SI.
if (!Flags->IsSink && !MSSA->dominates(SIMD, MU))
return false;
} else if (const auto *MD = dyn_cast<MemoryDef>(&MA))
} else if (const auto *MD = dyn_cast<MemoryDef>(&MA)) {
if (auto *LI = dyn_cast<LoadInst>(MD->getMemoryInst())) {
(void)LI; // Silence warning.
assert(!LI->isUnordered() && "Expected unordered load");
return false;
}
// Any call, while it may not be clobbering SI, it may be a use.
if (auto *CI = dyn_cast<CallInst>(MD->getMemoryInst())) {
// Check if the call may read from the memory locattion written
// to by SI. Check CI's attributes and arguments; the number of
// such checks performed is limited above by NoOfMemAccTooLarge.
ModRefInfo MRI = AA->getModRefInfo(CI, MemoryLocation::get(SI));
if (isModOrRefSet(MRI))
return false;
}
}
}
auto *Source = MSSA->getSkipSelfWalker()->getClobberingMemoryAccess(SI);

34
test/Analysis/MemorySSA/pr43540.ll Normal file
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@ -0,0 +1,34 @@
; RUN: opt -S -licm -enable-mssa-loop-dependency=true %s | FileCheck %s
@v_1 = global i8 0, align 1
@v_2 = global i8 0, align 1
; CHECK-LABEL: @foo()
; CHECK: for.cond:
; CHECK-NOT: store
; CHECK: for.body:
; CHECK: call void @llvm.memcpy.p0i8.p0i8.i64
; CHECK: store
define void @foo() {
entry:
br label %for.cond
for.cond: ; preds = %for.body, %entry
%0 = phi i16 [ %inc, %for.body ], [ 0, %entry ]
%cmp = icmp slt i16 %0, 1
br i1 %cmp, label %for.body, label %for.end
for.body: ; preds = %for.cond
call void @llvm.memcpy.p0i8.p0i8.i64(i8* @v_1, i8 * @v_2, i64 1, i1 false)
store i8 1, i8 * @v_2, align 1
%inc = add nsw i16 %0, 1
br label %for.cond
for.end: ; preds = %for.cond
ret void
}
; Function Attrs: argmemonly nounwind willreturn
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* noalias nocapture writeonly, i8 * noalias nocapture readonly, i64, i1 immarg) #2
attributes #2 = { argmemonly nounwind willreturn }

2
test/Transforms/LICM/guards.ll
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@ -84,7 +84,7 @@ loop:
}
; But can hoist if the side effect is hoisted with MSSA
define void @test2b_prime(i1 %cond, i32* %ptr) {
define void @test2b_prime(i1 %cond, i32* noalias %ptr) {
; MSSA-LABEL: @test2b_prime(
; MSSA-NEXT: entry:
; MSSA-NEXT: [[P2:%.*]] = getelementptr i32, i32* [[PTR:%.*]], i32 1