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[InlineCost] Skip volatile loads when looking for repeated loads

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This is a follow-up fix of r320814.  A test case is also added.

llvm-svn: 321075
This commit is contained in:
Haicheng Wu 2017-12-19 13:42:58 +00:00
parent 804c89f41f
commit 354d0a92b6
2 changed files with 20 additions and 1 deletions
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3
lib/Analysis/InlineCost.cpp
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@ -363,6 +363,7 @@ void CallAnalyzer::accumulateSROACost(DenseMap<Value *, int>::iterator CostIt,
void CallAnalyzer::disableLoadElimination() {
if (EnableLoadElimination) {
Cost += LoadEliminationCost;
LoadEliminationCost = 0;
EnableLoadElimination = false;
}
}
@ -1097,7 +1098,7 @@ bool CallAnalyzer::visitLoad(LoadInst &I) {
// by any stores or calls, this load is likely to be redundant and can be
// eliminated.
if (EnableLoadElimination &&
!LoadAddrSet.insert(I.getPointerOperand()).second) {
!LoadAddrSet.insert(I.getPointerOperand()).second && I.isUnordered()) {
LoadEliminationCost += InlineConstants::InstrCost;
return true;
}

18
test/Transforms/Inline/redundant-loads.ll
View File

@ -184,3 +184,21 @@ define void @inner9(i32* %a, void ()* %f) {
call void @pad()
ret void
}
define void @outer10(i32* %a) {
; CHECK-LABEL: @outer10(
; CHECK: call void @inner10
%b = alloca i32
call void @inner10(i32* %a, i32* %b)
ret void
}
define void @inner10(i32* %a, i32* %b) {
%1 = load i32, i32* %a
store i32 %1, i32 * %b
%2 = load volatile i32, i32* %a ; volatile load should be kept.
call void @pad()
%3 = load volatile i32, i32* %a ; Same as the above.
ret void
}