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[LICM] Kill SCEV loop dispositions if needed

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SCEV caches whether SCEV expressions are loop invariant, variant or
computable.  LICM breaks this cache, almost by definition; so clear the
SCEV disposition cache if LICM changed anything.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@268408 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjoy Das 2016-05-03 17:50:11 +00:00
parent 26fc3018c2
commit 2845c75fa6
2 changed files with 35 additions and 0 deletions
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4
lib/Transforms/Scalar/LICM.cpp
View File

@ -258,6 +258,10 @@ bool LICM::runOnLoop(Loop *L, LPPassManager &LPM) {
LoopToAliasSetMap[L] = CurAST;
else
delete CurAST;
if (Changed)
if (auto *SEWP = getAnalysisIfAvailable<ScalarEvolutionWrapperPass>())
SEWP->getSE().forgetLoopDispositions(L);
return Changed;
}

31
test/Transforms/LICM/update-scev.ll Normal file
View File

@ -0,0 +1,31 @@
; RUN: opt -S -licm < %s | FileCheck %s --check-prefix=IR-AFTER-TRANSFORM
; RUN: opt -analyze -scalar-evolution -licm -scalar-evolution < %s | FileCheck %s --check-prefix=SCEV-EXPRS
declare void @clobber()
define void @f_0(i1* %loc) {
; IR-AFTER-TRANSFORM-LABEL: @f_0(
; IR-AFTER-TRANSFORM: loop.outer:
; IR-AFTER-TRANSFORM-NEXT: call void @clobber()
; IR-AFTER-TRANSFORM-NEXT: %cond = load i1, i1* %loc
; IR-AFTER-TRANSFORM-NEXT: br label %loop.inner
; SCEV-EXPRS: Classifying expressions for: @f_0
; SCEV-EXPRS: Classifying expressions for: @f_0
; SCEV-EXPRS: %cond = load i1, i1* %loc
; SCEV-EXPRS-NEXT: --> {{.*}} LoopDispositions: { %loop.outer: Variant, %loop.inner: Invariant }
entry:
br label %loop.outer
loop.outer:
call void @clobber()
br label %loop.inner
loop.inner:
%cond = load i1, i1* %loc
br i1 %cond, label %loop.inner, label %leave.inner
leave.inner:
br label %loop.outer
}