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When expanding expressions which are using post-inc mode for multiple loops, 

ensure that the expansion is dominated by the increments of those loops.

llvm-svn: 100748
This commit is contained in:
Dan Gohman 2010-04-08 05:57:57 +00:00
parent 8ee6760971
commit 4506539d84
2 changed files with 43 additions and 0 deletions
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16
llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
View File

@ -2820,6 +2820,22 @@ Value *LSRInstance::Expand(const LSRFixup &LF,
else
Inputs.push_back(IVIncInsertPos);
}
// The expansion must also be dominated by the increment positions of any
// loops it for which it is using post-inc mode.
for (PostIncLoopSet::const_iterator I = LF.PostIncLoops.begin(),
E = LF.PostIncLoops.end(); I != E; ++I) {
const Loop *PIL = *I;
if (PIL == L) continue;
SmallVector<BasicBlock *, 4> ExitingBlocks;
PIL->getExitingBlocks(ExitingBlocks);
if (!ExitingBlocks.empty()) {
BasicBlock *BB = ExitingBlocks[0];
for (unsigned i = 1, e = ExitingBlocks.size(); i != e; ++i)
BB = DT.findNearestCommonDominator(BB, ExitingBlocks[i]);
Inputs.push_back(BB->getTerminator());
}
}
// Then, climb up the immediate dominator tree as far as we can go while
// still being dominated by the input positions.

27
llvm/test/CodeGen/X86/multiple-loop-post-inc.ll
View File

@ -275,3 +275,30 @@ bb14: ; preds = %bb12, %bb11
return: ; preds = %entry
ret void
}
; Codegen shouldn't crash on this testcase.
define void @bar(i32 %a, i32 %b) nounwind {
entry: ; preds = %bb1, %entry, %for.end204
br label %outer
outer: ; preds = %bb1, %entry
%i6 = phi i32 [ %storemerge171, %bb1 ], [ %a, %entry ] ; <i32> [#uses=2]
%storemerge171 = add i32 %i6, 1 ; <i32> [#uses=1]
br label %inner
inner: ; preds = %bb0, %if.end275
%i8 = phi i32 [ %a, %outer ], [ %indvar.next159, %bb0 ] ; <i32> [#uses=2]
%t338 = load i32* undef ; <i32> [#uses=1]
%t191 = mul i32 %i8, %t338 ; <i32> [#uses=1]
%t179 = add i32 %i6, %t191 ; <i32> [#uses=1]
br label %bb0
bb0: ; preds = %for.body332
%indvar.next159 = add i32 %i8, 1 ; <i32> [#uses=1]
br i1 undef, label %bb1, label %inner
bb1: ; preds = %bb0, %outer
%midx.4 = phi i32 [ %t179, %bb0 ] ; <i32> [#uses=0]
br label %outer
}