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Fix a problem I introduced in r187029 where we would over-eagerly

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schedule an alloca for another iteration in SROA. This only showed up
with a mixture of promotable and unpromotable selects and phis. Added
a test case for this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187031 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2013-07-24 12:12:17 +00:00
parent e3809eed34
commit b7f27824fb
2 changed files with 46 additions and 3 deletions
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12
lib/Transforms/Scalar/SROA.cpp
View File

@ -2576,7 +2576,6 @@ private:
// occurs.
if (isSafePHIToSpeculate(PN, &DL)) {
Pass.SpeculatablePHIs.insert(&PN);
Pass.Worklist.insert(&NewAI);
IsUsedByRewrittenSpeculatableInstructions = true;
return true;
}
@ -2606,7 +2605,6 @@ private:
// speculation occurs.
if (isSafeSelectToSpeculate(SI, &DL)) {
Pass.SpeculatableSelects.insert(&SI);
Pass.Worklist.insert(&NewAI);
IsUsedByRewrittenSpeculatableInstructions = true;
return true;
}
@ -3090,10 +3088,18 @@ bool SROA::rewritePartition(AllocaInst &AI, AllocaSlices &S,
if (Promotable && !Rewriter.isUsedByRewrittenSpeculatableInstructions()) {
DEBUG(dbgs() << " and queuing for promotion\n");
PromotableAllocas.push_back(NewAI);
} else if (NewAI != &AI) {
} else if (NewAI != &AI ||
(Promotable &&
Rewriter.isUsedByRewrittenSpeculatableInstructions())) {
// If we can't promote the alloca, iterate on it to check for new
// refinements exposed by splitting the current alloca. Don't iterate on an
// alloca which didn't actually change and didn't get promoted.
//
// Alternatively, if we could promote the alloca but have speculatable
// instructions then we will speculate them after finishing our processing
// of the original alloca. Mark the new one for re-visiting in the next
// iteration so the speculated operations can be rewritten.
//
// FIXME: We should actually track whether the rewriter changed anything.
Worklist.insert(NewAI);
}

37
test/Transforms/SROA/phi-and-select.ll
View File

@ -346,6 +346,43 @@ exit:
ret i32 %load
}
define i32 @test14(i1 %b1, i1 %b2, i32* %ptr) {
; Check for problems when there are both selects and phis and one is
; speculatable toward promotion but the other is not. That should block all of
; the speculation.
; CHECK-LABEL: @test14(
; CHECK: alloca
; CHECK: alloca
; CHECK: select
; CHECK: phi
; CHECK: phi
; CHECK: select
; CHECK: ret i32
entry:
%f = alloca i32
%g = alloca i32
store i32 0, i32* %f
store i32 0, i32* %g
%f.select = select i1 %b1, i32* %f, i32* %ptr
br i1 %b2, label %then, label %else
then:
br label %exit
else:
br label %exit
exit:
%f.phi = phi i32* [ %f, %then ], [ %f.select, %else ]
%g.phi = phi i32* [ %g, %then ], [ %ptr, %else ]
%f.loaded = load i32* %f.phi
%g.select = select i1 %b1, i32* %g, i32* %g.phi
%g.loaded = load i32* %g.select
%result = add i32 %f.loaded, %g.loaded
ret i32 %result
}
define i32 @PR13905() {
; Check a pattern where we have a chain of dead phi nodes to ensure they are
; deleted and promotion can proceed.