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[SimplifyCFG] Update (AND) IR flags when CSE'ing instructions

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We were updating metadata but not IR flags. Because we pick an arbitrary instruction to be the CSE candidate, it comes down to luck (50% or less chance) if this results in broken codegen or not, which is why PR30373 which is actually not the fault of the commit it was bisected down to.

Fixes PR30373.

llvm-svn: 281889
This commit is contained in:
James Molloy 2016-09-19 08:23:08 +00:00
parent c7f779bf05
commit 1f17c2f83a
2 changed files with 60 additions and 2 deletions
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6
lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -1527,10 +1527,12 @@ static bool sinkLastInstruction(ArrayRef<BasicBlock*> Blocks) {
I0->getOperandUse(O).set(NewOperands[O]);
I0->moveBefore(&*BBEnd->getFirstInsertionPt());
// Update metadata.
// Update metadata and IR flags.
for (auto *I : Insts)
if (I != I0)
if (I != I0) {
combineMetadataForCSE(I0, I);
I0->andIRFlags(I);
}
if (!isa<StoreInst>(I0)) {
// canSinkLastInstruction checked that all instructions were used by

56
test/Transforms/SimplifyCFG/sink-common-code.ll
View File

@ -699,6 +699,62 @@ if.end:
; CHECK: store
; CHECK: store
define i32 @test_pr30373a(i1 zeroext %flag, i32 %x, i32 %y) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
%x0 = call i32 @foo(i32 %x, i32 0) nounwind readnone
%y0 = call i32 @foo(i32 %x, i32 1) nounwind readnone
%z0 = lshr i32 %y0, 8
br label %if.end
if.else:
%x1 = call i32 @foo(i32 %y, i32 0) nounwind readnone
%y1 = call i32 @foo(i32 %y, i32 1) nounwind readnone
%z1 = lshr exact i32 %y1, 8
br label %if.end
if.end:
%xx = phi i32 [ %x0, %if.then ], [ %x1, %if.else ]
%yy = phi i32 [ %z0, %if.then ], [ %z1, %if.else ]
%ret = add i32 %xx, %yy
ret i32 %ret
}
; CHECK-LABEL: test_pr30373a
; CHECK: lshr
; CHECK-NOT: exact
; CHECK: }
define i32 @test_pr30373b(i1 zeroext %flag, i32 %x, i32 %y) {
entry:
br i1 %flag, label %if.then, label %if.else
if.then:
%x0 = call i32 @foo(i32 %x, i32 0) nounwind readnone
%y0 = call i32 @foo(i32 %x, i32 1) nounwind readnone
%z0 = lshr exact i32 %y0, 8
br label %if.end
if.else:
%x1 = call i32 @foo(i32 %y, i32 0) nounwind readnone
%y1 = call i32 @foo(i32 %y, i32 1) nounwind readnone
%z1 = lshr i32 %y1, 8
br label %if.end
if.end:
%xx = phi i32 [ %x0, %if.then ], [ %x1, %if.else ]
%yy = phi i32 [ %z0, %if.then ], [ %z1, %if.else ]
%ret = add i32 %xx, %yy
ret i32 %ret
}
; CHECK-LABEL: test_pr30373b
; CHECK: lshr
; CHECK-NOT: exact
; CHECK: }
; CHECK: !0 = !{!1, !1, i64 0}
; CHECK: !1 = !{!"float", !2}
; CHECK: !2 = !{!"an example type tree"}