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NewGVN: Fix PHI evaluation bug exposed by new verifier. We were checking whether the incoming block was reachable instead of whether the specific edge was reachable

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llvm-svn: 298187
This commit is contained in:
Daniel Berlin 2017-03-18 15:41:36 +00:00
parent a267a93237
commit 54d98b54f5
2 changed files with 66 additions and 4 deletions
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10
lib/Transforms/Scalar/NewGVN.cpp
View File

@ -444,7 +444,7 @@ PHIExpression *NewGVN::createPHIExpression(Instruction *I) {
// Filter out unreachable phi operands.
auto Filtered = make_filter_range(PN->operands(), [&](const Use &U) {
return ReachableBlocks.count(PN->getIncomingBlock(U));
return ReachableEdges.count({PN->getIncomingBlock(U), PHIBlock});
});
std::transform(Filtered.begin(), Filtered.end(), op_inserter(E),
@ -1740,10 +1740,11 @@ void NewGVN::valueNumberMemoryPhi(MemoryPhi *MP) {
// If all the arguments are the same, the MemoryPhi has the same value as the
// argument.
// Filter out unreachable blocks and self phis from our operands.
const BasicBlock *PHIBlock = MP->getBlock();
auto Filtered = make_filter_range(MP->operands(), [&](const Use &U) {
return lookupMemoryAccessEquiv(cast<MemoryAccess>(U)) != MP &&
!isMemoryAccessTop(cast<MemoryAccess>(U)) &&
ReachableBlocks.count(MP->getIncomingBlock(U));
ReachableEdges.count({MP->getIncomingBlock(U), PHIBlock});
});
// If all that is left is nothing, our memoryphi is undef. We keep it as
// InitialClass. Note: The only case this should happen is if we have at
@ -1822,7 +1823,7 @@ bool NewGVN::singleReachablePHIPath(const MemoryAccess *First,
} else {
auto *MP = cast<MemoryPhi>(First);
auto ReachableOperandPred = [&](const Use &U) {
return ReachableBlocks.count(MP->getIncomingBlock(U));
return ReachableEdges.count({MP->getIncomingBlock(U), MP->getBlock()});
};
auto FilteredPhiArgs =
make_filter_range(MP->operands(), ReachableOperandPred);
@ -1879,7 +1880,8 @@ void NewGVN::verifyMemoryCongruency() const {
// We can only sanely verify that MemoryDefs in the operand list all have
// the same class.
auto ReachableOperandPred = [&](const Use &U) {
return ReachableBlocks.count(FirstMP->getIncomingBlock(U)) &&
return ReachableEdges.count(
{FirstMP->getIncomingBlock(U), FirstMP->getBlock()}) &&
isa<MemoryDef>(U);
};

60
test/Transforms/NewGVN/phi-edge-handling.ll Normal file
View File

@ -0,0 +1,60 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -newgvn -S | FileCheck %s
;; Block 6 is reachable, but edge 6->4 is not
;; This means the phi value is undef, not 0
; Function Attrs: ssp uwtable
define i16 @hoge() local_unnamed_addr #0 align 2 {
; CHECK-LABEL: @hoge(
; CHECK-NEXT: bb:
; CHECK-NEXT: switch i8 undef, label [[BB7:%.*]] [
; CHECK-NEXT: i8 0, label [[BB1:%.*]]
; CHECK-NEXT: i8 12, label [[BB2:%.*]]
; CHECK-NEXT: ]
; CHECK: bb1:
; CHECK-NEXT: br label [[BB6:%.*]]
; CHECK: bb2:
; CHECK-NEXT: br label [[BB4:%.*]]
; CHECK: bb3:
; CHECK-NEXT: unreachable
; CHECK: bb4:
; CHECK-NEXT: ret i16 undef
; CHECK: bb6:
; CHECK-NEXT: br i1 true, label [[BB3:%.*]], label [[BB4]], !llvm.loop !1
; CHECK: bb7:
; CHECK-NEXT: unreachable
;
bb:
switch i8 undef, label %bb7 [
i8 0, label %bb1
i8 12, label %bb2
]
bb1: ; preds = %bb
br label %bb6
bb2: ; preds = %bb
br label %bb4
bb3: ; preds = %bb6
unreachable
bb4: ; preds = %bb6, %bb2
%tmp = phi i16 [ 0, %bb6 ], [ undef, %bb2 ]
ret i16 %tmp
bb6: ; preds = %bb4
br i1 true, label %bb3, label %bb4, !llvm.loop !1
bb7: ; preds = %bb
unreachable
}
attributes #0 = { ssp uwtable "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="penryn" "target-features"="+cx16,+fxsr,+mmx,+sse,+sse2,+sse3,+sse4.1,+ssse3,+x87" "unsafe-fp-math"="false" "use-soft-float"="false" }
!llvm.ident = !{!0}
!0 = !{!"clang version 5.0.0 (http://llvm.org/git/clang.git a8b933d4d1d133594fdaed35ee5814514b738f6d) (/Users/dannyb/sources/llvm-clean fc630a9b5613f544c07a8f16abcc173793df62cf)"}
!1 = distinct !{!1, !2}
!2 = !{!"llvm.loop.unroll.disable"}