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[GVN] Set phi entries of unreachable predecessors to poison instead of undef 

This matches NewGVN's behavior.
This commit is contained in:
Nuno Lopes 2021-12-30 13:25:57 +00:00
parent 9b8f9d33db
commit 84b285d6eb
6 changed files with 10 additions and 10 deletions
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6
llvm/lib/Transforms/Scalar/GVN.cpp
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@ -1769,7 +1769,7 @@ bool GVNPass::processAssumeIntrinsic(AssumeInst *IntrinsicI) {
// Insert a new store to null instruction before the load to indicate that
// this code is not reachable. FIXME: We could insert unreachable
// instruction directly because we can modify the CFG.
auto *NewS = new StoreInst(UndefValue::get(Int8Ty),
auto *NewS = new StoreInst(PoisonValue::get(Int8Ty),
Constant::getNullValue(Int8Ty->getPointerTo()),
IntrinsicI);
if (MSSAU) {
@ -2991,12 +2991,12 @@ void GVNPass::addDeadBlock(BasicBlock *BB) {
}
}
// Now undef the incoming values from the dead predecessors.
// Now poison the incoming values from the dead predecessors.
for (BasicBlock *P : predecessors(B)) {
if (!DeadBlocks.count(P))
continue;
for (PHINode &Phi : B->phis()) {
Phi.setIncomingValueForBlock(P, UndefValue::get(Phi.getType()));
Phi.setIncomingValueForBlock(P, PoisonValue::get(Phi.getType()));
if (MD)
MD->invalidateCachedPointerInfo(&Phi);
}

2
llvm/test/Transforms/GVN/assume-equal.ll
View File

@ -217,7 +217,7 @@ entry:
bb2:
; CHECK-NOT: %cmp3 =
%cmp3 = icmp eq i32 %p, 43
; CHECK: store i8 undef, i8* null
; CHECK: store i8 poison, i8* null
call void @llvm.assume(i1 %cmp3)
ret i32 15
bb3:

2
llvm/test/Transforms/GVN/calls-nonlocal.ll
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@ -68,7 +68,7 @@ return: ; preds = %bb27
; CHECK: bb26:
; CHECK: br label %bb27
; CHECK: bb27:
; CHECK: %tmp.0 = phi i32 [ 11, %bb26 ], [ undef, %bb24 ], [ undef, %bb14 ], [ %g, %bb ]
; CHECK: %tmp.0 = phi i32 [ 11, %bb26 ], [ poison, %bb24 ], [ poison, %bb14 ], [ %g, %bb ]
; CHECK: ret i32 %tmp.0
; CHECK: }

2
llvm/test/Transforms/GVN/condprop.ll
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@ -31,7 +31,7 @@ define i32 @test1() nounwind {
; CHECK: bb7:
; CHECK-NEXT: br label [[BB8]]
; CHECK: bb8:
; CHECK-NEXT: [[DOT0:%.*]] = phi i32 [ [[TMP0]], [[BB7]] ], [ undef, [[BB6]] ], [ undef, [[BB4]] ], [ 4, [[BB2]] ], [ 5, [[BB]] ]
; CHECK-NEXT: [[DOT0:%.*]] = phi i32 [ [[TMP0]], [[BB7]] ], [ poison, [[BB6]] ], [ poison, [[BB4]] ], [ 4, [[BB2]] ], [ 5, [[BB]] ]
; CHECK-NEXT: ret i32 [[DOT0]]
;
entry:

2
llvm/test/Transforms/GVN/equality-assume.ll
View File

@ -149,7 +149,7 @@ merge:
define i32 @conflicting_constants(i32* %p) {
; CHECK-LABEL: @conflicting_constants(
; CHECK-NEXT: store i8 undef, i8* null
; CHECK-NEXT: store i8 poison, i8* null
; CHECK-NEXT: br i1 undef, label [[TAKEN:%.*]], label [[MERGE:%.*]]
; CHECK: taken:
; CHECK-NEXT: br label [[MERGE]]

6
llvm/test/Transforms/GVN/preserve-memoryssa.ll
View File

@ -97,7 +97,7 @@ for.body.i22:
define void @test_assume_false_to_store_undef_1(i32* %ptr) {
; CHECK-LABEL: @test_assume_false_to_store_undef_1(
; CHECK-NEXT: store i32 10, i32* [[PTR:%.*]], align 4
; CHECK-NEXT: store i8 undef, i8* null, align 1
; CHECK-NEXT: store i8 poison, i8* null, align 1
; CHECK-NEXT: call void @f()
; CHECK-NEXT: ret void
;
@ -113,7 +113,7 @@ define i32 @test_assume_false_to_store_undef_2(i32* %ptr, i32* %ptr.2) {
; CHECK-LABEL: @test_assume_false_to_store_undef_2(
; CHECK-NEXT: store i32 10, i32* [[PTR:%.*]], align 4
; CHECK-NEXT: [[LV:%.*]] = load i32, i32* [[PTR_2:%.*]], align 4
; CHECK-NEXT: store i8 undef, i8* null, align 1
; CHECK-NEXT: store i8 poison, i8* null, align 1
; CHECK-NEXT: call void @f()
; CHECK-NEXT: ret i32 [[LV]]
;
@ -130,7 +130,7 @@ define i32 @test_assume_false_to_store_undef_3(i32* %ptr, i32* %ptr.2) {
; CHECK-LABEL: @test_assume_false_to_store_undef_3(
; CHECK-NEXT: store i32 10, i32* [[PTR:%.*]], align 4
; CHECK-NEXT: [[LV:%.*]] = load i32, i32* [[PTR_2:%.*]], align 4
; CHECK-NEXT: store i8 undef, i8* null, align 1
; CHECK-NEXT: store i8 poison, i8* null, align 1
; CHECK-NEXT: ret i32 [[LV]]
;
store i32 10, i32* %ptr