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[SimplifyCFG] Handle llvm.assume in passingValueIsAlwaysUndefined #89929

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Merged
merged 3 commits into from
Apr 25, 2024
Merged

[SimplifyCFG] Handle llvm.assume in passingValueIsAlwaysUndefined #89929

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11df44e
[SimplifyCFG] Add pre-commit tests. NFC.
dtcxzyw Apr 24, 2024
41fc4c3
[SimplifyCFG] Handle `llvm.assume` in `passingValueIsAlwaysUndefined`
dtcxzyw Apr 24, 2024
c31691d
[SimplifyCFG] Add additional tests. NFC.
dtcxzyw Apr 24, 2024
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7 changes: 7 additions & 0 deletions llvm/lib/Transforms/Utils/SimplifyCFG.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -7516,6 +7516,13 @@ static bool passingValueIsAlwaysUndefined(Value *V, Instruction *I, bool PtrValu
SI->getPointerAddressSpace())) &&
SI->getPointerOperand() == I;

// llvm.assume(false/undef) always triggers immediate UB.
if (auto *Assume = dyn_cast<AssumeInst>(Use)) {
// Ignore assume operand bundles.
if (I == Assume->getArgOperand(0))
return true;
}

if (auto *CB = dyn_cast<CallBase>(Use)) {
if (C->isNullValue() && NullPointerIsDefined(CB->getFunction()))
return false;
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226 changes: 226 additions & 0 deletions llvm/test/Transforms/SimplifyCFG/UnreachableEliminate.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -627,7 +627,233 @@ else:
ret void
}

define i32 @test_assume_false(i32 %cond) {
; CHECK-LABEL: @test_assume_false(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[COND:%.*]], label [[DEFAULT:%.*]] [
; CHECK-NEXT: i32 0, label [[EXIT:%.*]]
; CHECK-NEXT: i32 1, label [[CASE1:%.*]]
; CHECK-NEXT: i32 2, label [[CASE2:%.*]]
; CHECK-NEXT: ]
; CHECK: case1:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: case2:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: default:
; CHECK-NEXT: unreachable
; CHECK: exit:
; CHECK-NEXT: [[RES:%.*]] = phi i32 [ 2, [[CASE1]] ], [ 3, [[CASE2]] ], [ 1, [[ENTRY:%.*]] ]
; CHECK-NEXT: call void @llvm.assume(i1 true)
; CHECK-NEXT: ret i32 [[RES]]
;
entry:
switch i32 %cond, label %default [
i32 0, label %case0
i32 1, label %case1
i32 2, label %case2
]

case0:
br label %exit

case1:
br label %exit

case2:
br label %exit

default:
br label %exit

exit:
%bool = phi i1 [ false, %default ], [ true, %case0 ], [ true, %case1 ], [ true, %case2 ]
%res = phi i32 [ 0, %default ], [ 1, %case0 ], [ 2, %case1 ], [ 3, %case2 ]
call void @llvm.assume(i1 %bool)
ret i32 %res
}

define i32 @test_assume_undef(i32 %cond) {
; CHECK-LABEL: @test_assume_undef(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[COND:%.*]], label [[DEFAULT:%.*]] [
; CHECK-NEXT: i32 0, label [[EXIT:%.*]]
; CHECK-NEXT: i32 1, label [[CASE1:%.*]]
; CHECK-NEXT: i32 2, label [[CASE2:%.*]]
; CHECK-NEXT: ]
; CHECK: case1:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: case2:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: default:
; CHECK-NEXT: unreachable
; CHECK: exit:
; CHECK-NEXT: [[RES:%.*]] = phi i32 [ 2, [[CASE1]] ], [ 3, [[CASE2]] ], [ 1, [[ENTRY:%.*]] ]
; CHECK-NEXT: call void @llvm.assume(i1 true)
; CHECK-NEXT: ret i32 [[RES]]
;
entry:
switch i32 %cond, label %default [
i32 0, label %case0
i32 1, label %case1
i32 2, label %case2
]

case0:
br label %exit

case1:
br label %exit

case2:
br label %exit

default:
br label %exit

exit:
%bool = phi i1 [ undef, %default ], [ true, %case0 ], [ true, %case1 ], [ true, %case2 ]
%res = phi i32 [ 0, %default ], [ 1, %case0 ], [ 2, %case1 ], [ 3, %case2 ]
call void @llvm.assume(i1 %bool)
ret i32 %res
}

define i32 @test_assume_var(i32 %cond, i1 %var) {
; CHECK-LABEL: @test_assume_var(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[COND:%.*]], label [[DEFAULT:%.*]] [
; CHECK-NEXT: i32 0, label [[EXIT:%.*]]
; CHECK-NEXT: i32 1, label [[CASE1:%.*]]
; CHECK-NEXT: i32 2, label [[CASE2:%.*]]
; CHECK-NEXT: ]
; CHECK: case1:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: case2:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: default:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: [[BOOL:%.*]] = phi i1 [ [[VAR:%.*]], [[DEFAULT]] ], [ true, [[CASE1]] ], [ true, [[CASE2]] ], [ true, [[ENTRY:%.*]] ]
; CHECK-NEXT: [[RES:%.*]] = phi i32 [ 0, [[DEFAULT]] ], [ 2, [[CASE1]] ], [ 3, [[CASE2]] ], [ 1, [[ENTRY]] ]
; CHECK-NEXT: call void @llvm.assume(i1 [[BOOL]])
; CHECK-NEXT: ret i32 [[RES]]
;
entry:
switch i32 %cond, label %default [
i32 0, label %case0
i32 1, label %case1
i32 2, label %case2
]

case0:
br label %exit

case1:
br label %exit

case2:
br label %exit

default:
br label %exit

exit:
%bool = phi i1 [ %var, %default ], [ true, %case0 ], [ true, %case1 ], [ true, %case2 ]
%res = phi i32 [ 0, %default ], [ 1, %case0 ], [ 2, %case1 ], [ 3, %case2 ]
call void @llvm.assume(i1 %bool)
ret i32 %res
}

define i32 @test_assume_bundle_nonnull(i32 %cond, ptr nonnull %p) {
; CHECK-LABEL: @test_assume_bundle_nonnull(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[COND:%.*]], label [[DEFAULT:%.*]] [
; CHECK-NEXT: i32 0, label [[EXIT:%.*]]
; CHECK-NEXT: i32 1, label [[CASE1:%.*]]
; CHECK-NEXT: i32 2, label [[CASE2:%.*]]
; CHECK-NEXT: ]
; CHECK: case1:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: case2:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: default:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: [[PTR:%.*]] = phi ptr [ null, [[DEFAULT]] ], [ [[P:%.*]], [[CASE1]] ], [ [[P]], [[CASE2]] ], [ [[P]], [[ENTRY:%.*]] ]
; CHECK-NEXT: [[RES:%.*]] = phi i32 [ 0, [[DEFAULT]] ], [ 2, [[CASE1]] ], [ 3, [[CASE2]] ], [ 1, [[ENTRY]] ]
; CHECK-NEXT: call void @llvm.assume(i1 true) [ "nonnull"(ptr [[PTR]]) ]
; CHECK-NEXT: ret i32 [[RES]]
;
entry:
switch i32 %cond, label %default [
i32 0, label %case0
i32 1, label %case1
i32 2, label %case2
]

case0:
br label %exit

case1:
br label %exit

case2:
br label %exit

default:
br label %exit

exit:
%ptr = phi ptr [ null, %default ], [ %p, %case0 ], [ %p, %case1 ], [ %p, %case2 ]
%res = phi i32 [ 0, %default ], [ 1, %case0 ], [ 2, %case1 ], [ 3, %case2 ]
call void @llvm.assume(i1 true) [ "nonnull"(ptr %ptr) ]
ret i32 %res
}

define i32 @test_assume_bundle_align(i32 %cond, ptr nonnull %p) {
; CHECK-LABEL: @test_assume_bundle_align(
; CHECK-NEXT: entry:
; CHECK-NEXT: switch i32 [[COND:%.*]], label [[DEFAULT:%.*]] [
; CHECK-NEXT: i32 0, label [[EXIT:%.*]]
; CHECK-NEXT: i32 1, label [[CASE1:%.*]]
; CHECK-NEXT: i32 2, label [[CASE2:%.*]]
; CHECK-NEXT: ]
; CHECK: case1:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: case2:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: default:
; CHECK-NEXT: br label [[EXIT]]
; CHECK: exit:
; CHECK-NEXT: [[PTR:%.*]] = phi ptr [ null, [[DEFAULT]] ], [ [[P:%.*]], [[CASE1]] ], [ [[P]], [[CASE2]] ], [ [[P]], [[ENTRY:%.*]] ]
; CHECK-NEXT: [[RES:%.*]] = phi i32 [ 0, [[DEFAULT]] ], [ 2, [[CASE1]] ], [ 3, [[CASE2]] ], [ 1, [[ENTRY]] ]
; CHECK-NEXT: call void @llvm.assume(i1 true) [ "align"(ptr [[PTR]], i32 8) ]
; CHECK-NEXT: ret i32 [[RES]]
;
entry:
switch i32 %cond, label %default [
i32 0, label %case0
i32 1, label %case1
i32 2, label %case2
]

case0:
br label %exit

case1:
br label %exit

case2:
br label %exit

default:
br label %exit

exit:
%ptr = phi ptr [ null, %default ], [ %p, %case0 ], [ %p, %case1 ], [ %p, %case2 ]
%res = phi i32 [ 0, %default ], [ 1, %case0 ], [ 2, %case1 ], [ 3, %case2 ]
call void @llvm.assume(i1 true) [ "align"(ptr %ptr, i32 8) ]
ret i32 %res
}

attributes #0 = { null_pointer_is_valid }
;.
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