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llvm-mirror/test/Transforms/DeadStoreElimination/invariant.start.ll
Nikita Popov 59f9149f4e [DSE] Remove MemDep-based implementation
The MemorySSA-based implementation has been enabled without issue
for a while now, so keeping the old implementation around doesn't
seem useful anymore. This drops the MemDep-based implementation.

Differential Revision: https://reviews.llvm.org/D97877
2021-03-07 18:17:31 +01:00

35 lines
1.2 KiB
LLVM

; Test to make sure llvm.invariant.start calls are not treated as clobbers.
; RUN: opt < %s -basic-aa -dse -S | FileCheck %s
declare {}* @llvm.invariant.start.p0i8(i64, i8* nocapture) nounwind readonly
; We cannot remove the store 1 to %p.
; FIXME: By the semantics of invariant.start, the store 3 to p is unreachable.
define void @test(i8 *%p) {
store i8 1, i8* %p, align 4
%i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %p)
store i8 3, i8* %p, align 4
ret void
; CHECK-LABEL: @test(
; CHECK-NEXT: store i8 1, i8* %p, align 4
; CHECK-NEXT: %i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %p)
; CHECK-NEXT: store i8 3, i8* %p, align 4
; CHECK-NEXT: ret void
}
; FIXME: We should be able to remove the first store to p, even though p and q
; may alias.
define void @test2(i8* %p, i8* %q) {
store i8 1, i8* %p, align 4
store i8 2, i8* %q, align 4
%i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %q)
store i8 3, i8* %p, align 4
ret void
; CHECK-LABEL: @test2(
; CHECK-NEXT: store i8 1, i8* %p, align 4
; CHECK-NEXT: store i8 2, i8* %q, align 4
; CHECK-NEXT: %i = call {}* @llvm.invariant.start.p0i8(i64 1, i8* %q)
; CHECK-NEXT: store i8 3, i8* %p, align 4
; CHECK-NEXT: ret void
}