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cd98794503
Summary:
Readnone attribute would cause CSE of two barriers with
the same argument, which is invalid by example:
struct Base {
virtual int foo() { return 42; }
};
struct Derived1 : Base {
int foo() override { return 50; }
};
struct Derived2 : Base {
int foo() override { return 100; }
};
void foo() {
Base *x = new Base{};
new (x) Derived1{};
int a = std::launder(x)->foo();
new (x) Derived2{};
int b = std::launder(x)->foo();
}
Here 2 calls of std::launder will produce @llvm.invariant.group.barrier,
which would be merged into one call, causing devirtualization
to devirtualize second call into Derived1::foo() instead of
Derived2::foo()
Reviewers: chandlerc, dberlin, hfinkel
Subscribers: llvm-commits, rsmith, amharc
Differential Revision: https://reviews.llvm.org/D31531
llvm-svn: 300101
63 lines
2.0 KiB
LLVM
63 lines
2.0 KiB
LLVM
; RUN: opt -S -early-cse < %s | FileCheck %s
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; RUN: opt -S -gvn < %s | FileCheck %s
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; RUN: opt -S -newgvn < %s | FileCheck %s
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; RUN: opt -S -O3 < %s | FileCheck %s
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; These tests checks if passes with CSE functionality can do CSE on
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; invariant.group.barrier, that is prohibited if there is a memory clobber
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; between barriers call.
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; CHECK-LABEL: define i8 @optimizable()
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define i8 @optimizable() {
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entry:
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%ptr = alloca i8
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store i8 42, i8* %ptr, !invariant.group !0
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; CHECK: call i8* @llvm.invariant.group.barrier
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%ptr2 = call i8* @llvm.invariant.group.barrier(i8* %ptr)
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; CHECK-NOT: call i8* @llvm.invariant.group.barrier
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%ptr3 = call i8* @llvm.invariant.group.barrier(i8* %ptr)
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; CHECK: call void @clobber(i8* {{.*}}%ptr)
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call void @clobber(i8* %ptr)
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; CHECK: call void @use(i8* {{.*}}%ptr2)
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call void @use(i8* %ptr2)
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; CHECK: call void @use(i8* {{.*}}%ptr2)
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call void @use(i8* %ptr3)
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; CHECK: load i8, i8* %ptr2, {{.*}}!invariant.group
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%v = load i8, i8* %ptr3, !invariant.group !0
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ret i8 %v
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}
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; CHECK-LABEL: define i8 @unoptimizable()
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define i8 @unoptimizable() {
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entry:
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%ptr = alloca i8
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store i8 42, i8* %ptr, !invariant.group !0
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; CHECK: call i8* @llvm.invariant.group.barrier
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%ptr2 = call i8* @llvm.invariant.group.barrier(i8* %ptr)
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call void @clobber(i8* %ptr)
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; CHECK: call i8* @llvm.invariant.group.barrier
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%ptr3 = call i8* @llvm.invariant.group.barrier(i8* %ptr)
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; CHECK: call void @clobber(i8* {{.*}}%ptr)
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call void @clobber(i8* %ptr)
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; CHECK: call void @use(i8* {{.*}}%ptr2)
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call void @use(i8* %ptr2)
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; CHECK: call void @use(i8* {{.*}}%ptr3)
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call void @use(i8* %ptr3)
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; CHECK: load i8, i8* %ptr3, {{.*}}!invariant.group
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%v = load i8, i8* %ptr3, !invariant.group !0
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ret i8 %v
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}
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declare void @use(i8* readonly)
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declare void @clobber(i8*)
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; CHECK: Function Attrs: argmemonly nounwind readonly
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; CHECK-NEXT: declare i8* @llvm.invariant.group.barrier(i8*)
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declare i8* @llvm.invariant.group.barrier(i8*)
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!0 = !{}
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