[llvm] [llvm][sroa] Disable support for `invariant.group` (PR #151743)

[Nikita Popov via llvm-commits]

Tommy =?utf-8?q?MᶜMichen?= <mcmichen at u.northwestern.edu>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/151743 at github.com>


================
@@ -155,6 +175,76 @@ define void @partial_promotion_of_alloca() {
   ret void
 }
 
+define void @memcpy_after_laundering_alloca(ptr %ptr) {
+; CHECK-LABEL: @memcpy_after_laundering_alloca(
+; CHECK-NEXT:    [[ALLOCA:%.*]] = alloca { i64, i64 }, align 8
+; CHECK-NEXT:    [[LAUNDER:%.*]] = call ptr @llvm.launder.invariant.group.p0(ptr [[ALLOCA]])
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr [[LAUNDER]], ptr [[PTR:%.*]], i64 16, i1 false)
+; CHECK-NEXT:    ret void
+;
+  %alloca = alloca { i64, i64 }, align 8
+  %launder = call ptr @llvm.launder.invariant.group.p0(ptr %alloca)
+  call void @llvm.memcpy.p0.p0.i64(ptr %launder, ptr %ptr, i64 16, i1 false)
+  ret void
+}
+
+define void @memcpy_after_laundering_alloca_slices(ptr %ptr) {
+; CHECK-LABEL: @memcpy_after_laundering_alloca_slices(
+; CHECK-NEXT:    [[ALLOCA:%.*]] = alloca { [16 x i8], i64, [16 x i8] }, align 8
+; CHECK-NEXT:    [[LAUNDER:%.*]] = call ptr @llvm.launder.invariant.group.p0(ptr [[ALLOCA]])
+; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i8, ptr [[LAUNDER]], i64 16
+; CHECK-NEXT:    store i64 0, ptr [[GEP]], align 4
+; CHECK-NEXT:    call void @llvm.memcpy.p0.p0.i64(ptr [[LAUNDER]], ptr [[PTR:%.*]], i64 40, i1 false)
+; CHECK-NEXT:    ret void
+;
+  %alloca = alloca { [16 x i8], i64, [16 x i8] }, align 8
+  %launder = call ptr @llvm.launder.invariant.group.p0(ptr %alloca)
+  %gep = getelementptr i8, ptr %launder, i64 16
+  store i64 0, ptr %gep
+  call void @llvm.memcpy.p0.p0.i64(ptr %launder, ptr %ptr, i64 40, i1 false)
+  ret void
+}
+
+define void @launder_in_loop() {
----------------
nikic wrote:

I don't think the fact that it's in a loop is actually relevant?

```
%t = type { i32, i32 }

define void @test_agg_store() {
  %struct_ptr = alloca %t, align 4
  %struct_ptr_fresh = call ptr @llvm.launder.invariant.group.p0(ptr %struct_ptr)
  store %t zeroinitializer, ptr %struct_ptr_fresh, align 4, !invariant.group !{}
  ret void
}
```

is enough to reproduce the crash. To avoid everything being optimized away only keeping the loop body is sufficient:
```
%t = type { i32, i32 }

define void @test_agg_store() {
  %struct_ptr = alloca %t, align 4
  %struct_ptr_fresh = call ptr @llvm.launder.invariant.group.p0(ptr %struct_ptr)
  %struct = call %t @make_t()
  store %t %struct, ptr %struct_ptr_fresh, align 4, !invariant.group !{}
  %first_ptr = getelementptr %t, ptr %struct_ptr_fresh, i32 0, i32 0
  %first = load i32, ptr %first_ptr, align 4
  %second_ptr = getelementptr %t, ptr %struct_ptr_fresh, i32 0, i32 1
  %second = load i32, ptr %second_ptr, align 4
  ret void
}

declare %t @make_t()
```

https://github.com/llvm/llvm-project/pull/151743