Auto merge of #111007 - JakobDegen:nrvo, r=tmiasko

Disable nrvo mir opt

See #111005 and #110902 . The ICE can definitely be hit on stable, the miscompilation I'm not sure about. The pass makes some pretty sketchy assumptions though, and we should not have it on while that's the case.

I'm not going to work on actually fixing this, it's probably not excessively difficult though.

r? rust-lang/mir-opt

4 files changed, 20 insertions, 18 deletions

diff --git a/tests/codegen/fewer-names.rs b/tests/codegen/fewer-names.rs
index 7f383a5c149..df1080bff2b 100644
--- a/tests/codegen/fewer-names.rs
+++ b/tests/codegen/fewer-names.rs
@@ -7,14 +7,14 @@
 
 #[no_mangle]
 pub fn sum(x: u32, y: u32) -> u32 {
-// YES-LABEL: define{{.*}}i32 @sum(i32 noundef %0, i32 noundef %1)
-// YES-NEXT:    %3 = add i32 %1, %0
-// YES-NEXT:    ret i32 %3
+    // YES-LABEL: define{{.*}}i32 @sum(i32 noundef %0, i32 noundef %1)
+    // YES-NEXT:    %3 = add i32 %1, %0
+    // YES-NEXT:    ret i32 %3
 
-// NO-LABEL: define{{.*}}i32 @sum(i32 noundef %x, i32 noundef %y)
-// NO-NEXT:  start:
-// NO-NEXT:    %0 = add i32 %y, %x
-// NO-NEXT:    ret i32 %0
+    // NO-LABEL: define{{.*}}i32 @sum(i32 noundef %x, i32 noundef %y)
+    // NO-NEXT:  start:
+    // NO-NEXT:    %z = add i32 %y, %x
+    // NO-NEXT:    ret i32 %z
     let z = x + y;
     z
 }
diff --git a/tests/codegen/mem-replace-big-type.rs b/tests/codegen/mem-replace-big-type.rs
index 81e56b5490d..acf759ebe54 100644
--- a/tests/codegen/mem-replace-big-type.rs
+++ b/tests/codegen/mem-replace-big-type.rs
@@ -13,7 +13,8 @@ pub struct Big([u64; 7]);
 pub fn replace_big(dst: &mut Big, src: Big) -> Big {
     // Back in 1.68, this emitted six `memcpy`s.
     // `read_via_copy` in 1.69 got that down to three.
-    // `write_via_move` has it down to just the two essential ones.
+    // `write_via_move` it was originally down to the essential two, however
+    // with nrvo disabled it is back at 3
     std::mem::replace(dst, src)
 }
 
@@ -22,13 +23,14 @@ pub fn replace_big(dst: &mut Big, src: Big) -> Big {
 
 // CHECK-NOT: call void @llvm.memcpy
 
-// For a large type, we expect exactly two `memcpy`s
+// For a large type, we expect exactly three `memcpy`s
 // CHECK-LABEL: define internal void @{{.+}}mem{{.+}}replace{{.+}}sret(%Big)
-    // CHECK-NOT: alloca
-    // CHECK-NOT: call void @llvm.memcpy
-    // CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %0, {{i8\*|ptr}} align 8 %dest, i{{.*}} 56, i1 false)
-    // CHECK-NOT: call void @llvm.memcpy
-    // CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %dest, {{i8\*|ptr}} align 8 %src, i{{.*}} 56, i1 false)
-    // CHECK-NOT: call void @llvm.memcpy
+// CHECK-NOT: call void @llvm.memcpy
+// CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %result, {{i8\*|ptr}} align 8 %dest, i{{.*}} 56, i1 false)
+// CHECK-NOT: call void @llvm.memcpy
+// CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %dest, {{i8\*|ptr}} align 8 %src, i{{.*}} 56, i1 false)
+// CHECK-NOT: call void @llvm.memcpy
+// CHECK: call void @llvm.memcpy.{{.+}}({{i8\*|ptr}} align 8 %0, {{i8\*|ptr}} align 8 %result, i{{.*}} 56, i1 false)
+// CHECK-NOT: call void @llvm.memcpy
 
 // CHECK-NOT: call void @llvm.memcpy
diff --git a/tests/codegen/nrvo.rs b/tests/codegen/nrvo.rs
index fddb0d1fb3c..b2ae99f3761 100644
--- a/tests/codegen/nrvo.rs
+++ b/tests/codegen/nrvo.rs
@@ -8,7 +8,7 @@
 pub fn nrvo(init: fn(&mut [u8; 4096])) -> [u8; 4096] {
     // CHECK-LABEL: nrvo
     // CHECK: @llvm.memset
-    // CHECK-NOT: @llvm.memcpy
+    // FIXME: turn on nrvo then check-not: @llvm.memcpy
     // CHECK: ret
     // CHECK-EMPTY
     let mut buf = [0; 4096];
diff --git a/tests/codegen/var-names.rs b/tests/codegen/var-names.rs
index 53841df32e8..d4715efad73 100644
--- a/tests/codegen/var-names.rs
+++ b/tests/codegen/var-names.rs
@@ -9,7 +9,7 @@ pub fn test(a: u32, b: u32) -> u32 {
     // CHECK: %c = add i32 %a, %b
     let d = c;
     let e = d * a;
-    // CHECK-NEXT: %0 = mul i32 %c, %a
+    // CHECK-NEXT: %e = mul i32 %c, %a
     e
-    // CHECK-NEXT: ret i32 %0
+    // CHECK-NEXT: ret i32 %e
 }