Rollup merge of #131523 - nbdd0121:asm, r=compiler-errors

Fix asm goto with outputs and move it to a separate feature gate

Tracking issue: #119364

This PR addresses 3 aspects of asm goto with outputs:
* Codegen is fixed. My initial implementation has an oversight which cause the output to be only stored in fallthrough path, but not in label blocks.
* Outputs can now be used with `options(noreturn)` if a label block is given.
* All of this is moved to a new feature gate, because we likely want to stabilise `asm_goto` before asm goto with outputs.

`@rustbot` labels: +A-inline-assembly +F-asm

1 files changed, 25 insertions, 13 deletions

diff --git a/tests/codegen/asm/goto.rs b/tests/codegen/asm/goto.rs
index e522d0da5b4..c40a43fbe1b 100644
--- a/tests/codegen/asm/goto.rs
+++ b/tests/codegen/asm/goto.rs
@@ -2,21 +2,10 @@
 //@ only-x86_64
 
 #![crate_type = "rlib"]
-#![feature(asm_goto)]
+#![feature(asm_goto, asm_goto_with_outputs)]
 
 use std::arch::asm;
 
-#[no_mangle]
-pub extern "C" fn panicky() {}
-
-struct Foo;
-
-impl Drop for Foo {
-    fn drop(&mut self) {
-        println!();
-    }
-}
-
 // CHECK-LABEL: @asm_goto
 #[no_mangle]
 pub unsafe fn asm_goto() {
@@ -38,14 +27,37 @@ pub unsafe fn asm_goto_with_outputs() -> u64 {
     out
 }
 
+// CHECK-LABEL: @asm_goto_with_outputs_use_in_label
+#[no_mangle]
+pub unsafe fn asm_goto_with_outputs_use_in_label() -> u64 {
+    let out: u64;
+    // CHECK: [[RES:%[0-9]+]] = callbr i64 asm sideeffect alignstack inteldialect "
+    // CHECK-NEXT: to label %[[FALLTHROUGHBB:[a-b0-9]+]] [label %[[JUMPBB:[a-b0-9]+]]]
+    asm!("{} /* {} */", out(reg) out, label { return out; });
+    // CHECK: [[JUMPBB]]:
+    // CHECK-NEXT: [[RET:%.+]] = phi i64 [ 1, %[[FALLTHROUGHBB]] ], [ [[RES]], %start ]
+    // CHECK-NEXT: ret i64 [[RET]]
+    1
+}
+
 // CHECK-LABEL: @asm_goto_noreturn
 #[no_mangle]
 pub unsafe fn asm_goto_noreturn() -> u64 {
-    let out: u64;
     // CHECK: callbr void asm sideeffect alignstack inteldialect "
     // CHECK-NEXT: to label %unreachable [label %[[JUMPBB:[a-b0-9]+]]]
     asm!("jmp {}", label { return 1; }, options(noreturn));
     // CHECK: [[JUMPBB]]:
     // CHECK-NEXT: ret i64 1
+}
+
+// CHECK-LABEL: @asm_goto_noreturn_with_outputs
+#[no_mangle]
+pub unsafe fn asm_goto_noreturn_with_outputs() -> u64 {
+    let out: u64;
+    // CHECK: [[RES:%[0-9]+]] = callbr i64 asm sideeffect alignstack inteldialect "
+    // CHECK-NEXT: to label %[[FALLTHROUGHBB:[a-b0-9]+]] [label %[[JUMPBB:[a-b0-9]+]]]
+    asm!("mov {}, 1", "jmp {}", out(reg) out, label { return out; });
+    // CHECK: [[JUMPBB]]:
+    // CHECK-NEXT: ret i64 [[RES]]
     out
 }