Auto merge of #94127 - erikdesjardins:debugattr, r=nikic

At opt-level=0, apply only ABI-affecting attributes to functions

This should provide a small perf improvement for debug builds,
and should more than cancel out the perf regression from adding noundef (https://github.com/rust-lang/rust/pull/93670#issuecomment-1038347581, #94106).

r? `@nikic`

5 files changed, 67 insertions, 4 deletions

diff --git a/src/test/codegen/fastcall-inreg.rs b/src/test/codegen/fastcall-inreg.rs
index ec7a6791592..f550ac11f64 100644
--- a/src/test/codegen/fastcall-inreg.rs
+++ b/src/test/codegen/fastcall-inreg.rs
@@ -2,7 +2,7 @@
 // as "inreg" like the C/C++ compilers for the platforms.
 // x86 only.
 
-// compile-flags: --target i686-unknown-linux-gnu -C no-prepopulate-passes
+// compile-flags: --target i686-unknown-linux-gnu -O -C no-prepopulate-passes
 // needs-llvm-components: x86
 
 #![crate_type = "lib"]
diff --git a/src/test/codegen/function-arguments-noopt.rs b/src/test/codegen/function-arguments-noopt.rs
new file mode 100644
index 00000000000..94561288dc5
--- /dev/null
+++ b/src/test/codegen/function-arguments-noopt.rs
@@ -0,0 +1,63 @@
+// compile-flags: -C opt-level=0 -C no-prepopulate-passes
+
+// This test checks that arguments/returns in opt-level=0 builds,
+// while lacking attributes used for optimization, still have ABI-affecting attributes.
+
+#![crate_type = "lib"]
+#![feature(rustc_attrs)]
+
+pub struct S {
+  _field: [i32; 8],
+}
+
+// CHECK: zeroext i1 @boolean(i1 zeroext %x)
+#[no_mangle]
+pub fn boolean(x: bool) -> bool {
+  x
+}
+
+// CHECK-LABEL: @boolean_call
+#[no_mangle]
+pub fn boolean_call(x: bool, f: fn(bool) -> bool) -> bool {
+// CHECK: call zeroext i1 %f(i1 zeroext %x)
+  f(x)
+}
+
+// CHECK: align 4 i32* @borrow(i32* align 4 %x)
+#[no_mangle]
+pub fn borrow(x: &i32) -> &i32 {
+  x
+}
+
+// CHECK-LABEL: @borrow_call
+#[no_mangle]
+pub fn borrow_call(x: &i32, f: fn(&i32) -> &i32) -> &i32 {
+  // CHECK: call align 4 i32* %f(i32* align 4 %x)
+  f(x)
+}
+
+// CHECK: void @struct_(%S* sret(%S){{( %0)?}}, %S* %x)
+#[no_mangle]
+pub fn struct_(x: S) -> S {
+  x
+}
+
+// CHECK-LABEL: @struct_call
+#[no_mangle]
+pub fn struct_call(x: S, f: fn(S) -> S) -> S {
+  // CHECK: call void %f(%S* sret(%S){{( %0)?}}, %S* %{{.+}})
+  f(x)
+}
+
+// CHECK: { i8, i8 } @enum_(i1 zeroext %x.0, i8 %x.1)
+#[no_mangle]
+pub fn enum_(x: Option<u8>) -> Option<u8> {
+  x
+}
+
+// CHECK-LABEL: @enum_call
+#[no_mangle]
+pub fn enum_call(x: Option<u8>, f: fn(Option<u8>) -> Option<u8>) -> Option<u8> {
+  // CHECK: call { i8, i8 } %f(i1 zeroext %x.0, i8 %x.1)
+  f(x)
+}
diff --git a/src/test/codegen/repr-transparent-aggregates-1.rs b/src/test/codegen/repr-transparent-aggregates-1.rs
index a61dad218cd..4ad3642c03d 100644
--- a/src/test/codegen/repr-transparent-aggregates-1.rs
+++ b/src/test/codegen/repr-transparent-aggregates-1.rs
@@ -1,4 +1,4 @@
-// compile-flags: -C no-prepopulate-passes
+// compile-flags: -O -C no-prepopulate-passes
 //
 
 // ignore-arm
diff --git a/src/test/codegen/riscv-abi/riscv64-lp64-lp64f-lp64d-abi.rs b/src/test/codegen/riscv-abi/riscv64-lp64-lp64f-lp64d-abi.rs
index c67406ea693..faf81b5ae76 100644
--- a/src/test/codegen/riscv-abi/riscv64-lp64-lp64f-lp64d-abi.rs
+++ b/src/test/codegen/riscv-abi/riscv64-lp64-lp64f-lp64d-abi.rs
@@ -1,4 +1,4 @@
-// compile-flags: --target riscv64gc-unknown-linux-gnu -C no-prepopulate-passes
+// compile-flags: --target riscv64gc-unknown-linux-gnu -O -C no-prepopulate-passes
 // needs-llvm-components: riscv
 
 #![crate_type = "lib"]
diff --git a/src/test/codegen/union-abi.rs b/src/test/codegen/union-abi.rs
index bb87d263bdf..99576a5f57e 100644
--- a/src/test/codegen/union-abi.rs
+++ b/src/test/codegen/union-abi.rs
@@ -1,5 +1,5 @@
 // ignore-emscripten vectors passed directly
-// compile-flags: -C no-prepopulate-passes
+// compile-flags: -O -C no-prepopulate-passes
 
 // This test that using union forward the abi of the inner type, as
 // discussed in #54668