Rollup merge of #133587 - taiki-e:loongarch-asm-freg, r=Amanieu

Fix target_feature handling in freg of LoongArch inline assembly

In LoongArch inline assembly, freg currently always accepts f32/f64 as input/output.

https://github.com/rust-lang/rust/blob/9b4d7c6a40b328d212095c28670c629facf1557d/compiler/rustc_target/src/asm/loongarch.rs#L41

However, these types actually require f/d target features as in RISC-V.
Otherwise, an (ugly) compile error will occur: https://godbolt.org/z/K61Gq1E9E

f32/f64 without f:

```
error: couldn't allocate output register for constraint '{$f1}'
  --> <source>:12:11
   |
12 |     asm!("", in("$f1") x, lateout("$f1") y);
   |           ^
```

f64 with f but without d:

```
error: scalar-to-vector conversion failed, possible invalid constraint for vector type
  --> <source>:19:11
   |
19 |     asm!("", in("$f1") x, lateout("$f1") y);
   |           ^
```

cc ``@heiher``

r? ``@Amanieu``

``@rustbot`` label +O-LoongArch +A-inline-assembly

Author: jieyouxu

Diff for: compiler/rustc_target/src/asm/loongarch.rs

@@ -38,7 +38,7 @@ impl LoongArchInlineAsmRegClass {
     ) -> &'static [(InlineAsmType, Option<Symbol>)] {
         match self {
             Self::reg => types! { _: I8, I16, I32, I64, F32, F64; },
-            Self::freg => types! { _: F32, F64; },
+            Self::freg => types! { f: F32; d: F64; },
         }
     }
 }

Diff for: tests/ui/asm/loongarch/bad-reg.loongarch64_lp64d.stderr

@@ -0,0 +1,38 @@
+error: invalid register `$r0`: constant zero cannot be used as an operand for inline asm
+  --> $DIR/bad-reg.rs:22:18
+   |
+LL |         asm!("", out("$r0") _);
+   |                  ^^^^^^^^^^^^
+
+error: invalid register `$tp`: reserved for TLS
+  --> $DIR/bad-reg.rs:24:18
+   |
+LL |         asm!("", out("$tp") _);
+   |                  ^^^^^^^^^^^^
+
+error: invalid register `$sp`: the stack pointer cannot be used as an operand for inline asm
+  --> $DIR/bad-reg.rs:26:18
+   |
+LL |         asm!("", out("$sp") _);
+   |                  ^^^^^^^^^^^^
+
+error: invalid register `$r21`: reserved by the ABI
+  --> $DIR/bad-reg.rs:28:18
+   |
+LL |         asm!("", out("$r21") _);
+   |                  ^^^^^^^^^^^^^
+
+error: invalid register `$fp`: the frame pointer cannot be used as an operand for inline asm
+  --> $DIR/bad-reg.rs:30:18
+   |
+LL |         asm!("", out("$fp") _);
+   |                  ^^^^^^^^^^^^
+
+error: invalid register `$r31`: $r31 is used internally by LLVM and cannot be used as an operand for inline asm
+  --> $DIR/bad-reg.rs:32:18
+   |
+LL |         asm!("", out("$r31") _);
+   |                  ^^^^^^^^^^^^^
+
+error: aborting due to 6 previous errors
+

Diff for: tests/ui/asm/loongarch/bad-reg.loongarch64_lp64s.stderr

@@ -0,0 +1,62 @@
+error: invalid register `$r0`: constant zero cannot be used as an operand for inline asm
+  --> $DIR/bad-reg.rs:22:18
+   |
+LL |         asm!("", out("$r0") _);
+   |                  ^^^^^^^^^^^^
+
+error: invalid register `$tp`: reserved for TLS
+  --> $DIR/bad-reg.rs:24:18
+   |
+LL |         asm!("", out("$tp") _);
+   |                  ^^^^^^^^^^^^
+
+error: invalid register `$sp`: the stack pointer cannot be used as an operand for inline asm
+  --> $DIR/bad-reg.rs:26:18
+   |
+LL |         asm!("", out("$sp") _);
+   |                  ^^^^^^^^^^^^
+
+error: invalid register `$r21`: reserved by the ABI
+  --> $DIR/bad-reg.rs:28:18
+   |
+LL |         asm!("", out("$r21") _);
+   |                  ^^^^^^^^^^^^^
+
+error: invalid register `$fp`: the frame pointer cannot be used as an operand for inline asm
+  --> $DIR/bad-reg.rs:30:18
+   |
+LL |         asm!("", out("$fp") _);
+   |                  ^^^^^^^^^^^^
+
+error: invalid register `$r31`: $r31 is used internally by LLVM and cannot be used as an operand for inline asm
+  --> $DIR/bad-reg.rs:32:18
+   |
+LL |         asm!("", out("$r31") _);
+   |                  ^^^^^^^^^^^^^
+
+error: register class `freg` requires at least one of the following target features: d, f
+  --> $DIR/bad-reg.rs:36:26
+   |
+LL |         asm!("/* {} */", in(freg) f);
+   |                          ^^^^^^^^^^
+
+error: register class `freg` requires at least one of the following target features: d, f
+  --> $DIR/bad-reg.rs:38:26
+   |
+LL |         asm!("/* {} */", out(freg) _);
+   |                          ^^^^^^^^^^^
+
+error: register class `freg` requires at least one of the following target features: d, f
+  --> $DIR/bad-reg.rs:40:26
+   |
+LL |         asm!("/* {} */", in(freg) d);
+   |                          ^^^^^^^^^^
+
+error: register class `freg` requires at least one of the following target features: d, f
+  --> $DIR/bad-reg.rs:42:26
+   |
+LL |         asm!("/* {} */", out(freg) d);
+   |                          ^^^^^^^^^^^
+
+error: aborting due to 10 previous errors
+

Diff for: tests/ui/asm/loongarch/bad-reg.rs

@@ -0,0 +1,45 @@
+//@ add-core-stubs
+//@ needs-asm-support
+//@ revisions: loongarch64_lp64d loongarch64_lp64s
+//@[loongarch64_lp64d] compile-flags: --target loongarch64-unknown-linux-gnu
+//@[loongarch64_lp64d] needs-llvm-components: loongarch
+//@[loongarch64_lp64s] compile-flags: --target loongarch64-unknown-none-softfloat
+//@[loongarch64_lp64s] needs-llvm-components: loongarch
+
+#![crate_type = "lib"]
+#![feature(no_core, rustc_attrs)]
+#![no_core]
+
+extern crate minicore;
+use minicore::*;
+
+fn f() {
+    let mut x = 0;
+    let mut f = 0.0_f32;
+    let mut d = 0.0_f64;
+    unsafe {
+        // Unsupported registers
+        asm!("", out("$r0") _);
+        //~^ ERROR constant zero cannot be used as an operand for inline asm
+        asm!("", out("$tp") _);
+        //~^ ERROR invalid register `$tp`: reserved for TLS
+        asm!("", out("$sp") _);
+        //~^ ERROR invalid register `$sp`: the stack pointer cannot be used as an operand for inline asm
+        asm!("", out("$r21") _);
+        //~^ ERROR invalid register `$r21`: reserved by the ABI
+        asm!("", out("$fp") _);
+        //~^ ERROR invalid register `$fp`: the frame pointer cannot be used as an operand for inline asm
+        asm!("", out("$r31") _);
+        //~^ ERROR invalid register `$r31`: $r31 is used internally by LLVM and cannot be used as an operand for inline asm
+
+        asm!("", out("$f0") _); // ok
+        asm!("/* {} */", in(freg) f);
+        //[loongarch64_lp64s]~^ ERROR register class `freg` requires at least one of the following target features: d, f
+        asm!("/* {} */", out(freg) _);
+        //[loongarch64_lp64s]~^ ERROR register class `freg` requires at least one of the following target features: d, f
+        asm!("/* {} */", in(freg) d);
+        //[loongarch64_lp64s]~^ ERROR register class `freg` requires at least one of the following target features: d, f
+        asm!("/* {} */", out(freg) d);
+        //[loongarch64_lp64s]~^ ERROR register class `freg` requires at least one of the following target features: d, f
+    }
+}