Allow PowerPC spe_acc as clobber-only register

This register is only supported on the *powerpc*spe targets. It is
only recognized by LLVM. gcc does not accept this as a clobber, nor
does it support these targets.

This is a volatile register, thus it is included with clobber_abi.

compiler/rustc_codegen_gcc/src/asm.rs

@@ -209,10 +209,16 @@ fn codegen_inline_asm(
                                 }
                                 ("r", dummy_output_type(self.cx, reg.reg_class()))
                             } else {
-                                // `clobber_abi` can add lots of clobbers that are not supported by the target,
-                                // such as AVX-512 registers, so we just ignore unsupported registers
-                                let is_target_supported =
-                                    reg.reg_class().supported_types(asm_arch, true).iter().any(
+                                let is_target_supported = match reg.reg_class() {
+                                    // `clobber_abi` clobbers spe_acc on all PowerPC targets. This
+                                    // register is unique to the powerpc*spe target, and the target
+                                    // is not supported by gcc. Ignore it.
+                                    InlineAsmRegClass::PowerPC(
+                                        PowerPCInlineAsmRegClass::spe_acc,
+                                    ) => false,
+                                    // `clobber_abi` can add lots of clobbers that are not supported by the target,
+                                    // such as AVX-512 registers, so we just ignore unsupported registers
+                                    x => x.supported_types(asm_arch, true).iter().any(
                                         |&(_, feature)| {
                                             if let Some(feature) = feature {
                                                 self.tcx
@@ -222,7 +228,8 @@ fn codegen_inline_asm(
                                                 true // Register class is unconditionally supported
                                             }
                                         },
-                                    );
+                                    ),
+                                };
 
                                 if is_target_supported && !clobbers.contains(&reg_name) {
                                     clobbers.push(reg_name);
@@ -710,7 +717,8 @@ fn reg_class_to_gcc(reg_class: InlineAsmRegClass) -> &'static str {
             PowerPCInlineAsmRegClass::cr
             | PowerPCInlineAsmRegClass::ctr
             | PowerPCInlineAsmRegClass::lr
-            | PowerPCInlineAsmRegClass::xer,
+            | PowerPCInlineAsmRegClass::xer
+            | PowerPCInlineAsmRegClass::spe_acc,
         ) => {
             unreachable!("clobber-only")
         }
@@ -793,7 +801,8 @@ fn dummy_output_type<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, reg: InlineAsmRegCl
             PowerPCInlineAsmRegClass::cr
             | PowerPCInlineAsmRegClass::ctr
             | PowerPCInlineAsmRegClass::lr
-            | PowerPCInlineAsmRegClass::xer,
+            | PowerPCInlineAsmRegClass::xer
+            | PowerPCInlineAsmRegClass::spe_acc,
         ) => {
             unreachable!("clobber-only")
         }

compiler/rustc_codegen_llvm/src/asm.rs

@@ -663,7 +663,8 @@ fn reg_to_llvm(reg: InlineAsmRegOrRegClass, layout: Option<&TyAndLayout<'_>>) ->
                 PowerPCInlineAsmRegClass::cr
                 | PowerPCInlineAsmRegClass::ctr
                 | PowerPCInlineAsmRegClass::lr
-                | PowerPCInlineAsmRegClass::xer,
+                | PowerPCInlineAsmRegClass::xer
+                | PowerPCInlineAsmRegClass::spe_acc,
             ) => {
                 unreachable!("clobber-only")
             }
@@ -843,7 +844,8 @@ fn dummy_output_type<'ll>(cx: &CodegenCx<'ll, '_>, reg: InlineAsmRegClass) -> &'
             PowerPCInlineAsmRegClass::cr
             | PowerPCInlineAsmRegClass::ctr
             | PowerPCInlineAsmRegClass::lr
-            | PowerPCInlineAsmRegClass::xer,
+            | PowerPCInlineAsmRegClass::xer
+            | PowerPCInlineAsmRegClass::spe_acc,
         ) => {
             unreachable!("clobber-only")
         }

compiler/rustc_span/src/symbol.rs

@@ -2143,6 +2143,7 @@
         sparc,
         sparc64,
         sparc_target_feature,
+        spe_acc,
         specialization,
         speed,
         spirv,

compiler/rustc_target/src/asm/mod.rs

@@ -1271,6 +1271,9 @@ macro_rules! clobbered_regs {
                     ctr,
                     lr,
                     xer,
+
+                    // These are only supported on PowerPC SPE targets.
+                    spe_acc,
                 }
             },
             InlineAsmClobberAbi::S390x => clobbered_regs! {

compiler/rustc_target/src/asm/powerpc.rs

@@ -17,6 +17,7 @@
         ctr,
         lr,
         xer,
+        spe_acc,
     }
 }
 
@@ -63,7 +64,7 @@ pub fn supported_types(
             Self::vsreg => types! {
                 vsx: F32, F64, VecI8(16), VecI16(8), VecI32(4), VecI64(2), VecF32(4), VecF64(2);
             },
-            Self::cr | Self::ctr | Self::lr | Self::xer => &[],
+            Self::cr | Self::ctr | Self::lr | Self::xer | Self::spe_acc => &[],
         }
     }
 }
@@ -285,6 +286,7 @@ fn reserved_v20to31(
         ctr: ctr = ["ctr"],
         lr: lr = ["lr"],
         xer: xer = ["xer"],
+        spe_acc: spe_acc = ["spe_acc"],
         #error = ["r1", "1", "sp"] =>
             "the stack pointer cannot be used as an operand for inline asm",
         #error = ["r2", "2"] =>
@@ -342,6 +344,7 @@ macro_rules! do_emit {
             (ctr, "ctr");
             (lr, "lr");
             (xer, "xer");
+            (spe_acc, "spe_acc");
         }
     }
 

src/doc/unstable-book/src/language-features/asm-experimental-arch.md

@@ -40,6 +40,7 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 | PowerPC      | `ctr`          | `ctr`                              | Only clobbers        |
 | PowerPC      | `lr`           | `lr`                               | Only clobbers        |
 | PowerPC      | `xer`          | `xer`                              | Only clobbers        |
+| PowerPC      | `spe_acc`      | `spe_acc`                          | Only clobbers        |
 | wasm32       | `local`        | None\*                             | `r`                  |
 | BPF          | `reg`          | `r[0-10]`                          | `r`                  |
 | BPF          | `wreg`         | `w[0-10]`                          | `w`                  |
@@ -63,6 +64,8 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 > - WebAssembly doesn't have registers, so named registers are not supported.
 >
 > - r29 is reserved only on 32 bit PowerPC targets.
+>
+> - spe_acc is only available on PowerPC SPE targets.
 
 # Register class supported types
 
@@ -87,6 +90,7 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 | PowerPC      | `ctr`                           | N/A            | Only clobbers                           |
 | PowerPC      | `lr`                            | N/A            | Only clobbers                           |
 | PowerPC      | `xer`                           | N/A            | Only clobbers                           |
+| PowerPC      | `spe_acc`                       | N/A            | Only clobbers                           |
 | wasm32       | `local`                         | None           | `i8` `i16` `i32` `i64` `f32` `f64`      |
 | BPF          | `reg`                           | None           | `i8` `i16` `i32` `i64`                  |
 | BPF          | `wreg`                          | `alu32`        | `i8` `i16` `i32`                        |

tests/codegen-llvm/asm/powerpc-clobbers.rs

@@ -69,10 +69,10 @@ pub unsafe fn vs32_clobber() {
 
 // Output format depends on the availability of altivec and vsx
 // CHECK-LABEL: @clobber_abi
-// powerpc: asm sideeffect "", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},~{vs0},~{vs1},~{vs2},~{vs3},~{vs4},~{vs5},~{vs6},~{vs7},~{vs8},~{vs9},~{vs10},~{vs11},~{vs12},~{vs13},~{vs14},~{vs15},~{vs16},~{vs17},~{vs18},~{vs19},~{vs20},~{vs21},~{vs22},~{vs23},~{vs24},~{vs25},~{vs26},~{vs27},~{vs28},~{vs29},~{vs30},~{vs31},~{v0},~{v1},~{v2},~{v3},~{v4},~{v5},~{v6},~{v7},~{v8},~{v9},~{v10},~{v11},~{v12},~{v13},~{v14},~{v15},~{v16},~{v17},~{v18},~{v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer}"()
-// powerpc64: asm sideeffect "", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{vs0},~{vs1},~{vs2},~{vs3},~{vs4},~{vs5},~{vs6},~{vs7},~{vs8},~{vs9},~{vs10},~{vs11},~{vs12},~{vs13},~{vs14},~{vs15},~{vs16},~{vs17},~{vs18},~{vs19},~{vs20},~{vs21},~{vs22},~{vs23},~{vs24},~{vs25},~{vs26},~{vs27},~{vs28},~{vs29},~{vs30},~{vs31},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer}"()
-// powerpc64le: asm sideeffect "", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={vs0},={vs1},={vs2},={vs3},={vs4},={vs5},={vs6},={vs7},={vs8},={vs9},={vs10},={vs11},={vs12},={vs13},={vs14},={vs15},={vs16},={vs17},={vs18},={vs19},={vs20},={vs21},={vs22},={vs23},={vs24},={vs25},={vs26},={vs27},={vs28},={vs29},={vs30},={vs31},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer}"()
-// aix64: asm sideeffect "", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={vs0},={vs1},={vs2},={vs3},={vs4},={vs5},={vs6},={vs7},={vs8},={vs9},={vs10},={vs11},={vs12},={vs13},={vs14},={vs15},={vs16},={vs17},={vs18},={vs19},={vs20},={vs21},={vs22},={vs23},={vs24},={vs25},={vs26},={vs27},={vs28},={vs29},={vs30},={vs31},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer}"()
+// powerpc: asm sideeffect "", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},~{vs0},~{vs1},~{vs2},~{vs3},~{vs4},~{vs5},~{vs6},~{vs7},~{vs8},~{vs9},~{vs10},~{vs11},~{vs12},~{vs13},~{vs14},~{vs15},~{vs16},~{vs17},~{vs18},~{vs19},~{vs20},~{vs21},~{vs22},~{vs23},~{vs24},~{vs25},~{vs26},~{vs27},~{vs28},~{vs29},~{vs30},~{vs31},~{v0},~{v1},~{v2},~{v3},~{v4},~{v5},~{v6},~{v7},~{v8},~{v9},~{v10},~{v11},~{v12},~{v13},~{v14},~{v15},~{v16},~{v17},~{v18},~{v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer},~{spe_acc}"()
+// powerpc64: asm sideeffect "", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{vs0},~{vs1},~{vs2},~{vs3},~{vs4},~{vs5},~{vs6},~{vs7},~{vs8},~{vs9},~{vs10},~{vs11},~{vs12},~{vs13},~{vs14},~{vs15},~{vs16},~{vs17},~{vs18},~{vs19},~{vs20},~{vs21},~{vs22},~{vs23},~{vs24},~{vs25},~{vs26},~{vs27},~{vs28},~{vs29},~{vs30},~{vs31},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer},~{spe_acc}"()
+// powerpc64le: asm sideeffect "", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={vs0},={vs1},={vs2},={vs3},={vs4},={vs5},={vs6},={vs7},={vs8},={vs9},={vs10},={vs11},={vs12},={vs13},={vs14},={vs15},={vs16},={vs17},={vs18},={vs19},={vs20},={vs21},={vs22},={vs23},={vs24},={vs25},={vs26},={vs27},={vs28},={vs29},={vs30},={vs31},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer},~{spe_acc}"()
+// aix64: asm sideeffect "", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={vs0},={vs1},={vs2},={vs3},={vs4},={vs5},={vs6},={vs7},={vs8},={vs9},={vs10},={vs11},={vs12},={vs13},={vs14},={vs15},={vs16},={vs17},={vs18},={vs19},={vs20},={vs21},={vs22},={vs23},={vs24},={vs25},={vs26},={vs27},={vs28},={vs29},={vs30},={vs31},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer},~{spe_acc}"()
 #[no_mangle]
 pub unsafe fn clobber_abi() {
     asm!("", clobber_abi("C"), options(nostack, nomem, preserves_flags));
@@ -104,10 +104,10 @@ pub unsafe fn clobber_preservesflags() {
 // Output format depends on the availability of altivec and vsx
 // CHECK-LABEL: @clobber_abi_no_preserves_flags
 #[no_mangle]
-// powerpc: asm sideeffect "nop", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},~{vs0},~{vs1},~{vs2},~{vs3},~{vs4},~{vs5},~{vs6},~{vs7},~{vs8},~{vs9},~{vs10},~{vs11},~{vs12},~{vs13},~{vs14},~{vs15},~{vs16},~{vs17},~{vs18},~{vs19},~{vs20},~{vs21},~{vs22},~{vs23},~{vs24},~{vs25},~{vs26},~{vs27},~{vs28},~{vs29},~{vs30},~{vs31},~{v0},~{v1},~{v2},~{v3},~{v4},~{v5},~{v6},~{v7},~{v8},~{v9},~{v10},~{v11},~{v12},~{v13},~{v14},~{v15},~{v16},~{v17},~{v18},~{v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer}"()
-// powerpc64: asm sideeffect "nop", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{vs0},~{vs1},~{vs2},~{vs3},~{vs4},~{vs5},~{vs6},~{vs7},~{vs8},~{vs9},~{vs10},~{vs11},~{vs12},~{vs13},~{vs14},~{vs15},~{vs16},~{vs17},~{vs18},~{vs19},~{vs20},~{vs21},~{vs22},~{vs23},~{vs24},~{vs25},~{vs26},~{vs27},~{vs28},~{vs29},~{vs30},~{vs31},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer}"()
-// powerpc64le: asm sideeffect "nop", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={vs0},={vs1},={vs2},={vs3},={vs4},={vs5},={vs6},={vs7},={vs8},={vs9},={vs10},={vs11},={vs12},={vs13},={vs14},={vs15},={vs16},={vs17},={vs18},={vs19},={vs20},={vs21},={vs22},={vs23},={vs24},={vs25},={vs26},={vs27},={vs28},={vs29},={vs30},={vs31},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer}"()
-// aix64: asm sideeffect "nop", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={vs0},={vs1},={vs2},={vs3},={vs4},={vs5},={vs6},={vs7},={vs8},={vs9},={vs10},={vs11},={vs12},={vs13},={vs14},={vs15},={vs16},={vs17},={vs18},={vs19},={vs20},={vs21},={vs22},={vs23},={vs24},={vs25},={vs26},={vs27},={vs28},={vs29},={vs30},={vs31},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer}"()
+// powerpc: asm sideeffect "nop", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},~{vs0},~{vs1},~{vs2},~{vs3},~{vs4},~{vs5},~{vs6},~{vs7},~{vs8},~{vs9},~{vs10},~{vs11},~{vs12},~{vs13},~{vs14},~{vs15},~{vs16},~{vs17},~{vs18},~{vs19},~{vs20},~{vs21},~{vs22},~{vs23},~{vs24},~{vs25},~{vs26},~{vs27},~{vs28},~{vs29},~{vs30},~{vs31},~{v0},~{v1},~{v2},~{v3},~{v4},~{v5},~{v6},~{v7},~{v8},~{v9},~{v10},~{v11},~{v12},~{v13},~{v14},~{v15},~{v16},~{v17},~{v18},~{v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer},~{spe_acc}"()
+// powerpc64: asm sideeffect "nop", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{vs0},~{vs1},~{vs2},~{vs3},~{vs4},~{vs5},~{vs6},~{vs7},~{vs8},~{vs9},~{vs10},~{vs11},~{vs12},~{vs13},~{vs14},~{vs15},~{vs16},~{vs17},~{vs18},~{vs19},~{vs20},~{vs21},~{vs22},~{vs23},~{vs24},~{vs25},~{vs26},~{vs27},~{vs28},~{vs29},~{vs30},~{vs31},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer},~{spe_acc}"()
+// powerpc64le: asm sideeffect "nop", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={vs0},={vs1},={vs2},={vs3},={vs4},={vs5},={vs6},={vs7},={vs8},={vs9},={vs10},={vs11},={vs12},={vs13},={vs14},={vs15},={vs16},={vs17},={vs18},={vs19},={vs20},={vs21},={vs22},={vs23},={vs24},={vs25},={vs26},={vs27},={vs28},={vs29},={vs30},={vs31},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer},~{spe_acc}"()
+// aix64: asm sideeffect "nop", "={r0},={r3},={r4},={r5},={r6},={r7},={r8},={r9},={r10},={r11},={r12},={f0},={f1},={f2},={f3},={f4},={f5},={f6},={f7},={f8},={f9},={f10},={f11},={f12},={f13},={vs0},={vs1},={vs2},={vs3},={vs4},={vs5},={vs6},={vs7},={vs8},={vs9},={vs10},={vs11},={vs12},={vs13},={vs14},={vs15},={vs16},={vs17},={vs18},={vs19},={vs20},={vs21},={vs22},={vs23},={vs24},={vs25},={vs26},={vs27},={vs28},={vs29},={vs30},={vs31},={v0},={v1},={v2},={v3},={v4},={v5},={v6},={v7},={v8},={v9},={v10},={v11},={v12},={v13},={v14},={v15},={v16},={v17},={v18},={v19},~{cr0},~{cr1},~{cr5},~{cr6},~{cr7},~{ctr},~{lr},~{xer},~{spe_acc}"()
 pub unsafe fn clobber_abi_no_preserves_flags() {
     // Use a nop to prevent aliasing of identical functions here.
     asm!("nop", clobber_abi("C"), options(nostack, nomem));