From 4945d21ed9ef70657c0ea527fb356b94e5345f64 Mon Sep 17 00:00:00 2001 From: Paul Murphy Date: Mon, 22 Sep 2025 09:28:21 -0500 Subject: [PATCH] Implement ppc/ppc64 preserves_flags option for inline asm Implemented preserves_flags on powerpc by making it do nothing. This prevents having two different ways to mark `cr0` as clobbered. clang and gcc alias `cr0` to `cc`. The gcc inline documentation does not state what this does on powerpc* targets, but inspection of the source shows it is equivalent to condition register field `cr0`, so it should not be added. --- compiler/rustc_codegen_gcc/src/asm.rs | 13 ++++++-- tests/codegen-llvm/asm/powerpc-clobbers.rs | 35 ++++++++++++++++++++++ 2 files changed, 45 insertions(+), 3 deletions(-) diff --git a/compiler/rustc_codegen_gcc/src/asm.rs b/compiler/rustc_codegen_gcc/src/asm.rs index 81cdfc68737f..f237861b1595 100644 --- a/compiler/rustc_codegen_gcc/src/asm.rs +++ b/compiler/rustc_codegen_gcc/src/asm.rs @@ -546,9 +546,16 @@ impl<'a, 'gcc, 'tcx> AsmBuilderMethods<'tcx> for Builder<'a, 'gcc, 'tcx> { } if !options.contains(InlineAsmOptions::PRESERVES_FLAGS) { - // TODO(@Commeownist): I'm not 100% sure this one clobber is sufficient - // on all architectures. For instance, what about FP stack? - extended_asm.add_clobber("cc"); + match asm_arch { + InlineAsmArch::PowerPC | InlineAsmArch::PowerPC64 => { + // "cc" is cr0 on powerpc. + } + // TODO(@Commeownist): I'm not 100% sure this one clobber is sufficient + // on all architectures. For instance, what about FP stack? + _ => { + extended_asm.add_clobber("cc"); + } + } } if !options.contains(InlineAsmOptions::NOMEM) { extended_asm.add_clobber("memory"); diff --git a/tests/codegen-llvm/asm/powerpc-clobbers.rs b/tests/codegen-llvm/asm/powerpc-clobbers.rs index 042016956b8e..9d8204fa3be9 100644 --- a/tests/codegen-llvm/asm/powerpc-clobbers.rs +++ b/tests/codegen-llvm/asm/powerpc-clobbers.rs @@ -77,3 +77,38 @@ pub unsafe fn vs32_clobber() { pub unsafe fn clobber_abi() { asm!("", clobber_abi("C"), options(nostack, nomem, preserves_flags)); } + +// CHECK-LABEL: @clobber_no_preserves_flags +// CHECK: call void asm sideeffect "nop", ""() +#[no_mangle] +pub unsafe fn clobber_no_preserves_flags() { + // Use a nop to prevent aliasing of identical functions here. + asm!("nop", options(nostack, nomem)); +} + +// CHECK-LABEL: @cr0_clobber_no_preserves_flags +// CHECK: call void asm sideeffect "nop; nop", "~{cr0}"() +#[no_mangle] +pub unsafe fn cr0_clobber_no_preserves_flags() { + // Use nop; nop to prevent aliasing of identical functions here. + asm!("nop; nop", out("cr0") _, options(nostack, nomem)); +} + +// CHECK-LABEL: @clobber_preservesflags +// CHECK: call void asm sideeffect "", "~{memory}"() +#[no_mangle] +pub unsafe fn clobber_preservesflags() { + asm!("", options(nostack, preserves_flags)); +} + +// 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}"() +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)); +}