add support for clobbering xer, cr, and cr[0-7] for asm! on OpenPower/PowerPC

Fixes #88315

Author: programmerjake

compiler/rustc_codegen_llvm/src/asm.rs

@@ -615,6 +615,10 @@ fn reg_to_llvm(reg: InlineAsmRegOrRegClass, layout: Option<&TyAndLayout<'tcx>>)
             InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg) => "r",
             InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg_nonzero) => "b",
             InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::freg) => "f",
+            InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::cr)
+            | InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::xer) => {
+                unreachable!("clobber-only")
+            }
             InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::reg) => "r",
             InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::freg) => "f",
             InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::vreg) => {
@@ -751,6 +755,10 @@ fn dummy_output_type(cx: &CodegenCx<'ll, 'tcx>, reg: InlineAsmRegClass) -> &'ll
         InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg) => cx.type_i32(),
         InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::reg_nonzero) => cx.type_i32(),
         InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::freg) => cx.type_f64(),
+        InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::cr)
+        | InlineAsmRegClass::PowerPC(PowerPCInlineAsmRegClass::xer) => {
+            unreachable!("clobber-only")
+        }
         InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::reg) => cx.type_i32(),
         InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::freg) => cx.type_f32(),
         InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::vreg) => {

compiler/rustc_span/src/symbol.rs

@@ -478,6 +478,7 @@ symbols! {
         core_panic_macro,
         cosf32,
         cosf64,
+        cr,
         crate_id,
         crate_in_paths,
         crate_local,
@@ -1415,6 +1416,7 @@ symbols! {
         wreg,
         write_bytes,
         x87_reg,
+        xer,
         xmm_reg,
         ymm_reg,
         zmm_reg,

compiler/rustc_target/src/asm/mod.rs

@@ -344,7 +344,7 @@ impl InlineAsmReg {
             Self::Arm(r) => r.overlapping_regs(|r| cb(Self::Arm(r))),
             Self::AArch64(_) => cb(self),
             Self::RiscV(_) => cb(self),
-            Self::PowerPC(_) => cb(self),
+            Self::PowerPC(r) => r.overlapping_regs(|r| cb(Self::PowerPC(r))),
             Self::Hexagon(r) => r.overlapping_regs(|r| cb(Self::Hexagon(r))),
             Self::Mips(_) => cb(self),
             Self::Bpf(r) => r.overlapping_regs(|r| cb(Self::Bpf(r))),

compiler/rustc_target/src/asm/powerpc.rs

@@ -7,6 +7,8 @@ def_reg_class! {
         reg,
         reg_nonzero,
         freg,
+        cr,
+        xer,
     }
 }
 
@@ -44,6 +46,7 @@ impl PowerPCInlineAsmRegClass {
                 }
             }
             Self::freg => types! { _: F32, F64; },
+            Self::cr | Self::xer => &[],
         }
     }
 }
@@ -108,6 +111,16 @@ def_regs! {
         f29: freg = ["f29", "fr29"],
         f30: freg = ["f30", "fr30"],
         f31: freg = ["f31", "fr31"],
+        cr: cr = ["cr"],
+        cr0: cr = ["cr0"],
+        cr1: cr = ["cr1"],
+        cr2: cr = ["cr2"],
+        cr3: cr = ["cr3"],
+        cr4: cr = ["cr4"],
+        cr5: cr = ["cr5"],
+        cr6: cr = ["cr6"],
+        cr7: cr = ["cr7"],
+        xer: xer = ["xer"],
         #error = ["r1", "1", "sp"] =>
             "the stack pointer cannot be used as an operand for inline asm",
         #error = ["r2", "2"] =>
@@ -136,17 +149,55 @@ impl PowerPCInlineAsmReg {
         _arch: InlineAsmArch,
         _modifier: Option<char>,
     ) -> fmt::Result {
+        macro_rules! do_emit {
+            (
+                $($(($reg:ident, $value:literal)),*;)*
+            ) => {
+                out.write_str(match self {
+                    $($(Self::$reg => $value,)*)*
+                })
+            };
+        }
         // Strip off the leading prefix.
-        if self as u32 <= Self::r28 as u32 {
-            let index = self as u32 - Self::r28 as u32;
-            write!(out, "{}", index)
-        } else if self as u32 >= Self::f0 as u32 && self as u32 <= Self::f31 as u32 {
-            let index = self as u32 - Self::f31 as u32;
-            write!(out, "{}", index)
-        } else {
-            unreachable!()
+        do_emit! {
+            (r0, "0"), (r3, "3"), (r4, "4"), (r5, "5"), (r6, "6"), (r7, "7");
+            (r8, "8"), (r9, "9"), (r10, "10"), (r11, "11"), (r12, "12"), (r14, "14"), (r15, "15");
+            (r16, "16"), (r17, "17"), (r18, "18"), (r19, "19"), (r20, "20"), (r21, "21"), (r22, "22"), (r23, "23");
+            (r24, "24"), (r25, "25"), (r26, "26"), (r27, "27"), (r28, "28");
+            (f0, "0"), (f1, "1"), (f2, "2"), (f3, "3"), (f4, "4"), (f5, "5"), (f6, "6"), (f7, "7");
+            (f8, "8"), (f9, "9"), (f10, "10"), (f11, "11"), (f12, "12"), (f13, "13"), (f14, "14"), (f15, "15");
+            (f16, "16"), (f17, "17"), (f18, "18"), (f19, "19"), (f20, "20"), (f21, "21"), (f22, "22"), (f23, "23");
+            (f24, "24"), (f25, "25"), (f26, "26"), (f27, "27"), (f28, "28"), (f29, "29"), (f30, "30"), (f31, "31");
+            (cr, "cr");
+            (cr0, "0"), (cr1, "1"), (cr2, "2"), (cr3, "3"), (cr4, "4"), (cr5, "5"), (cr6, "6"), (cr7, "7");
+            (xer, "xer");
         }
     }
 
-    pub fn overlapping_regs(self, mut _cb: impl FnMut(PowerPCInlineAsmReg)) {}
+    pub fn overlapping_regs(self, mut cb: impl FnMut(PowerPCInlineAsmReg)) {
+        macro_rules! reg_conflicts {
+            (
+                $(
+                    $full:ident : $($field:ident)*
+                ),*;
+            ) => {
+                match self {
+                    $(
+                        Self::$full => {
+                            cb(Self::$full);
+                            $(cb(Self::$field);)*
+                        }
+                        $(Self::$field)|* => {
+                            cb(Self::$full);
+                            cb(self);
+                        }
+                    )*
+                    r => cb(r),
+                }
+            };
+        }
+        reg_conflicts! {
+            cr : cr0 cr1 cr2 cr3 cr4 cr5 cr6 cr7;
+        }
+    }
 }

src/doc/unstable-book/src/library-features/asm.md

@@ -584,6 +584,8 @@ Here is the list of currently supported register classes:
 | PowerPC | `reg` | `r[0-31]` | `r` |
 | PowerPC | `reg_nonzero` | | `r[1-31]` | `b` |
 | PowerPC | `freg` | `f[0-31]` | `f` |
+| PowerPC | `cr` | `cr[0-7]`, `cr` | Only clobbers |
+| PowerPC | `xer` | `xer` | Only clobbers |
 | wasm32 | `local` | None\* | `r` |
 | BPF | `reg` | `r[0-10]` | `r` |
 | BPF | `wreg` | `w[0-10]` | `w` |
@@ -637,6 +639,8 @@ Each register class has constraints on which value types they can be used with.
 | PowerPC | `reg` | None | `i8`, `i16`, `i32` |
 | PowerPC | `reg_nonzero` | None | `i8`, `i16`, `i32` |
 | PowerPC | `freg` | None | `f32`, `f64` |
+| PowerPC | `cr` | N/A | Only clobbers |
+| PowerPC | `xer` | 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` |

src/test/assembly/asm/powerpc-types.rs

@@ -194,3 +194,15 @@ check_reg!(reg_f32_f0, f32, "0", "f0", "fmr");
 // CHECK: fmr 0, 0
 // CHECK: #NO_APP
 check_reg!(reg_f64_f0, f64, "0", "f0", "fmr");
+
+// CHECK-LABEL: reg_f32_f18:
+// CHECK: #APP
+// CHECK: fmr 18, 18
+// CHECK: #NO_APP
+check_reg!(reg_f32_f18, f32, "18", "f18", "fmr");
+
+// CHECK-LABEL: reg_f64_f18:
+// CHECK: #APP
+// CHECK: fmr 18, 18
+// CHECK: #NO_APP
+check_reg!(reg_f64_f18, f64, "18", "f18", "fmr");

src/test/codegen/asm-powerpc-clobbers.rs

@@ -0,0 +1,48 @@
+// min-llvm-version: 10.0.1
+// revisions: powerpc powerpc64 powerpc64le
+//[powerpc] compile-flags: --target powerpc-unknown-linux-gnu
+//[powerpc] needs-llvm-components: powerpc
+//[powerpc64] compile-flags: --target powerpc64-unknown-linux-gnu
+//[powerpc64] needs-llvm-components: powerpc
+//[powerpc64le] compile-flags: --target powerpc64le-unknown-linux-gnu
+//[powerpc64le] needs-llvm-components: powerpc
+
+#![crate_type = "rlib"]
+#![feature(no_core, rustc_attrs, lang_items)]
+#![no_core]
+
+#[lang = "sized"]
+trait Sized {}
+
+#[rustc_builtin_macro]
+macro_rules! asm {
+    () => {};
+}
+
+// CHECK-LABEL: @cr_clobber
+// CHECK: call void asm sideeffect "", "~{cr}"()
+#[no_mangle]
+pub unsafe fn cr_clobber() {
+    asm!("", out("cr") _, options(nostack, nomem));
+}
+
+// CHECK-LABEL: @cr0_clobber
+// CHECK: call void asm sideeffect "", "~{cr0}"()
+#[no_mangle]
+pub unsafe fn cr0_clobber() {
+    asm!("", out("cr0") _, options(nostack, nomem));
+}
+
+// CHECK-LABEL: @cr5_clobber
+// CHECK: call void asm sideeffect "", "~{cr5}"()
+#[no_mangle]
+pub unsafe fn cr5_clobber() {
+    asm!("", out("cr5") _, options(nostack, nomem));
+}
+
+// CHECK-LABEL: @xer_clobber
+// CHECK: call void asm sideeffect "", "~{xer}"()
+#[no_mangle]
+pub unsafe fn xer_clobber() {
+    asm!("", out("xer") _, options(nostack, nomem));
+}