Rollup merge of #90796 - Amanieu:remove_reg_thumb, r=joshtriplett

Remove the reg_thumb register class for asm! on ARM

Also restricts r8-r14 from being used on Thumb1 targets as per #90736.

cc ``@Lokathor``

r? ``@joshtriplett``

8 files changed, 30 insertions, 65 deletions

diff --git a/compiler/rustc_codegen_gcc/src/asm.rs b/compiler/rustc_codegen_gcc/src/asm.rs
index 7481b5db755..10edcf36955 100644
--- a/compiler/rustc_codegen_gcc/src/asm.rs
+++ b/compiler/rustc_codegen_gcc/src/asm.rs
@@ -568,7 +568,6 @@ fn reg_to_gcc(reg: InlineAsmRegOrRegClass) -> ConstraintOrRegister {
             InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg) => unimplemented!(),
             InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg_low16) => unimplemented!(),
             InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg) => unimplemented!(),
-            InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg_thumb) => unimplemented!(),
             InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg)
             | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg_low16)
             | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg_low8) => unimplemented!(),
@@ -628,8 +627,7 @@ fn dummy_output_type<'gcc, 'tcx>(cx: &CodegenCx<'gcc, 'tcx>, reg: InlineAsmRegCl
         | InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg_low16) => {
             unimplemented!()
         }
-        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg)
-        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg_thumb) => cx.type_i32(),
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg)=> cx.type_i32(),
         InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg)
         | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg_low16) => cx.type_f32(),
         InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg)
@@ -737,8 +735,7 @@ fn modifier_to_gcc(arch: InlineAsmArch, reg: InlineAsmRegClass, modifier: Option
         | InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::vreg_low16) => {
             unimplemented!()
         }
-        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg)
-        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg_thumb) => unimplemented!(),
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg)  => unimplemented!(),
         InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg)
         | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg_low16) => unimplemented!(),
         InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg)
diff --git a/compiler/rustc_codegen_llvm/src/asm.rs b/compiler/rustc_codegen_llvm/src/asm.rs
index 90d3c0fb2f1..f3c3a174908 100644
--- a/compiler/rustc_codegen_llvm/src/asm.rs
+++ b/compiler/rustc_codegen_llvm/src/asm.rs
@@ -632,7 +632,6 @@ fn reg_to_llvm(reg: InlineAsmRegOrRegClass, layout: Option<&TyAndLayout<'tcx>>)
                 unreachable!("clobber-only")
             }
             InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg) => "r",
-            InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg_thumb) => "l",
             InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg)
             | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg_low16)
             | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg_low8) => "t",
@@ -703,8 +702,7 @@ fn modifier_to_llvm(
         InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::preg) => {
             unreachable!("clobber-only")
         }
-        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg)
-        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg_thumb) => None,
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg) => None,
         InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg)
         | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg_low16) => None,
         InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg)
@@ -785,8 +783,7 @@ fn dummy_output_type(cx: &CodegenCx<'ll, 'tcx>, reg: InlineAsmRegClass) -> &'ll
         InlineAsmRegClass::AArch64(AArch64InlineAsmRegClass::preg) => {
             unreachable!("clobber-only")
         }
-        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg)
-        | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg_thumb) => cx.type_i32(),
+        InlineAsmRegClass::Arm(ArmInlineAsmRegClass::reg) => cx.type_i32(),
         InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg)
         | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::sreg_low16) => cx.type_f32(),
         InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg)
diff --git a/compiler/rustc_codegen_ssa/src/target_features.rs b/compiler/rustc_codegen_ssa/src/target_features.rs
index b4420df5df4..ba72e3cfafc 100644
--- a/compiler/rustc_codegen_ssa/src/target_features.rs
+++ b/compiler/rustc_codegen_ssa/src/target_features.rs
@@ -35,6 +35,7 @@ const ARM_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
     // since it should be enabled per-function using #[instruction_set], not
     // #[target_feature].
     ("thumb-mode", Some(sym::arm_target_feature)),
+    ("thumb2", Some(sym::arm_target_feature)),
 ];
 
 const AARCH64_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index f3ba6843096..0b851f1df5b 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -1058,7 +1058,6 @@ symbols! {
         reg_nonzero,
         reg_pair,
         reg_ptr,
-        reg_thumb,
         reg_upper,
         register_attr,
         register_tool,
diff --git a/compiler/rustc_target/src/asm/arm.rs b/compiler/rustc_target/src/asm/arm.rs
index 4c323fc35d6..4eeb7fcc71b 100644
--- a/compiler/rustc_target/src/asm/arm.rs
+++ b/compiler/rustc_target/src/asm/arm.rs
@@ -6,7 +6,6 @@ use std::fmt;
 def_reg_class! {
     Arm ArmInlineAsmRegClass {
         reg,
-        reg_thumb,
         sreg,
         sreg_low16,
         dreg,
@@ -47,7 +46,7 @@ impl ArmInlineAsmRegClass {
         _arch: InlineAsmArch,
     ) -> &'static [(InlineAsmType, Option<&'static str>)] {
         match self {
-            Self::reg | Self::reg_thumb => types! { _: I8, I16, I32, F32; },
+            Self::reg => types! { _: I8, I16, I32, F32; },
             Self::sreg | Self::sreg_low16 => types! { "vfp2": I32, F32; },
             Self::dreg | Self::dreg_low16 | Self::dreg_low8 => types! {
                 "vfp2": I64, F64, VecI8(8), VecI16(4), VecI32(2), VecI64(1), VecF32(2);
@@ -88,20 +87,32 @@ fn frame_pointer_r7(
     }
 }
 
+fn not_thumb1(
+    _arch: InlineAsmArch,
+    mut has_feature: impl FnMut(&str) -> bool,
+    _target: &Target,
+) -> Result<(), &'static str> {
+    if has_feature("thumb-mode") && !has_feature("thumb2") {
+        Err("high registers (r8+) cannot be used in Thumb-1 code")
+    } else {
+        Ok(())
+    }
+}
+
 def_regs! {
     Arm ArmInlineAsmReg ArmInlineAsmRegClass {
-        r0: reg, reg_thumb = ["r0", "a1"],
-        r1: reg, reg_thumb = ["r1", "a2"],
-        r2: reg, reg_thumb = ["r2", "a3"],
-        r3: reg, reg_thumb = ["r3", "a4"],
-        r4: reg, reg_thumb = ["r4", "v1"],
-        r5: reg, reg_thumb = ["r5", "v2"],
-        r7: reg, reg_thumb = ["r7", "v4"] % frame_pointer_r7,
-        r8: reg = ["r8", "v5"],
-        r10: reg = ["r10", "sl"],
+        r0: reg = ["r0", "a1"],
+        r1: reg = ["r1", "a2"],
+        r2: reg = ["r2", "a3"],
+        r3: reg = ["r3", "a4"],
+        r4: reg = ["r4", "v1"],
+        r5: reg = ["r5", "v2"],
+        r7: reg = ["r7", "v4"] % frame_pointer_r7,
+        r8: reg = ["r8", "v5"] % not_thumb1,
+        r10: reg = ["r10", "sl"] % not_thumb1,
         r11: reg = ["r11", "fp"] % frame_pointer_r11,
-        r12: reg = ["r12", "ip"],
-        r14: reg = ["r14", "lr"],
+        r12: reg = ["r12", "ip"] % not_thumb1,
+        r14: reg = ["r14", "lr"] % not_thumb1,
         s0: sreg, sreg_low16 = ["s0"],
         s1: sreg, sreg_low16 = ["s1"],
         s2: sreg, sreg_low16 = ["s2"],
diff --git a/src/doc/unstable-book/src/library-features/asm.md b/src/doc/unstable-book/src/library-features/asm.md
index dffa3a8b80f..59987cccde6 100644
--- a/src/doc/unstable-book/src/library-features/asm.md
+++ b/src/doc/unstable-book/src/library-features/asm.md
@@ -564,12 +564,8 @@ Here is the list of currently supported register classes:
 | AArch64 | `vreg` | `v[0-31]` | `w` |
 | AArch64 | `vreg_low16` | `v[0-15]` | `x` |
 | AArch64 | `preg` | `p[0-15]`, `ffr` | Only clobbers |
-| ARM (ARM) | `reg` | `r[0-12]`, `r14` | `r` |
-| ARM (Thumb2) | `reg` | `r[0-12]`, `r14` | `r` |
+| ARM (ARM/Thumb2) | `reg` | `r[0-12]`, `r14` | `r` |
 | ARM (Thumb1) | `reg` | `r[0-7]` | `r` |
-| ARM (ARM) | `reg_thumb` | `r[0-r12]`, `r14` | `l` |
-| ARM (Thumb2) | `reg_thumb` | `r[0-7]` | `l` |
-| ARM (Thumb1) | `reg_thumb` | `r[0-7]` | `l` |
 | ARM | `sreg` | `s[0-31]` | `t` |
 | ARM | `sreg_low16` | `s[0-15]` | `x` |
 | ARM | `dreg` | `d[0-31]` | `w` |
diff --git a/src/test/assembly/asm/arm-modifiers.rs b/src/test/assembly/asm/arm-modifiers.rs
index a6985a3bf5c..88ffeaecfec 100644
--- a/src/test/assembly/asm/arm-modifiers.rs
+++ b/src/test/assembly/asm/arm-modifiers.rs
@@ -59,12 +59,6 @@ macro_rules! check {
 // CHECK: @NO_APP
 check!(reg "" reg i32 "mov");
 
-// CHECK-LABEL: reg_thumb:
-// CHECK: @APP
-// CHECK: mov r0, r0
-// CHECK: @NO_APP
-check!(reg_thumb "" reg_thumb i32 "mov");
-
 // CHECK-LABEL: sreg:
 // CHECK: @APP
 // CHECK: vmov.f32 s0, s0
diff --git a/src/test/assembly/asm/arm-types.rs b/src/test/assembly/asm/arm-types.rs
index 0c57b1fc478..5ac1af6afd6 100644
--- a/src/test/assembly/asm/arm-types.rs
+++ b/src/test/assembly/asm/arm-types.rs
@@ -163,36 +163,6 @@ check!(reg_f32 f32 reg "mov");
 // CHECK: @NO_APP
 check!(reg_ptr ptr reg "mov");
 
-// CHECK-LABEL: reg_thumb_i8:
-// CHECK: @APP
-// CHECK: mov {{[a-z0-9]+}}, {{[a-z0-9]+}}
-// CHECK: @NO_APP
-check!(reg_thumb_i8 i8 reg_thumb "mov");
-
-// CHECK-LABEL: reg_thumb_i16:
-// CHECK: @APP
-// CHECK: mov {{[a-z0-9]+}}, {{[a-z0-9]+}}
-// CHECK: @NO_APP
-check!(reg_thumb_i16 i16 reg_thumb "mov");
-
-// CHECK-LABEL: reg_thumb_i32:
-// CHECK: @APP
-// CHECK: mov {{[a-z0-9]+}}, {{[a-z0-9]+}}
-// CHECK: @NO_APP
-check!(reg_thumb_i32 i32 reg_thumb "mov");
-
-// CHECK-LABEL: reg_thumb_f32:
-// CHECK: @APP
-// CHECK: mov {{[a-z0-9]+}}, {{[a-z0-9]+}}
-// CHECK: @NO_APP
-check!(reg_thumb_f32 f32 reg_thumb "mov");
-
-// CHECK-LABEL: reg_thumb_ptr:
-// CHECK: @APP
-// CHECK: mov {{[a-z0-9]+}}, {{[a-z0-9]+}}
-// CHECK: @NO_APP
-check!(reg_thumb_ptr ptr reg_thumb "mov");
-
 // CHECK-LABEL: sreg_i32:
 // CHECK: @APP
 // CHECK: vmov.f32 s{{[0-9]+}}, s{{[0-9]+}}