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asm: Allow the use of r8-r14 as clobbers on Thumb1
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Previously these were entirely disallowed, except for r11 which was
allowed by accident.
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@Amanieu
Amanieu committed Feb 18, 2022
1 parent 930fc4f commit 11250b8
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Showing 7 changed files with 97 additions and 46 deletions.
11 changes: 6 additions & 5 deletions compiler/rustc_ast_lowering/src/asm.rs
View file
Expand Up @@ -129,13 +129,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
.operands
.iter()
.map(|(op, op_sp)| {
let lower_reg = |reg| match reg {
let lower_reg = |reg, is_clobber| match reg {
InlineAsmRegOrRegClass::Reg(s) => {
asm::InlineAsmRegOrRegClass::Reg(if let Some(asm_arch) = asm_arch {
asm::InlineAsmReg::parse(
asm_arch,
&sess.target_features,
&sess.target,
is_clobber,
s,
)
.unwrap_or_else(|e| {
Expand All @@ -162,24 +163,24 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {

let op = match *op {
InlineAsmOperand::In { reg, ref expr } => hir::InlineAsmOperand::In {
reg: lower_reg(reg),
reg: lower_reg(reg, false),
expr: self.lower_expr_mut(expr),
},
InlineAsmOperand::Out { reg, late, ref expr } => hir::InlineAsmOperand::Out {
reg: lower_reg(reg),
reg: lower_reg(reg, expr.is_none()),
late,
expr: expr.as_ref().map(|expr| self.lower_expr_mut(expr)),
},
InlineAsmOperand::InOut { reg, late, ref expr } => {
hir::InlineAsmOperand::InOut {
reg: lower_reg(reg),
reg: lower_reg(reg, false),
late,
expr: self.lower_expr_mut(expr),
}
}
InlineAsmOperand::SplitInOut { reg, late, ref in_expr, ref out_expr } => {
hir::InlineAsmOperand::SplitInOut {
reg: lower_reg(reg),
reg: lower_reg(reg, false),
late,
in_expr: self.lower_expr_mut(in_expr),
out_expr: out_expr.as_ref().map(|expr| self.lower_expr_mut(expr)),
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_target/src/asm/aarch64.rs
View file
Expand Up @@ -77,6 +77,7 @@ pub fn reserved_x18(
_arch: InlineAsmArch,
_target_features: &FxHashSet<Symbol>,
target: &Target,
_is_clobber: bool,
) -> Result<(), &'static str> {
if target.os == "android"
|| target.is_like_fuchsia
Expand Down
17 changes: 13 additions & 4 deletions compiler/rustc_target/src/asm/arm.rs
View file
Expand Up @@ -66,10 +66,13 @@ fn frame_pointer_is_r7(target_features: &FxHashSet<Symbol>, target: &Target) ->
}

fn frame_pointer_r11(
_arch: InlineAsmArch,
arch: InlineAsmArch,
target_features: &FxHashSet<Symbol>,
target: &Target,
is_clobber: bool,
) -> Result<(), &'static str> {
not_thumb1(arch, target_features, target, is_clobber)?;

if !frame_pointer_is_r7(target_features, target) {
Err("the frame pointer (r11) cannot be used as an operand for inline asm")
} else {
Expand All @@ -81,6 +84,7 @@ fn frame_pointer_r7(
_arch: InlineAsmArch,
target_features: &FxHashSet<Symbol>,
target: &Target,
_is_clobber: bool,
) -> Result<(), &'static str> {
if frame_pointer_is_r7(target_features, target) {
Err("the frame pointer (r7) cannot be used as an operand for inline asm")
Expand All @@ -93,9 +97,13 @@ fn not_thumb1(
_arch: InlineAsmArch,
target_features: &FxHashSet<Symbol>,
_target: &Target,
is_clobber: bool,
) -> Result<(), &'static str> {
if target_features.contains(&sym::thumb_mode) && !target_features.contains(&sym::thumb2) {
Err("high registers (r8+) cannot be used in Thumb-1 code")
if !is_clobber
&& target_features.contains(&sym::thumb_mode)
&& !target_features.contains(&sym::thumb2)
{
Err("high registers (r8+) can only be used as clobbers in Thumb-1 code")
} else {
Ok(())
}
Expand All @@ -105,8 +113,9 @@ fn reserved_r9(
arch: InlineAsmArch,
target_features: &FxHashSet<Symbol>,
target: &Target,
is_clobber: bool,
) -> Result<(), &'static str> {
not_thumb1(arch, target_features, target)?;
not_thumb1(arch, target_features, target, is_clobber)?;

// We detect this using the reserved-r9 feature instead of using the target
// because the relocation model can be changed with compiler options.
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_target/src/asm/bpf.rs
View file
Expand Up @@ -47,6 +47,7 @@ fn only_alu32(
_arch: InlineAsmArch,
target_features: &FxHashSet<Symbol>,
_target: &Target,
_is_clobber: bool,
) -> Result<(), &'static str> {
if !target_features.contains(&sym::alu32) {
Err("register can't be used without the `alu32` target feature")
Expand Down
108 changes: 71 additions & 37 deletions compiler/rustc_target/src/asm/mod.rs
View file
Expand Up @@ -83,12 +83,13 @@ macro_rules! def_regs {
_arch: super::InlineAsmArch,
_target_features: &rustc_data_structures::fx::FxHashSet<Symbol>,
_target: &crate::spec::Target,
_is_clobber: bool,
name: &str,
) -> Result<Self, &'static str> {
match name {
$(
$($alias)|* | $reg_name => {
$($filter(_arch, _target_features, _target)?;)?
$($filter(_arch, _target_features, _target, _is_clobber)?;)?
Ok(Self::$reg)
}
)*
Expand All @@ -112,7 +113,7 @@ macro_rules! def_regs {
#[allow(unused_imports)]
use super::{InlineAsmReg, InlineAsmRegClass};
$(
if $($filter(_arch, _target_features, _target).is_ok() &&)? true {
if $($filter(_arch, _target_features, _target, false).is_ok() &&)? true {
if let Some(set) = _map.get_mut(&InlineAsmRegClass::$arch($arch_regclass::$class)) {
set.insert(InlineAsmReg::$arch($arch_reg::$reg));
}
Expand Down Expand Up @@ -298,54 +299,87 @@ impl InlineAsmReg {
arch: InlineAsmArch,
target_features: &FxHashSet<Symbol>,
target: &Target,
is_clobber: bool,
name: Symbol,
) -> Result<Self, &'static str> {
// FIXME: use direct symbol comparison for register names
// Use `Symbol::as_str` instead of `Symbol::with` here because `has_feature` may access `Symbol`.
let name = name.as_str();
Ok(match arch {
InlineAsmArch::X86 | InlineAsmArch::X86_64 => {
Self::X86(X86InlineAsmReg::parse(arch, target_features, target, name)?)
Self::X86(X86InlineAsmReg::parse(arch, target_features, target, is_clobber, name)?)
}
InlineAsmArch::Arm => {
Self::Arm(ArmInlineAsmReg::parse(arch, target_features, target, name)?)
}
InlineAsmArch::AArch64 => {
Self::AArch64(AArch64InlineAsmReg::parse(arch, target_features, target, name)?)
}
InlineAsmArch::RiscV32 | InlineAsmArch::RiscV64 => {
Self::RiscV(RiscVInlineAsmReg::parse(arch, target_features, target, name)?)
}
InlineAsmArch::Nvptx64 => {
Self::Nvptx(NvptxInlineAsmReg::parse(arch, target_features, target, name)?)
}
InlineAsmArch::PowerPC | InlineAsmArch::PowerPC64 => {
Self::PowerPC(PowerPCInlineAsmReg::parse(arch, target_features, target, name)?)
}
InlineAsmArch::Hexagon => {
Self::Hexagon(HexagonInlineAsmReg::parse(arch, target_features, target, name)?)
}
InlineAsmArch::Mips | InlineAsmArch::Mips64 => {
Self::Mips(MipsInlineAsmReg::parse(arch, target_features, target, name)?)
}
InlineAsmArch::S390x => {
Self::S390x(S390xInlineAsmReg::parse(arch, target_features, target, name)?)
}
InlineAsmArch::SpirV => {
Self::SpirV(SpirVInlineAsmReg::parse(arch, target_features, target, name)?)
}
InlineAsmArch::Wasm32 | InlineAsmArch::Wasm64 => {
Self::Wasm(WasmInlineAsmReg::parse(arch, target_features, target, name)?)
Self::Arm(ArmInlineAsmReg::parse(arch, target_features, target, is_clobber, name)?)
}
InlineAsmArch::AArch64 => Self::AArch64(AArch64InlineAsmReg::parse(
arch,
target_features,
target,
is_clobber,
name,
)?),
InlineAsmArch::RiscV32 | InlineAsmArch::RiscV64 => Self::RiscV(
RiscVInlineAsmReg::parse(arch, target_features, target, is_clobber, name)?,
),
InlineAsmArch::Nvptx64 => Self::Nvptx(NvptxInlineAsmReg::parse(
arch,
target_features,
target,
is_clobber,
name,
)?),
InlineAsmArch::PowerPC | InlineAsmArch::PowerPC64 => Self::PowerPC(
PowerPCInlineAsmReg::parse(arch, target_features, target, is_clobber, name)?,
),
InlineAsmArch::Hexagon => Self::Hexagon(HexagonInlineAsmReg::parse(
arch,
target_features,
target,
is_clobber,
name,
)?),
InlineAsmArch::Mips | InlineAsmArch::Mips64 => Self::Mips(MipsInlineAsmReg::parse(
arch,
target_features,
target,
is_clobber,
name,
)?),
InlineAsmArch::S390x => Self::S390x(S390xInlineAsmReg::parse(
arch,
target_features,
target,
is_clobber,
name,
)?),
InlineAsmArch::SpirV => Self::SpirV(SpirVInlineAsmReg::parse(
arch,
target_features,
target,
is_clobber,
name,
)?),
InlineAsmArch::Wasm32 | InlineAsmArch::Wasm64 => Self::Wasm(WasmInlineAsmReg::parse(
arch,
target_features,
target,
is_clobber,
name,
)?),
InlineAsmArch::Bpf => {
Self::Bpf(BpfInlineAsmReg::parse(arch, target_features, target, name)?)
Self::Bpf(BpfInlineAsmReg::parse(arch, target_features, target, is_clobber, name)?)
}
InlineAsmArch::Avr => {
Self::Avr(AvrInlineAsmReg::parse(arch, target_features, target, name)?)
}
InlineAsmArch::Msp430 => {
Self::Msp430(Msp430InlineAsmReg::parse(arch, target_features, target, name)?)
Self::Avr(AvrInlineAsmReg::parse(arch, target_features, target, is_clobber, name)?)
}
InlineAsmArch::Msp430 => Self::Msp430(Msp430InlineAsmReg::parse(
arch,
target_features,
target,
is_clobber,
name,
)?),
})
}

Expand Down Expand Up @@ -844,7 +878,7 @@ impl InlineAsmClobberAbi {
},
InlineAsmArch::AArch64 => match name {
"C" | "system" | "efiapi" => {
Ok(if aarch64::reserved_x18(arch, target_features, target).is_err() {
Ok(if aarch64::reserved_x18(arch, target_features, target, true).is_err() {
InlineAsmClobberAbi::AArch64NoX18
} else {
InlineAsmClobberAbi::AArch64
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_target/src/asm/riscv.rs
View file
Expand Up @@ -56,6 +56,7 @@ fn not_e(
_arch: InlineAsmArch,
target_features: &FxHashSet<Symbol>,
_target: &Target,
_is_clobber: bool,
) -> Result<(), &'static str> {
if target_features.contains(&sym::e) {
Err("register can't be used with the `e` target feature")
Expand Down
4 changes: 4 additions & 0 deletions compiler/rustc_target/src/asm/x86.rs
View file
Expand Up @@ -141,6 +141,7 @@ fn x86_64_only(
arch: InlineAsmArch,
_target_features: &FxHashSet<Symbol>,
_target: &Target,
_is_clobber: bool,
) -> Result<(), &'static str> {
match arch {
InlineAsmArch::X86 => Err("register is only available on x86_64"),
Expand All @@ -153,6 +154,7 @@ fn high_byte(
arch: InlineAsmArch,
_target_features: &FxHashSet<Symbol>,
_target: &Target,
_is_clobber: bool,
) -> Result<(), &'static str> {
match arch {
InlineAsmArch::X86_64 => Err("high byte registers cannot be used as an operand on x86_64"),
Expand All @@ -164,6 +166,7 @@ fn rbx_reserved(
arch: InlineAsmArch,
_target_features: &FxHashSet<Symbol>,
_target: &Target,
_is_clobber: bool,
) -> Result<(), &'static str> {
match arch {
InlineAsmArch::X86 => Ok(()),
Expand All @@ -178,6 +181,7 @@ fn esi_reserved(
arch: InlineAsmArch,
_target_features: &FxHashSet<Symbol>,
_target: &Target,
_is_clobber: bool,
) -> Result<(), &'static str> {
match arch {
InlineAsmArch::X86 => {
Expand Down

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