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32-bit ARM: Emit lr instead of r14 when specified as an asm! output register.

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On 32-bit ARM platforms, the register `r14` has the alias `lr`. When used as an output register in `asm!`, rustc canonicalizes the name to `r14`. LLVM only knows the register by the name `lr`, and rejects it. This changes rustc's LLVM code generation to output `lr` instead.
This commit is contained in:
Johnathan Van Why 2021-02-14 22:05:33 -08:00
parent 9503ea19ed
commit fd21eb18e9
2 changed files with 12 additions and 0 deletions
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3
compiler/rustc_codegen_llvm/src/asm.rs
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@ -487,6 +487,9 @@ fn reg_to_llvm(reg: InlineAsmRegOrRegClass, layout: Option<&TyAndLayout<'tcx>>)
} else if reg == InlineAsmReg::AArch64(AArch64InlineAsmReg::x30) {
// LLVM doesn't recognize x30
"{lr}".to_string()
} else if reg == InlineAsmReg::Arm(ArmInlineAsmReg::r14) {
// LLVM doesn't recognize r14
"{lr}".to_string()
} else {
format!("{{{}}}", reg.name())
}