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Support inline asm on AArch64
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Also stop changing the frame pointer on x86_64. This confuses unwinders.
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@bjorn3
bjorn3 committed Oct 5, 2023
1 parent a47b9fd commit b1421de
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Showing 3 changed files with 55 additions and 9 deletions.
6 changes: 6 additions & 0 deletions example/mini_core.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -683,6 +683,12 @@ pub macro cfg() {
/* compiler built-in */
}

#[rustc_builtin_macro]
#[rustc_macro_transparency = "semitransparent"]
pub macro asm() {
/* compiler built-in */
}

#[rustc_builtin_macro]
#[rustc_macro_transparency = "semitransparent"]
pub macro global_asm() {
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23 changes: 17 additions & 6 deletions src/global_asm.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,16 +9,22 @@ use std::sync::Arc;
use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use rustc_hir::{InlineAsmOperand, ItemId};
use rustc_session::config::{OutputFilenames, OutputType};
use rustc_target::asm::InlineAsmArch;

use crate::prelude::*;

pub(crate) fn codegen_global_asm_item(tcx: TyCtxt<'_>, global_asm: &mut String, item_id: ItemId) {
let item = tcx.hir().item(item_id);
if let rustc_hir::ItemKind::GlobalAsm(asm) = item.kind {
if !asm.options.contains(InlineAsmOptions::ATT_SYNTAX) {
global_asm.push_str("\n.intel_syntax noprefix\n");
} else {
global_asm.push_str("\n.att_syntax\n");
let is_x86 =
matches!(tcx.sess.asm_arch.unwrap(), InlineAsmArch::X86 | InlineAsmArch::X86_64);

if is_x86 {
if !asm.options.contains(InlineAsmOptions::ATT_SYNTAX) {
global_asm.push_str("\n.intel_syntax noprefix\n");
} else {
global_asm.push_str("\n.att_syntax\n");
}
}
for piece in asm.template {
match *piece {
Expand Down Expand Up @@ -65,7 +71,11 @@ pub(crate) fn codegen_global_asm_item(tcx: TyCtxt<'_>, global_asm: &mut String,
}
}
}
global_asm.push_str("\n.att_syntax\n\n");

global_asm.push('\n');
if is_x86 {
global_asm.push_str(".att_syntax\n\n");
}
} else {
bug!("Expected GlobalAsm found {:?}", item);
}
Expand Down Expand Up @@ -115,11 +125,12 @@ pub(crate) fn compile_global_asm(
}

// Remove all LLVM style comments
let global_asm = global_asm
let mut global_asm = global_asm
.lines()
.map(|line| if let Some(index) = line.find("//") { &line[0..index] } else { line })
.collect::<Vec<_>>()
.join("\n");
global_asm.push('\n');

let output_object_file = config.output_filenames.temp_path(OutputType::Object, Some(cgu_name));

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35 changes: 32 additions & 3 deletions src/inline_asm.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -701,21 +701,32 @@ impl<'tcx> InlineAssemblyGenerator<'_, 'tcx> {
match arch {
InlineAsmArch::X86_64 => {
generated_asm.push_str(" push rbp\n");
generated_asm.push_str(" mov rbp,rdi\n");
generated_asm.push_str(" mov rbp,rsp\n");
generated_asm.push_str(" push rbx\n"); // rbx is callee saved
// rbx is reserved by LLVM for the "base pointer", so rustc doesn't allow using it
generated_asm.push_str(" mov rbx,rdi\n");
}
InlineAsmArch::RiscV64 => {
generated_asm.push_str(" addi sp, sp, -16\n");
generated_asm.push_str(" sd ra, 8(sp)\n");
generated_asm.push_str(" sd s0, 0(sp)\n");
generated_asm.push_str(" mv s0, a0\n");
}
InlineAsmArch::AArch64 => {
generated_asm.push_str(" stp fp, lr, [sp, #-32]!\n");
generated_asm.push_str(" mov fp, sp\n");
generated_asm.push_str(" str x19, [sp, #24]\n"); // x19 is callee saved
// x19 is reserved by LLVM for the "base pointer", so rustc doesn't allow using it
generated_asm.push_str(" mov x19, x0\n");
}
_ => unimplemented!("prologue for {:?}", arch),
}
}

fn epilogue(generated_asm: &mut String, arch: InlineAsmArch) {
match arch {
InlineAsmArch::X86_64 => {
generated_asm.push_str(" pop rbx\n");
generated_asm.push_str(" pop rbp\n");
generated_asm.push_str(" ret\n");
}
Expand All @@ -725,6 +736,11 @@ impl<'tcx> InlineAssemblyGenerator<'_, 'tcx> {
generated_asm.push_str(" addi sp, sp, 16\n");
generated_asm.push_str(" ret\n");
}
InlineAsmArch::AArch64 => {
generated_asm.push_str(" ldr x19, [sp, #24]\n");
generated_asm.push_str(" ldp fp, lr, [sp], #32\n");
generated_asm.push_str(" ret\n");
}
_ => unimplemented!("epilogue for {:?}", arch),
}
}
Expand All @@ -737,6 +753,9 @@ impl<'tcx> InlineAssemblyGenerator<'_, 'tcx> {
InlineAsmArch::RiscV64 => {
generated_asm.push_str(" ebreak\n");
}
InlineAsmArch::AArch64 => {
generated_asm.push_str(" brk #0x1");
}
_ => unimplemented!("epilogue_noreturn for {:?}", arch),
}
}
Expand All @@ -749,7 +768,7 @@ impl<'tcx> InlineAssemblyGenerator<'_, 'tcx> {
) {
match arch {
InlineAsmArch::X86_64 => {
write!(generated_asm, " mov [rbp+0x{:x}], ", offset.bytes()).unwrap();
write!(generated_asm, " mov [rbx+0x{:x}], ", offset.bytes()).unwrap();
reg.emit(generated_asm, InlineAsmArch::X86_64, None).unwrap();
generated_asm.push('\n');
}
Expand All @@ -758,6 +777,11 @@ impl<'tcx> InlineAssemblyGenerator<'_, 'tcx> {
reg.emit(generated_asm, InlineAsmArch::RiscV64, None).unwrap();
writeln!(generated_asm, ", 0x{:x}(s0)", offset.bytes()).unwrap();
}
InlineAsmArch::AArch64 => {
generated_asm.push_str(" str ");
reg.emit(generated_asm, InlineAsmArch::AArch64, None).unwrap();
writeln!(generated_asm, ", [x19, 0x{:x}]", offset.bytes()).unwrap();
}
_ => unimplemented!("save_register for {:?}", arch),
}
}
Expand All @@ -772,13 +796,18 @@ impl<'tcx> InlineAssemblyGenerator<'_, 'tcx> {
InlineAsmArch::X86_64 => {
generated_asm.push_str(" mov ");
reg.emit(generated_asm, InlineAsmArch::X86_64, None).unwrap();
writeln!(generated_asm, ", [rbp+0x{:x}]", offset.bytes()).unwrap();
writeln!(generated_asm, ", [rbx+0x{:x}]", offset.bytes()).unwrap();
}
InlineAsmArch::RiscV64 => {
generated_asm.push_str(" ld ");
reg.emit(generated_asm, InlineAsmArch::RiscV64, None).unwrap();
writeln!(generated_asm, ", 0x{:x}(s0)", offset.bytes()).unwrap();
}
InlineAsmArch::AArch64 => {
generated_asm.push_str(" ldr ");
reg.emit(generated_asm, InlineAsmArch::AArch64, None).unwrap();
writeln!(generated_asm, ", [x19, 0x{:x}]", offset.bytes()).unwrap();
}
_ => unimplemented!("restore_register for {:?}", arch),
}
}
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