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Auto merge of rust-lang#118347 - Mark-Simulacrum:asm-code-size, r=spa…
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…storino

Avoid per-register closure expansions

Best reviewed with whitespace ignored.

This hopefully reduces overall size of the binary. Probably zero impact in instructions/cycles in rustc-perf since we don't really have any asm benchmarks AFAIK...
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@bors
bors committed Dec 2, 2023
2 parents d5fab33 + 5980a17 commit 90e321d
Showing 1 changed file with 63 additions and 58 deletions.
121 changes: 63 additions & 58 deletions compiler/rustc_ast_lowering/src/asm.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -342,70 +342,75 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {

// Flag to output the error only once per operand
let mut skip = false;
reg.overlapping_regs(|r| {
let mut check = |used_regs: &mut FxHashMap<asm::InlineAsmReg, usize>,
input| {
match used_regs.entry(r) {
Entry::Occupied(o) => {
if skip {
return;
}
skip = true;

let idx2 = *o.get();
let (ref op2, op_sp2) = operands[idx2];

let in_out = match (op, op2) {
(
hir::InlineAsmOperand::In { .. },
hir::InlineAsmOperand::Out { late, .. },
)
| (
hir::InlineAsmOperand::Out { late, .. },
hir::InlineAsmOperand::In { .. },
) => {
assert!(!*late);
let out_op_sp = if input { op_sp2 } else { op_sp };
Some(out_op_sp)
}
_ => None,
};
let mut check = |used_regs: &mut FxHashMap<asm::InlineAsmReg, usize>,
input,
r: asm::InlineAsmReg| {
match used_regs.entry(r) {
Entry::Occupied(o) => {
if skip {
return;
}
skip = true;

let reg_str = |idx| -> &str {
// HIR asm doesn't preserve the original alias string of the explicit register,
// so we have to retrieve it from AST
let (op, _): &(InlineAsmOperand, Span) = &asm.operands[idx];
if let Some(ast::InlineAsmRegOrRegClass::Reg(reg_sym)) =
op.reg()
{
reg_sym.as_str()
} else {
unreachable!();
}
};
let idx2 = *o.get();
let (ref op2, op_sp2) = operands[idx2];

sess.emit_err(RegisterConflict {
op_span1: op_sp,
op_span2: op_sp2,
reg1_name: reg_str(idx),
reg2_name: reg_str(idx2),
in_out,
});
}
Entry::Vacant(v) => {
if r == reg {
v.insert(idx);
let in_out = match (op, op2) {
(
hir::InlineAsmOperand::In { .. },
hir::InlineAsmOperand::Out { late, .. },
)
| (
hir::InlineAsmOperand::Out { late, .. },
hir::InlineAsmOperand::In { .. },
) => {
assert!(!*late);
let out_op_sp = if input { op_sp2 } else { op_sp };
Some(out_op_sp)
}
_ => None,
};
let reg_str = |idx| -> &str {
// HIR asm doesn't preserve the original alias string of the explicit register,
// so we have to retrieve it from AST
let (op, _): &(InlineAsmOperand, Span) = &asm.operands[idx];
if let Some(ast::InlineAsmRegOrRegClass::Reg(reg_sym)) =
op.reg()
{
reg_sym.as_str()
} else {
unreachable!();
}
};

sess.emit_err(RegisterConflict {
op_span1: op_sp,
op_span2: op_sp2,
reg1_name: reg_str(idx),
reg2_name: reg_str(idx2),
in_out,
});
}
Entry::Vacant(v) => {
if r == reg {
v.insert(idx);
}
}
};
}
};
let mut overlapping_with = vec![];
reg.overlapping_regs(|r| {
overlapping_with.push(r);
});
for r in overlapping_with {
if input {
check(&mut used_input_regs, true);
check(&mut used_input_regs, true, r);
}
if output {
check(&mut used_output_regs, false);
check(&mut used_output_regs, false, r);
}
});
}
}
}
}
Expand All @@ -420,12 +425,12 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
continue;
}

let mut output_used = false;
let mut overlapping_with = vec![];
clobber.overlapping_regs(|reg| {
if used_output_regs.contains_key(&reg) {
output_used = true;
}
overlapping_with.push(reg);
});
let output_used =
overlapping_with.iter().any(|reg| used_output_regs.contains_key(&reg));

if !output_used {
operands.push((
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