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Skip registers saved by calling convention

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This commit is contained in:
Gary Guo 2021-11-22 02:38:50 +00:00
parent 703027f0fc
commit 14aa039d30
1 changed files with 26 additions and 4 deletions
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30
src/inline_asm.rs
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@ -320,21 +320,44 @@ fn allocate_stack_slots(&mut self) {
offset
};
// Allocate stack slots for saving clobbered registers
let abi_clobber =
InlineAsmClobberAbi::parse(self.arch, &self.tcx.sess.target, Symbol::intern("C"))
.unwrap()
.clobbered_regs();
for (i, reg) in self.registers.iter().enumerate().filter_map(|(i, r)| r.map(|r| (i, r))) {
let mut need_save = true;
// If the register overlaps with a register clobbered by function call, then
// we don't need to save it.
for r in abi_clobber {
r.overlapping_regs(|r| {
if r == reg {
need_save = false;
}
});
if !need_save {
break;
}
}
if need_save {
slots_clobber[i] = Some(new_slot(reg.reg_class()));
}
}
// FIXME overlap input and output slots to save stack space
for (i, operand) in self.operands.iter().enumerate() {
match *operand {
InlineAsmOperand::In { reg, .. } => {
slots_clobber[i] = Some(new_slot(reg.reg_class()));
slots_input[i] = Some(new_slot(reg.reg_class()));
}
InlineAsmOperand::Out { reg, place, .. } => {
slots_clobber[i] = Some(new_slot(reg.reg_class()));
if place.is_some() {
slots_output[i] = Some(new_slot(reg.reg_class()));
}
}
InlineAsmOperand::InOut { reg, out_place, .. } => {
slots_clobber[i] = Some(new_slot(reg.reg_class()));
let slot = new_slot(reg.reg_class());
slots_input[i] = Some(slot);
if out_place.is_some() {
@ -366,7 +389,6 @@ fn generate_asm_wrapper(&self, asm_name: &str) -> String {
// Save clobbered registers
if !self.options.contains(InlineAsmOptions::NORETURN) {
// FIXME skip registers saved by the calling convention
for (reg, slot) in self
.registers
.iter()