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machinst x64: fix checked div sequence

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- it should mark as clobbering (def) rdx, not modifying it
- the signed-div check requires a temporary to compare against int64_min
This commit is contained in:
Benjamin Bouvier
2020-07-06 18:45:07 +02:00
parent f932bccaf8
commit d9310e8d90
4 changed files with 38 additions and 7 deletions
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15
cranelift/codegen/src/isa/x64/inst/emit.rs
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@@ -666,6 +666,7 @@ pub(crate) fn emit(
size,
divisor,
loc,
tmp,
} => {
// Generates the following code sequence:
//
@@ -727,8 +728,18 @@ pub(crate) fn emit(
(Some(do_op), Some(done_label))
} else {
// Check for integer overflow.
let inst = Inst::cmp_rmi_r(*size, RegMemImm::imm(0x80000000), regs::rax());
inst.emit(sink, flags, state);
if *size == 8 {
let tmp = tmp.expect("temporary for i64 sdiv");
let inst = Inst::imm_r(true, 0x8000000000000000, tmp);
inst.emit(sink, flags, state);
let inst = Inst::cmp_rmi_r(8, RegMemImm::reg(tmp.to_reg()), regs::rax());
inst.emit(sink, flags, state);
} else {
let inst = Inst::cmp_rmi_r(*size, RegMemImm::imm(0x80000000), regs::rax());
inst.emit(sink, flags, state);
}
// If not equal, jump over the trap.
let inst = Inst::trap_if(CC::Z, TrapCode::IntegerOverflow, *loc);