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fix Num.shift_right_by to not mutate src register

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The intent of this change is to fix a bug calling `Num.shift_right_by(a, b)`
mutates `a`. This was happening in the dev backend only, and the cause was
some generated assembly which writes to register a is stored in.
This commit is contained in:
shua 2025-01-12 00:32:54 +01:00
parent 2331aa1d77
commit c195cff8e3
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1 changed files with 21 additions and 40 deletions
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61
crates/compiler/gen_dev/src/generic64/mod.rs
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@ -4561,46 +4561,27 @@ impl<
// be for our particular integer width
let sign_extend_shift_amount = 64 - (int_width.stack_size() as i64 * 8);
if sign_extend_shift_amount > 0 {
self.storage_manager.with_tmp_general_reg(
buf,
|storage_manager, buf, tmp_reg| {
ASM::mov_reg64_imm64(buf, tmp_reg, sign_extend_shift_amount);
ASM::shl_reg64_reg64_reg64(
buf,
storage_manager,
src1_reg,
src1_reg,
tmp_reg,
);
},
)
}
ASM::sar_reg64_reg64_reg64(
buf,
&mut self.storage_manager,
dst_reg,
src1_reg,
src2_reg,
);
if sign_extend_shift_amount > 0 {
// shift back if needed
self.storage_manager.with_tmp_general_reg(
&mut self.buf,
|storage_manager, buf, tmp_reg| {
ASM::mov_reg64_imm64(buf, tmp_reg, sign_extend_shift_amount);
ASM::shr_reg64_reg64_reg64(
buf,
storage_manager,
dst_reg,
dst_reg,
tmp_reg,
);
},
)
}
// PERF: could just be one shr for unsigned ints cases
// PERF: the shl/shr can be skipped when sign_extend_shift_amount is 0
self.storage_manager
.with_tmp_general_reg(buf, |storage_manager, buf, tmp_reg| {
ASM::mov_reg64_imm64(buf, tmp_reg, sign_extend_shift_amount);
ASM::shl_reg64_reg64_reg64(
buf,
storage_manager,
dst_reg,
src1_reg,
tmp_reg,
);
ASM::sar_reg64_reg64_reg64(
buf,
storage_manager,
dst_reg,
dst_reg,
src2_reg,
);
ASM::shr_reg64_reg64_reg64(buf, storage_manager, dst_reg, dst_reg, tmp_reg);
});
}
}
}