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Avoid negation of signed integers in C that may hold INT*_MIN.

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Reported by minoki.
Recent C compilers 'take advantage' of the undefined behavior.
This completely changes the meaning of expressions like (k == -k).
This commit is contained in:
Mike Pall
2022-12-22 00:03:06 +01:00
parent b2791179ef
commit 8a5e398c52
12 changed files with 32 additions and 32 deletions
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2
src/lj_emit_arm.h
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@@ -154,7 +154,7 @@ static int emit_kdelta2(ASMState *as, Reg d, int32_t i)
if (other) {
int32_t delta = i - other;
uint32_t sh, inv = 0, k2, k;
if (delta < 0) { delta = -delta; inv = ARMI_ADD^ARMI_SUB; }
if (delta < 0) { delta = (int32_t)(~(uint32_t)delta+1u); inv = ARMI_ADD^ARMI_SUB; }
sh = lj_ffs(delta) & ~1;
k2 = emit_isk12(0, delta & (255 << sh));
k = emit_isk12(0, delta & ~(255 << sh));