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tcg/optimize: Handle known-zeros masks for ANDC

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Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>
This commit is contained in:
Richard Henderson 2014-01-28 12:03:24 -08:00
parent c8d7027253
commit 23ec69ed37
1 changed files with 11 additions and 0 deletions
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11
tcg/optimize.c
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@ -727,6 +727,17 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
mask = temps[args[1]].mask & mask;
break;
CASE_OP_32_64(andc):
/* Known-zeros does not imply known-ones. Therefore unless
args[2] is constant, we can't infer anything from it. */
if (temps[args[2]].state == TCG_TEMP_CONST) {
mask = ~temps[args[2]].mask;
goto and_const;
}
/* But we certainly know nothing outside args[1] may be set. */
mask = temps[args[1]].mask;
break;
case INDEX_op_sar_i32:
if (temps[args[2]].state == TCG_TEMP_CONST) {
mask = (int32_t)temps[args[1]].mask >> temps[args[2]].val;