diff mbox

[PULL,07/15] tcg/optimize: Handle known-zeros masks for ANDC

Message ID 1392686165-10706-8-git-send-email-rth@twiddle.net
State New
Headers show

Commit Message

Richard Henderson Feb. 18, 2014, 1:15 a.m. UTC 
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Richard Henderson <rth@twiddle.net>
---
 tcg/optimize.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
diff mbox

Patch

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 1b9fea5..4bea8a5 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -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;