Patchwork [2/4] tcg/optimize: fix known-zero bits for right shift ops

login
register
mail settings
Submitter Aurelien Jarno
Date Sept. 3, 2013, 6:27 a.m.
Message ID <1378189680-11987-3-git-send-email-aurelien@aurel32.net>
Download mbox | patch
Permalink /patch/272120/
State New
Headers show

Comments

Aurelien Jarno - Sept. 3, 2013, 6:27 a.m.
32-bit versions of sar and shr ops should not propagate known-zero bits
from the unused 32 high bits. For sar it could even lead to wrong code
being generated.

Cc: Richard Henderson <rth@twiddle.net>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
---
 tcg/optimize.c |   21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

Patch

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 41f2906..0ed8983 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -731,16 +731,29 @@  static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
             mask = temps[args[1]].mask & mask;
             break;
 
-        CASE_OP_32_64(sar):
+        case INDEX_op_sar_i32:
+            if (temps[args[2]].state == TCG_TEMP_CONST) {
+                mask = ((int32_t)temps[args[1]].mask
+                        >> temps[args[2]].val);
+            }
+            break;
+        case INDEX_op_sar_i64:
             if (temps[args[2]].state == TCG_TEMP_CONST) {
-                mask = ((tcg_target_long)temps[args[1]].mask
+                mask = ((int64_t)temps[args[1]].mask
                         >> temps[args[2]].val);
             }
             break;
 
-        CASE_OP_32_64(shr):
+        case INDEX_op_shr_i32:
             if (temps[args[2]].state == TCG_TEMP_CONST) {
-                mask = temps[args[1]].mask >> temps[args[2]].val;
+                mask = ((uint32_t)temps[args[1]].mask
+                        >> temps[args[2]].val);
+            }
+            break;
+        case INDEX_op_shr_i64:
+            if (temps[args[2]].state == TCG_TEMP_CONST) {
+                mask = ((uint64_t)temps[args[1]].mask
+                        >> temps[args[2]].val);
             }
             break;