[Qemu-devel] [PATCH 1/2] tcg/optimize: fix end of basic bloc detection

[Aurelien Jarno <aurelien@aurel32.net>]

Commit e31b0a7c050711884ad570fe73df806520953618 fixed copy propagation on
32-bit host by restricting the copy between different types. This was the
wrong fix.

The real problem is that the all temps states should be reset at the end
of a basic bloc. This was done by adding such operations in the switch,
but brcond2 was forgotten (that's why the crash was only observed on 32-bit
hosts).

Fix that by looking at the TCG_OPF_BB_END instead.

Cc: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
---
 tcg/optimize.c |   23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 9c65474..64aa35b 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -487,22 +487,17 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
                 i--;
             }
             break;
-        case INDEX_op_set_label:
-        case INDEX_op_jmp:
-        case INDEX_op_br:
-        CASE_OP_32_64(brcond):
-            memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
-            for (i = 0; i < def->nb_args; i++) {
-                *gen_args = *args;
-                args++;
-                gen_args++;
-            }
-            break;
         default:
             /* Default case: we do know nothing about operation so no
-               propagation is done.  We only trash output args.  */
-            for (i = 0; i < def->nb_oargs; i++) {
-                reset_temp(args[i], nb_temps, nb_globals);
+               propagation is done.  We trash everything if the operation
+               is the end of a basic block, otherwise we only trash the
+               output args.  */
+            if (def->flags & TCG_OPF_BB_END) {
+                memset(temps, 0, nb_temps * sizeof(struct tcg_temp_info));
+            } else {
+                for (i = 0; i < def->nb_oargs; i++) {
+                    reset_temp(args[i], nb_temps, nb_globals);
+                }
             }
             for (i = 0; i < def->nb_args; i++) {
                 gen_args[i] = args[i];
-- 
1.7.10.4