tcg/optimize: Flush data at labels not TCG_OPF_BB_END

We can easily propagate temp values through the entire extended
basic block (in this case, the set of blocks connected by fallthru),
simply by not discarding the register state at the branch.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 220f4601d5a3e50d9b7124fb460469f6e60f3157..9952c28bdc6a6fd0e0c758951aef1458deb74423 100644 (file)
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1484,29 +1484,30 @@ void tcg_optimize(TCGContext *s)
                     }
                 }
             }
-            goto do_reset_output;
+            /* fall through */
 
         default:
         do_default:
-            /* Default case: we know nothing about operation (or were unable
-               to compute the operation result) so no propagation is done.
-               We trash everything if the operation is the end of a basic
-               block, otherwise we only trash the output args.  "mask" is
-               the non-zero bits mask for the first output arg.  */
-            if (def->flags & TCG_OPF_BB_END) {
-                bitmap_zero(temps_used.l, nb_temps);
-            } else {
-        do_reset_output:
-                for (i = 0; i < nb_oargs; i++) {
-                    reset_temp(op->args[i]);
-                    /* Save the corresponding known-zero bits mask for the
-                       first output argument (only one supported so far). */
-                    if (i == 0) {
-                        arg_info(op->args[i])->mask = mask;
-                    }
+            /*
+             * Default case: we know nothing about operation (or were unable
+             * to compute the operation result) so no propagation is done.
+             */
+            for (i = 0; i < nb_oargs; i++) {
+                reset_temp(op->args[i]);
+                /*
+                 * Save the corresponding known-zero bits mask for the
+                 * first output argument (only one supported so far).
+                 */
+                if (i == 0) {
+                    arg_info(op->args[i])->mask = mask;
                 }
             }
             break;
+
+        case INDEX_op_set_label:
+            /* Trash everything at the start of a new extended bb. */
+            bitmap_zero(temps_used.l, nb_temps);
+            break;
         }
 
         /* Eliminate duplicate and redundant fence instructions.  */