tcg/optimize: swap brcond/setcond arguments when possible

brcond and setcond ops are not commutative, but it's easy to compute the
new condition after swapping the arguments. Try to always put the constant
argument in second position like for commutative ops, to help backends to
generate better code.

Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

1 files changed, 18 insertions, 0 deletions

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 1698ba39b3..7debc8a36a 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -318,6 +318,24 @@ static TCGArg *tcg_constant_folding(TCGContext *s, uint16_t *tcg_opc_ptr,
                 args[2] = tmp;
             }
             break;
+        CASE_OP_32_64(brcond):
+            if (temps[args[0]].state == TCG_TEMP_CONST
+                && temps[args[1]].state != TCG_TEMP_CONST) {
+                tmp = args[0];
+                args[0] = args[1];
+                args[1] = tmp;
+                args[2] = tcg_swap_cond(args[2]);
+            }
+            break;
+        CASE_OP_32_64(setcond):
+            if (temps[args[1]].state == TCG_TEMP_CONST
+                && temps[args[2]].state != TCG_TEMP_CONST) {
+                tmp = args[1];
+                args[1] = args[2];
+                args[2] = tmp;
+                args[3] = tcg_swap_cond(args[3]);
+            }
+            break;
         default:
             break;
         }