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>

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 1698ba39b36b48dd10dcaa1905b1992ea34538dc..7debc8a36acbad7c4bd1d2aaea735d079fccf9d3 100644 (file)
--- 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;
         }