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[3/4] tcg/optimize: Canonicalize sub2 with constants to add2

Message ID 20231026013945.1152174-4-richard.henderson@linaro.org
State Superseded
Headers show
Series tcg: Canonicalize SUBI to ANDI | expand

Commit Message

Richard Henderson Oct. 26, 2023, 1:39 a.m. UTC 
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/optimize.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

Comments

Philippe Mathieu-Daudé Nov. 6, 2023, 2:43 p.m. UTC | #1 
On 26/10/23 03:39, Richard Henderson wrote:
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>   tcg/optimize.c | 21 +++++++++++++++++++--
>   1 file changed, 19 insertions(+), 2 deletions(-)

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
diff mbox series

Patch

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 9d91c25f68..280e6089a6 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1030,8 +1030,10 @@  static bool fold_add_vec(OptContext *ctx, TCGOp *op)
 
 static bool fold_addsub2(OptContext *ctx, TCGOp *op, bool add)
 {
-    if (arg_is_const(op->args[2]) && arg_is_const(op->args[3]) &&
-        arg_is_const(op->args[4]) && arg_is_const(op->args[5])) {
+    bool a_const = arg_is_const(op->args[2]) && arg_is_const(op->args[3]);
+    bool b_const = arg_is_const(op->args[4]) && arg_is_const(op->args[5]);
+
+    if (a_const && b_const) {
         uint64_t al = arg_info(op->args[2])->val;
         uint64_t ah = arg_info(op->args[3])->val;
         uint64_t bl = arg_info(op->args[4])->val;
@@ -1075,6 +1077,21 @@  static bool fold_addsub2(OptContext *ctx, TCGOp *op, bool add)
         tcg_opt_gen_movi(ctx, op2, rh, ah);
         return true;
     }
+
+    /* Fold sub2 r,x,i to add2 r,x,-i */
+    if (!add && b_const) {
+        uint64_t bl = arg_info(op->args[4])->val;
+        uint64_t bh = arg_info(op->args[5])->val;
+
+        /* Negate the two parts without assembling and disassembling. */
+        bl = -bl;
+        bh = ~bh + !bl;
+
+        op->opc = (ctx->type == TCG_TYPE_I32
+                   ? INDEX_op_add2_i32 : INDEX_op_add2_i64);
+        op->args[4] = arg_new_constant(ctx, bl);
+        op->args[5] = arg_new_constant(ctx, bh);
+    }
     return false;
 }