From cbe42fb2f22b9adb8b78374f6ff4ca5f58807208 Mon Sep 17 00:00:00 2001
From: Richard Henderson <richard.henderson@linaro.org>
Date: Wed, 25 Aug 2021 13:02:00 -0700
Subject: [PATCH] tcg/optimize: Split out fold_xx_to_i
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Pull the "op r, a, a => movi r, 0" optimization into a function,
and use it in the outer opcode fold functions.

Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/optimize.c | 41 ++++++++++++++++++++++++-----------------
 1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 5f1bd7cd78..2f55dc56c0 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -695,6 +695,15 @@ static bool fold_const2(OptContext *ctx, TCGOp *op)
     return false;
 }
 
+/* If the binary operation has both arguments equal, fold to @i. */
+static bool fold_xx_to_i(OptContext *ctx, TCGOp *op, uint64_t i)
+{
+    if (args_are_copies(op->args[1], op->args[2])) {
+        return tcg_opt_gen_movi(ctx, op, op->args[0], i);
+    }
+    return false;
+}
+
 /*
  * These outermost fold_<op> functions are sorted alphabetically.
  */
@@ -744,7 +753,11 @@ static bool fold_and(OptContext *ctx, TCGOp *op)
 
 static bool fold_andc(OptContext *ctx, TCGOp *op)
 {
-    return fold_const2(ctx, op);
+    if (fold_const2(ctx, op) ||
+        fold_xx_to_i(ctx, op, 0)) {
+        return true;
+    }
+    return false;
 }
 
 static bool fold_brcond(OptContext *ctx, TCGOp *op)
@@ -1224,7 +1237,11 @@ static bool fold_shift(OptContext *ctx, TCGOp *op)
 
 static bool fold_sub(OptContext *ctx, TCGOp *op)
 {
-    return fold_const2(ctx, op);
+    if (fold_const2(ctx, op) ||
+        fold_xx_to_i(ctx, op, 0)) {
+        return true;
+    }
+    return false;
 }
 
 static bool fold_sub2_i32(OptContext *ctx, TCGOp *op)
@@ -1234,7 +1251,11 @@ static bool fold_sub2_i32(OptContext *ctx, TCGOp *op)
 
 static bool fold_xor(OptContext *ctx, TCGOp *op)
 {
-    return fold_const2(ctx, op);
+    if (fold_const2(ctx, op) ||
+        fold_xx_to_i(ctx, op, 0)) {
+        return true;
+    }
+    return false;
 }
 
 /* Propagate constants and copies, fold constant expressions. */
@@ -1739,20 +1760,6 @@ void tcg_optimize(TCGContext *s)
             break;
         }
 
-        /* Simplify expression for "op r, a, a => movi r, 0" cases */
-        switch (opc) {
-        CASE_OP_32_64_VEC(andc):
-        CASE_OP_32_64_VEC(sub):
-        CASE_OP_32_64_VEC(xor):
-            if (args_are_copies(op->args[1], op->args[2])) {
-                tcg_opt_gen_movi(&ctx, op, op->args[0], 0);
-                continue;
-            }
-            break;
-        default:
-            break;
-        }
-
         /*
          * Process each opcode.
          * Sorted alphabetically by opcode as much as possible.