[PULL,36/56] tcg/optimize: Split out fold_xx_to_x

Commit Message

Richard Henderson Oct. 28, 2021, 2:41 a.m. UTC

Pull the "op r, a, a => mov r, a" optimization into a function,
and use it in the outer opcode fold functions.

Reviewed-by: Luis Pires <[e-mail]>
Reviewed-by: Philippe Mathieu-Daudé <[e-mail]>
Signed-off-by: Richard Henderson <[e-mail]>
---
 tcg/optimize.c | 39 ++++++++++++++++++++++++---------------
 1 file changed, 24 insertions(+), 15 deletions(-)

Patch

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 2f55dc56c0..ab96849edf 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -704,8 +704,22 @@  static bool fold_xx_to_i(OptContext *ctx, TCGOp *op, uint64_t i)
     return false;
 }
 
+/* If the binary operation has both arguments equal, fold to identity. */
+static bool fold_xx_to_x(OptContext *ctx, TCGOp *op)
+{
+    if (args_are_copies(op->args[1], op->args[2])) {
+        return tcg_opt_gen_mov(ctx, op, op->args[0], op->args[1]);
+    }
+    return false;
+}
+
 /*
  * These outermost fold_<op> functions are sorted alphabetically.
+ *
+ * The ordering of the transformations should be:
+ *   1) those that produce a constant
+ *   2) those that produce a copy
+ *   3) those that produce information about the result value.
  */
 
 static bool fold_add(OptContext *ctx, TCGOp *op)
@@ -748,7 +762,11 @@  static bool fold_add2_i32(OptContext *ctx, TCGOp *op)
 
 static bool fold_and(OptContext *ctx, TCGOp *op)
 {
-    return fold_const2(ctx, op);
+    if (fold_const2(ctx, op) ||
+        fold_xx_to_x(ctx, op)) {
+        return true;
+    }
+    return false;
 }
 
 static bool fold_andc(OptContext *ctx, TCGOp *op)
@@ -1111,7 +1129,11 @@  static bool fold_not(OptContext *ctx, TCGOp *op)
 
 static bool fold_or(OptContext *ctx, TCGOp *op)
 {
-    return fold_const2(ctx, op);
+    if (fold_const2(ctx, op) ||
+        fold_xx_to_x(ctx, op)) {
+        return true;
+    }
+    return false;
 }
 
 static bool fold_orc(OptContext *ctx, TCGOp *op)
@@ -1747,19 +1769,6 @@  void tcg_optimize(TCGContext *s)
             break;
         }
 
-        /* Simplify expression for "op r, a, a => mov r, a" cases */
-        switch (opc) {
-        CASE_OP_32_64_VEC(or):
-        CASE_OP_32_64_VEC(and):
-            if (args_are_copies(op->args[1], op->args[2])) {
-                tcg_opt_gen_mov(&ctx, op, op->args[0], op->args[1]);
-                continue;
-            }
-            break;
-        default:
-            break;
-        }
-
         /*
          * Process each opcode.
          * Sorted alphabetically by opcode as much as possible.