tcg/optimize: Split out fold_xi_to_x

Pull the "op r, a, i => mov r, a" optimization into a function,
and use them in the outer-most logical operations.

Reviewed-by: Luis Pires <luis.pires@eldorado.org.br>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tcg/optimize.c

@@ -749,6 +749,15 @@ static bool fold_xi_to_i(OptContext *ctx, TCGOp *op, uint64_t i)
     return false;
 }
 
+/* If the binary operation has second argument @i, fold to identity. */
+static bool fold_xi_to_x(OptContext *ctx, TCGOp *op, uint64_t i)
+{
+    if (arg_is_const(op->args[2]) && arg_info(op->args[2])->val == i) {
+        return tcg_opt_gen_mov(ctx, op, op->args[0], op->args[1]);
+    }
+    return false;
+}
+
 /* If the binary operation has second argument @i, fold to NOT. */
 static bool fold_xi_to_not(OptContext *ctx, TCGOp *op, uint64_t i)
 {
@@ -787,7 +796,11 @@ static bool fold_xx_to_x(OptContext *ctx, TCGOp *op)
 
 static bool fold_add(OptContext *ctx, TCGOp *op)
 {
-    return fold_const2(ctx, op);
+    if (fold_const2(ctx, op) ||
+        fold_xi_to_x(ctx, op, 0)) {
+        return true;
+    }
+    return false;
 }
 
 static bool fold_addsub2_i32(OptContext *ctx, TCGOp *op, bool add)
@@ -827,6 +840,7 @@ static bool fold_and(OptContext *ctx, TCGOp *op)
 {
     if (fold_const2(ctx, op) ||
         fold_xi_to_i(ctx, op, 0) ||
+        fold_xi_to_x(ctx, op, -1) ||
         fold_xx_to_x(ctx, op)) {
         return true;
     }
@@ -837,6 +851,7 @@ static bool fold_andc(OptContext *ctx, TCGOp *op)
 {
     if (fold_const2(ctx, op) ||
         fold_xx_to_i(ctx, op, 0) ||
+        fold_xi_to_x(ctx, op, 0) ||
         fold_ix_to_not(ctx, op, -1)) {
         return true;
     }
@@ -1044,6 +1059,7 @@ static bool fold_dup2(OptContext *ctx, TCGOp *op)
 static bool fold_eqv(OptContext *ctx, TCGOp *op)
 {
     if (fold_const2(ctx, op) ||
+        fold_xi_to_x(ctx, op, -1) ||
         fold_xi_to_not(ctx, op, 0)) {
         return true;
     }
@@ -1237,6 +1253,7 @@ static bool fold_not(OptContext *ctx, TCGOp *op)
 static bool fold_or(OptContext *ctx, TCGOp *op)
 {
     if (fold_const2(ctx, op) ||
+        fold_xi_to_x(ctx, op, 0) ||
         fold_xx_to_x(ctx, op)) {
         return true;
     }
@@ -1246,6 +1263,7 @@ static bool fold_or(OptContext *ctx, TCGOp *op)
 static bool fold_orc(OptContext *ctx, TCGOp *op)
 {
     if (fold_const2(ctx, op) ||
+        fold_xi_to_x(ctx, op, -1) ||
         fold_ix_to_not(ctx, op, 0)) {
         return true;
     }
@@ -1365,7 +1383,11 @@ static bool fold_sextract(OptContext *ctx, TCGOp *op)
 
 static bool fold_shift(OptContext *ctx, TCGOp *op)
 {
-    return fold_const2(ctx, op);
+    if (fold_const2(ctx, op) ||
+        fold_xi_to_x(ctx, op, 0)) {
+        return true;
+    }
+    return false;
 }
 
 static bool fold_sub_to_neg(OptContext *ctx, TCGOp *op)
@@ -1408,6 +1430,7 @@ static bool fold_sub(OptContext *ctx, TCGOp *op)
 {
     if (fold_const2(ctx, op) ||
         fold_xx_to_i(ctx, op, 0) ||
+        fold_xi_to_x(ctx, op, 0) ||
         fold_sub_to_neg(ctx, op)) {
         return true;
     }
@@ -1423,6 +1446,7 @@ static bool fold_xor(OptContext *ctx, TCGOp *op)
 {
     if (fold_const2(ctx, op) ||
         fold_xx_to_i(ctx, op, 0) ||
+        fold_xi_to_x(ctx, op, 0) ||
         fold_xi_to_not(ctx, op, -1)) {
         return true;
     }
@@ -1546,39 +1570,6 @@ void tcg_optimize(TCGContext *s)
             break;
         }
 
-        /* Simplify expression for "op r, a, const => mov r, a" cases */
-        switch (opc) {
-        CASE_OP_32_64_VEC(add):
-        CASE_OP_32_64_VEC(sub):
-        CASE_OP_32_64_VEC(or):
-        CASE_OP_32_64_VEC(xor):
-        CASE_OP_32_64_VEC(andc):
-        CASE_OP_32_64(shl):
-        CASE_OP_32_64(shr):
-        CASE_OP_32_64(sar):
-        CASE_OP_32_64(rotl):
-        CASE_OP_32_64(rotr):
-            if (!arg_is_const(op->args[1])
-                && arg_is_const(op->args[2])
-                && arg_info(op->args[2])->val == 0) {
-                tcg_opt_gen_mov(&ctx, op, op->args[0], op->args[1]);
-                continue;
-            }
-            break;
-        CASE_OP_32_64_VEC(and):
-        CASE_OP_32_64_VEC(orc):
-        CASE_OP_32_64(eqv):
-            if (!arg_is_const(op->args[1])
-                && arg_is_const(op->args[2])
-                && arg_info(op->args[2])->val == -1) {
-                tcg_opt_gen_mov(&ctx, op, op->args[0], op->args[1]);
-                continue;
-            }
-            break;
-        default:
-            break;
-        }
-
         /* Simplify using known-zero bits. Currently only ops with a single
            output argument is supported. */
         z_mask = -1;