[PATCH v3 35/48] tcg/optimize: Split out fold_sub_to_neg

[Richard Henderson <richard.henderson@linaro.org>]

Even though there is only one user, place this more complex
conversion into its own helper.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 tcg/optimize.c | 84 ++++++++++++++++++++++++++++----------------------
 1 file changed, 47 insertions(+), 37 deletions(-)

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 71b4c3edb4..e4cf746321 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1189,7 +1189,15 @@ static bool fold_nand(OptContext *ctx, TCGOp *op)
 
 static bool fold_neg(OptContext *ctx, TCGOp *op)
 {
-    return fold_const1(ctx, op);
+    if (fold_const1(ctx, op)) {
+        return true;
+    }
+    /*
+     * Because of fold_sub_to_neg, we want to always return true,
+     * via finish_folding.
+     */
+    finish_folding(ctx, op);
+    return true;
 }
 
 static bool fold_nor(OptContext *ctx, TCGOp *op)
@@ -1341,10 +1349,47 @@ static bool fold_shift(OptContext *ctx, TCGOp *op)
     return fold_const2(ctx, op);
 }
 
+static bool fold_sub_to_neg(OptContext *ctx, TCGOp *op)
+{
+    TCGOpcode neg_op;
+    bool have_neg;
+
+    if (!arg_is_const(op->args[1]) || arg_info(op->args[1])->val != 0) {
+        return false;
+    }
+
+    switch (ctx->type) {
+    case TCG_TYPE_I32:
+        neg_op = INDEX_op_neg_i32;
+        have_neg = TCG_TARGET_HAS_neg_i32;
+        break;
+    case TCG_TYPE_I64:
+        neg_op = INDEX_op_neg_i64;
+        have_neg = TCG_TARGET_HAS_neg_i64;
+        break;
+    case TCG_TYPE_V64:
+    case TCG_TYPE_V128:
+    case TCG_TYPE_V256:
+        neg_op = INDEX_op_neg_vec;
+        have_neg = (TCG_TARGET_HAS_neg_vec &&
+                    tcg_can_emit_vec_op(neg_op, ctx->type, TCGOP_VECE(op)) > 0);
+        break;
+    default:
+        g_assert_not_reached();
+    }
+    if (have_neg) {
+        op->opc = neg_op;
+        op->args[1] = op->args[2];
+        return fold_neg(ctx, op);
+    }
+    return false;
+}
+
 static bool fold_sub(OptContext *ctx, TCGOp *op)
 {
     if (fold_const2(ctx, op) ||
-        fold_xx_to_i(ctx, op, 0)) {
+        fold_xx_to_i(ctx, op, 0) ||
+        fold_sub_to_neg(ctx, op)) {
         return true;
     }
     return false;
@@ -1478,41 +1523,6 @@ void tcg_optimize(TCGContext *s)
                 continue;
             }
             break;
-        CASE_OP_32_64_VEC(sub):
-            {
-                TCGOpcode neg_op;
-                bool have_neg;
-
-                if (arg_is_const(op->args[2])) {
-                    /* Proceed with possible constant folding. */
-                    break;
-                }
-                switch (ctx.type) {
-                case TCG_TYPE_I32:
-                    neg_op = INDEX_op_neg_i32;
-                    have_neg = TCG_TARGET_HAS_neg_i32;
-                    break;
-                case TCG_TYPE_I64:
-                    neg_op = INDEX_op_neg_i64;
-                    have_neg = TCG_TARGET_HAS_neg_i64;
-                    break;
-                default:
-                    neg_op = INDEX_op_neg_vec;
-                    have_neg = tcg_can_emit_vec_op(neg_op, ctx.type, TCGOP_VECE(op)) > 0;
-                    break;
-                }
-                if (!have_neg) {
-                    break;
-                }
-                if (arg_is_const(op->args[1])
-                    && arg_info(op->args[1])->val == 0) {
-                    op->opc = neg_op;
-                    reset_temp(op->args[0]);
-                    op->args[1] = op->args[2];
-                    continue;
-                }
-            }
-            break;
         default:
             break;
         }
-- 
2.25.1