tcg: Convert sub to TCGOutOpSubtract

Create a special subclass for sub, because two backends can
support "subtract from immediate".  Drop all backend support
for an immediate as the second operand, as we transform sub
to add during optimize.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 28 insertions, 2 deletions

diff --git a/tcg/tcg.c b/tcg/tcg.c
index c0178030ce..d7a44ac1b1 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -986,6 +986,14 @@ typedef struct TCGOutOpBinary {
                     TCGReg a0, TCGReg a1, tcg_target_long a2);
 } TCGOutOpBinary;
 
+typedef struct TCGOutOpSubtract {
+    TCGOutOp base;
+    void (*out_rrr)(TCGContext *s, TCGType type,
+                    TCGReg a0, TCGReg a1, TCGReg a2);
+    void (*out_rir)(TCGContext *s, TCGType type,
+                    TCGReg a0, tcg_target_long a1, TCGReg a2);
+} TCGOutOpSubtract;
+
 #include "tcg-target.c.inc"
 
 #ifndef CONFIG_TCG_INTERPRETER
@@ -1012,6 +1020,8 @@ static const TCGOutOp * const all_outop[NB_OPS] = {
     OUTOP(INDEX_op_nor, TCGOutOpBinary, outop_nor),
     OUTOP(INDEX_op_or, TCGOutOpBinary, outop_or),
     OUTOP(INDEX_op_orc, TCGOutOpBinary, outop_orc),
+    OUTOP(INDEX_op_sub_i32, TCGOutOpSubtract, outop_sub),
+    OUTOP(INDEX_op_sub_i64, TCGOutOpSubtract, outop_sub),
     OUTOP(INDEX_op_xor, TCGOutOpBinary, outop_xor),
 };
 
@@ -2231,7 +2241,6 @@ bool tcg_op_supported(TCGOpcode op, TCGType type, unsigned flags)
     case INDEX_op_st8_i32:
     case INDEX_op_st16_i32:
     case INDEX_op_st_i32:
-    case INDEX_op_sub_i32:
     case INDEX_op_neg_i32:
     case INDEX_op_mul_i32:
     case INDEX_op_shl_i32:
@@ -2301,7 +2310,6 @@ bool tcg_op_supported(TCGOpcode op, TCGType type, unsigned flags)
     case INDEX_op_st16_i64:
     case INDEX_op_st32_i64:
     case INDEX_op_st_i64:
-    case INDEX_op_sub_i64:
     case INDEX_op_neg_i64:
     case INDEX_op_mul_i64:
     case INDEX_op_shl_i64:
@@ -5449,6 +5457,24 @@ static void tcg_reg_alloc_op(TCGContext *s, const TCGOp *op)
         }
         break;
 
+    case INDEX_op_sub_i32:
+    case INDEX_op_sub_i64:
+        {
+            const TCGOutOpSubtract *out = &outop_sub;
+
+            /*
+             * Constants should never appear in the second source operand.
+             * These are folded to add with negative constant.
+             */
+            tcg_debug_assert(!const_args[2]);
+            if (const_args[1]) {
+                out->out_rir(s, type, new_args[0], new_args[1], new_args[2]);
+            } else {
+                out->out_rrr(s, type, new_args[0], new_args[1], new_args[2]);
+            }
+        }
+        break;
+
     default:
         if (def->flags & TCG_OPF_VECTOR) {
             tcg_out_vec_op(s, op->opc, type - TCG_TYPE_V64,