tcg/optimize: Use fold_masks_zs, fold_masks_s in fold_shift

Avoid the use of the OptContext slots.  Find TempOptInfo once.

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

tcg/optimize.c

@@ -2531,6 +2531,7 @@ static bool fold_sextract(OptContext *ctx, TCGOp *op)
 static bool fold_shift(OptContext *ctx, TCGOp *op)
 {
     uint64_t s_mask, z_mask, sign;
+    TempOptInfo *t1, *t2;
 
     if (fold_const2(ctx, op) ||
         fold_ix_to_i(ctx, op, 0) ||
@@ -2538,17 +2539,18 @@ static bool fold_shift(OptContext *ctx, TCGOp *op)
         return true;
     }
 
-    s_mask = arg_info(op->args[1])->s_mask;
-    z_mask = arg_info(op->args[1])->z_mask;
-
-    if (arg_is_const(op->args[2])) {
-        int sh = arg_info(op->args[2])->val;
+    t1 = arg_info(op->args[1]);
+    t2 = arg_info(op->args[2]);
+    s_mask = t1->s_mask;
+    z_mask = t1->z_mask;
 
-        ctx->z_mask = do_constant_folding(op->opc, ctx->type, z_mask, sh);
+    if (ti_is_const(t2)) {
+        int sh = ti_const_val(t2);
 
+        z_mask = do_constant_folding(op->opc, ctx->type, z_mask, sh);
         s_mask = do_constant_folding(op->opc, ctx->type, s_mask, sh);
 
-        return fold_masks(ctx, op);
+        return fold_masks_zs(ctx, op, z_mask, s_mask);
     }
 
     switch (op->opc) {
@@ -2557,23 +2559,22 @@ static bool fold_shift(OptContext *ctx, TCGOp *op)
          * Arithmetic right shift will not reduce the number of
          * input sign repetitions.
          */
-        ctx->s_mask = s_mask;
-        break;
+        return fold_masks_s(ctx, op, s_mask);
     CASE_OP_32_64(shr):
         /*
          * If the sign bit is known zero, then logical right shift
-         * will not reduced the number of input sign repetitions.
+         * will not reduce the number of input sign repetitions.
          */
-        sign = (s_mask & -s_mask) >> 1;
+        sign = -s_mask;
         if (sign && !(z_mask & sign)) {
-            ctx->s_mask = s_mask;
+            return fold_masks_s(ctx, op, s_mask);
         }
         break;
     default:
         break;
     }
 
-    return false;
+    return finish_folding(ctx, op);
 }
 
 static bool fold_sub_to_neg(OptContext *ctx, TCGOp *op)