tcg/optimize: Optimize bitsel_vec

Fold matching true/false operands.
Fold true/false operands with 0/-1 to simpler logicals.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tcg/optimize.c

@@ -2737,6 +2737,61 @@ static bool fold_xor(OptContext *ctx, TCGOp *op)
     return fold_masks(ctx, op);
 }
 
+static bool fold_bitsel_vec(OptContext *ctx, TCGOp *op)
+{
+    /* If true and false values are the same, eliminate the cmp. */
+    if (args_are_copies(op->args[2], op->args[3])) {
+        return tcg_opt_gen_mov(ctx, op, op->args[0], op->args[2]);
+    }
+
+    if (arg_is_const(op->args[2]) && arg_is_const(op->args[3])) {
+        uint64_t tv = arg_info(op->args[2])->val;
+        uint64_t fv = arg_info(op->args[3])->val;
+
+        if (tv == -1 && fv == 0) {
+            return tcg_opt_gen_mov(ctx, op, op->args[0], op->args[1]);
+        }
+        if (tv == 0 && fv == -1) {
+            if (TCG_TARGET_HAS_not_vec) {
+                op->opc = INDEX_op_not_vec;
+                return fold_not(ctx, op);
+            } else {
+                op->opc = INDEX_op_xor_vec;
+                op->args[2] = arg_new_constant(ctx, -1);
+                return fold_xor(ctx, op);
+            }
+        }
+    }
+    if (arg_is_const(op->args[2])) {
+        uint64_t tv = arg_info(op->args[2])->val;
+        if (tv == -1) {
+            op->opc = INDEX_op_or_vec;
+            op->args[2] = op->args[3];
+            return fold_or(ctx, op);
+        }
+        if (tv == 0 && TCG_TARGET_HAS_andc_vec) {
+            op->opc = INDEX_op_andc_vec;
+            op->args[2] = op->args[1];
+            op->args[1] = op->args[3];
+            return fold_andc(ctx, op);
+        }
+    }
+    if (arg_is_const(op->args[3])) {
+        uint64_t fv = arg_info(op->args[3])->val;
+        if (fv == 0) {
+            op->opc = INDEX_op_and_vec;
+            return fold_and(ctx, op);
+        }
+        if (fv == -1 && TCG_TARGET_HAS_orc_vec) {
+            op->opc = INDEX_op_orc_vec;
+            op->args[2] = op->args[1];
+            op->args[1] = op->args[3];
+            return fold_orc(ctx, op);
+        }
+    }
+    return false;
+}
+
 /* Propagate constants and copies, fold constant expressions. */
 void tcg_optimize(TCGContext *s)
 {
@@ -2964,6 +3019,9 @@ void tcg_optimize(TCGContext *s)
         case INDEX_op_cmpsel_vec:
             done = fold_cmpsel_vec(&ctx, op);
             break;
+        case INDEX_op_bitsel_vec:
+            done = fold_bitsel_vec(&ctx, op);
+            break;
         CASE_OP_32_64(sextract):
             done = fold_sextract(&ctx, op);
             break;