tcg/optimize: Build and use o_bits in fold_andc

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

diff --git a/tcg/optimize.c b/tcg/optimize.c
index d9ccbb36e2b266af9f2321886f86a306ff5c6956..123734b167dd5dc75a4369fd6b2f23b047087488 100644 (file)
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1452,7 +1452,7 @@ static bool fold_and(OptContext *ctx, TCGOp *op)
 
 static bool fold_andc(OptContext *ctx, TCGOp *op)
 {
-    uint64_t z_mask, s_mask;
+    uint64_t z_mask, o_mask, s_mask, a_mask;
     TempOptInfo *t1, *t2;
 
     if (fold_const2(ctx, op) ||
@@ -1464,7 +1464,6 @@ static bool fold_andc(OptContext *ctx, TCGOp *op)
 
     t1 = arg_info(op->args[1]);
     t2 = arg_info(op->args[2]);
-    z_mask = t1->z_mask;
 
     if (ti_is_const(t2)) {
         /* Fold andc r,x,i to and r,x,~i. */
@@ -1485,20 +1484,14 @@ static bool fold_andc(OptContext *ctx, TCGOp *op)
         return fold_and(ctx, op);
     }
 
-    /*
-     * Known-zeros does not imply known-ones.  Therefore unless
-     * arg2 is constant, we can't infer anything from it.
-     */
-    if (ti_is_const(t2)) {
-        uint64_t v2 = ti_const_val(t2);
-        if (fold_affected_mask(ctx, op, z_mask & v2)) {
-            return true;
-        }
-        z_mask &= ~v2;
-    }
-
+    z_mask = t1->z_mask & ~t2->o_mask;
+    o_mask = t1->o_mask & ~t2->z_mask;
     s_mask = t1->s_mask & t2->s_mask;
-    return fold_masks_zs(ctx, op, z_mask, s_mask);
+
+    /* Affected bits are those not known zero, masked by those known zero. */
+    a_mask = t1->z_mask & t2->z_mask;
+
+    return fold_masks_zosa(ctx, op, z_mask, o_mask, s_mask, a_mask);
 }
 
 static bool fold_bitsel_vec(OptContext *ctx, TCGOp *op)