[v3,05/51] tcg/optimize: Augment s_mask from z_mask in fold_masks_zs

Commit Message

Richard Henderson Dec. 22, 2024, 4:24 p.m. UTC

Consider the passed s_mask to be a minimum deduced from
either existing s_mask or from a sign-extension operation.
We may be able to deduce more from the set of known zeros.
Remove identical logic from several opcode folders.

Reviewed-by: Pierrick Bouvier <[e-mail]>
Signed-off-by: Richard Henderson <[e-mail]>
---
 tcg/optimize.c | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

Patch

diff --git a/tcg/optimize.c b/tcg/optimize.c
index d70127b88d..d8f6542c4f 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -1048,6 +1048,7 @@  static bool fold_const2_commutative(OptContext *ctx, TCGOp *op)
  * Record "zero" and "sign" masks for the single output of @op.
  * See TempOptInfo definition of z_mask and s_mask.
  * If z_mask allows, fold the output to constant zero.
+ * The passed s_mask may be augmented by z_mask.
  */
 static bool fold_masks_zs(OptContext *ctx, TCGOp *op,
                           uint64_t z_mask, uint64_t s_mask)
@@ -1080,7 +1081,7 @@  static bool fold_masks_zs(OptContext *ctx, TCGOp *op,
 
     ti = ts_info(ts);
     ti->z_mask = z_mask;
-    ti->s_mask = s_mask;
+    ti->s_mask = s_mask | smask_from_zmask(z_mask);
     return true;
 }
 
@@ -1519,8 +1520,8 @@  static bool fold_bswap(OptContext *ctx, TCGOp *op)
     default:
         g_assert_not_reached();
     }
-    s_mask = smask_from_zmask(z_mask);
 
+    s_mask = 0;
     switch (op->args[2] & (TCG_BSWAP_OZ | TCG_BSWAP_OS)) {
     case TCG_BSWAP_OZ:
         break;
@@ -1534,7 +1535,6 @@  static bool fold_bswap(OptContext *ctx, TCGOp *op)
     default:
         /* The high bits are undefined: force all bits above the sign to 1. */
         z_mask |= sign << 1;
-        s_mask = 0;
         break;
     }
     ctx->z_mask = z_mask;
@@ -1605,7 +1605,6 @@  static bool fold_count_zeros(OptContext *ctx, TCGOp *op)
         g_assert_not_reached();
     }
     ctx->z_mask = arg_info(op->args[2])->z_mask | z_mask;
-    ctx->s_mask = smask_from_zmask(ctx->z_mask);
     return false;
 }
 
@@ -1625,7 +1624,6 @@  static bool fold_ctpop(OptContext *ctx, TCGOp *op)
     default:
         g_assert_not_reached();
     }
-    ctx->s_mask = smask_from_zmask(ctx->z_mask);
     return false;
 }
 
@@ -1746,7 +1744,6 @@  static bool fold_extract(OptContext *ctx, TCGOp *op)
         return true;
     }
     ctx->z_mask = z_mask;
-    ctx->s_mask = smask_from_zmask(z_mask);
 
     return fold_masks(ctx, op);
 }
@@ -1851,7 +1848,6 @@  static bool fold_extu(OptContext *ctx, TCGOp *op)
     }
 
     ctx->z_mask = z_mask;
-    ctx->s_mask = smask_from_zmask(z_mask);
     if (!type_change && fold_affected_mask(ctx, op, z_mask_old ^ z_mask)) {
         return true;
     }
@@ -2116,10 +2112,10 @@  static bool fold_qemu_ld(OptContext *ctx, TCGOp *op)
     int width = 8 * memop_size(mop);
 
     if (width < 64) {
-        ctx->s_mask = MAKE_64BIT_MASK(width, 64 - width);
-        if (!(mop & MO_SIGN)) {
+        if (mop & MO_SIGN) {
+            ctx->s_mask = MAKE_64BIT_MASK(width, 64 - width);
+        } else {
             ctx->z_mask = MAKE_64BIT_MASK(0, width);
-            ctx->s_mask <<= 1;
         }
     }
 
@@ -2354,7 +2350,6 @@  static bool fold_setcond(OptContext *ctx, TCGOp *op)
     fold_setcond_tst_pow2(ctx, op, false);
 
     ctx->z_mask = 1;
-    ctx->s_mask = smask_from_zmask(1);
     return false;
 }
 
@@ -2455,7 +2450,6 @@  static bool fold_setcond2(OptContext *ctx, TCGOp *op)
     }
 
     ctx->z_mask = 1;
-    ctx->s_mask = smask_from_zmask(1);
     return false;
 
  do_setcond_const:
@@ -2649,21 +2643,18 @@  static bool fold_tcg_ld(OptContext *ctx, TCGOp *op)
         break;
     CASE_OP_32_64(ld8u):
         ctx->z_mask = MAKE_64BIT_MASK(0, 8);
-        ctx->s_mask = MAKE_64BIT_MASK(9, 55);
         break;
     CASE_OP_32_64(ld16s):
         ctx->s_mask = MAKE_64BIT_MASK(16, 48);
         break;
     CASE_OP_32_64(ld16u):
         ctx->z_mask = MAKE_64BIT_MASK(0, 16);
-        ctx->s_mask = MAKE_64BIT_MASK(17, 47);
         break;
     case INDEX_op_ld32s_i64:
         ctx->s_mask = MAKE_64BIT_MASK(32, 32);
         break;
     case INDEX_op_ld32u_i64:
         ctx->z_mask = MAKE_64BIT_MASK(0, 32);
-        ctx->s_mask = MAKE_64BIT_MASK(33, 31);
         break;
     default:
         g_assert_not_reached();