[PATCH 45/48] tcg/optimize: Propagate sign info for logical operations

[Richard Henderson]

Sign repetitions are perforce all identical, whether they are 1 or 0.
Bitwise operations preserve the relative quantity of the repetitions.

Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
 tcg/optimize.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/tcg/optimize.c b/tcg/optimize.c
index 9a752fbe29..cbb5700f44 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -952,6 +952,13 @@ static bool fold_and(OptContext *ctx, TCGOp *op)
     z2 = arg_info(op->args[2])->z_mask;
     ctx->z_mask = z1 & z2;
 
+    /*
+     * Sign repetitions are perforce all identical, whether they are 1 or 0.
+     * Bitwise operations preserve the relative quantity of the repetitions.
+     */
+    ctx->s_mask = arg_info(op->args[1])->s_mask
+                & arg_info(op->args[2])->s_mask;
+
     /*
      * Known-zeros does not imply known-ones.  Therefore unless
      * arg2 is constant, we can't infer affected bits from it.
@@ -987,6 +994,8 @@ static bool fold_andc(OptContext *ctx, TCGOp *op)
     }
     ctx->z_mask = z1;
 
+    ctx->s_mask = arg_info(op->args[1])->s_mask
+                & arg_info(op->args[2])->s_mask;
     return fold_masks(ctx, op);
 }
 
@@ -1278,6 +1287,9 @@ static bool fold_eqv(OptContext *ctx, TCGOp *op)
         fold_xi_to_not(ctx, op, 0)) {
         return true;
     }
+
+    ctx->s_mask = arg_info(op->args[1])->s_mask
+                & arg_info(op->args[2])->s_mask;
     return false;
 }
 
@@ -1466,6 +1478,8 @@ static bool fold_movcond(OptContext *ctx, TCGOp *op)
 
     ctx->z_mask = arg_info(op->args[3])->z_mask
                 | arg_info(op->args[4])->z_mask;
+    ctx->s_mask = arg_info(op->args[3])->s_mask
+                & arg_info(op->args[4])->s_mask;
 
     if (arg_is_const(op->args[3]) && arg_is_const(op->args[4])) {
         uint64_t tv = arg_info(op->args[3])->val;
@@ -1545,6 +1559,9 @@ static bool fold_nand(OptContext *ctx, TCGOp *op)
         fold_xi_to_not(ctx, op, -1)) {
         return true;
     }
+
+    ctx->s_mask = arg_info(op->args[1])->s_mask
+                & arg_info(op->args[2])->s_mask;
     return false;
 }
 
@@ -1574,6 +1591,9 @@ static bool fold_nor(OptContext *ctx, TCGOp *op)
         fold_xi_to_not(ctx, op, 0)) {
         return true;
     }
+
+    ctx->s_mask = arg_info(op->args[1])->s_mask
+                & arg_info(op->args[2])->s_mask;
     return false;
 }
 
@@ -1583,6 +1603,8 @@ static bool fold_not(OptContext *ctx, TCGOp *op)
         return true;
     }
 
+    ctx->s_mask = arg_info(op->args[1])->s_mask;
+
     /* Because of fold_to_not, we want to always return true, via finish. */
     finish_folding(ctx, op);
     return true;
@@ -1598,6 +1620,8 @@ static bool fold_or(OptContext *ctx, TCGOp *op)
 
     ctx->z_mask = arg_info(op->args[1])->z_mask
                 | arg_info(op->args[2])->z_mask;
+    ctx->s_mask = arg_info(op->args[1])->s_mask
+                & arg_info(op->args[2])->s_mask;
     return fold_masks(ctx, op);
 }
 
@@ -1609,6 +1633,9 @@ static bool fold_orc(OptContext *ctx, TCGOp *op)
         fold_xi_to_not(ctx, op, 0)) {
         return true;
     }
+
+    ctx->s_mask = arg_info(op->args[1])->s_mask
+                & arg_info(op->args[2])->s_mask;
     return false;
 }
 
@@ -1873,6 +1900,8 @@ static bool fold_xor(OptContext *ctx, TCGOp *op)
 
     ctx->z_mask = arg_info(op->args[1])->z_mask
                 | arg_info(op->args[2])->z_mask;
+    ctx->s_mask = arg_info(op->args[1])->s_mask
+                & arg_info(op->args[2])->s_mask;
     return fold_masks(ctx, op);
 }
 
-- 
2.25.1