[PATCH v4 48/51] 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.

Reviewed-by: Alex Bennée <alex.ben...@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>
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 742417ca1e..311d9779f2 100644
--- a/tcg/optimize.c
+++ b/tcg/optimize.c
@@ -966,6 +966,13 @@ 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.
@@ -1001,6 +1008,8 @@ 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);
 }
 
@@ -1299,6 +1308,9 @@ 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;
 }
 
@@ -1486,6 +1498,8 @@ 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;
@@ -1584,6 +1598,9 @@ 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;
 }
 
@@ -1613,6 +1630,9 @@ 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;
 }
 
@@ -1622,6 +1642,8 @@ 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;
@@ -1637,6 +1659,8 @@ 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);
 }
 
@@ -1648,6 +1672,9 @@ static bool fold_orc(OptContext *ctx, TCGOp *op)
         fold_ix_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;
 }
 
@@ -1921,6 +1948,8 @@ 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