------- Additional Comments From pinskia at gcc dot gnu dot org  2005-07-04 
17:03 -------
s/face/fact/
This is the patch I am testing right now:

      * fold-const.c (fold_build1): Add checksum for the operands.
      (fold_build2): Likewise.
      (fold_build3): Likewise.

Index: fold-const.c
===============================================================
====
RCS file: /cvs/gcc/gcc/gcc/fold-const.c,v
retrieving revision 1.600
diff -u -p -r1.600 fold-const.c
--- fold-const.c        2 Jul 2005 16:24:25 -0000       1.600
+++ fold-const.c        4 Jul 2005 17:02:26 -0000
@@ -10322,11 +10322,33 @@ recursive_label:
 tree
 fold_build1 (enum tree_code code, tree type, tree op0)
 {
-  tree tem = fold_unary (code, type, op0);
-  if (tem)
-    return tem;
-
-  return build1 (code, type, op0);
+  tree tem;
+#ifdef ENABLE_FOLD_CHECKING
+  unsigned char checksum_before[16], checksum_after[16];
+  struct md5_ctx ctx;
+  htab_t ht;
+
+  ht = htab_create (32, htab_hash_pointer, htab_eq_pointer, NULL);
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op0, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_before);
+  htab_empty (ht);
+#endif
+  
+  tem = fold_unary (code, type, op0);
+  if (!tem)
+    tem = build1 (code, type, op0);
+  
+#ifdef ENABLE_FOLD_CHECKING
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op0, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_after);
+  htab_delete (ht);
+
+  if (memcmp (checksum_before, checksum_after, 16))
+    fold_check_failed (op0, tem);
+#endif
+  return tem;
 }
 
 /* Fold a binary tree expression with code CODE of type TYPE with
@@ -10337,11 +10359,49 @@ fold_build1 (enum tree_code code, tree t
 tree
 fold_build2 (enum tree_code code, tree type, tree op0, tree op1)
 {
-  tree tem = fold_binary (code, type, op0, op1);
-  if (tem)
-    return tem;
+  tree tem;
+#ifdef ENABLE_FOLD_CHECKING
+  unsigned char checksum_before_op0[16],
+                checksum_before_op1[16],
+               checksum_after_op0[16],
+               checksum_after_op1[16];
+  struct md5_ctx ctx;
+  htab_t ht;
+
+  ht = htab_create (32, htab_hash_pointer, htab_eq_pointer, NULL);
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op0, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_before_op0);
+  htab_empty (ht);
+
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op1, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_before_op1);
+  htab_empty (ht);
+#endif
+
+  tem = fold_binary (code, type, op0, op1);
+  if (!tem)
+    tem = build2 (code, type, op0, op1);
+  
+#ifdef ENABLE_FOLD_CHECKING
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op0, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_after_op0);
+  htab_empty (ht);
 
-  return build2 (code, type, op0, op1);
+  if (memcmp (checksum_before_op0, checksum_after_op0, 16))
+    fold_check_failed (op0, tem);
+  
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op1, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_after_op1);
+  htab_delete (ht);
+
+  if (memcmp (checksum_before_op1, checksum_after_op1, 16))
+    fold_check_failed (op1, tem);
+#endif
+  return tem;
 }
 
 /* Fold a ternary tree expression with code CODE of type TYPE with
@@ -10351,12 +10411,64 @@ fold_build2 (enum tree_code code, tree t
 
 tree
 fold_build3 (enum tree_code code, tree type, tree op0, tree op1, tree op2)
-{
-  tree tem = fold_ternary (code, type, op0, op1, op2);
-  if (tem)
-    return tem;
+{  tree tem;
+#ifdef ENABLE_FOLD_CHECKING
+  unsigned char checksum_before_op0[16],
+                checksum_before_op1[16],
+                checksum_before_op2[16],
+               checksum_after_op0[16],
+               checksum_after_op1[16],
+               checksum_after_op2[16];
+  struct md5_ctx ctx;
+  htab_t ht;
+
+  ht = htab_create (32, htab_hash_pointer, htab_eq_pointer, NULL);
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op0, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_before_op0);
+  htab_empty (ht);
+
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op1, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_before_op1);
+  htab_empty (ht);
+
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op2, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_before_op2);
+  htab_empty (ht);
+#endif
+  
+  tem = fold_ternary (code, type, op0, op1, op2);
+  if (!tem)
+    tem =  build3 (code, type, op0, op1, op2);
+      
+#ifdef ENABLE_FOLD_CHECKING
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op0, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_after_op0);
+  htab_empty (ht);
 
-  return build3 (code, type, op0, op1, op2);
+  if (memcmp (checksum_before_op0, checksum_after_op0, 16))
+    fold_check_failed (op0, tem);
+  
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op1, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_after_op1);
+  htab_empty (ht);
+
+  if (memcmp (checksum_before_op1, checksum_after_op1, 16))
+    fold_check_failed (op1, tem);
+  
+  md5_init_ctx (&ctx);
+  fold_checksum_tree (op2, &ctx, ht);
+  md5_finish_ctx (&ctx, checksum_after_op2);
+  htab_delete (ht);
+
+  if (memcmp (checksum_before_op2, checksum_after_op2, 16))
+    fold_check_failed (op2, tem);
+#endif
+  return tem;
 }
 
 /* Perform constant folding and related simplification of initializer




-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21180

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