re PR rtl-optimization/51924 (wrong code with -O -free -fno-rename-registers -ftree...

	PR rtl-optimization/51924
	* ree.c (combine_set_extension): Improve debugging message.
	(combine_reaching_defs): Likewise.
	(get_defs): Rename confusingly named variable.
	(find_and_remove_re): Skip a candidate if the extension expression has
	been modified.

From-SVN: r183390

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 325d2fc88a309c3a9ae324867694a5f387eefff4..71df98e6699241328970464a980ef6af7e0cf9a9 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2012-01-22  Eric Botcazou  <ebotcazou@adacore.com>
+
+       PR rtl-optimization/51924
+       * ree.c (combine_set_extension): Improve debugging message.
+       (combine_reaching_defs): Likewise.
+       (get_defs): Rename confusingly named variable.
+       (find_and_remove_re): Skip a candidate if the extension expression has
+       been modified.
+
 2012-01-21  Robert Millan  <rmh@gnu.org>
            Gerald Pfeifer  <gerald@pfeifer.com>
 

diff --git a/gcc/ree.c b/gcc/ree.c
index 48113a966ba9cb92c7553f4f5621a04f355cd758..4cab20ed50e9ce63ad4326ca3d37e3f03b9ea629 100644 (file)
--- a/gcc/ree.c
+++ b/gcc/ree.c
@@ -346,7 +346,8 @@ combine_set_extension (ext_cand *cand, rtx curr_insn, rtx *orig_set)
     {
       if (dump_file)
         {
-          fprintf (dump_file, "Merged instruction with extension:\n");
+          fprintf (dump_file,
+                  "Tentatively merged extension with definition:\n");
           print_rtl_single (dump_file, curr_insn);
         }
       return true;
@@ -407,21 +408,21 @@ transform_ifelse (ext_cand *cand, rtx def_insn)
 static struct df_link *
 get_defs (rtx insn, rtx reg, VEC (rtx,heap) **dest)
 {
-  df_ref reg_info, *defs;
+  df_ref reg_info, *uses;
   struct df_link *ref_chain, *ref_link;
 
   reg_info = NULL;
 
-  for (defs = DF_INSN_USES (insn); *defs; defs++)
+  for (uses = DF_INSN_USES (insn); *uses; uses++)
     {
-      reg_info = *defs;
+      reg_info = *uses;
       if (GET_CODE (DF_REF_REG (reg_info)) == SUBREG)
         return NULL;
       if (REGNO (DF_REF_REG (reg_info)) == REGNO (reg))
         break;
     }
 
-  gcc_assert (reg_info != NULL && defs != NULL);
+  gcc_assert (reg_info != NULL && uses != NULL);
 
   ref_chain = DF_REF_CHAIN (reg_info);
 
@@ -686,11 +687,10 @@ combine_reaching_defs (ext_cand *cand, rtx set_pat)
              purposes.  This extension cannot be deleted.  */
           if (dump_file)
             {
-              FOR_EACH_VEC_ELT (rtx, vec, i, def_insn)
-                {
-                  fprintf (dump_file, "Non-mergeable definitions:\n");
-                  print_rtl_single (dump_file, def_insn);
-                }
+             fprintf (dump_file,
+                      "Merge cancelled, non-mergeable definitions:\n");
+             FOR_EACH_VEC_ELT (rtx, vec, i, def_insn)
+               print_rtl_single (dump_file, def_insn);
             }
         }
     }
@@ -843,6 +843,12 @@ find_and_remove_re (void)
     {
       num_re_opportunities++;
 
+      /* If the candidate insn is itself a definition insn for another
+         candidate, it may have been modified and the UD chain broken.
+         FIXME: the handling of successive extensions can be improved.  */
+      if (!reg_mentioned_p (curr_cand->expr, PATTERN (curr_cand->insn)))
+       continue;
+
       /* Try to combine the extension with the definition.  */
       if (dump_file)
         {

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index f0b4a793ef7b9806ad0e1c2a72ad779700a3f4d6..07b1fef7697e48d30463c9ee11ddbbab667b8b5a 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2012-01-22  Eric Botcazou  <ebotcazou@adacore.com>
+
+       * gcc.dg/ext-elim-1.c: New test.
+
 2012-01-22  Richard Sandiford  <rdsandiford@googlemail.com>
 
        PR target/51931

diff --git a/gcc/testsuite/gcc.dg/ext-elim-1.c b/gcc/testsuite/gcc.dg/ext-elim-1.c
new file mode 100644 (file)
index 0000000..5e899a2
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ext-elim-1.c
@@ -0,0 +1,39 @@
+/* PR rtl-optimization/51924 */
+/* Testcase by Zdenek Sojka <zsojka@seznam.cz> */
+
+/* { dg-do run } */
+/* { dg-options "-O -free -fno-rename-registers -ftree-vectorize -funroll-loops" } */
+
+typedef __UINT64_TYPE__ uint64_t;
+
+uint64_t __attribute__ ((noinline, noclone))
+bn_sub_words (uint64_t * r, const uint64_t * a, const uint64_t * b, int n)
+{
+  uint64_t t1, t2;
+  unsigned c = 0;
+
+  while (n)
+    {
+      t1 = a[0];
+      t2 = b[0];
+      r[0] = (t1 - t2 - c);
+      if (t1 != t2)
+       c = (t1 < t2);
+      a++;
+      b++;
+      r++;
+      n--;
+    }
+  return (c);
+}
+
+int
+main (void)
+{
+  uint64_t r[2];
+  uint64_t a[2] = { -1, -1 };
+  uint64_t b[2] = { 0, 0 };
+  if (bn_sub_words (r, a, b, 2) != 0)
+    __builtin_abort ();
+  return 0;
+}