PR rtl-optimization/52060

	* combine.c (try_combine): Add i0src_copy and i0src_copy2 variables,
	copy i1src to i1src_copy whenever added_sets_2 && i1_feeds_i2_n already
	before i1dest -> i1src substitution in newpat, copy i0src to i0src_copy
	and/or i0src_copy2 when needed.

	* gcc.dg/torture/pr52060.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@183972 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 17 insertions, 8 deletions

diff --git a/gcc/combine.c b/gcc/combine.c
index 582db1ffe0d..d06de04041e 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -2591,8 +2591,8 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx i0, int *new_direct_jump_p,
   rtx i3dest_killed = 0;
   /* SET_DEST and SET_SRC of I2, I1 and I0.  */
   rtx i2dest = 0, i2src = 0, i1dest = 0, i1src = 0, i0dest = 0, i0src = 0;
-  /* Copy of SET_SRC of I1, if needed.  */
-  rtx i1src_copy = 0;
+  /* Copy of SET_SRC of I1 and I0, if needed.  */
+  rtx i1src_copy = 0, i0src_copy = 0, i0src_copy2 = 0;
   /* Set if I2DEST was reused as a scratch register.  */
   bool i2scratch = false;
   /* The PATTERNs of I0, I1, and I2, or a copy of them in certain cases.  */
@@ -3246,6 +3246,11 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx i0, int *new_direct_jump_p,
       n_occurrences = 0;
       subst_low_luid = DF_INSN_LUID (i1);
 
+      /* If the following substitution will modify I1SRC, make a copy of it
+	 for the case where it is substituted for I1DEST in I2PAT later.  */
+      if (added_sets_2 && i1_feeds_i2_n)
+	i1src_copy = copy_rtx (i1src);
+
       /* If I0 feeds into I1 and I0DEST is in I0SRC, we need to make a unique
 	 copy of I1SRC each time we substitute it, in order to avoid creating
 	 self-referential RTL when we will be substituting I0SRC for I0DEST
@@ -3273,10 +3278,14 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx i0, int *new_direct_jump_p,
 	  return 0;
 	}
 
-      /* If the following substitution will modify I1SRC, make a copy of it
-	 for the case where it is substituted for I1DEST in I2PAT later.  */
-      if (i0_feeds_i1_n && added_sets_2 && i1_feeds_i2_n)
-	i1src_copy = copy_rtx (i1src);
+      /* If the following substitution will modify I0SRC, make a copy of it
+	 for the case where it is substituted for I0DEST in I1PAT later.  */
+      if (added_sets_1 && i0_feeds_i1_n)
+	i0src_copy = copy_rtx (i0src);
+      /* And a copy for I0DEST in I2PAT substitution.  */
+      if (added_sets_2 && ((i0_feeds_i1_n && i1_feeds_i2_n)
+			   || (i0_feeds_i2_n)))
+	i0src_copy2 = copy_rtx (i0src);
 
       n_occurrences = 0;
       subst_low_luid = DF_INSN_LUID (i0);
@@ -3342,7 +3351,7 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx i0, int *new_direct_jump_p,
 	{
 	  rtx t = i1pat;
 	  if (i0_feeds_i1_n)
-	    t = subst (t, i0dest, i0src, 0, 0, 0);
+	    t = subst (t, i0dest, i0src_copy ? i0src_copy : i0src, 0, 0, 0);
 
 	  XVECEXP (newpat, 0, --total_sets) = t;
 	}
@@ -3353,7 +3362,7 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx i0, int *new_direct_jump_p,
 	    t = subst (t, i1dest, i1src_copy ? i1src_copy : i1src, 0, 0,
 		       i0_feeds_i1_n && i0dest_in_i0src);
 	  if ((i0_feeds_i1_n && i1_feeds_i2_n) || i0_feeds_i2_n)
-	    t = subst (t, i0dest, i0src, 0, 0, 0);
+	    t = subst (t, i0dest, i0src_copy2 ? i0src_copy2 : i0src, 0, 0, 0);
 
 	  XVECEXP (newpat, 0, --total_sets) = t;
 	}