PR rtl-optimization/45695

	* combine.c (try_combine): When splitting a two set pattern,
	make sure the pattern which will be put into i2 doesn't use REGs
	or MEMs set by insns in between i2 and i3.

	* gcc.c-torture/execute/pr45695.c: New test.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@164431 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 24 insertions, 52 deletions

diff --git a/gcc/combine.c b/gcc/combine.c
index 618e07df4f0..6131b413d1d 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -3690,36 +3690,41 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx i0, int *new_direct_jump_p)
 	   && GET_CODE (XVECEXP (newpat, 0, 1)) == SET
 	   && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != ZERO_EXTRACT
 	   && GET_CODE (SET_DEST (XVECEXP (newpat, 0, 1))) != STRICT_LOW_PART
-	   && ! use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 1)),
-				   DF_INSN_LUID (i2))
 	   && ! reg_referenced_p (SET_DEST (XVECEXP (newpat, 0, 1)),
 				  XVECEXP (newpat, 0, 0))
 	   && ! reg_referenced_p (SET_DEST (XVECEXP (newpat, 0, 0)),
 				  XVECEXP (newpat, 0, 1))
 	   && ! (contains_muldiv (SET_SRC (XVECEXP (newpat, 0, 0)))
-		 && contains_muldiv (SET_SRC (XVECEXP (newpat, 0, 1))))
-#ifdef HAVE_cc0
-	   /* We cannot split the parallel into two sets if both sets
-	      reference cc0.  */
-	   && ! (reg_referenced_p (cc0_rtx, XVECEXP (newpat, 0, 0))
-		 && reg_referenced_p (cc0_rtx, XVECEXP (newpat, 0, 1)))
-#endif
-	   )
+		 && contains_muldiv (SET_SRC (XVECEXP (newpat, 0, 1)))))
     {
       /* Normally, it doesn't matter which of the two is done first,
-	 but it does if one references cc0.  In that case, it has to
+	 but the one that references cc0 can't be the second, and
+	 one which uses any regs/memory set in between i2 and i3 can't
 	 be first.  */
+      if (!use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 1)),
+			      DF_INSN_LUID (i2))
+#ifdef HAVE_cc0
+	  && !reg_referenced_p (cc0_rtx, XVECEXP (newpat, 0, 0))
+#endif
+	 )
+	{
+	  newi2pat = XVECEXP (newpat, 0, 1);
+	  newpat = XVECEXP (newpat, 0, 0);
+	}
+      else if (!use_crosses_set_p (SET_SRC (XVECEXP (newpat, 0, 0)),
+				   DF_INSN_LUID (i2))
 #ifdef HAVE_cc0
-      if (reg_referenced_p (cc0_rtx, XVECEXP (newpat, 0, 0)))
+	       && !reg_referenced_p (cc0_rtx, XVECEXP (newpat, 0, 1))
+#endif
+	      )
 	{
 	  newi2pat = XVECEXP (newpat, 0, 0);
 	  newpat = XVECEXP (newpat, 0, 1);
 	}
       else
-#endif
 	{
-	  newi2pat = XVECEXP (newpat, 0, 1);
-	  newpat = XVECEXP (newpat, 0, 0);
+	  undo_all ();
+	  return 0;
 	}
 
       i2_code_number = recog_for_combine (&newi2pat, i2, &new_i2_notes);
@@ -3735,44 +3740,11 @@ try_combine (rtx i3, rtx i2, rtx i1, rtx i0, int *new_direct_jump_p)
 		  {
 		    rtx reg = XEXP (XVECEXP (newi2pat, 0, i), 0);
 		    if (reg_overlap_mentioned_p (reg, newpat))
-		      break;
+		      {
+			undo_all ();
+			return 0;
+		      }
 		  }
-
-	      if (i >= 0)
-		{
-		  /* CLOBBERs on newi2pat prevent it going first.
-		     Try the other order of the insns if possible.  */
-		  temp = newpat;
-		  newpat = XVECEXP (newi2pat, 0, 0);
-		  newi2pat = temp;
-#ifdef HAVE_cc0
-		  if (reg_referenced_p (cc0_rtx, newpat))
-		    {
-		      undo_all ();
-		      return 0;
-		    }
-#endif
-
-		  i2_code_number = recog_for_combine (&newi2pat, i2,
-						      &new_i2_notes);
-		  if (i2_code_number < 0)
-		    {
-		      undo_all ();
-		      return 0;
-		    }
-
-		  if (GET_CODE (newi2pat) == PARALLEL)
-		    for (i = XVECLEN (newi2pat, 0) - 1; i >= 0; i--)
-		      if (GET_CODE (XVECEXP (newi2pat, 0, i)) == CLOBBER)
-			{
-			  rtx reg = XEXP (XVECEXP (newi2pat, 0, i), 0);
-			  if (reg_overlap_mentioned_p (reg, newpat))
-			    {
-			      undo_all ();
-			      return 0;
-			    }
-			}
-		}
 	    }
 
 	  insn_code_number = recog_for_combine (&newpat, i3, &new_i3_notes);