Re: [PATCH, rs6000] Fix PR target/42427

[Peter Bergner <bergner at vnet dot ibm dot com>]

On Thu, 2010-01-21 at 10:13 -0500, David Edelsohn wrote:
> Testing for the existence of PRE_INC, PRE_DEC and PRE_MODIFY and then
> testing for their absence is overly confusing.  The patch is adding
> another layer to the existing logic instead of cleaning it up.  No one
> will be able to maintain the code when it next needs to be modified.
> If one needs to test the same RTL code multiple times, the code should
> be rearranged.  I also am not confident that LO_SUM should have been
> omitted.

Here's a new patch with the auto-increment tests factored out from the
other tests.  I checked and we do not want the LO_SUM code handled the
same as the PRE_* forms.  This passed bootstrap and regtesting on
powerpc64-linux with -m32/-m64.  Is this ok now?

Peter


	PR target/42427
	* config/rs6000/rs6000.md (*movdf_hardfloat32): Move auto-increment
	code into its own "if" test.
	(*movdf_softfloat32): Add test for auto-increment form instructions.
	* gfortran.dg/pr42427.f: New test.

Index: config/rs6000/rs6000.md
===================================================================
--- config/rs6000/rs6000.md	(revision 155844)
+++ config/rs6000/rs6000.md	(working copy)
@@ -9149,17 +9149,17 @@ (define_insn "*movdf_hardfloat32"
       else
 	return \"mr %0,%1\;mr %L0,%L1\";
     case 1:
-      if (rs6000_offsettable_memref_p (operands[1])
-	  || (GET_CODE (operands[1]) == MEM
-	      && (GET_CODE (XEXP (operands[1], 0)) == LO_SUM
-		  || GET_CODE (XEXP (operands[1], 0)) == PRE_INC
-		  || GET_CODE (XEXP (operands[1], 0)) == PRE_DEC
-		  || GET_CODE (XEXP (operands[1], 0)) == PRE_MODIFY)))
+      if (GET_CODE (operands[1]) == MEM
+	  && (GET_CODE (XEXP (operands[1], 0)) == PRE_MODIFY
+	      || GET_CODE (XEXP (operands[1], 0)) == PRE_DEC
+	      || GET_CODE (XEXP (operands[1], 0)) == PRE_INC))
+	return \"{l%U1%X1|lwz%U1%X1} %0,%1\;{l|lwz} %L0,%L1\";
+      else if (rs6000_offsettable_memref_p (operands[1])
+	       || (GET_CODE (operands[1]) == MEM
+		   && GET_CODE (XEXP (operands[1], 0)) == LO_SUM))
 	{
 	  /* If the low-address word is used in the address, we must load
-	     it last.  Otherwise, load it first.  Note that we cannot have
-	     auto-increment in that case since the address register is
-	     known to be dead.  */
+	     it last.  Otherwise, load it first.  */
 	  if (refers_to_regno_p (REGNO (operands[0]), REGNO (operands[0]) + 1,
 				 operands[1], 0))
 	    return \"{l|lwz} %L0,%L1\;{l|lwz} %0,%1\";
@@ -9257,15 +9257,21 @@ (define_insn "*movdf_softfloat32"
       else
 	return \"mr %0,%1\;mr %L0,%L1\";
     case 1:
-      /* If the low-address word is used in the address, we must load
-	 it last.  Otherwise, load it first.  Note that we cannot have
-	 auto-increment in that case since the address register is
-	 known to be dead.  */
-      if (refers_to_regno_p (REGNO (operands[0]), REGNO (operands[0]) + 1,
-			     operands[1], 0))
-	return \"{l|lwz} %L0,%L1\;{l|lwz} %0,%1\";
-      else
+      /* If the low-address word is used in the address of a non
+	 auto-increment form instruction, then we must load it last.
+	 Otherwise, load it first.  Auto-increment form instructions
+	 are not a problem, since either the low-address word is not
+	 used in the address, or if it is, it must be used as the
+	 offset register of an indexed form instruction.  */
+      if ((GET_CODE (operands[1]) == MEM
+	   && (GET_CODE (XEXP (operands[1], 0)) == PRE_MODIFY
+	       || GET_CODE (XEXP (operands[1], 0)) == PRE_DEC
+	       || GET_CODE (XEXP (operands[1], 0)) == PRE_INC))
+	  || !refers_to_regno_p (REGNO (operands[0]), REGNO (operands[0]) + 1,
+				 operands[1], 0))
 	return \"{l%U1%X1|lwz%U1%X1} %0,%1\;{l|lwz} %L0,%L1\";
+      else
+	return \"{l|lwz} %L0,%L1\;{l|lwz} %0,%1\";
     case 2:
       return \"{st%U0%X0|stw%U0%X0} %1,%0\;{st|stw} %L1,%L0\";
     case 3:
Index: gfortran.dg/pr42427.f
===================================================================
--- gfortran.dg/pr42427.f	(revision 0)
+++ gfortran.dg/pr42427.f	(revision 0)
@@ -0,0 +1,16 @@
+! { dg-do assemble }
+! { dg-options "-O2 -fexceptions -fnon-call-exceptions -fpeel-loops" }
+! { dg-require-effective-target ilp32 }
+
+      SUBROUTINE TEST(HELP,WM,NZ)
+      IMPLICIT REAL*8 (A-H, O-Z)
+      REAL*8 HELP(NZ)
+      COMPLEX*16 WM(NZ)
+
+      DO K=1,NZ
+         ZNEW=ABS(WM(K))
+         ZOLD=HELP(K)
+         HELP(K)=ZNEW
+      ENDDO
+      RETURN
+      END