[patch] Fix PR42326: convert expressions in chrec_fold_plus

[Sebastian Pop <sebpop at gmail dot com>]

Hi,

The problem in http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42326 is
that we currently do not handle correctly convert expressions in
chrec_fold_{plus,multiply}: for now we consider that a convert
expression does not contain any evolution in any loop, and this leads
to scevs that have no defined semantics: for example, when
op0 = (integer(kind=4)) {0, +, 1}_4 gets added to op1 = {0, +, 1}_1,
the result is: {(integer(kind=4)) {0, +, 1}_4, +, 1}_1
the initial value of the result variates in loop_4 but that loop is
contained in loop_1.

The solution for now is to avoid these cases.  This patch passed
make -k check RUNTESTFLAGS=tree-ssa.exp, graphite.exp and vect.exp on
both amd64-linux and i686-linux.  I am now bootstraping and testing
the attached patch on i686-linux and amd64-linux.

Sebastian Pop
--
AMD / Open Source Compiler Engineering / GNU Tools

From 860461cfb86ec362d2776932f2db614f5d08f933 Mon Sep 17 00:00:00 2001
From: Sebastian Pop <sebpop@gmail.com>
Date: Fri, 5 Mar 2010 05:49:48 -0600
Subject: [PATCH] Fix PR42326: Handle more carefully convert expressions in chrec_fold_plus and chrec_fold_mult.

2010-03-05  Sebastian Pop  <sebastian.pop@amd.com>

	PR middle-end/42326
	* tree-chrec.c (chrec_fold_plus_1): Do not handle convert expressions
	that contain scevs.
	(chrec_fold_multiply): Same.

	* gfortran.dg/graphite/pr42326.f90: New.
	* gfortran.dg/graphite/pr42326-1.f90: New.
---
 gcc/testsuite/gfortran.dg/graphite/pr42326-1.f90 |   16 ++++++++++
 gcc/testsuite/gfortran.dg/graphite/pr42326.f90   |   33 ++++++++++++++++++++++
 gcc/tree-chrec.c                                 |   24 ++++++++++++++++
 3 files changed, 73 insertions(+), 0 deletions(-)
 create mode 100644 gcc/testsuite/gfortran.dg/graphite/pr42326-1.f90
 create mode 100644 gcc/testsuite/gfortran.dg/graphite/pr42326.f90

diff --git a/gcc/testsuite/gfortran.dg/graphite/pr42326-1.f90 b/gcc/testsuite/gfortran.dg/graphite/pr42326-1.f90
new file mode 100644
index 0000000..8163fd4
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/graphite/pr42326-1.f90
@@ -0,0 +1,16 @@
+! { dg-options "-O2 -floop-parallelize-all -fprefetch-loop-arrays" }
+
+subroutine phasad(t,i,ium)
+  implicit none
+  real t(5,4)
+  integer i,l,ll,ium
+
+  do l=1,2
+     ll=2*l
+     do i=1,ium
+        t(i,ll-1)=t(i,ll-1)+t(i,ll)
+     enddo
+  enddo
+  return
+end subroutine phasad
+
diff --git a/gcc/testsuite/gfortran.dg/graphite/pr42326.f90 b/gcc/testsuite/gfortran.dg/graphite/pr42326.f90
new file mode 100644
index 0000000..c603a6e
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/graphite/pr42326.f90
@@ -0,0 +1,33 @@
+! { dg-options "-O2 -floop-strip-mine -fprefetch-loop-arrays" }
+
+subroutine blts ( ldmx, ldmy, v, tmp1, i, j, k)
+  implicit none
+  integer ldmx, ldmy, i, j, k, ip, m, l
+  real*8 tmp, tmp1, v( 5, ldmx, ldmy, *), tmat(5,5)
+
+  do ip = 1, 4
+     do m = ip+1, 5
+        tmp = tmp1 * tmat( m, ip )
+        do l = ip+1, 5
+           tmat( m, l ) =  tmat( m, l ) - tmat( ip, l )
+        end do
+        v( m, i, j, k ) = tmp
+     end do
+  end do
+  return
+end subroutine blts
+
+subroutine phasad(t,i,ium)
+  implicit none
+  real t(5,4)
+  integer i,l,ll,ium
+
+  do l=1,2
+     ll=2*l
+     do i=1,ium
+        t(i,ll-1)=t(i,ll-1)+t(i,ll)
+     enddo
+  enddo
+  return
+end subroutine phasad
+
diff --git a/gcc/tree-chrec.c b/gcc/tree-chrec.c
index 18ed4ed..c945f93 100644
--- a/gcc/tree-chrec.c
+++ b/gcc/tree-chrec.c
@@ -283,6 +283,10 @@ chrec_fold_plus_1 (enum tree_code code, tree type,
 	case POLYNOMIAL_CHREC:
 	  return chrec_fold_plus_poly_poly (code, type, op0, op1);
 
+	CASE_CONVERT:
+	  if (tree_contains_chrecs (op1, NULL))
+	    return chrec_dont_know;
+
 	default:
 	  if (code == PLUS_EXPR || code == POINTER_PLUS_EXPR)
 	    return build_polynomial_chrec
@@ -296,6 +300,10 @@ chrec_fold_plus_1 (enum tree_code code, tree type,
 	       CHREC_RIGHT (op0));
 	}
 
+    CASE_CONVERT:
+      if (tree_contains_chrecs (op0, NULL))
+	return chrec_dont_know;
+
     default:
       switch (TREE_CODE (op1))
 	{
@@ -314,6 +322,10 @@ chrec_fold_plus_1 (enum tree_code code, tree type,
 				    ? build_real (type, dconstm1)
 				    : build_int_cst_type (type, -1)));
 
+	CASE_CONVERT:
+	  if (tree_contains_chrecs (op1, NULL))
+	    return chrec_dont_know;
+
 	default:
 	  {
 	    int size = 0;
@@ -393,6 +405,10 @@ chrec_fold_multiply (tree type,
 	case POLYNOMIAL_CHREC:
 	  return chrec_fold_multiply_poly_poly (type, op0, op1);
 
+	CASE_CONVERT:
+	  if (tree_contains_chrecs (op1, NULL))
+	    return chrec_dont_know;
+
 	default:
 	  if (integer_onep (op1))
 	    return op0;
@@ -405,6 +421,10 @@ chrec_fold_multiply (tree type,
 	     chrec_fold_multiply (type, CHREC_RIGHT (op0), op1));
 	}
 
+    CASE_CONVERT:
+      if (tree_contains_chrecs (op0, NULL))
+	return chrec_dont_know;
+
     default:
       if (integer_onep (op0))
 	return op1;
@@ -420,6 +440,10 @@ chrec_fold_multiply (tree type,
 	     chrec_fold_multiply (type, CHREC_LEFT (op1), op0),
 	     chrec_fold_multiply (type, CHREC_RIGHT (op1), op0));
 
+	CASE_CONVERT:
+	  if (tree_contains_chrecs (op1, NULL))
+	    return chrec_dont_know;
+
 	default:
 	  if (integer_onep (op1))
 	    return op0;
-- 
1.6.3.3