re PR middle-end/40281 (-fprefetch-loop-arrays: ICE: in initialize_matrix_A, at…

re PR middle-end/40281 (-fprefetch-loop-arrays: ICE: in initialize_matrix_A, at tree-data-ref.c:1887)

2009-11-18  Sebastian Pop  <sebastian.pop@amd.com>

	PR middle-end/40281
	* testsuite/gcc.dg/graphite/pr40281.c: New.

	* tree-scalar-evolution.c (instantiate_scev_poly): Base and stride
	evolutions should not variate in inner loops.

From-SVN: r154641

gcc/ChangeLog.graphite

 2009-11-18  Sebastian Pop  <sebastian.pop@amd.com>
 
+	PR middle-end/40281
+	* testsuite/gcc.dg/graphite/pr40281.c: New.
+
+	* tree-scalar-evolution.c (instantiate_scev_poly): Base and stride
+	evolutions should not variate in inner loops.
+
+2009-11-18  Sebastian Pop  <sebastian.pop@amd.com>
+
 	PR middle-end/42050
 	* testsuite/gfortran.dg/graphite/pr42050.f90: New.
 

gcc/tree-scalar-evolution.c

@@ -2226,9 +2226,21 @@ instantiate_scev_poly (basic_block instantiate_below,
   if (CHREC_LEFT (chrec) != op0
       || CHREC_RIGHT (chrec) != op1)
     {
+      unsigned var = CHREC_VARIABLE (chrec);
+
+      /* When the instantiated stride or base has an evolution in an
+	 innermost loop, return chrec_dont_know, as this is not a
+	 valid SCEV representation.  In the reduced testcase for
+	 PR40281 we would have {0, +, {1, +, 1}_2}_1 that has no
+	 meaning.  */
+      if ((tree_is_chrec (op0) && CHREC_VARIABLE (op0) > var)
+	  || (tree_is_chrec (op1) && CHREC_VARIABLE (op1) > var))
+	return chrec_dont_know;
+
       op1 = chrec_convert_rhs (chrec_type (op0), op1, NULL);
-      chrec = build_polynomial_chrec (CHREC_VARIABLE (chrec), op0, op1);
+      chrec = build_polynomial_chrec (var, op0, op1);
     }
+
   return chrec;
 }