[PATCH][GRAPHITE] Fix PR82449

[Richard Biener]

The following fences off a few more SCEVs through scev_analyzable_p given
at the end we need those pass chrec_apply when getting a rename through
SCEV.

The SCEV in question is

  {(integer(kind=4)) {0, +, {1, +, 1}_1}_1, + 1}_2

which fails to chrec_apply in the CHREC_LEFT part because that part
is not affine (and we're usually not replacing a IV with a constant
where chrec_apply might handle one or the other case).

Bootstrapped and tested on x86_64-unknown-linux-gnu.

This fixes three out of the remaining 8 codegen errors in SPEC CPU 2006.

Ok?

Thanks,
Richard.

2017-10-06  Richard Biener  <rguent...@suse.de>

        PR tree-optimization/82449
        * sese.c (can_chrec_apply): New function.
        (scev_analyzable_p): Check we can call chrec_apply on the SCEV.

        * gfortran.dg/graphite/pr82449.f: New testcase.

Index: gcc/sese.c
===================================================================
--- gcc/sese.c  (revision 253477)
+++ gcc/sese.c  (working copy)
@@ -421,6 +421,27 @@ invariant_in_sese_p_rec (tree t, const s
   return true;
 }
 
+/* Check whether we can call chrec_apply on CHREC with arbitrary X and VAR.  */
+
+static bool
+can_chrec_apply (tree chrec)
+{
+  if (automatically_generated_chrec_p (chrec))
+    return false;
+  switch (TREE_CODE (chrec))
+    {
+    case POLYNOMIAL_CHREC:
+      if (evolution_function_is_affine_p (chrec))
+       return (can_chrec_apply (CHREC_LEFT (chrec))
+               && can_chrec_apply (CHREC_RIGHT (chrec)));
+      return false;
+    CASE_CONVERT:
+      return can_chrec_apply (TREE_OPERAND (chrec, 0));
+    default:;
+      return tree_does_not_contain_chrecs (chrec);
+    }
+}
+
 /* Return true when DEF can be analyzed in REGION by the scalar
    evolution analyzer.  */
 
@@ -449,6 +470,7 @@ scev_analyzable_p (tree def, sese_l &reg
        || !defined_in_sese_p (scev, region))
     && (tree_does_not_contain_chrecs (scev)
        || evolution_function_is_affine_p (scev))
+    && can_chrec_apply (scev)
     && (! loop
        || ! loop_in_sese_p (loop, region)
        || ! chrec_contains_symbols_defined_in_loop (scev, loop->num));
Index: gcc/testsuite/gfortran.dg/graphite/pr82449.f
===================================================================
--- gcc/testsuite/gfortran.dg/graphite/pr82449.f        (nonexistent)
+++ gcc/testsuite/gfortran.dg/graphite/pr82449.f        (working copy)
@@ -0,0 +1,11 @@
+! { dg-do compile }
+! { dg-options "-O2 -floop-nest-optimize" }
+
+      SUBROUTINE JDFIDX(MKL,KGSH)
+      DIMENSION MKL(6,6)
+      NKL=0
+  400 DO 40 KG = 1,KGSH
+      DO 40 LG = 1,KG
+      NKL = NKL + 1
+   40 MKL(LG,KG) = NKL
+      END