Fix delinearization of fortran arrays

The patch fixes Bug 25759 produced by inappropriate handling of unsigned
maximum SCEV expressions by SCEVRemoveMax. Without a fix, we get an infinite
loop and a segmentation fault, if we try to process, for example,
'((-1 + (-1 * %b1)) umax {(-1 + (-1 * %yStart)),+,-1}<%.preheader>)'.
It also fixes a potential issue related to signed maximum SCEV expressions.

Tested-by: Roman Gareev <gareevroman@gmail.com>
Fixed-by: Tobias Grosser <tobias@grosser.es>

Differential Revision: http://reviews.llvm.org/D15563

llvm-svn: 255922

1 files changed, 2 insertions, 2 deletions

diff --git a/polly/lib/Analysis/ScopDetection.cpp b/polly/lib/Analysis/ScopDetection.cpp
index 778ebff7158..b360419d894 100644
--- a/polly/lib/Analysis/ScopDetection.cpp
+++ b/polly/lib/Analysis/ScopDetection.cpp
@@ -524,7 +524,7 @@ public:
   const SCEV *visitUDivExpr(const SCEVUDivExpr *Expr) { return Expr; }
 
   const SCEV *visitSMaxExpr(const SCEVSMaxExpr *Expr) {
-    if (Expr->getOperand(0)->isZero()) {
+    if ((Expr->getNumOperands() == 2) and Expr->getOperand(0)->isZero()) {
       auto Res = visit(Expr->getOperand(1));
       if (Terms)
         (*Terms).push_back(Res);
@@ -534,7 +534,7 @@ public:
     return Expr;
   }
 
-  const SCEV *visitUMaxExpr(const SCEVUMaxExpr *Expr) { return visit(Expr); }
+  const SCEV *visitUMaxExpr(const SCEVUMaxExpr *Expr) { return Expr; }
 
   const SCEV *visitUnknown(const SCEVUnknown *Expr) { return Expr; }