[FIX] Handle accesses to "null" in MemIntrinsics

  This fixes PR27035. While we now exclude MemIntrinsics from the
  polyhedral model if they would access "null" we could exploit this
  even more, e.g., remove all parameter combinations that would lead to
  the execution of this statement from the context.

llvm-svn: 264284

1 files changed, 12 insertions, 8 deletions

diff --git a/polly/lib/Analysis/ScopDetection.cpp b/polly/lib/Analysis/ScopDetection.cpp
index 2ceb3fa62dc..7810b94c4e5 100644
--- a/polly/lib/Analysis/ScopDetection.cpp
+++ b/polly/lib/Analysis/ScopDetection.cpp
@@ -533,17 +533,21 @@ bool ScopDetection::isValidIntrinsicInst(IntrinsicInst &II,
   case llvm::Intrinsic::memmove:
   case llvm::Intrinsic::memcpy:
     AF = SE->getSCEVAtScope(cast<MemTransferInst>(II).getSource(), L);
-    BP = dyn_cast<SCEVUnknown>(SE->getPointerBase(AF));
-    // Bail if the source pointer is not valid.
-    if (!isValidAccess(&II, AF, BP, Context))
-      return false;
+    if (!AF->isZero()) {
+      BP = dyn_cast<SCEVUnknown>(SE->getPointerBase(AF));
+      // Bail if the source pointer is not valid.
+      if (!isValidAccess(&II, AF, BP, Context))
+        return false;
+    }
   // Fall through
   case llvm::Intrinsic::memset:
     AF = SE->getSCEVAtScope(cast<MemIntrinsic>(II).getDest(), L);
-    BP = dyn_cast<SCEVUnknown>(SE->getPointerBase(AF));
-    // Bail if the destination pointer is not valid.
-    if (!isValidAccess(&II, AF, BP, Context))
-      return false;
+    if (!AF->isZero()) {
+      BP = dyn_cast<SCEVUnknown>(SE->getPointerBase(AF));
+      // Bail if the destination pointer is not valid.
+      if (!isValidAccess(&II, AF, BP, Context))
+        return false;
+    }
 
     // Bail if the length is not affine.
     if (!isAffine(SE->getSCEVAtScope(cast<MemIntrinsic>(II).getLength(), L), L,