[ScheduleDAGInstrs] fix behavior of getUnderlyingObjectsForCodeGen when no identifiable object found

This patch fixes the bug introduced in https://reviews.llvm.org/D35907; the bug is reported by http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20171002/491452.html.

Before D35907, when GetUnderlyingObjects fails to find an identifiable object, allMMOsOkay lambda in getUnderlyingObjectsForInstr returns false and Objects vector is cleared. This behavior is unintentionally changed by D35907.

This patch makes the behavior for such case same as the previous behavior.
Since D35907 introduced a wrapper function getUnderlyingObjectsForCodeGen around GetUnderlyingObjects, getUnderlyingObjectsForCodeGen is modified to return a boolean value to ask the caller to clear the Objects vector.

Differential Revision: https://reviews.llvm.org/D38735

llvm-svn: 315565

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index e505b1cc5a1..d9e164500c3 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -3430,7 +3430,8 @@ static const Value *getUnderlyingObjectFromInt(const Value *V) {
 
 /// This is a wrapper around GetUnderlyingObjects and adds support for basic
 /// ptrtoint+arithmetic+inttoptr sequences.
-void llvm::getUnderlyingObjectsForCodeGen(const Value *V,
+/// It returns false if unidentified object is found in GetUnderlyingObjects.
+bool llvm::getUnderlyingObjectsForCodeGen(const Value *V,
                           SmallVectorImpl<Value *> &Objects,
                           const DataLayout &DL) {
   SmallPtrSet<const Value *, 16> Visited;
@@ -3456,11 +3457,12 @@ void llvm::getUnderlyingObjectsForCodeGen(const Value *V,
       // getUnderlyingObjectsForCodeGen also fails for safety.
       if (!isIdentifiedObject(V)) {
         Objects.clear();
-        return;
+        return false;
       }
       Objects.push_back(const_cast<Value *>(V));
     }
   } while (!Working.empty());
+  return true;
 }
 
 /// Return true if the only users of this pointer are lifetime markers.