[ScheduleDAGInstrs] fix behavior of getUnderlyingObjectsForCodeGen when no identifiab...

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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315565 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/ValueTracking.h b/include/llvm/Analysis/ValueTracking.h
index 603b3a210b82cb3cd605cbe2d9760027dc3d507b..0afe22da1c8ae08197d0edce04657be7da23d2da 100644 (file)
--- a/include/llvm/Analysis/ValueTracking.h
+++ b/include/llvm/Analysis/ValueTracking.h
@@ -323,7 +323,7 @@ class Value;
 
   /// This is a wrapper around GetUnderlyingObjects and adds support for basic
   /// ptrtoint+arithmetic+inttoptr sequences.
-  void getUnderlyingObjectsForCodeGen(const Value *V,
+  bool getUnderlyingObjectsForCodeGen(const Value *V,
                             SmallVectorImpl<Value *> &Objects,
                             const DataLayout &DL);
 

diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index e505b1cc5a1cc1116d727d10fa1f2bfab865f6d4..d9e164500c30eea2bee52074c4d76bbf0994ff1a 100644 (file)
--- a/lib/Analysis/ValueTracking.cpp
+++ b/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.

diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp
index 08b785d742ad4809061c750cb3b6891c42951fad..be129b8766a347babac89098ea5aa84242c2808a 100644 (file)
--- a/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -121,9 +121,11 @@ ScheduleDAGInstrs::ScheduleDAGInstrs(MachineFunction &mf,
   SchedModel.init(ST.getSchedModel(), &ST, TII);
 }
 
-/// If this machine instr has memory reference information and it can be tracked
-/// to a normal reference to a known object, return the Value for that object.
-static void getUnderlyingObjectsForInstr(const MachineInstr *MI,
+/// If this machine instr has memory reference information and it can be
+/// tracked to a normal reference to a known object, return the Value
+/// for that object. This function returns false the memory location is
+/// unknown or may alias anything.
+static bool getUnderlyingObjectsForInstr(const MachineInstr *MI,
                                          const MachineFrameInfo &MFI,
                                          UnderlyingObjectsVector &Objects,
                                          const DataLayout &DL) {
@@ -151,7 +153,8 @@ static void getUnderlyingObjectsForInstr(const MachineInstr *MI,
         Objects.push_back(UnderlyingObjectsVector::value_type(PSV, MayAlias));
       } else if (const Value *V = MMO->getValue()) {
         SmallVector<Value *, 4> Objs;
-        getUnderlyingObjectsForCodeGen(V, Objs, DL);
+        if (!getUnderlyingObjectsForCodeGen(V, Objs, DL))
+          return false;
 
         for (Value *V : Objs) {
           assert(isIdentifiedObject(V));
@@ -163,8 +166,12 @@ static void getUnderlyingObjectsForInstr(const MachineInstr *MI,
     return true;
   };
 
-  if (!allMMOsOkay())
+  if (!allMMOsOkay()) {
     Objects.clear();
+    return false;
+  }
+
+  return true;
 }
 
 void ScheduleDAGInstrs::startBlock(MachineBasicBlock *bb) {
@@ -860,13 +867,13 @@ void ScheduleDAGInstrs::buildSchedGraph(AliasAnalysis *AA,
 
     // Find the underlying objects for MI. The Objs vector is either
     // empty, or filled with the Values of memory locations which this
-    // SU depends on. An empty vector means the memory location is
-    // unknown, and may alias anything.
+    // SU depends on.
     UnderlyingObjectsVector Objs;
-    getUnderlyingObjectsForInstr(&MI, MFI, Objs, MF.getDataLayout());
+    bool ObjsFound = getUnderlyingObjectsForInstr(&MI, MFI, Objs,
+                                                  MF.getDataLayout());
 
     if (MI.mayStore()) {
-      if (Objs.empty()) {
+      if (!ObjsFound) {
         // An unknown store depends on all stores and loads.
         addChainDependencies(SU, Stores);
         addChainDependencies(SU, NonAliasStores);
@@ -901,7 +908,7 @@ void ScheduleDAGInstrs::buildSchedGraph(AliasAnalysis *AA,
         addChainDependencies(SU, Stores, UnknownValue);
       }
     } else { // SU is a load.
-      if (Objs.empty()) {
+      if (!ObjsFound) {
         // An unknown load depends on all stores.
         addChainDependencies(SU, Stores);
         addChainDependencies(SU, NonAliasStores);