Allow getBlockFreq to return 0.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135742 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/BlockFrequency.h

@@ -40,11 +40,11 @@ public:
 
   bool runOnFunction(Function &F);
 
-  /// getblockFreq - Return block frequency. Never return 0, value must be
+  /// getblockFreq - Return block frequency. Return 0 if we don't have the
-  /// positive. Please note that initial frequency is equal to 1024. It means
+  /// information. Please note that initial frequency is equal to 1024. It means
   /// that we should not rely on the value itself, but only on the comparison to
-  /// the other block frequencies. We do this to avoid using of the floating
+  /// the other block frequencies. We do this to avoid using of floating points.
-  /// points.
+  ///
   uint32_t getBlockFreq(BasicBlock *BB);
 };
 

include/llvm/Analysis/BlockFrequencyImpl.h

@@ -314,13 +314,12 @@ class BlockFrequencyImpl {
   }
 
 public:
-  /// getBlockFreq - Return block frequency. Never return 0, value must be
+  /// getBlockFreq - Return block frequency. Return 0 if we don't have it.
-  /// positive.
   uint32_t getBlockFreq(BlockT *BB) const {
     typename DenseMap<BlockT *, uint32_t>::const_iterator I = Freqs.find(BB);
     if (I != Freqs.end())
-      return I->second ? I->second : 1;
+      return I->second;
-    return 1;
+    return 0;
   }
 
   void print(raw_ostream &OS) const {

include/llvm/CodeGen/MachineBlockFrequency.h

@@ -40,11 +40,11 @@ public:
 
   bool runOnMachineFunction(MachineFunction &F);
 
-  /// getblockFreq - Return block frequency. Never return 0, value must be
+  /// getblockFreq - Return block frequency. Return 0 if we don't have the
-  /// positive. Please note that initial frequency is equal to 1024. It means
+  /// information. Please note that initial frequency is equal to 1024. It means
   /// that we should not rely on the value itself, but only on the comparison to
-  /// the other block frequencies. We do this to avoid using of the floating
+  /// the other block frequencies. We do this to avoid using of floating points.
-  /// points.
+  ///
   uint32_t getBlockFreq(MachineBasicBlock *MBB);
 };
 

lib/Analysis/BlockFrequency.cpp

@@ -49,10 +49,10 @@ bool BlockFrequency::runOnFunction(Function &F) {
   return false;
 }
 
-/// getblockFreq - Return block frequency. Never return 0, value must be
+/// getblockFreq - Return block frequency. Return 0 if we don't have the
-/// positive. Please note that initial frequency is equal to 1024. It means that
+/// information. Please note that initial frequency is equal to 1024. It means
-/// we should not rely on the value itself, but only on the comparison to the
+/// that we should not rely on the value itself, but only on the comparison to
-/// other block frequencies. We do this to avoid using of floating points.
+/// the other block frequencies. We do this to avoid using of floating points.
 ///
 uint32_t BlockFrequency::getBlockFreq(BasicBlock *BB) {
   return BFI->getBlockFreq(BB);

lib/CodeGen/MachineBlockFrequency.cpp

@@ -50,10 +50,10 @@ bool MachineBlockFrequency::runOnMachineFunction(MachineFunction &F) {
   return false;
 }
 
-/// getblockFreq - Return block frequency. Never return 0, value must be
+/// getblockFreq - Return block frequency. Return 0 if we don't have the
-/// positive. Please note that initial frequency is equal to 1024. It means that
+/// information. Please note that initial frequency is equal to 1024. It means
-/// we should not rely on the value itself, but only on the comparison to the
+/// that we should not rely on the value itself, but only on the comparison to
-/// other block frequencies. We do this to avoid using of floating points.
+/// the other block frequencies. We do this to avoid using of floating points.
 ///
 uint32_t MachineBlockFrequency::getBlockFreq(MachineBasicBlock *MBB) {
   return MBFI->getBlockFreq(MBB);