RegisterPressure: Hide non-const iterators of PressureDiff

It is too easy to accidentally violate the ordering requirements when
modifying the PressureDiff entries through iterators.

llvm-svn: 250590

2 files changed, 6 insertions, 4 deletions

diff --git a/llvm/include/llvm/CodeGen/RegisterPressure.h b/llvm/include/llvm/CodeGen/RegisterPressure.h
index c64087c5965..dd549da02c6 100644
--- a/llvm/include/llvm/CodeGen/RegisterPressure.h
+++ b/llvm/include/llvm/CodeGen/RegisterPressure.h
@@ -125,11 +125,13 @@ class PressureDiff {
   enum { MaxPSets = 16 };
 
   PressureChange PressureChanges[MaxPSets];
-public:
+
   typedef PressureChange* iterator;
+  iterator nonconst_begin() { return &PressureChanges[0]; }
+  iterator nonconst_end() { return &PressureChanges[MaxPSets]; }
+
+public:
   typedef const PressureChange* const_iterator;
-  iterator begin() { return &PressureChanges[0]; }
-  iterator end() { return &PressureChanges[MaxPSets]; }
   const_iterator begin() const { return &PressureChanges[0]; }
   const_iterator end() const { return &PressureChanges[MaxPSets]; }
 
diff --git a/llvm/lib/CodeGen/RegisterPressure.cpp b/llvm/lib/CodeGen/RegisterPressure.cpp
index 87c3d46866e..88566d88732 100644
--- a/llvm/lib/CodeGen/RegisterPressure.cpp
+++ b/llvm/lib/CodeGen/RegisterPressure.cpp
@@ -389,7 +389,7 @@ void PressureDiff::addPressureChange(unsigned RegUnit, bool IsDec,
   int Weight = IsDec ? -PSetI.getWeight() : PSetI.getWeight();
   for (; PSetI.isValid(); ++PSetI) {
     // Find an existing entry in the pressure diff for this PSet.
-    PressureDiff::iterator I = begin(), E = end();
+    PressureDiff::iterator I = nonconst_begin(), E = nonconst_end();
     for (; I != E && I->isValid(); ++I) {
       if (I->getPSet() >= *PSetI)
         break;