Remove MachineRegisterInfo::getLastVirtReg(), it was giving wrong results

when no virtual registers have been allocated.

It was only used to resize IndexedMaps, so provide an IndexedMap::resize()
method such that

 Map.grow(MRI.getLastVirtReg());

can be replaced with the simpler

 Map.resize(MRI.getNumVirtRegs());

This works correctly when no virtuals are allocated, and it bypasses the to/from
index conversions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123130 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 5 insertions, 7 deletions

diff --git a/include/llvm/ADT/IndexedMap.h b/include/llvm/ADT/IndexedMap.h
index 04c5815e35..87126ea491 100644
--- a/include/llvm/ADT/IndexedMap.h
+++ b/include/llvm/ADT/IndexedMap.h
@@ -59,6 +59,10 @@ namespace llvm {
       storage_.reserve(s);
     }
 
+    void resize(typename StorageT::size_type s) {
+      storage_.resize(s, nullVal_);
+    }
+
     void clear() {
       storage_.clear();
     }
@@ -66,7 +70,7 @@ namespace llvm {
     void grow(IndexT n) {
       unsigned NewSize = toIndex_(n) + 1;
       if (NewSize > storage_.size())
-        storage_.resize(NewSize, nullVal_);
+        resize(NewSize);
     }
 
     bool inBounds(IndexT n) const {
diff --git a/include/llvm/CodeGen/MachineRegisterInfo.h b/include/llvm/CodeGen/MachineRegisterInfo.h
index 02242b1fea..0ae1065351 100644
--- a/include/llvm/CodeGen/MachineRegisterInfo.h
+++ b/include/llvm/CodeGen/MachineRegisterInfo.h
@@ -216,12 +216,6 @@ public:
   ///
   unsigned getNumVirtRegs() const { return VRegInfo.size(); }
 
-  /// getLastVirtReg - Return the highest currently assigned virtual register.
-  ///
-  unsigned getLastVirtReg() const {
-    return TargetRegisterInfo::index2VirtReg(getNumVirtRegs() - 1);
-  }
-
   /// getRegClassVirtRegs - Return the list of virtual registers of the given
   /// target register class.
   const std::vector<unsigned> &