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.

llvm-svn: 123130

2 files changed, 9 insertions, 10 deletions

diff --git a/llvm/lib/CodeGen/RegAllocFast.cpp b/llvm/lib/CodeGen/RegAllocFast.cpp
index 109da42e9c3..6666d9aaf40 100644
--- a/llvm/lib/CodeGen/RegAllocFast.cpp
+++ b/llvm/lib/CodeGen/RegAllocFast.cpp
@@ -1024,8 +1024,7 @@ bool RAFast::runOnMachineFunction(MachineFunction &Fn) {
 
   // initialize the virtual->physical register map to have a 'null'
   // mapping for all virtual registers
-  unsigned LastVirtReg = MRI->getLastVirtReg();
-  StackSlotForVirtReg.grow(LastVirtReg);
+  StackSlotForVirtReg.resize(MRI->getNumVirtRegs());
 
   // Loop over all of the basic blocks, eliminating virtual register references
   for (MachineFunction::iterator MBBi = Fn.begin(), MBBe = Fn.end();
diff --git a/llvm/lib/CodeGen/VirtRegMap.cpp b/llvm/lib/CodeGen/VirtRegMap.cpp
index bc295ef30ca..df8a021d14a 100644
--- a/llvm/lib/CodeGen/VirtRegMap.cpp
+++ b/llvm/lib/CodeGen/VirtRegMap.cpp
@@ -88,14 +88,14 @@ bool VirtRegMap::runOnMachineFunction(MachineFunction &mf) {
 }
 
 void VirtRegMap::grow() {
-  unsigned LastVirtReg = MF->getRegInfo().getLastVirtReg();
-  Virt2PhysMap.grow(LastVirtReg);
-  Virt2StackSlotMap.grow(LastVirtReg);
-  Virt2ReMatIdMap.grow(LastVirtReg);
-  Virt2SplitMap.grow(LastVirtReg);
-  Virt2SplitKillMap.grow(LastVirtReg);
-  ReMatMap.grow(LastVirtReg);
-  ImplicitDefed.resize(MF->getRegInfo().getNumVirtRegs());
+  unsigned NumRegs = MF->getRegInfo().getNumVirtRegs();
+  Virt2PhysMap.resize(NumRegs);
+  Virt2StackSlotMap.resize(NumRegs);
+  Virt2ReMatIdMap.resize(NumRegs);
+  Virt2SplitMap.resize(NumRegs);
+  Virt2SplitKillMap.resize(NumRegs);
+  ReMatMap.resize(NumRegs);
+  ImplicitDefed.resize(NumRegs);
 }
 
 unsigned VirtRegMap::createSpillSlot(const TargetRegisterClass *RC) {