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Branch folding may invalidate liveness.

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Branch folding can use a register scavenger to update liveness
information when required. Don't do that if liveness information is
already invalid.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153517 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2012-03-27 17:06:09 +00:00
parent 33fa614b16
commit 80799fbe3c
1 changed files with 8 additions and 1 deletions
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9
lib/CodeGen/BranchFolding.cpp
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@ -23,6 +23,7 @@
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
@ -183,8 +184,14 @@ bool BranchFolder::OptimizeFunction(MachineFunction &MF,
TII = tii;
TRI = tri;
MMI = mmi;
RS = NULL;
RS = TRI->requiresRegisterScavenging(MF) ? new RegScavenger() : NULL;
// Use a RegScavenger to help update liveness when required.
MachineRegisterInfo &MRI = MF.getRegInfo();
if (MRI.tracksLiveness() && TRI->requiresRegisterScavenging(MF))
RS = new RegScavenger();
else
MRI.invalidateLiveness();
// Fix CFG. The later algorithms expect it to be right.
bool MadeChange = false;