Record CodeGen optimization level in the BranchFolding pass so that we can
use it to control tail merging when there is a tradeoff between performance
and code size. When there is only 1 instruction in the common tail, we have
been merging. That can be good for code size but is a definite loss for
performance. Now we will avoid tail merging in that case when the
optimization level is "Aggressive", i.e., "-O3". Radar 7338114.
Since the IfConversion pass invokes BranchFolding, it too needs to know
the optimization level. Note that I removed the RegisterPass instantiation
for IfConversion because it required a default constructor. If someone
wants to keep that for some reason, we can add a default constructor with
a hard-wired optimization level.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85346 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/BranchFolding.h b/lib/CodeGen/BranchFolding.h
index 9763e33..5d35525 100644
--- a/lib/CodeGen/BranchFolding.h
+++ b/lib/CodeGen/BranchFolding.h
@@ -12,6 +12,7 @@
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/Target/TargetMachine.h"
#include <vector>
namespace llvm {
@@ -23,7 +24,7 @@
class BranchFolder {
public:
- explicit BranchFolder(bool defaultEnableTailMerge);
+ explicit BranchFolder(bool defaultEnableTailMerge, CodeGenOpt::Level OL);
bool OptimizeFunction(MachineFunction &MF,
const TargetInstrInfo *tii,
@@ -37,6 +38,7 @@
typedef std::pair<MPIterator, MachineBasicBlock::iterator> SameTailElt;
std::vector<SameTailElt> SameTails;
+ CodeGenOpt::Level OptLevel;
bool EnableTailMerge;
const TargetInstrInfo *TII;
const TargetRegisterInfo *TRI;
@@ -73,8 +75,10 @@
public BranchFolder {
public:
static char ID;
- explicit BranchFolderPass(bool defaultEnableTailMerge)
- : MachineFunctionPass(&ID), BranchFolder(defaultEnableTailMerge) {}
+ explicit BranchFolderPass(bool defaultEnableTailMerge,
+ CodeGenOpt::Level OptLevel)
+ : MachineFunctionPass(&ID),
+ BranchFolder(defaultEnableTailMerge, OptLevel) {}
virtual bool runOnMachineFunction(MachineFunction &MF);
virtual const char *getPassName() const { return "Control Flow Optimizer"; }