MachineSink: Collect registers before clearing their killflags.
Currently whenever we sink any instruction, we do clearKillFlags for
every use of every use operand for that instruction, apparently there
are a lot of duplication, therefore compile time penalties.
This patch collect all the interested registers first, do clearKillFlags
for it all together at once at the end, so we only need to do
clearKillFlags once for one register, duplication is avoided.
Patch by Lawrence Hu!
Differential Revision: http://reviews.llvm.org/D9719
llvm-svn: 237510
diff --git a/llvm/lib/CodeGen/MachineSink.cpp b/llvm/lib/CodeGen/MachineSink.cpp
index 90ca25a..c35d6e0 100644
--- a/llvm/lib/CodeGen/MachineSink.cpp
+++ b/llvm/lib/CodeGen/MachineSink.cpp
@@ -19,6 +19,7 @@
#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/SparseBitVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
@@ -70,6 +71,8 @@
// will be split.
SetVector<std::pair<MachineBasicBlock*,MachineBasicBlock*> > ToSplit;
+ SparseBitVector<> RegsToClearKillFlags;
+
public:
static char ID; // Pass identification
MachineSinking() : MachineFunctionPass(ID) {
@@ -287,6 +290,12 @@
if (!MadeChange) break;
EverMadeChange = true;
}
+
+ // Now clear any kill flags for recorded registers.
+ for (auto I : RegsToClearKillFlags)
+ MRI->clearKillFlags(I);
+ RegsToClearKillFlags.clear();
+
return EverMadeChange;
}
@@ -761,7 +770,7 @@
// used registers.
for (MachineOperand &MO : MI->operands()) {
if (MO.isReg() && MO.isUse())
- MRI->clearKillFlags(MO.getReg());
+ RegsToClearKillFlags.set(MO.getReg()); // Remember to clear kill flags.
}
return true;