//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "phielim"
#include "llvm/CodeGen/LiveVariables.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
-#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Compiler.h"
#include <algorithm>
using namespace llvm;
+STATISTIC(NumAtomic, "Number of atomic phis lowered");
+//STATISTIC(NumSimple, "Number of simple phis lowered");
+
namespace {
- static Statistic<> NumAtomic("phielim", "Number of atomic phis lowered");
- static Statistic<> NumSimple("phielim", "Number of simple phis lowered");
-
struct VISIBILITY_HIDDEN PNE : public MachineFunctionPass {
+ static char ID; // Pass identification, replacement for typeid
+ PNE() : MachineFunctionPass((intptr_t)&ID) {}
+
bool runOnMachineFunction(MachineFunction &Fn) {
analyzePHINodes(Fn);
/// register which is used in a PHI node. We map that to the BB the
/// vreg is coming from. This is used later to determine when the vreg
/// is killed in the BB.
- ///
+ ///
void analyzePHINodes(const MachineFunction& Fn);
typedef std::pair<const MachineBasicBlock*, unsigned> BBVRegPair;
VRegPHIUse VRegPHIUseCount;
};
+ char PNE::ID = 0;
RegisterPass<PNE> X("phi-node-elimination",
"Eliminate PHI nodes for register allocation");
}
unsigned DestReg = MPhi->getOperand(0).getReg();
- // Create a new register for the incoming PHI arguments/
+ // Create a new register for the incoming PHI arguments.
MachineFunction &MF = *MBB.getParent();
const TargetRegisterClass *RC = MF.getSSARegMap()->getRegClass(DestReg);
unsigned IncomingReg = MF.getSSARegMap()->createVirtualRegister(RC);
// into the phi node destination.
//
const MRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
- RegInfo->copyRegToReg(MBB, AfterPHIsIt, DestReg, IncomingReg, RC);
+ RegInfo->copyRegToReg(MBB, AfterPHIsIt, DestReg, IncomingReg, RC, RC);
// Update live variable information if there is any...
LiveVariables *LV = getAnalysisToUpdate<LiveVariables>();
if (LV) {
MachineInstr *PHICopy = prior(AfterPHIsIt);
+ // Increment use count of the newly created virtual register.
+ LV->getVarInfo(IncomingReg).NumUses++;
+
// Add information to LiveVariables to know that the incoming value is
// killed. Note that because the value is defined in several places (once
// each for each incoming block), the "def" block and instruction fields
// Adjust the VRegPHIUseCount map to account for the removal of this PHI
// node.
- unsigned NumPreds = (MPhi->getNumOperands()-1)/2;
for (unsigned i = 1; i != MPhi->getNumOperands(); i += 2)
- VRegPHIUseCount[BBVRegPair(
- MPhi->getOperand(i + 1).getMachineBasicBlock(),
- MPhi->getOperand(i).getReg())] -= NumPreds;
+ --VRegPHIUseCount[BBVRegPair(
+ MPhi->getOperand(i + 1).getMachineBasicBlock(),
+ MPhi->getOperand(i).getReg())];
// Now loop over all of the incoming arguments, changing them to copy into
// the IncomingReg register in the corresponding predecessor basic block.
MachineBasicBlock::iterator I = opBlock.getFirstTerminator();
// Insert the copy.
- RegInfo->copyRegToReg(opBlock, I, IncomingReg, SrcReg, RC);
+ RegInfo->copyRegToReg(opBlock, I, IncomingReg, SrcReg, RC, RC);
// Now update live variable information if we have it. Otherwise we're done
if (!LV) continue;
//
// Is it used by any PHI instructions in this block?
- bool ValueIsLive =
- VRegPHIUseCount[BBVRegPair(
- MPhi->getOperand(i).getMachineBasicBlock(),
- SrcReg)] != 0;
+ bool ValueIsLive = VRegPHIUseCount[BBVRegPair(&opBlock, SrcReg)] != 0;
std::vector<MachineBasicBlock*> OpSuccBlocks;
/// particular, we want to map the number of uses of a virtual register which is
/// used in a PHI node. We map that to the BB the vreg is coming from. This is
/// used later to determine when the vreg is killed in the BB.
-///
+///
void PNE::analyzePHINodes(const MachineFunction& Fn) {
for (MachineFunction::const_iterator I = Fn.begin(), E = Fn.end();
I != E; ++I)
for (MachineBasicBlock::const_iterator BBI = I->begin(), BBE = I->end();
BBI != BBE && BBI->getOpcode() == TargetInstrInfo::PHI; ++BBI)
for (unsigned i = 1, e = BBI->getNumOperands(); i != e; i += 2)
- VRegPHIUseCount[BBVRegPair(
- BBI->getOperand(i + 1).getMachineBasicBlock(),
- BBI->getOperand(i).getReg())]++;
+ ++VRegPHIUseCount[BBVRegPair(
+ BBI->getOperand(i + 1).getMachineBasicBlock(),
+ BBI->getOperand(i).getReg())];
}