[llvm-commits] CVS: llvm/lib/CodeGen/RegAllocBigBlock.cpp
Duraid Madina
duraid at octopus.com.au
Mon Jun 25 16:47:36 PDT 2007
Changes in directory llvm/lib/CodeGen:
RegAllocBigBlock.cpp updated: 1.1 -> 1.2
---
Log message:
A bunch of fixes to the BigBlock allocator improve compile-time by ~20%
and code quality by ~2% on my tests.
A big thank you to Roman Levenstein for this patch! See
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20070618/050717.html
for more details.
---
Diffs of the changes: (+65 -72)
RegAllocBigBlock.cpp | 137 ++++++++++++++++++++++++---------------------------
1 files changed, 65 insertions(+), 72 deletions(-)
Index: llvm/lib/CodeGen/RegAllocBigBlock.cpp
diff -u llvm/lib/CodeGen/RegAllocBigBlock.cpp:1.1 llvm/lib/CodeGen/RegAllocBigBlock.cpp:1.2
--- llvm/lib/CodeGen/RegAllocBigBlock.cpp:1.1 Fri Jun 22 03:27:12 2007
+++ llvm/lib/CodeGen/RegAllocBigBlock.cpp Mon Jun 25 18:46:54 2007
@@ -40,6 +40,7 @@
#include "llvm/ADT/IndexedMap.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include <algorithm>
using namespace llvm;
@@ -69,15 +70,17 @@
const MRegisterInfo *RegInfo;
LiveVariables *LV;
- // InsnTimes - maps machine instructions to their "execute times"
- std::map<MachineInstr *, unsigned> InsnTimes;
-
// VRegReadTable - maps VRegs in a BB to the set of times they are read
- DenseMap<unsigned, SmallVector<unsigned, 2>*, VRegKeyInfo> VRegReadTable;
+ // This is a sorted list
+ typedef SmallVector<unsigned, 2> VRegTimes;
+
+ DenseMap<unsigned, VRegTimes*, VRegKeyInfo> VRegReadTable;
+ DenseMap<unsigned, unsigned , VRegKeyInfo> VRegReadIdx;
// StackSlotForVirtReg - Maps virtual regs to the frame index where these
// values are spilled.
- std::map<unsigned, int> StackSlotForVirtReg;
+ //DenseMap<unsigned, int, VRegKeyInf> StackSlotForVirtReg;
+ IndexedMap<unsigned, VirtReg2IndexFunctor> StackSlotForVirtReg;
// Virt2PhysRegMap - This map contains entries for each virtual register
// that is currently available in a physical register.
@@ -87,6 +90,11 @@
return Virt2PhysRegMap[VirtReg];
}
+ unsigned &getVirt2StackSlot(unsigned VirtReg) {
+ return StackSlotForVirtReg[VirtReg];
+ }
+
+
// PhysRegsUsed - This array is effectively a map, containing entries for
// each physical register that currently has a value (ie, it is in
// Virt2PhysRegMap). The value mapped to is the virtual register
@@ -98,22 +106,19 @@
//
std::vector<int> PhysRegsUsed;
- // PhysRegsUseOrder - This contains a list of the physical registers that
- // currently have a virtual register value in them. This list provides an
- // ordering of registers, imposing a reallocation order. This list is only
- // used if all registers are allocated and we have to spill one, in which
- // case we spill the least recently used register. Entries at the front of
- // the list are the least recently used registers, entries at the back are
- // the most recently used.
- //
- std::vector<unsigned> PhysRegsUseOrder;
// VirtRegModified - This bitset contains information about which virtual
// registers need to be spilled back to memory when their registers are
// scavenged. If a virtual register has simply been rematerialized, there
// is no reason to spill it to memory when we need the register back.
//
- std::vector<bool> VirtRegModified;
+ std::vector<int> VirtRegModified;
+
+ // MBBLastInsnTime - the number of the the last instruction in MBB
+ int MBBLastInsnTime;
+
+ // MBBCurTime - the number of the the instruction being currently processed
+ int MBBCurTime;
void markVirtRegModified(unsigned Reg, bool Val = true) {
assert(MRegisterInfo::isVirtualRegister(Reg) && "Illegal VirtReg!");
@@ -129,21 +134,6 @@
return VirtRegModified[Reg - MRegisterInfo::FirstVirtualRegister];
}
- void MarkPhysRegRecentlyUsed(unsigned Reg) {
- if (PhysRegsUseOrder.empty() ||
- PhysRegsUseOrder.back() == Reg) return; // Already most recently used
-
- for (unsigned i = PhysRegsUseOrder.size(); i != 0; --i)
- if (areRegsEqual(Reg, PhysRegsUseOrder[i-1])) {
- unsigned RegMatch = PhysRegsUseOrder[i-1]; // remove from middle
- PhysRegsUseOrder.erase(PhysRegsUseOrder.begin()+i-1);
- // Add it to the end of the list
- PhysRegsUseOrder.push_back(RegMatch);
- if (RegMatch == Reg)
- return; // Found an exact match, exit early
- }
- }
-
public:
virtual const char *getPassName() const {
return "BigBlock Register Allocator";
@@ -256,17 +246,17 @@
/// to be held on the stack.
int RABigBlock::getStackSpaceFor(unsigned VirtReg, const TargetRegisterClass *RC) {
// Find the location Reg would belong...
- std::map<unsigned, int>::iterator I =StackSlotForVirtReg.lower_bound(VirtReg);
+ int FrameIdx = getVirt2StackSlot(VirtReg);
- if (I != StackSlotForVirtReg.end() && I->first == VirtReg)
- return I->second; // Already has space allocated?
+ if (FrameIdx)
+ return FrameIdx - 1; // Already has space allocated?
// Allocate a new stack object for this spill location...
- int FrameIdx = MF->getFrameInfo()->CreateStackObject(RC->getSize(),
+ FrameIdx = MF->getFrameInfo()->CreateStackObject(RC->getSize(),
RC->getAlignment());
// Assign the slot...
- StackSlotForVirtReg.insert(I, std::make_pair(VirtReg, FrameIdx));
+ getVirt2StackSlot(VirtReg) = FrameIdx + 1;
return FrameIdx;
}
@@ -276,11 +266,6 @@
///
void RABigBlock::removePhysReg(unsigned PhysReg) {
PhysRegsUsed[PhysReg] = -1; // PhyReg no longer used
-
- std::vector<unsigned>::iterator It =
- std::find(PhysRegsUseOrder.begin(), PhysRegsUseOrder.end(), PhysReg);
- if (It != PhysRegsUseOrder.end())
- PhysRegsUseOrder.erase(It);
}
@@ -362,7 +347,6 @@
// it holds VirtReg.
PhysRegsUsed[PhysReg] = VirtReg;
getVirt2PhysRegMapSlot(VirtReg) = PhysReg;
- PhysRegsUseOrder.push_back(PhysReg); // New use of PhysReg
}
@@ -426,9 +410,9 @@
// read at the most distant point in time.
if (PhysReg == 0) {
unsigned delay=0, longest_delay=0;
- SmallVector<unsigned, 2> *ReadTimes;
+ VRegTimes* ReadTimes;
- unsigned curTime = InsnTimes[I];
+ unsigned curTime = MBBCurTime;
// for all physical regs in the RC,
for(TargetRegisterClass::iterator pReg = RC->begin();
@@ -436,11 +420,23 @@
// how long until they're read?
if(PhysRegsUsed[*pReg]>0) { // ignore non-allocatable regs
ReadTimes = VRegReadTable[PhysRegsUsed[*pReg]];
- SmallVector<unsigned, 2>::iterator pt =
- std::lower_bound(ReadTimes->begin(),
- ReadTimes->end(),
- curTime);
- delay = *pt - curTime;
+ if(ReadTimes && !ReadTimes->empty()) {
+ unsigned& pt = VRegReadIdx[PhysRegsUsed[*pReg]];
+ while(pt < ReadTimes->size() && (*ReadTimes)[pt] < curTime) {
+ ++pt;
+ }
+
+ if(pt < ReadTimes->size())
+ delay = (*ReadTimes)[pt] - curTime;
+ else
+ delay = MBBLastInsnTime + 1 - curTime;
+ } else {
+ // This register is only defined, but never
+ // read in this MBB. Therefore the next read
+ // happens after the end of this MBB
+ delay = MBBLastInsnTime + 1 - curTime;
+ }
+
if(delay > longest_delay) {
longest_delay = delay;
@@ -533,25 +529,34 @@
for(ReadTime=0, MII = MBB.begin(); MII != MBB.end(); ++ReadTime, ++MII) {
MachineInstr *MI = MII;
- InsnTimes[MI] = ReadTime;
-
for (unsigned i = 0; i != MI->getNumOperands(); ++i) {
MachineOperand& MO = MI->getOperand(i);
// look for vreg reads..
if (MO.isRegister() && !MO.isDef() && MO.getReg() &&
MRegisterInfo::isVirtualRegister(MO.getReg())) {
- // ..and add them to the read table.
- if(!VRegReadTable[MO.getReg()])
- VRegReadTable[MO.getReg()] = new SmallVector<unsigned, 2>;
-
- VRegReadTable[MO.getReg()]->push_back(ReadTime);
+ // ..and add them to the read table.
+ VRegTimes* &Times = VRegReadTable[MO.getReg()];
+ if(!VRegReadTable[MO.getReg()]) {
+ Times = new VRegTimes;
+ VRegReadIdx[MO.getReg()] = 0;
+ }
+ Times->push_back(ReadTime);
}
}
}
+ MBBLastInsnTime = ReadTime;
+
+ for(DenseMap<unsigned, VRegTimes*, VRegKeyInfo>::iterator Reads = VRegReadTable.begin();
+ Reads != VRegReadTable.end(); ++Reads) {
+ if(Reads->second) {
+ DOUT << "Reads[" << Reads->first << "]=" << Reads->second->size() << "\n";
+ }
+ }
}
+
void RABigBlock::AllocateBasicBlock(MachineBasicBlock &MBB) {
// loop over each instruction
MachineBasicBlock::iterator MII = MBB.begin();
@@ -568,11 +573,9 @@
unsigned Reg = I->first;
MF->setPhysRegUsed(Reg);
PhysRegsUsed[Reg] = 0; // It is free and reserved now
- PhysRegsUseOrder.push_back(Reg);
for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
*AliasSet; ++AliasSet) {
if (PhysRegsUsed[*AliasSet] != -2) {
- PhysRegsUseOrder.push_back(*AliasSet);
PhysRegsUsed[*AliasSet] = 0; // It is free and reserved now
MF->setPhysRegUsed(*AliasSet);
}
@@ -581,10 +584,12 @@
}
// Otherwise, sequentially allocate each instruction in the MBB.
+ MBBCurTime = -1;
while (MII != MBB.end()) {
MachineInstr *MI = MII++;
+ MBBCurTime++;
const TargetInstrDescriptor &TID = TII.get(MI->getOpcode());
- DEBUG(DOUT << "\nStarting RegAlloc of: " << *MI;
+ DEBUG(DOUT << "\nTime=" << MBBCurTime << " Starting RegAlloc of: " << *MI;
DOUT << " Regs have values: ";
for (unsigned i = 0; i != RegInfo->getNumRegs(); ++i)
if (PhysRegsUsed[i] != -1 && PhysRegsUsed[i] != -2)
@@ -592,14 +597,6 @@
<< ",%reg" << PhysRegsUsed[i] << "] ";
DOUT << "\n");
- // Loop over the implicit uses, making sure that they are at the head of the
- // use order list, so they don't get reallocated.
- if (TID.ImplicitUses) {
- for (const unsigned *ImplicitUses = TID.ImplicitUses;
- *ImplicitUses; ++ImplicitUses)
- MarkPhysRegRecentlyUsed(*ImplicitUses);
- }
-
SmallVector<unsigned, 8> Kills;
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand& MO = MI->getOperand(i);
@@ -667,11 +664,9 @@
MF->setPhysRegUsed(Reg);
spillPhysReg(MBB, MI, Reg, true); // Spill any existing value in reg
PhysRegsUsed[Reg] = 0; // It is free and reserved now
- PhysRegsUseOrder.push_back(Reg);
for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
*AliasSet; ++AliasSet) {
if (PhysRegsUsed[*AliasSet] != -2) {
- PhysRegsUseOrder.push_back(*AliasSet);
PhysRegsUsed[*AliasSet] = 0; // It is free and reserved now
MF->setPhysRegUsed(*AliasSet);
}
@@ -687,7 +682,6 @@
bool IsNonAllocatable = PhysRegsUsed[Reg] == -2;
if (!IsNonAllocatable) {
spillPhysReg(MBB, MI, Reg, true);
- PhysRegsUseOrder.push_back(Reg);
PhysRegsUsed[Reg] = 0; // It is free and reserved now
}
MF->setPhysRegUsed(Reg);
@@ -696,7 +690,6 @@
*AliasSet; ++AliasSet) {
if (PhysRegsUsed[*AliasSet] != -2) {
if (!IsNonAllocatable) {
- PhysRegsUseOrder.push_back(*AliasSet);
PhysRegsUsed[*AliasSet] = 0; // It is free and reserved now
}
MF->setPhysRegUsed(*AliasSet);
@@ -800,7 +793,6 @@
// Clear any physical register which appear live at the end of the basic
// block, but which do not hold any virtual registers. e.g., the stack
// pointer.
- PhysRegsUseOrder.clear();
}
/// runOnMachineFunction - Register allocate the whole function
@@ -827,6 +819,8 @@
// initialize the virtual->physical register map to have a 'null'
// mapping for all virtual registers
Virt2PhysRegMap.grow(MF->getSSARegMap()->getLastVirtReg());
+ StackSlotForVirtReg.grow(MF->getSSARegMap()->getLastVirtReg());
+ VirtRegModified.resize(MF->getSSARegMap()->getLastVirtReg() - MRegisterInfo::FirstVirtualRegister + 1,0);
// Loop over all of the basic blocks, eliminating virtual register references
for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end();
@@ -849,4 +843,3 @@
FunctionPass *llvm::createBigBlockRegisterAllocator() {
return new RABigBlock();
}
-
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