#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Statistic.h"
using namespace llvm;
-STATISTIC(NumCPEs, "Number of constpool entries");
-STATISTIC(NumSplit, "Number of uncond branches inserted");
-STATISTIC(NumCBrFixed, "Number of cond branches fixed");
-STATISTIC(NumUBrFixed, "Number of uncond branches fixed");
-STATISTIC(NumTBs, "Number of table branches generated");
+STATISTIC(NumCPEs, "Number of constpool entries");
+STATISTIC(NumSplit, "Number of uncond branches inserted");
+STATISTIC(NumCBrFixed, "Number of cond branches fixed");
+STATISTIC(NumUBrFixed, "Number of uncond branches fixed");
+STATISTIC(NumTBs, "Number of table branches generated");
+STATISTIC(NumT2CPShrunk, "Number of Thumb2 constantpool instructions shrunk");
+STATISTIC(NumT2BrShrunk, "Number of Thumb2 immediate branches shrunk");
namespace {
/// ARMConstantIslands - Due to limited PC-relative displacements, ARM
/// to a return, unreachable, or unconditional branch).
std::vector<MachineBasicBlock*> WaterList;
+ typedef std::vector<MachineBasicBlock*>::iterator water_iterator;
+
/// CPUser - One user of a constant pool, keeping the machine instruction
/// pointer, the constant pool being referenced, and the max displacement
/// allowed from the instruction to the CP.
bool LookForWater(CPUser&U, unsigned UserOffset,
MachineBasicBlock** NewMBB);
MachineBasicBlock* AcceptWater(MachineBasicBlock *WaterBB,
- std::vector<MachineBasicBlock*>::iterator IP);
+ water_iterator IP);
void CreateNewWater(unsigned CPUserIndex, unsigned UserOffset,
MachineBasicBlock** NewMBB);
bool HandleConstantPoolUser(MachineFunction &MF, unsigned CPUserIndex);
bool FixUpConditionalBr(MachineFunction &MF, ImmBranch &Br);
bool FixUpUnconditionalBr(MachineFunction &MF, ImmBranch &Br);
bool UndoLRSpillRestore();
+ bool OptimizeThumb2Instructions(MachineFunction &MF);
+ bool OptimizeThumb2Branches(MachineFunction &MF);
bool OptimizeThumb2JumpTables(MachineFunction &MF);
unsigned GetOffsetOf(MachineInstr *MI) const;
/// print block size and offset information - debugging
void ARMConstantIslands::dumpBBs() {
for (unsigned J = 0, E = BBOffsets.size(); J !=E; ++J) {
- DOUT << "block " << J << " offset " << BBOffsets[J] <<
- " size " << BBSizes[J] << "\n";
+ DEBUG(errs() << "block " << J << " offset " << BBOffsets[J]
+ << " size " << BBSizes[J] << "\n");
}
}
MadeChange = true;
}
- // Let's see if we can use tbb / tbh to do jump tables.
- MadeChange |= OptimizeThumb2JumpTables(MF);
+ // Shrink 32-bit Thumb2 branch, load, and store instructions.
+ if (isThumb2)
+ MadeChange |= OptimizeThumb2Instructions(MF);
// After a while, this might be made debug-only, but it is not expensive.
verify(MF);
CPEs.push_back(CPEntry(CPEMI, i));
CPEntries.push_back(CPEs);
NumCPEs++;
- DOUT << "Moved CPI#" << i << " to end of function as #" << i << "\n";
+ DEBUG(errs() << "Moved CPI#" << i << " to end of function as #" << i
+ << "\n");
}
}
bool NegOk = false;
bool IsSoImm = false;
- // FIXME: Temporary workaround until I can figure out what's going on.
- unsigned Slack = T2JumpTables.empty() ? 0 : 4;
switch (Opc) {
default:
llvm_unreachable("Unknown addressing mode for CP reference!");
// Remember that this is a user of a CP entry.
unsigned CPI = I->getOperand(op).getIndex();
MachineInstr *CPEMI = CPEMIs[CPI];
- unsigned MaxOffs = ((1 << Bits)-1) * Scale - Slack;
+ unsigned MaxOffs = ((1 << Bits)-1) * Scale;
CPUsers.push_back(CPUser(I, CPEMI, MaxOffs, NegOk, IsSoImm));
// Increment corresponding CPEntry reference count.
// Next, update WaterList. Specifically, we need to add NewMBB as having
// available water after it.
- std::vector<MachineBasicBlock*>::iterator IP =
+ water_iterator IP =
std::lower_bound(WaterList.begin(), WaterList.end(), NewBB,
CompareMBBNumbers);
WaterList.insert(IP, NewBB);
// available water after it (but not if it's already there, which happens
// when splitting before a conditional branch that is followed by an
// unconditional branch - in that case we want to insert NewBB).
- std::vector<MachineBasicBlock*>::iterator IP =
+ water_iterator IP =
std::lower_bound(WaterList.begin(), WaterList.end(), OrigBB,
CompareMBBNumbers);
MachineBasicBlock* WaterBB = *IP;
// purposes of the displacement computation; compensate for that here.
// Effectively, the valid range of displacements is 2 bytes smaller for such
// references.
- if (isThumb && UserOffset%4 !=0)
+ unsigned TotalAdj = 0;
+ if (isThumb && UserOffset%4 !=0) {
UserOffset -= 2;
+ TotalAdj = 2;
+ }
// CPEs will be rounded up to a multiple of 4.
- if (isThumb && TrialOffset%4 != 0)
+ if (isThumb && TrialOffset%4 != 0) {
TrialOffset += 2;
+ TotalAdj += 2;
+ }
+
+ // In Thumb2 mode, later branch adjustments can shift instructions up and
+ // cause alignment change. In the worst case scenario this can cause the
+ // user's effective address to be subtracted by 2 and the CPE's address to
+ // be plus 2.
+ if (isThumb2 && TotalAdj != 4)
+ MaxDisp -= (4 - TotalAdj);
if (UserOffset <= TrialOffset) {
// User before the Trial.
assert(CPEOffset%4 == 0 && "Misaligned CPE");
if (DoDump) {
- DOUT << "User of CPE#" << CPEMI->getOperand(0).getImm()
- << " max delta=" << MaxDisp
- << " insn address=" << UserOffset
- << " CPE address=" << CPEOffset
- << " offset=" << int(CPEOffset-UserOffset) << "\t" << *MI;
+ DEBUG(errs() << "User of CPE#" << CPEMI->getOperand(0).getImm()
+ << " max delta=" << MaxDisp
+ << " insn address=" << UserOffset
+ << " CPE address=" << CPEOffset
+ << " offset=" << int(CPEOffset-UserOffset) << "\t" << *MI);
}
return OffsetIsInRange(UserOffset, CPEOffset, MaxDisp, NegOk);
// Check to see if the CPE is already in-range.
if (CPEIsInRange(UserMI, UserOffset, CPEMI, U.MaxDisp, U.NegOk, true)) {
- DOUT << "In range\n";
+ DEBUG(errs() << "In range\n");
return 1;
}
if (CPEs[i].CPEMI == NULL)
continue;
if (CPEIsInRange(UserMI, UserOffset, CPEs[i].CPEMI, U.MaxDisp, U.NegOk)) {
- DOUT << "Replacing CPE#" << CPI << " with CPE#" << CPEs[i].CPI << "\n";
+ DEBUG(errs() << "Replacing CPE#" << CPI << " with CPE#"
+ << CPEs[i].CPI << "\n");
// Point the CPUser node to the replacement
U.CPEMI = CPEs[i].CPEMI;
// Change the CPI in the instruction operand to refer to the clone.
/// AcceptWater - Small amount of common code factored out of the following.
MachineBasicBlock* ARMConstantIslands::AcceptWater(MachineBasicBlock *WaterBB,
- std::vector<MachineBasicBlock*>::iterator IP) {
- DOUT << "found water in range\n";
+ water_iterator IP) {
+ DEBUG(errs() << "found water in range\n");
// Remove the original WaterList entry; we want subsequent
// insertions in this vicinity to go after the one we're
// about to insert. This considerably reduces the number
/// group, prefer the water that's farthest away.
bool ARMConstantIslands::LookForWater(CPUser &U, unsigned UserOffset,
MachineBasicBlock** NewMBB) {
- std::vector<MachineBasicBlock*>::iterator IPThatWouldPad;
+ water_iterator IPThatWouldPad;
MachineBasicBlock* WaterBBThatWouldPad = NULL;
if (!WaterList.empty()) {
- for (std::vector<MachineBasicBlock*>::iterator IP = prior(WaterList.end()),
+ for (water_iterator IP = prior(WaterList.end()),
B = WaterList.begin();; --IP) {
MachineBasicBlock* WaterBB = *IP;
if (WaterIsInRange(UserOffset, WaterBB, U)) {
if (&UserMBB->back() == UserMI ||
OffsetIsInRange(UserOffset, OffsetOfNextBlock + (isThumb1 ? 2: 4),
U.MaxDisp, U.NegOk, U.IsSoImm)) {
- DOUT << "Split at end of block\n";
+ DEBUG(errs() << "Split at end of block\n");
if (&UserMBB->back() == UserMI)
assert(BBHasFallthrough(UserMBB) && "Expected a fallthrough BB!");
*NewMBB = next(MachineFunction::iterator(UserMBB));
CPUIndex++;
}
}
- DOUT << "Split in middle of big block\n";
+ DEBUG(errs() << "Split in middle of big block\n");
*NewMBB = SplitBlockBeforeInstr(prior(MI));
}
}
unsigned Size = CPEMI->getOperand(2).getImm();
MachineBasicBlock *NewMBB;
// Compute this only once, it's expensive. The 4 or 8 is the value the
- // hardware keeps in the PC (2 insns ahead of the reference).
+ // hardware keeps in the PC.
unsigned UserOffset = GetOffsetOf(UserMI) + (isThumb ? 4 : 8);
// See if the current entry is within range, or there is a clone of it
if (!LookForWater(U, UserOffset, &NewMBB)) {
// No water found.
- DOUT << "No water found\n";
+ DEBUG(errs() << "No water found\n");
CreateNewWater(CPUserIndex, UserOffset, &NewMBB);
}
break;
}
- DOUT << " Moved CPE to #" << ID << " CPI=" << CPI << "\t" << *UserMI;
+ DEBUG(errs() << " Moved CPE to #" << ID << " CPI=" << CPI
+ << '\t' << *UserMI);
return true;
}
unsigned BrOffset = GetOffsetOf(MI) + PCAdj;
unsigned DestOffset = BBOffsets[DestBB->getNumber()];
- DOUT << "Branch of destination BB#" << DestBB->getNumber()
- << " from BB#" << MI->getParent()->getNumber()
- << " max delta=" << MaxDisp
- << " from " << GetOffsetOf(MI) << " to " << DestOffset
- << " offset " << int(DestOffset-BrOffset) << "\t" << *MI;
+ DEBUG(errs() << "Branch of destination BB#" << DestBB->getNumber()
+ << " from BB#" << MI->getParent()->getNumber()
+ << " max delta=" << MaxDisp
+ << " from " << GetOffsetOf(MI) << " to " << DestOffset
+ << " offset " << int(DestOffset-BrOffset) << "\t" << *MI);
if (BrOffset <= DestOffset) {
// Branch before the Dest.
HasFarJump = true;
NumUBrFixed++;
- DOUT << " Changed B to long jump " << *MI;
+ DEBUG(errs() << " Changed B to long jump " << *MI);
return true;
}
// b L1
MachineBasicBlock *NewDest = BMI->getOperand(0).getMBB();
if (BBIsInRange(MI, NewDest, Br.MaxDisp)) {
- DOUT << " Invert Bcc condition and swap its destination with " << *BMI;
+ DEBUG(errs() << " Invert Bcc condition and swap its destination with "
+ << *BMI);
BMI->getOperand(0).setMBB(DestBB);
MI->getOperand(0).setMBB(NewDest);
MI->getOperand(1).setImm(CC);
}
MachineBasicBlock *NextBB = next(MachineFunction::iterator(MBB));
- DOUT << " Insert B to BB#" << DestBB->getNumber()
- << " also invert condition and change dest. to BB#"
- << NextBB->getNumber() << "\n";
+ DEBUG(errs() << " Insert B to BB#" << DestBB->getNumber()
+ << " also invert condition and change dest. to BB#"
+ << NextBB->getNumber() << "\n");
// Insert a new conditional branch and a new unconditional branch.
// Also update the ImmBranch as well as adding a new entry for the new branch.
bool MadeChange = false;
for (unsigned i = 0, e = PushPopMIs.size(); i != e; ++i) {
MachineInstr *MI = PushPopMIs[i];
+ // First two operands are predicates, the third is a zero since there
+ // is no writeback.
if (MI->getOpcode() == ARM::tPOP_RET &&
- MI->getOperand(2).getReg() == ARM::PC &&
- MI->getNumExplicitOperands() == 3) {
+ MI->getOperand(3).getReg() == ARM::PC &&
+ MI->getNumExplicitOperands() == 4) {
BuildMI(MI->getParent(), MI->getDebugLoc(), TII->get(ARM::tBX_RET));
MI->eraseFromParent();
MadeChange = true;
return MadeChange;
}
+bool ARMConstantIslands::OptimizeThumb2Instructions(MachineFunction &MF) {
+ bool MadeChange = false;
+
+ // Shrink ADR and LDR from constantpool.
+ for (unsigned i = 0, e = CPUsers.size(); i != e; ++i) {
+ CPUser &U = CPUsers[i];
+ unsigned Opcode = U.MI->getOpcode();
+ unsigned NewOpc = 0;
+ unsigned Scale = 1;
+ unsigned Bits = 0;
+ switch (Opcode) {
+ default: break;
+ case ARM::t2LEApcrel:
+ if (isARMLowRegister(U.MI->getOperand(0).getReg())) {
+ NewOpc = ARM::tLEApcrel;
+ Bits = 8;
+ Scale = 4;
+ }
+ break;
+ case ARM::t2LDRpci:
+ if (isARMLowRegister(U.MI->getOperand(0).getReg())) {
+ NewOpc = ARM::tLDRpci;
+ Bits = 8;
+ Scale = 4;
+ }
+ break;
+ }
+
+ if (!NewOpc)
+ continue;
+
+ unsigned UserOffset = GetOffsetOf(U.MI) + 4;
+ unsigned MaxOffs = ((1 << Bits) - 1) * Scale;
+ // FIXME: Check if offset is multiple of scale if scale is not 4.
+ if (CPEIsInRange(U.MI, UserOffset, U.CPEMI, MaxOffs, false, true)) {
+ U.MI->setDesc(TII->get(NewOpc));
+ MachineBasicBlock *MBB = U.MI->getParent();
+ BBSizes[MBB->getNumber()] -= 2;
+ AdjustBBOffsetsAfter(MBB, -2);
+ ++NumT2CPShrunk;
+ MadeChange = true;
+ }
+ }
+
+ MadeChange |= OptimizeThumb2Branches(MF);
+ MadeChange |= OptimizeThumb2JumpTables(MF);
+ return MadeChange;
+}
+
+bool ARMConstantIslands::OptimizeThumb2Branches(MachineFunction &MF) {
+ bool MadeChange = false;
+
+ for (unsigned i = 0, e = ImmBranches.size(); i != e; ++i) {
+ ImmBranch &Br = ImmBranches[i];
+ unsigned Opcode = Br.MI->getOpcode();
+ unsigned NewOpc = 0;
+ unsigned Scale = 1;
+ unsigned Bits = 0;
+ switch (Opcode) {
+ default: break;
+ case ARM::t2B:
+ NewOpc = ARM::tB;
+ Bits = 11;
+ Scale = 2;
+ break;
+ case ARM::t2Bcc:
+ NewOpc = ARM::tBcc;
+ Bits = 8;
+ Scale = 2;
+ break;
+ }
+ if (!NewOpc)
+ continue;
+
+ unsigned MaxOffs = ((1 << (Bits-1))-1) * Scale;
+ MachineBasicBlock *DestBB = Br.MI->getOperand(0).getMBB();
+ if (BBIsInRange(Br.MI, DestBB, MaxOffs)) {
+ Br.MI->setDesc(TII->get(NewOpc));
+ MachineBasicBlock *MBB = Br.MI->getParent();
+ BBSizes[MBB->getNumber()] -= 2;
+ AdjustBBOffsetsAfter(MBB, -2);
+ ++NumT2BrShrunk;
+ MadeChange = true;
+ }
+ }
+
+ return MadeChange;
+}
+
+
+/// OptimizeThumb2JumpTables - Use tbb / tbh instructions to generate smaller
+/// jumptables when it's possible.
bool ARMConstantIslands::OptimizeThumb2JumpTables(MachineFunction &MF) {
bool MadeChange = false;
if (!OptOk)
continue;
- // The previous instruction should be a t2LEApcrelJT, we want to delete
- // it as well.
+ // The previous instruction should be a tLEApcrel or t2LEApcrelJT, we want
+ // to delete it as well.
MachineInstr *LeaMI = --PrevI;
- if (LeaMI->getOpcode() != ARM::t2LEApcrelJT ||
+ if ((LeaMI->getOpcode() != ARM::tLEApcrelJT &&
+ LeaMI->getOpcode() != ARM::t2LEApcrelJT) ||
LeaMI->getOperand(0).getReg() != BaseReg)
OptOk = false;
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