#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/Compiler.h"
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");
namespace {
/// ARMConstantIslands - Due to limited PC-relative displacements, ARM
///
SmallVector<MachineInstr*, 4> PushPopMIs;
+ /// T2JumpTables - Keep track of all the Thumb2 jumptable instructions.
+ SmallVector<MachineInstr*, 4> T2JumpTables;
+
/// HasFarJump - True if any far jump instruction has been emitted during
/// the branch fix up pass.
bool HasFarJump;
static char ID;
ARMConstantIslands() : MachineFunctionPass(&ID) {}
- virtual bool runOnMachineFunction(MachineFunction &Fn);
+ virtual bool runOnMachineFunction(MachineFunction &MF);
virtual const char *getPassName() const {
return "ARM constant island placement and branch shortening pass";
}
private:
- void DoInitialPlacement(MachineFunction &Fn,
+ void DoInitialPlacement(MachineFunction &MF,
std::vector<MachineInstr*> &CPEMIs);
CPEntry *findConstPoolEntry(unsigned CPI, const MachineInstr *CPEMI);
- void InitialFunctionScan(MachineFunction &Fn,
+ void InitialFunctionScan(MachineFunction &MF,
const std::vector<MachineInstr*> &CPEMIs);
MachineBasicBlock *SplitBlockBeforeInstr(MachineInstr *MI);
void UpdateForInsertedWaterBlock(MachineBasicBlock *NewBB);
std::vector<MachineBasicBlock*>::iterator IP);
void CreateNewWater(unsigned CPUserIndex, unsigned UserOffset,
MachineBasicBlock** NewMBB);
- bool HandleConstantPoolUser(MachineFunction &Fn, unsigned CPUserIndex);
+ bool HandleConstantPoolUser(MachineFunction &MF, unsigned CPUserIndex);
void RemoveDeadCPEMI(MachineInstr *CPEMI);
bool RemoveUnusedCPEntries();
bool CPEIsInRange(MachineInstr *MI, unsigned UserOffset,
bool OffsetIsInRange(unsigned UserOffset, unsigned TrialOffset,
unsigned Disp, bool NegativeOK, bool IsSoImm = false);
bool BBIsInRange(MachineInstr *MI, MachineBasicBlock *BB, unsigned Disp);
- bool FixUpImmediateBr(MachineFunction &Fn, ImmBranch &Br);
- bool FixUpConditionalBr(MachineFunction &Fn, ImmBranch &Br);
- bool FixUpUnconditionalBr(MachineFunction &Fn, ImmBranch &Br);
+ bool FixUpImmediateBr(MachineFunction &MF, ImmBranch &Br);
+ bool FixUpConditionalBr(MachineFunction &MF, ImmBranch &Br);
+ bool FixUpUnconditionalBr(MachineFunction &MF, ImmBranch &Br);
bool UndoLRSpillRestore();
+ bool OptimizeThumb2JumpTables(MachineFunction &MF);
unsigned GetOffsetOf(MachineInstr *MI) const;
void dumpBBs();
- void verify(MachineFunction &Fn);
+ void verify(MachineFunction &MF);
};
char ARMConstantIslands::ID = 0;
}
/// verify - check BBOffsets, BBSizes, alignment of islands
-void ARMConstantIslands::verify(MachineFunction &Fn) {
+void ARMConstantIslands::verify(MachineFunction &MF) {
assert(BBOffsets.size() == BBSizes.size());
for (unsigned i = 1, e = BBOffsets.size(); i != e; ++i)
assert(BBOffsets[i-1]+BBSizes[i-1] == BBOffsets[i]);
if (!isThumb)
return;
#ifndef NDEBUG
- for (MachineFunction::iterator MBBI = Fn.begin(), E = Fn.end();
+ for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
MBBI != E; ++MBBI) {
MachineBasicBlock *MBB = MBBI;
if (!MBB->empty() &&
return new ARMConstantIslands();
}
-bool ARMConstantIslands::runOnMachineFunction(MachineFunction &Fn) {
- MachineConstantPool &MCP = *Fn.getConstantPool();
+bool ARMConstantIslands::runOnMachineFunction(MachineFunction &MF) {
+ MachineConstantPool &MCP = *MF.getConstantPool();
- TII = Fn.getTarget().getInstrInfo();
- AFI =
Fn.getInfo<ARMFunctionInfo>();
+ TII = MF.getTarget().getInstrInfo();
+ AFI =
MF.getInfo<ARMFunctionInfo>();
isThumb = AFI->isThumbFunction();
isThumb1 = AFI->isThumb1OnlyFunction();
isThumb2 = AFI->isThumb2Function();
// Renumber all of the machine basic blocks in the function, guaranteeing that
// the numbers agree with the position of the block in the function.
- Fn.RenumberBlocks();
+ MF.RenumberBlocks();
// Thumb1 functions containing constant pools get 2-byte alignment.
// This is so we can keep exact track of where the alignment padding goes.
// we put them all at the end of the function.
std::vector<MachineInstr*> CPEMIs;
if (!MCP.isEmpty()) {
- DoInitialPlacement(Fn, CPEMIs);
+ DoInitialPlacement(MF, CPEMIs);
if (isThumb1)
AFI->setAlign(2U);
}
// Do the initial scan of the function, building up information about the
// sizes of each block, the location of all the water, and finding all of the
// constant pool users.
- InitialFunctionScan(Fn, CPEMIs);
+ InitialFunctionScan(MF, CPEMIs);
CPEMIs.clear();
/// Remove dead constant pool entries.
while (true) {
bool Change = false;
for (unsigned i = 0, e = CPUsers.size(); i != e; ++i)
- Change |= HandleConstantPoolUser(Fn, i);
+ Change |= HandleConstantPoolUser(MF, i);
DEBUG(dumpBBs());
for (unsigned i = 0, e = ImmBranches.size(); i != e; ++i)
- Change |= FixUpImmediateBr(Fn, ImmBranches[i]);
+ Change |= FixUpImmediateBr(MF, ImmBranches[i]);
DEBUG(dumpBBs());
if (!Change)
break;
}
// After a while, this might be made debug-only, but it is not expensive.
- verify(Fn);
+ verify(MF);
// If LR has been forced spilled and no far jumps (i.e. BL) has been issued.
// Undo the spill / restore of LR if possible.
- if (!HasFarJump && AFI->isLRSpilledForFarJump() && isThumb)
+ if (isThumb && !HasFarJump && AFI->isLRSpilledForFarJump())
MadeChange |= UndoLRSpillRestore();
+ // Let's see if we can use tbb / tbh to do jump tables.
+ MadeChange |= OptimizeThumb2JumpTables(MF);
+
BBSizes.clear();
BBOffsets.clear();
WaterList.clear();
CPEntries.clear();
ImmBranches.clear();
PushPopMIs.clear();
+ T2JumpTables.clear();
return MadeChange;
}
/// DoInitialPlacement - Perform the initial placement of the constant pool
/// entries. To start with, we put them all at the end of the function.
-void ARMConstantIslands::DoInitialPlacement(MachineFunction &Fn,
+void ARMConstantIslands::DoInitialPlacement(MachineFunction &MF,
std::vector<MachineInstr*> &CPEMIs) {
// Create the basic block to hold the CPE's.
- MachineBasicBlock *BB = Fn.CreateMachineBasicBlock();
- Fn.push_back(BB);
+ MachineBasicBlock *BB = MF.CreateMachineBasicBlock();
+ MF.push_back(BB);
// Add all of the constants from the constant pool to the end block, use an
// identity mapping of CPI's to CPE's.
const std::vector<MachineConstantPoolEntry> &CPs =
- Fn.getConstantPool()->getConstants();
+ MF.getConstantPool()->getConstants();
- const TargetData &TD = *Fn.getTarget().getTargetData();
+ const TargetData &TD = *MF.getTarget().getTargetData();
for (unsigned i = 0, e = CPs.size(); i != e; ++i) {
unsigned Size = TD.getTypeAllocSize(CPs[i].getType());
// Verify that all constant pool entries are a multiple of 4 bytes. If not,
/// InitialFunctionScan - Do the initial scan of the function, building up
/// information about the sizes of each block, the location of all the water,
/// and finding all of the constant pool users.
-void ARMConstantIslands::InitialFunctionScan(MachineFunction &Fn,
+void ARMConstantIslands::InitialFunctionScan(MachineFunction &MF,
const std::vector<MachineInstr*> &CPEMIs) {
unsigned Offset = 0;
- for (MachineFunction::iterator MBBI = Fn.begin(), E = Fn.end();
+ for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
MBBI != E; ++MBBI) {
MachineBasicBlock &MBB = *MBBI;
unsigned Scale = 1;
int UOpc = Opc;
switch (Opc) {
+ default:
+ continue; // Ignore other JT branches
case ARM::tBR_JTr:
// A Thumb1 table jump may involve padding; for the offsets to
// be right, functions containing these must be 4-byte aligned.
AFI->setAlign(2U);
if ((Offset+MBBSize)%4 != 0)
+ // FIXME: Add a pseudo ALIGN instruction instead.
MBBSize += 2; // padding
continue; // Does not get an entry in ImmBranches
- default:
- continue; // Ignore other JT branches
+ case ARM::t2BR_JT:
+ T2JumpTables.push_back(I);
+ continue; // Does not get an entry in ImmBranches
case ARM::Bcc:
isCond = true;
UOpc = ARM::B;
/// is out-of-range. If so, pick up the constant pool value and move it some
/// place in-range. Return true if we changed any addresses (thus must run
/// another pass of branch lengthening), false otherwise.
-bool ARMConstantIslands::HandleConstantPoolUser(MachineFunction &Fn,
+bool ARMConstantIslands::HandleConstantPoolUser(MachineFunction &MF,
unsigned CPUserIndex) {
CPUser &U = CPUsers[CPUserIndex];
MachineInstr *UserMI = U.MI;
}
// Okay, we know we can put an island before NewMBB now, do it!
- MachineBasicBlock *NewIsland = Fn.CreateMachineBasicBlock();
- Fn.insert(NewMBB, NewIsland);
+ MachineBasicBlock *NewIsland = MF.CreateMachineBasicBlock();
+ MF.insert(NewMBB, NewIsland);
// Update internal data structures to account for the newly inserted MBB.
UpdateForInsertedWaterBlock(NewIsland);
/// FixUpImmediateBr - Fix up an immediate branch whose destination is too far
/// away to fit in its displacement field.
-bool ARMConstantIslands::FixUpImmediateBr(MachineFunction &Fn, ImmBranch &Br) {
+bool ARMConstantIslands::FixUpImmediateBr(MachineFunction &MF, ImmBranch &Br) {
MachineInstr *MI = Br.MI;
MachineBasicBlock *DestBB = MI->getOperand(0).getMBB();
return false;
if (!Br.isCond)
- return FixUpUnconditionalBr(Fn, Br);
- return FixUpConditionalBr(Fn, Br);
+ return FixUpUnconditionalBr(MF, Br);
+ return FixUpConditionalBr(MF, Br);
}
/// FixUpUnconditionalBr - Fix up an unconditional branch whose destination is
/// spilled in the epilogue, then we can use BL to implement a far jump.
/// Otherwise, add an intermediate branch instruction to a branch.
bool
-ARMConstantIslands::FixUpUnconditionalBr(MachineFunction &Fn, ImmBranch &Br) {
+ARMConstantIslands::FixUpUnconditionalBr(MachineFunction &MF, ImmBranch &Br) {
MachineInstr *MI = Br.MI;
MachineBasicBlock *MBB = MI->getParent();
assert(isThumb && !isThumb2 && "Expected a Thumb1 function!");
/// far away to fit in its displacement field. It is converted to an inverse
/// conditional branch + an unconditional branch to the destination.
bool
-ARMConstantIslands::FixUpConditionalBr(MachineFunction &Fn, ImmBranch &Br) {
+ARMConstantIslands::FixUpConditionalBr(MachineFunction &MF, ImmBranch &Br) {
MachineInstr *MI = Br.MI;
MachineBasicBlock *DestBB = MI->getOperand(0).getMBB();
}
return MadeChange;
}
+
+bool ARMConstantIslands::OptimizeThumb2JumpTables(MachineFunction &MF) {
+ bool MadeChange = false;
+
+ // FIXME: After the tables are shrunk, can we get rid some of the
+ // constantpool tables?
+ const MachineJumpTableInfo *MJTI = MF.getJumpTableInfo();
+ const std::vector<MachineJumpTableEntry> &JT = MJTI->getJumpTables();
+ for (unsigned i = 0, e = T2JumpTables.size(); i != e; ++i) {
+ MachineInstr *MI = T2JumpTables[i];
+ const TargetInstrDesc &TID = MI->getDesc();
+ unsigned NumOps = TID.getNumOperands();
+ unsigned JTOpIdx = NumOps - (TID.isPredicable() ? 3 : 2);
+ MachineOperand JTOP = MI->getOperand(JTOpIdx);
+ unsigned JTI = JTOP.getIndex();
+ assert(JTI < JT.size());
+
+ bool ByteOk = true;
+ bool HalfWordOk = true;
+ unsigned JTOffset = GetOffsetOf(MI) + 4;
+ const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
+ for (unsigned j = 0, ee = JTBBs.size(); j != ee; ++j) {
+ MachineBasicBlock *MBB = JTBBs[j];
+ unsigned DstOffset = BBOffsets[MBB->getNumber()];
+ if (ByteOk && !OffsetIsInRange(JTOffset, DstOffset, (1<<8)-1, true, false))
+ ByteOk = false;
+ if (HalfWordOk &&
+ !OffsetIsInRange(JTOffset, DstOffset, (1<<16)-1, true, false))
+ HalfWordOk = false;
+ if (!ByteOk && !HalfWordOk)
+ break;
+ }
+
+ if (ByteOk || HalfWordOk) {
+ MachineBasicBlock *MBB = MI->getParent();
+ unsigned BaseReg = MI->getOperand(0).getReg();
+ bool BaseRegKill = MI->getOperand(0).isKill();
+ if (!BaseRegKill)
+ continue;
+ unsigned IdxReg = MI->getOperand(1).getReg();
+ bool IdxRegKill = MI->getOperand(1).isKill();
+ MachineBasicBlock::iterator PrevI = MI;
+ if (PrevI == MBB->begin())
+ continue;
+
+ MachineInstr *AddrMI = --PrevI;
+ bool OptOk = true;
+ // Examine the instruction that calculate the jumptable entry address.
+ // If it's not the one just before the t2BR_JT, we won't delete it, then
+ // it's not worth doing the optimization.
+ for (unsigned k = 0, eee = AddrMI->getNumOperands(); k != eee; ++k) {
+ const MachineOperand &MO = AddrMI->getOperand(k);
+ if (!MO.isReg() || !MO.getReg())
+ continue;
+ if (MO.isDef() && MO.getReg() != BaseReg) {
+ OptOk = false;
+ break;
+ }
+ if (MO.isUse() && !MO.isKill() && MO.getReg() != IdxReg) {
+ OptOk = false;
+ break;
+ }
+ }
+ if (!OptOk)
+ continue;
+
+ // The previous instruction should be a t2LEApcrelJT, we want to delete
+ // it as well.
+ MachineInstr *LeaMI = --PrevI;
+ if (LeaMI->getOpcode() != ARM::t2LEApcrelJT ||
+ LeaMI->getOperand(0).getReg() != BaseReg)
+ LeaMI = 0;
+
+ if (OptOk) {
+ unsigned Opc = ByteOk ? ARM::t2TBB : ARM::t2TBH;
+ AddDefaultPred(BuildMI(MBB, MI->getDebugLoc(), TII->get(Opc))
+ .addReg(IdxReg, getKillRegState(IdxRegKill))
+ .addJumpTableIndex(JTI, JTOP.getTargetFlags())
+ .addImm(MI->getOperand(JTOpIdx+1).getImm()));
+
+ AddrMI->eraseFromParent();
+ if (LeaMI)
+ LeaMI->eraseFromParent();
+ MI->eraseFromParent();
+ ++NumTBs;
+ MadeChange = true;
+ }
+ }
+ }
+
+ return MadeChange;
+}
--- /dev/null
+; RUN: llvm-as < %s | llc -mtriple=thumbv7-apple-darwin -relocation-model=pic | FileCheck %s
+
+ %struct.R_flstr = type { i32, i32, i8* }
+ %struct._T_tstr = type { i32, %struct.R_flstr*, %struct._T_tstr* }
+@_C_nextcmd = external global i32 ; <i32*> [#uses=3]
+@.str31 = external constant [28 x i8], align 1 ; <[28 x i8]*> [#uses=1]
+@_T_gtol = external global %struct._T_tstr* ; <%struct._T_tstr**> [#uses=2]
+
+declare arm_apcscc i32 @strlen(i8* nocapture) nounwind readonly
+
+declare arm_apcscc void @Z_fatal(i8*) noreturn nounwind
+
+declare arm_apcscc noalias i8* @calloc(i32, i32) nounwind
+
+define arm_apcscc i32 @main(i32 %argc, i8** nocapture %argv) nounwind {
+; CHECK: main:
+; CHECK: tbh
+entry:
+ br label %bb42.i
+
+bb1.i2: ; preds = %bb42.i
+ br label %bb40.i
+
+bb5.i: ; preds = %bb42.i
+ %0 = or i32 %_Y_flags.1, 32 ; <i32> [#uses=1]
+ br label %bb40.i
+
+bb7.i: ; preds = %bb42.i
+ call arm_apcscc void @_T_addtol(%struct._T_tstr** @_T_gtol, i32 0, i8* null) nounwind
+ unreachable
+
+bb15.i: ; preds = %bb42.i
+ call arm_apcscc void @_T_addtol(%struct._T_tstr** @_T_gtol, i32 2, i8* null) nounwind
+ unreachable
+
+bb23.i: ; preds = %bb42.i
+ %1 = call arm_apcscc i32 @strlen(i8* null) nounwind readonly ; <i32> [#uses=0]
+ unreachable
+
+bb33.i: ; preds = %bb42.i
+ store i32 0, i32* @_C_nextcmd, align 4
+ %2 = call arm_apcscc noalias i8* @calloc(i32 21, i32 1) nounwind ; <i8*> [#uses=0]
+ unreachable
+
+bb34.i: ; preds = %bb42.i
+ %3 = load i32* @_C_nextcmd, align 4 ; <i32> [#uses=1]
+ %4 = add i32 %3, 1 ; <i32> [#uses=1]
+ store i32 %4, i32* @_C_nextcmd, align 4
+ %5 = call arm_apcscc noalias i8* @calloc(i32 22, i32 1) nounwind ; <i8*> [#uses=0]
+ unreachable
+
+bb35.i: ; preds = %bb42.i
+ %6 = call arm_apcscc noalias i8* @calloc(i32 20, i32 1) nounwind ; <i8*> [#uses=0]
+ unreachable
+
+bb37.i: ; preds = %bb42.i
+ %7 = call arm_apcscc noalias i8* @calloc(i32 14, i32 1) nounwind ; <i8*> [#uses=0]
+ unreachable
+
+bb39.i: ; preds = %bb42.i
+ call arm_apcscc void @Z_fatal(i8* getelementptr ([28 x i8]* @.str31, i32 0, i32 0)) nounwind
+ unreachable
+
+bb40.i: ; preds = %bb42.i, %bb5.i, %bb1.i2
+ %_Y_flags.0 = phi i32 [ 0, %bb1.i2 ], [ %0, %bb5.i ], [ %_Y_flags.1, %bb42.i ] ; <i32> [#uses=1]
+ %_Y_eflag.b.0 = phi i1 [ %_Y_eflag.b.1, %bb1.i2 ], [ %_Y_eflag.b.1, %bb5.i ], [ true, %bb42.i ] ; <i1> [#uses=1]
+ br label %bb42.i
+
+bb42.i: ; preds = %bb40.i, %entry
+ %_Y_eflag.b.1 = phi i1 [ false, %entry ], [ %_Y_eflag.b.0, %bb40.i ] ; <i1> [#uses=2]
+ %_Y_flags.1 = phi i32 [ 0, %entry ], [ %_Y_flags.0, %bb40.i ] ; <i32> [#uses=2]
+ switch i32 undef, label %bb39.i [
+ i32 67, label %bb33.i
+ i32 70, label %bb35.i
+ i32 77, label %bb37.i
+ i32 83, label %bb34.i
+ i32 97, label %bb7.i
+ i32 100, label %bb5.i
+ i32 101, label %bb40.i
+ i32 102, label %bb23.i
+ i32 105, label %bb15.i
+ i32 116, label %bb1.i2
+ ]
+}
+
+declare arm_apcscc void @_T_addtol(%struct._T_tstr** nocapture, i32, i8*) nounwind
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