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-rw-r--r--llvm/lib/Target/ARM/ARMConstantIslandPass.cpp105
1 files changed, 14 insertions, 91 deletions
diff --git a/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp b/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
index 86c5995ccd4..b18835ca8a5 100644
--- a/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
+++ b/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
@@ -58,11 +58,6 @@ static cl::opt<unsigned>
CPMaxIteration("arm-constant-island-max-iteration", cl::Hidden, cl::init(30),
cl::desc("The max number of iteration for converge"));
-static cl::opt<bool> SynthesizeThumb1TBB(
- "arm-synthesize-thumb-1-tbb", cl::Hidden, cl::init(true),
- cl::desc("Use compressed jump tables in Thumb-1 by synthesizing an "
- "equivalent to the TBB/TBH instructions"));
-
namespace {
/// ARMConstantIslands - Due to limited PC-relative displacements, ARM
/// requires constant pool entries to be scattered among the instructions
@@ -194,7 +189,6 @@ namespace {
bool isThumb;
bool isThumb1;
bool isThumb2;
- bool isPositionIndependentOrROPI;
public:
static char ID;
ARMConstantIslands() : MachineFunctionPass(ID) {}
@@ -325,8 +319,6 @@ bool ARMConstantIslands::runOnMachineFunction(MachineFunction &mf) {
STI = &static_cast<const ARMSubtarget &>(MF->getSubtarget());
TII = STI->getInstrInfo();
- isPositionIndependentOrROPI =
- STI->getTargetLowering()->isPositionIndependent() || STI->isROPI();
AFI = MF->getInfo<ARMFunctionInfo>();
isThumb = AFI->isThumbFunction();
@@ -334,7 +326,6 @@ bool ARMConstantIslands::runOnMachineFunction(MachineFunction &mf) {
isThumb2 = AFI->isThumb2Function();
HasFarJump = false;
- bool GenerateTBB = isThumb2 || (isThumb1 && SynthesizeThumb1TBB);
// This pass invalidates liveness information when it splits basic blocks.
MF->getRegInfo().invalidateLiveness();
@@ -346,7 +337,7 @@ bool ARMConstantIslands::runOnMachineFunction(MachineFunction &mf) {
// Try to reorder and otherwise adjust the block layout to make good use
// of the TB[BH] instructions.
bool MadeChange = false;
- if (GenerateTBB && AdjustJumpTableBlocks) {
+ if (isThumb2 && AdjustJumpTableBlocks) {
scanFunctionJumpTables();
MadeChange |= reorderThumb2JumpTables();
// Data is out of date, so clear it. It'll be re-computed later.
@@ -423,7 +414,7 @@ bool ARMConstantIslands::runOnMachineFunction(MachineFunction &mf) {
MadeChange |= optimizeThumb2Branches();
// Optimize jump tables using TBB / TBH.
- if (GenerateTBB)
+ if (isThumb2)
MadeChange |= optimizeThumb2JumpTables();
// After a while, this might be made debug-only, but it is not expensive.
@@ -549,11 +540,9 @@ void ARMConstantIslands::doInitialJumpTablePlacement(
case ARM::t2BR_JT:
JTOpcode = ARM::JUMPTABLE_INSTS;
break;
- case ARM::tTBB_JT:
case ARM::t2TBB_JT:
JTOpcode = ARM::JUMPTABLE_TBB;
break;
- case ARM::tTBH_JT:
case ARM::t2TBH_JT:
JTOpcode = ARM::JUMPTABLE_TBH;
break;
@@ -649,8 +638,7 @@ unsigned ARMConstantIslands::getCPELogAlign(const MachineInstr *CPEMI) {
void ARMConstantIslands::scanFunctionJumpTables() {
for (MachineBasicBlock &MBB : *MF) {
for (MachineInstr &I : MBB)
- if (I.isBranch() &&
- (I.getOpcode() == ARM::t2BR_JT || I.getOpcode() == ARM::tBR_JTr))
+ if (I.isBranch() && I.getOpcode() == ARM::t2BR_JT)
T2JumpTables.push_back(&I);
}
}
@@ -691,7 +679,6 @@ initializeFunctionInfo(const std::vector<MachineInstr*> &CPEMIs) {
default:
continue; // Ignore other JT branches
case ARM::t2BR_JT:
- case ARM::tBR_JTr:
T2JumpTables.push_back(&I);
continue; // Does not get an entry in ImmBranches
case ARM::Bcc:
@@ -1956,7 +1943,7 @@ bool ARMConstantIslands::preserveBaseRegister(MachineInstr *JumpMI,
if (RemovableAdd) {
RemovableAdd->eraseFromParent();
- DeadSize += isThumb2 ? 4 : 2;
+ DeadSize += 4;
} else if (BaseReg == EntryReg) {
// The add wasn't removable, but clobbered the base for the TBB. So we can't
// preserve it.
@@ -2023,82 +2010,25 @@ bool ARMConstantIslands::optimizeThumb2JumpTables() {
if (!ByteOk && !HalfWordOk)
continue;
- CPUser &User = CPUsers[JumpTableUserIndices[JTI]];
MachineBasicBlock *MBB = MI->getParent();
if (!MI->getOperand(0).isKill()) // FIXME: needed now?
continue;
+ unsigned IdxReg = MI->getOperand(1).getReg();
+ bool IdxRegKill = MI->getOperand(1).isKill();
+ CPUser &User = CPUsers[JumpTableUserIndices[JTI]];
unsigned DeadSize = 0;
bool CanDeleteLEA = false;
bool BaseRegKill = false;
-
- unsigned IdxReg = ~0U;
- bool IdxRegKill = true;
- if (isThumb2) {
- IdxReg = MI->getOperand(1).getReg();
- IdxRegKill = MI->getOperand(1).isKill();
-
- bool PreservedBaseReg =
+ bool PreservedBaseReg =
preserveBaseRegister(MI, User.MI, DeadSize, CanDeleteLEA, BaseRegKill);
- if (!jumpTableFollowsTB(MI, User.CPEMI) && !PreservedBaseReg)
- continue;
- } else {
- // We're in thumb-1 mode, so we must have something like:
- // %idx = tLSLri %idx, 2
- // %base = tLEApcrelJT
- // %t = tLDRr %idx, %base
- unsigned BaseReg = User.MI->getOperand(0).getReg();
-
- if (User.MI->getIterator() == User.MI->getParent()->begin())
- continue;
- MachineInstr *Shift = User.MI->getPrevNode();
- if (Shift->getOpcode() != ARM::tLSLri ||
- Shift->getOperand(3).getImm() != 2 ||
- !Shift->getOperand(2).isKill())
- continue;
- IdxReg = Shift->getOperand(2).getReg();
- unsigned ShiftedIdxReg = Shift->getOperand(0).getReg();
- MachineInstr *Load = User.MI->getNextNode();
- if (Load->getOpcode() != ARM::tLDRr)
- continue;
- if (Load->getOperand(1).getReg() != ShiftedIdxReg ||
- Load->getOperand(2).getReg() != BaseReg ||
- !Load->getOperand(1).isKill())
- continue;
+ if (!jumpTableFollowsTB(MI, User.CPEMI) && !PreservedBaseReg)
+ continue;
- // If we're in PIC mode, there should be another ADD following.
- if (isPositionIndependentOrROPI) {
- MachineInstr *Add = Load->getNextNode();
- if (Add->getOpcode() != ARM::tADDrr ||
- Add->getOperand(2).getReg() != Load->getOperand(0).getReg() ||
- Add->getOperand(3).getReg() != BaseReg ||
- !Add->getOperand(2).isKill())
- continue;
- if (Add->getOperand(0).getReg() != MI->getOperand(0).getReg())
- continue;
-
- Add->eraseFromParent();
- DeadSize += 2;
- } else {
- if (Load->getOperand(0).getReg() != MI->getOperand(0).getReg())
- continue;
- }
-
-
- // Now safe to delete the load and lsl. The LEA will be removed later.
- CanDeleteLEA = true;
- Shift->eraseFromParent();
- Load->eraseFromParent();
- DeadSize += 4;
- }
-
DEBUG(dbgs() << "Shrink JT: " << *MI);
MachineInstr *CPEMI = User.CPEMI;
unsigned Opc = ByteOk ? ARM::t2TBB_JT : ARM::t2TBH_JT;
- if (!isThumb2)
- Opc = ByteOk ? ARM::tTBB_JT : ARM::tTBH_JT;
-
MachineBasicBlock::iterator MI_JT = MI;
MachineInstr *NewJTMI =
BuildMI(*MBB, MI_JT, MI->getDebugLoc(), TII->get(Opc))
@@ -2118,7 +2048,7 @@ bool ARMConstantIslands::optimizeThumb2JumpTables() {
if (CanDeleteLEA) {
User.MI->eraseFromParent();
- DeadSize += isThumb2 ? 4 : 2;
+ DeadSize += 4;
// The LEA was eliminated, the TBB instruction becomes the only new user
// of the jump table.
@@ -2234,16 +2164,9 @@ adjustJTTargetBlockForward(MachineBasicBlock *BB, MachineBasicBlock *JTBB) {
// Add an unconditional branch from NewBB to BB.
// There doesn't seem to be meaningful DebugInfo available; this doesn't
// correspond directly to anything in the source.
- if (isThumb2)
- BuildMI(NewBB, DebugLoc(), TII->get(ARM::t2B))
- .addMBB(BB)
- .addImm(ARMCC::AL)
- .addReg(0);
- else
- BuildMI(NewBB, DebugLoc(), TII->get(ARM::tB))
- .addMBB(BB)
- .addImm(ARMCC::AL)
- .addReg(0);
+ assert (isThumb2 && "Adjusting for TB[BH] but not in Thumb2?");
+ BuildMI(NewBB, DebugLoc(), TII->get(ARM::t2B)).addMBB(BB)
+ .addImm(ARMCC::AL).addReg(0);
// Update internal data structures to account for the newly inserted MBB.
MF->RenumberBlocks(NewBB);
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