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- Off by one bugs in maximum displacement calculation / testing.

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- In thumb mode, a new constpool island BB size should be 4 + 2 to
  compensate for the potential padding due to alignment requirement.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33753 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-02-01 10:16:15 +00:00
parent b25fe82671
commit b43216ee4a
1 changed files with 28 additions and 15 deletions
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43
lib/Target/ARM/ARMConstantIslandPass.cpp
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@ -281,8 +281,10 @@ void ARMConstantIslands::InitialFunctionScan(MachineFunction &Fn,
Scale = 2;
break;
}
unsigned MaxDisp = (1 << (Bits-1)) * Scale;
ImmBranches.push_back(ImmBranch(I, MaxDisp, isCond, UOpc));
// Record this immediate branch.
unsigned MaxOffs = (1 << (Bits-1)) * Scale;
ImmBranches.push_back(ImmBranch(I, MaxOffs, isCond, UOpc));
}
if (Opc == ARM::tPUSH || Opc == ARM::tPOP_RET)
@ -293,9 +295,10 @@ void ARMConstantIslands::InitialFunctionScan(MachineFunction &Fn,
if (I->getOperand(op).isConstantPoolIndex()) {
// We found one. The addressing mode tells us the max displacement
// from the PC that this instruction permits.
unsigned MaxOffs = 0;
// Basic size info comes from the TSFlags field.
unsigned Bits = 0;
unsigned Scale = 1;
unsigned TSFlags = I->getInstrDescriptor()->TSFlags;
switch (TSFlags & ARMII::AddrModeMask) {
default:
@ -304,34 +307,42 @@ void ARMConstantIslands::InitialFunctionScan(MachineFunction &Fn,
continue;
assert(0 && "Unknown addressing mode for CP reference!");
case ARMII::AddrMode1: // AM1: 8 bits << 2
MaxOffs = 1 << (8+2); // Taking the address of a CP entry.
Bits = 8;
Scale = 4; // Taking the address of a CP entry.
break;
case ARMII::AddrMode2:
MaxOffs = 1 << 12; // +-offset_12
Bits = 12;
Scale = 2; // +-offset_12
break;
case ARMII::AddrMode3:
MaxOffs = 1 << 8; // +-offset_8
Bits = 8;
Scale = 2; // +-offset_8
break;
// addrmode4 has no immediate offset.
case ARMII::AddrMode5:
MaxOffs = 1 << (8+2); // +-(offset_8*4)
Bits = 8;
Scale = 4; // +-(offset_8*4)
break;
case ARMII::AddrModeT1:
MaxOffs = 1 << 5;
Bits = 5; // +offset_5
break;
case ARMII::AddrModeT2:
MaxOffs = 1 << (5+1);
Bits = 5;
Scale = 2; // +(offset_5*2)
break;
case ARMII::AddrModeT4:
MaxOffs = 1 << (5+2);
Bits = 5;
Scale = 4; // +(offset_5*4)
break;
case ARMII::AddrModeTs:
MaxOffs = 1 << (8+2);
Bits = 8;
Scale = 4; // +(offset_8*4)
break;
}
// Remember that this is a user of a CP entry.
MachineInstr *CPEMI =CPEMIs[I->getOperand(op).getConstantPoolIndex()];
unsigned MaxOffs = (1 << (Bits-1)) * Scale;
CPUsers.push_back(CPUser(I, CPEMI, MaxOffs));
// Instructions can only use one CP entry, don't bother scanning the
@ -514,12 +525,12 @@ bool ARMConstantIslands::HandleConstantPoolUser(MachineFunction &Fn, CPUser &U){
// TODO: Search for the best place to split the code. In practice, using
// loop nesting information to insert these guys outside of loops would be
// sufficient.
bool isThumb = AFI->isThumbFunction();
if (&UserMBB->back() == UserMI) {
assert(BBHasFallthrough(UserMBB) && "Expected a fallthrough BB!");
NewMBB = next(MachineFunction::iterator(UserMBB));
// Add an unconditional branch from UserMBB to fallthrough block.
// Note the new unconditional branch is not being recorded.
bool isThumb = AFI->isThumbFunction();
BuildMI(UserMBB, TII->get(isThumb ? ARM::tB : ARM::B)).addMBB(NewMBB);
BBSizes[UserMBB->getNumber()] += isThumb ? 2 : 4;
} else {
@ -539,11 +550,13 @@ bool ARMConstantIslands::HandleConstantPoolUser(MachineFunction &Fn, CPUser &U){
unsigned ID = NextUID++;
unsigned CPI = CPEMI->getOperand(1).getConstantPoolIndex();
unsigned Size = CPEMI->getOperand(2).getImm();
// Build a new CPE for this user.
U.CPEMI = BuildMI(NewIsland, TII->get(ARM::CONSTPOOL_ENTRY))
.addImm(ID).addConstantPoolIndex(CPI).addImm(Size);
// Compensate for .align 2 in thumb mode.
if (isThumb) Size += 2;
// Increase the size of the island block to account for the new entry.
BBSizes[NewIsland->getNumber()] += Size;
@ -574,7 +587,7 @@ bool ARMConstantIslands::BBIsInRange(MachineInstr *MI,MachineBasicBlock *DestBB,
<< *MI);
if (BrOffset <= DestOffset) {
if (DestOffset - BrOffset < MaxDisp)
if (DestOffset - BrOffset <= MaxDisp)
return true;
} else {
if (BrOffset - DestOffset <= MaxDisp)