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Debug Info: Simplify Frame Index handling in DBG_VALUE Machine Instructions

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Rather than using the full power of target-specific addressing modes in
DBG_VALUEs with Frame Indicies, simply use Frame Index + Offset. This
reduces the complexity of debug info handling down to two
representations of values (reg+offset and frame index+offset) rather
than three or four.

Ideally we could ensure that frame indicies had been eliminated by the
time we reached an assembly or dwarf generation, but I haven't spent the
time to figure out where the FIs are leaking through into that & whether
there's a good place to convert them. Some FI+offset=>reg+offset
conversion is done (see PrologEpilogInserter, for example) which is
necessary for some SelectionDAG assumptions about registers, I believe,
but it might be possible to make this a more thorough conversion &
ensure there are no remaining FIs no matter how instruction selection
is performed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184066 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Blaikie
2013-06-16 20:34:15 +00:00
parent b7770e0b85
commit 6d9dbd5526
14 changed files with 115 additions and 139 deletions
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52
lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
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@ -1525,43 +1525,23 @@ DIE *CompileUnit::constructVariableDIE(DbgVariable *DV, bool isScopeAbstract) {
// Check if variable is described by a DBG_VALUE instruction.
if (const MachineInstr *DVInsn = DV->getMInsn()) {
bool updated = false;
if (DVInsn->getNumOperands() == 3) {
if (DVInsn->getOperand(0).isReg()) {
const MachineOperand RegOp = DVInsn->getOperand(0);
const TargetRegisterInfo *TRI = Asm->TM.getRegisterInfo();
if (DVInsn->getOperand(1).isImm() &&
TRI->getFrameRegister(*Asm->MF) == RegOp.getReg()) {
unsigned FrameReg = 0;
const TargetFrameLowering *TFI = Asm->TM.getFrameLowering();
int Offset =
TFI->getFrameIndexReference(*Asm->MF,
DVInsn->getOperand(1).getImm(),
FrameReg);
MachineLocation Location(FrameReg, Offset);
addVariableAddress(DV, VariableDie, Location);
} else if (RegOp.getReg())
addVariableAddress(DV, VariableDie,
MachineLocation(RegOp.getReg()));
updated = true;
}
else if (DVInsn->getOperand(0).isImm())
updated =
addConstantValue(VariableDie, DVInsn->getOperand(0),
DV->getType());
else if (DVInsn->getOperand(0).isFPImm())
updated =
addConstantFPValue(VariableDie, DVInsn->getOperand(0));
else if (DVInsn->getOperand(0).isCImm())
updated =
addConstantValue(VariableDie,
DVInsn->getOperand(0).getCImm(),
DV->getType().isUnsignedDIType());
} else {
addVariableAddress(DV, VariableDie,
Asm->getDebugValueLocation(DVInsn));
assert(DVInsn->getNumOperands() == 3);
if (DVInsn->getOperand(0).isReg()) {
const MachineOperand RegOp = DVInsn->getOperand(0);
if (int64_t Offset = DVInsn->getOperand(1).getImm()) {
MachineLocation Location(RegOp.getReg(), Offset);
addVariableAddress(DV, VariableDie, Location);
} else if (RegOp.getReg())
addVariableAddress(DV, VariableDie, MachineLocation(RegOp.getReg()));
updated = true;
}
} else if (DVInsn->getOperand(0).isImm())
updated =
addConstantValue(VariableDie, DVInsn->getOperand(0), DV->getType());
else if (DVInsn->getOperand(0).isFPImm())
updated = addConstantFPValue(VariableDie, DVInsn->getOperand(0));
else if (DVInsn->getOperand(0).isCImm())
updated = addConstantValue(VariableDie, DVInsn->getOperand(0).getCImm(),
DV->getType().isUnsignedDIType());
if (!updated) {
// If variableDie is not updated then DBG_VALUE instruction does not
// have valid variable info.