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Clean up the handling of an EBP/RBP unwind frame pointer. In particular, don't 

assert when the frame pointer is -1 (i.e., the function is "frameless").

Still to do: "frameless" unwind information.

llvm-svn: 135013
This commit is contained in:
Bill Wendling 2011-07-13 00:16:14 +00:00
parent 79dce0a66e
commit 929b90ff32
1 changed files with 26 additions and 23 deletions
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49
llvm/lib/Target/X86/X86FrameLowering.cpp
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@ -1064,7 +1064,7 @@ getCompactUnwindEncoding(ArrayRef<MCCFIInstruction> Instrs,
if (IsRelative)
CFAOffset += Src.getOffset();
else
CFAOffset = -Src.getOffset();
CFAOffset -= Src.getOffset();
} // else DW_CFA_def_cfa
continue;
@ -1072,6 +1072,13 @@ getCompactUnwindEncoding(ArrayRef<MCCFIInstruction> Instrs,
if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
// DW_CFA_def_cfa_register
assert(FramePointerReg != -1 && "Defining more than one frame pointer?");
if (TRI->getLLVMRegNum(FramePointerReg, IsEH) != X86::EBP &&
TRI->getLLVMRegNum(FramePointerReg, IsEH) != X86::RBP)
// The frame pointer isn't EBP/RBP. Cannot make unwind information
// compact.
return 0;
FramePointerReg = Dst.getReg();
continue;
}
@ -1088,7 +1095,9 @@ getCompactUnwindEncoding(ArrayRef<MCCFIInstruction> Instrs,
return 0;
} else if (Reg < 64) {
// DW_CFA_offset + Reg
SavedRegs.push_back(Reg);
int CURegNum = TRI->getCompactUnwindRegNum(Reg, IsEH);
if (CURegNum == -1) return 0;
SavedRegs.push_back(CURegNum);
} else {
// FIXME: Handle?
// DW_CFA_offset_extended
@ -1096,33 +1105,27 @@ getCompactUnwindEncoding(ArrayRef<MCCFIInstruction> Instrs,
}
}
CFAOffset /= 4;
// Check if the offset is too big.
CFAOffset /= 4;
if ((CFAOffset & 0xFF) != CFAOffset)
return 0;
Encoding |= (CFAOffset & 0xFF) << 16; // Size encoding.
// Bail if there are too many registers to encode.
unsigned NumRegsToEncode = SavedRegs.size() - (FramePointerReg != -1 ? 1 : 0);
if (NumRegsToEncode > 5) return 0;
if (FramePointerReg != -1) {
// Bail if there are too many registers to encode.
if (SavedRegs.size() - 1 > 5) return 0;
if (TRI->getLLVMRegNum(FramePointerReg, IsEH) != X86::EBP &&
TRI->getLLVMRegNum(FramePointerReg, IsEH) != X86::RBP)
Encoding |= 1 << 24; // EBP/RBP Unwind Frame
unsigned Idx = 0;
for (SmallVectorImpl<unsigned>::iterator
I = SavedRegs.begin(), E = SavedRegs.end(); I != E; ++I) {
unsigned Reg = *I;
if (Reg == unsigned(FramePointerReg)) continue;
Encoding |= (Reg & 0x7) << (Idx++ * 3); // Register encoding
}
} else {
// FIXME: Handle frameless version!
return 0;
Encoding |= 1 << 24;
Encoding |= (CFAOffset & 0xFF) << 16;
unsigned Idx = 0;
for (SmallVectorImpl<unsigned>::iterator
I = SavedRegs.begin(), E = SavedRegs.end(); I != E; ++I) {
if (*I == unsigned(FramePointerReg)) continue;
int CURegNum = TRI->getCompactUnwindRegNum(*I, IsEH);
if (CURegNum == -1) return 0;
Encoding |= (CURegNum & 0x7) << (Idx++ * 3);
}
return Encoding;