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Believe it or not, this is a simplification. :-)

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Basically, this patch is working towards removing the hard-coded values that are
output for the CIE. In particular, the CIE augmentation and the CIE augmentation
size. Both of these should be calculated. In the process, I was able to make a
bunch of code simpler.

The encodings for the personality, LSDA, and FDE in the CIE are still not
correct. They should be generated either from target-specific callbacks (blech!)
or grokked from first-principles.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81404 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2009-09-09 23:56:55 +00:00
parent 10bf734e6e
commit 52783c63a1
2 changed files with 86 additions and 37 deletions
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116
lib/CodeGen/AsmPrinter/DwarfException.cpp
View File

@ -51,6 +51,25 @@ DwarfException::~DwarfException() {
delete ExceptionTimer;
}
unsigned DwarfException::SizeOfEncodedValue(unsigned Encoding) {
if (Encoding == dwarf::DW_EH_PE_omit)
return 0;
switch (Encoding & 0x07) {
case dwarf::DW_EH_PE_absptr:
return TD->getPointerSize();
case dwarf::DW_EH_PE_udata2:
return 2;
case dwarf::DW_EH_PE_udata4:
return 4;
case dwarf::DW_EH_PE_udata8:
return 8;
}
llvm_unreachable("Invalid encoded value.");
return 0;
}
/// EmitCIE - Emit a Common Information Entry (CIE). This holds information that
/// is shared among many Frame Description Entries. There is at least one CIE
/// in every non-empty .debug_frame section.
@ -87,7 +106,40 @@ void DwarfException::EmitCIE(const Function *Personality, unsigned Index) {
// The personality presence indicates that language specific information will
// show up in the eh frame.
Asm->EmitString(Personality ? "zPLR" : "zR");
// FIXME: Don't hardcode these encodings.
unsigned PerEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
if (Personality && MAI->getNeedsIndirectEncoding())
PerEncoding |= dwarf::DW_EH_PE_indirect;
unsigned LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
unsigned FDEEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
char Augmentation[5] = { 0 };
unsigned AugmentationSize = 0;
char *APtr = Augmentation + 1;
if (Personality) {
// There is a personality function.
*APtr++ = 'P';
AugmentationSize += 1 + SizeOfEncodedValue(PerEncoding);
}
if (UsesLSDA[Index]) {
// An LSDA pointer is in the FDE augmentation.
*APtr++ = 'L';
++AugmentationSize;
}
if (FDEEncoding != dwarf::DW_EH_PE_absptr) {
// A non-default pointer encoding for the FDE.
*APtr++ = 'R';
++AugmentationSize;
}
if (APtr != Augmentation + 1)
Augmentation[0] = 'z';
Asm->EmitString(Augmentation);
Asm->EOL("CIE Augmentation");
// Round out reader.
@ -98,22 +150,14 @@ void DwarfException::EmitCIE(const Function *Personality, unsigned Index) {
Asm->EmitInt8(RI->getDwarfRegNum(RI->getRARegister(), true));
Asm->EOL("CIE Return Address Column");
Asm->EmitULEB128Bytes(AugmentationSize);
Asm->EOL("Augmentation Size");
Asm->EmitInt8(PerEncoding);
Asm->EOL("Personality", PerEncoding);
// If there is a personality, we need to indicate the function's location.
if (Personality) {
Asm->EmitULEB128Bytes(7);
Asm->EOL("Augmentation Size");
if (MAI->getNeedsIndirectEncoding()) {
Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4 |
dwarf::DW_EH_PE_indirect);
Asm->EOL("Personality",
dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4 |
dwarf::DW_EH_PE_indirect);
} else {
Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
Asm->EOL("Personality", dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
}
PrintRelDirective(true);
O << MAI->getPersonalityPrefix();
Asm->EmitExternalGlobal((const GlobalVariable *)(Personality));
@ -122,17 +166,11 @@ void DwarfException::EmitCIE(const Function *Personality, unsigned Index) {
O << "-" << MAI->getPCSymbol();
Asm->EOL("Personality");
Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
Asm->EOL("LSDA Encoding", dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
Asm->EmitInt8(LSDAEncoding);
Asm->EOL("LSDA Encoding", LSDAEncoding);
Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
Asm->EOL("FDE Encoding", dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
} else {
Asm->EmitULEB128Bytes(1);
Asm->EOL("Augmentation Size");
Asm->EmitInt8(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
Asm->EOL("FDE Encoding", dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4);
Asm->EmitInt8(FDEEncoding);
Asm->EOL("FDE Encoding", FDEEncoding);
}
// Indicate locations of general callee saved registers in frame.
@ -216,10 +254,10 @@ void DwarfException::EmitFDE(const FunctionEHFrameInfo &EHFrameInfo) {
if (EHFrameInfo.hasLandingPads)
EmitReference("exception", EHFrameInfo.Number, true, false);
else {
if (is4Byte)
Asm->EmitInt32((int)0);
else
Asm->EmitInt64((int)0);
if (is4Byte)
Asm->EmitInt32((int)0);
else
Asm->EmitInt64((int)0);
}
Asm->EOL("Language Specific Data Area");
} else {
@ -854,19 +892,20 @@ void DwarfException::EndModule() {
if (MAI->getExceptionHandlingType() != ExceptionHandling::Dwarf)
return;
if (!shouldEmitMovesModule && !shouldEmitTableModule)
return;
if (TimePassesIsEnabled)
ExceptionTimer->startTimer();
if (shouldEmitMovesModule || shouldEmitTableModule) {
const std::vector<Function *> Personalities = MMI->getPersonalities();
const std::vector<Function *> Personalities = MMI->getPersonalities();
for (unsigned i = 0, e = Personalities.size(); i < e; ++i)
EmitCIE(Personalities[i], i);
for (unsigned i = 0, e = Personalities.size(); i < e; ++i)
EmitCIE(Personalities[i], i);
for (std::vector<FunctionEHFrameInfo>::iterator
I = EHFrames.begin(), E = EHFrames.end(); I != E; ++I)
EmitFDE(*I);
}
for (std::vector<FunctionEHFrameInfo>::iterator
I = EHFrames.begin(), E = EHFrames.end(); I != E; ++I)
EmitFDE(*I);
if (TimePassesIsEnabled)
ExceptionTimer->stopTimer();
@ -925,6 +964,9 @@ void DwarfException::EndFunction() {
MMI->getFrameMoves(),
MF->getFunction()));
// Record if this personality index uses a landing pad.
UsesLSDA[MMI->getPersonalityIndex()] |= !MMI->getLandingPads().empty();
if (TimePassesIsEnabled)
ExceptionTimer->stopTimer();
}

7
lib/CodeGen/AsmPrinter/DwarfException.h
View File

@ -51,6 +51,11 @@ class VISIBILITY_HIDDEN DwarfException : public Dwarf {
std::vector<FunctionEHFrameInfo> EHFrames;
/// UsesLSDA - Indicates whether an FDE that uses the CIE at the given index
/// uses an LSDA. If so, then we need to encode that information in the CIE's
/// augmentation.
DenseMap<unsigned, bool> UsesLSDA;
/// shouldEmitTable - Per-function flag to indicate if EH tables should
/// be emitted.
bool shouldEmitTable;
@ -70,6 +75,8 @@ class VISIBILITY_HIDDEN DwarfException : public Dwarf {
/// ExceptionTimer - Timer for the Dwarf exception writer.
Timer *ExceptionTimer;
unsigned SizeOfEncodedValue(unsigned Encoding);
/// EmitCIE - Emit a Common Information Entry (CIE). This holds information
/// that is shared among many Frame Description Entries. There is at least
/// one CIE in every non-empty .debug_frame section.