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Indexes into the list of filter ids cannot be output

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directly: they need to be turned into byte offsets
(often the same, but may not be if there are many
type infos).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37942 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2007-07-06 12:46:24 +00:00
parent d14526cf33
commit fccf0a2b25
1 changed files with 47 additions and 27 deletions
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74
lib/CodeGen/DwarfWriter.cpp
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@ -2894,6 +2894,26 @@ private:
O << UsedDirective << EHFrameInfo.FnName << ".eh\n\n";
}
/// EmitExceptionTable - Emit landpads and actions.
///
/// The general organization of the table is complex, but the basic concepts
/// are easy. First there is a header which describes the location and
/// organization of the three components that follow.
/// 1. The landing pad site information describes the range of code covered
/// by the try. In our case it's an accumulation of the ranges covered
/// by the invokes in the try. There is also a reference to the landing
/// pad that handles the exception once processed. Finally an index into
/// the actions table.
/// 2. The action table, in our case, is composed of pairs of type ids
/// and next action offset. Starting with the action index from the
/// landing pad site, each type Id is checked for a match to the current
/// exception. If it matches then the exception and type id are passed
/// on to the landing pad. Otherwise the next action is looked up. This
/// chain is terminated with a next action of zero. If no type id is
/// found the the frame is unwound and handling continues.
/// 3. Type id table contains references to all the C++ typeinfo for all
/// catches in the function. This tables is reversed indexed base 1.
/// SharedTypeIds - How many leading type ids two landing pads have in common.
static unsigned SharedTypeIds(const LandingPadInfo *L,
const LandingPadInfo *R) {
@ -2922,26 +2942,6 @@ private:
return LSize < RSize;
}
/// EmitExceptionTable - Emit landpads and actions.
///
/// The general organization of the table is complex, but the basic concepts
/// are easy. First there is a header which describes the location and
/// organization of the three components that follow.
/// 1. The landing pad site information describes the range of code covered
/// by the try. In our case it's an accumulation of the ranges covered
/// by the invokes in the try. There is also a reference to the landing
/// pad that handles the exception once processed. Finally an index into
/// the actions table.
/// 2. The action table, in our case, is composed of pairs of type ids
/// and next action offset. Starting with the action index from the
/// landing pad site, each type Id is checked for a match to the current
/// exception. If it matches then the exception and type id are passed
/// on to the landing pad. Otherwise the next action is looked up. This
/// chain is terminated with a next action of zero. If no type id is
/// found the the frame is unwound and handling continues.
/// 3. Type id table contains references to all the C++ typeinfo for all
/// catches in the function. This tables is reversed indexed base 1.
struct KeyInfo {
static inline unsigned getEmptyKey() { return -1U; }
static inline unsigned getTombstoneKey() { return -2U; }
@ -2957,7 +2957,7 @@ private:
typedef DenseMap<unsigned, PadSite, KeyInfo> PadMapType;
struct ActionEntry {
int TypeID;
int ValueForTypeID; // The value to write - may not be equal to the type id.
int NextAction;
struct ActionEntry *Previous;
};
@ -2974,7 +2974,6 @@ private:
// Sort the landing pads in order of their type ids. This is used to fold
// duplicate actions.
SmallVector<const LandingPadInfo *, 64> LandingPads;
LandingPads.reserve(PadInfos.size());
for (unsigned i = 0, N = PadInfos.size(); i != N; ++i)
LandingPads.push_back(&PadInfos[i]);
@ -2987,6 +2986,25 @@ private:
// The actions table.
SmallVector<ActionEntry, 32> Actions;
// Negative type ids index into FilterIds, positive type ids index into
// TypeInfos. The value written for a positive type id is just the type
// id itself. For a negative type id, however, the value written is the
// (negative) byte offset of the corresponding FilterIds entry. The byte
// offset is usually equal to the type id, because the FilterIds entries
// are written using a variable width encoding which outputs one byte per
// entry as long as the value written is not too large, but can differ.
// This kind of complication does not occur for positive type ids because
// type infos are output using a fixed width encoding.
// FilterOffsets[i] holds the byte offset corresponding to FilterIds[i].
SmallVector<int, 16> FilterOffsets;
FilterOffsets.reserve(FilterIds.size());
int Offset = -1;
for(std::vector<unsigned>::const_iterator I = FilterIds.begin(),
E = FilterIds.end(); I != E; ++I) {
FilterOffsets.push_back(Offset);
Offset -= Asm->SizeSLEB128(*I);
}
// Compute sizes for exception table.
unsigned SizeSites = 0;
unsigned SizeActions = 0;
@ -3010,9 +3028,9 @@ private:
assert(Actions.size());
PrevAction = &Actions.back();
SizeAction = Asm->SizeSLEB128(PrevAction->NextAction) +
Asm->SizeSLEB128(PrevAction->TypeID);
Asm->SizeSLEB128(PrevAction->ValueForTypeID);
for (unsigned j = NumShared; j != SizePrevIds; ++j) {
SizeAction -= Asm->SizeSLEB128(PrevAction->TypeID);
SizeAction -= Asm->SizeSLEB128(PrevAction->ValueForTypeID);
SizeAction += -PrevAction->NextAction;
PrevAction = PrevAction->Previous;
}
@ -3021,13 +3039,15 @@ private:
// Compute the actions.
for (unsigned I = NumShared, M = TypeIds.size(); I != M; ++I) {
int TypeID = TypeIds[I];
unsigned SizeTypeID = Asm->SizeSLEB128(TypeID);
assert(-1-TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
unsigned SizeTypeID = Asm->SizeSLEB128(ValueForTypeID);
int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
SizeAction = SizeTypeID + Asm->SizeSLEB128(NextAction);
SizeSiteActions += SizeAction;
ActionEntry Action = {TypeID, NextAction, PrevAction};
ActionEntry Action = {ValueForTypeID, NextAction, PrevAction};
Actions.push_back(Action);
PrevAction = &Actions.back();
@ -3145,7 +3165,7 @@ private:
for (unsigned I = 0, N = Actions.size(); I != N; ++I) {
ActionEntry &Action = Actions[I];
Asm->EmitSLEB128Bytes(Action.TypeID);
Asm->EmitSLEB128Bytes(Action.ValueForTypeID);
Asm->EOL("TypeInfo index");
Asm->EmitSLEB128Bytes(Action.NextAction);
Asm->EOL("Next action");