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Stop inventing symbol sizes.

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MachO and COFF quite reasonably only define the size for common symbols.

We used to try to figure out the "size" by computing the gap from one symbol to
the next.

This would not be correct in general, since a part of a section can belong to no
visible symbol (padding, private globals).

It was also really expensive, since we would walk every symbol to find the size
of one.

If a caller really wants this, it can sort all the symbols once and get all the
gaps ("size") in O(n log n) instead of O(n^2).

On MachO this also has the advantage of centralizing all the checks for an
invalid n_sect.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238028 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola
2015-05-22 15:43:00 +00:00
parent 08bac7b901
commit 7b677dd986
7 changed files with 14 additions and 112 deletions
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52
lib/Object/MachOObjectFile.cpp
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@ -415,49 +415,13 @@ std::error_code MachOObjectFile::getSymbolAlignment(DataRefImpl DRI,
std::error_code MachOObjectFile::getSymbolSize(DataRefImpl DRI,
uint64_t &Result) const {
uint64_t BeginOffset;
uint64_t EndOffset = 0;
uint8_t SectionIndex;
MachO::nlist_base Entry = getSymbolTableEntryBase(this, DRI);
uint64_t Value;
getSymbolAddress(DRI, Value);
if (Value == UnknownAddressOrSize) {
uint32_t flags = getSymbolFlags(DRI);
if (flags & SymbolRef::SF_Common)
Result = Value;
else
Result = UnknownAddressOrSize;
return object_error::success;
}
BeginOffset = Value;
SectionIndex = Entry.n_sect;
if (!SectionIndex) {
uint32_t flags = getSymbolFlags(DRI);
if (flags & SymbolRef::SF_Common)
Result = Value;
else
Result = UnknownAddressOrSize;
return object_error::success;
}
// Unfortunately symbols are unsorted so we need to touch all
// symbols from load command
for (const SymbolRef &Symbol : symbols()) {
DataRefImpl DRI = Symbol.getRawDataRefImpl();
Entry = getSymbolTableEntryBase(this, DRI);
getSymbolAddress(DRI, Value);
if (Value == UnknownAddressOrSize)
continue;
if (Entry.n_sect == SectionIndex && Value > BeginOffset)
if (!EndOffset || Value < EndOffset)
EndOffset = Value;
}
if (!EndOffset) {
DataRefImpl Sec;
Sec.d.a = SectionIndex-1;
uint64_t Size = getSectionSize(Sec);
EndOffset = getSectionAddress(Sec);
EndOffset += Size;
}
Result = EndOffset - BeginOffset;
return object_error::success;
}
@ -2263,16 +2227,12 @@ MachOObjectFile::getNextLoadCommandInfo(const LoadCommandInfo &L) const {
}
MachO::section MachOObjectFile::getSection(DataRefImpl DRI) const {
// TODO: What if Sections.size() == 0?
if (DRI.d.a >= Sections.size())
report_fatal_error("getSection: Invalid section index.");
assert(DRI.d.a < Sections.size() && "Should have detected this earlier");
return getStruct<MachO::section>(this, Sections[DRI.d.a]);
}
MachO::section_64 MachOObjectFile::getSection64(DataRefImpl DRI) const {
// TODO: What if Sections.size() == 0?
if (DRI.d.a >= Sections.size())
report_fatal_error("getSection64: Invalid section index.");
assert(DRI.d.a < Sections.size() && "Should have detected this earlier");
return getStruct<MachO::section_64>(this, Sections[DRI.d.a]);
}