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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.

llvm-svn: 238028
This commit is contained in:
Rafael Espindola 2015-05-22 15:43:00 +00:00
parent f692ef9e47
commit 62a07cb59b
7 changed files with 14 additions and 112 deletions
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55
llvm/lib/Object/COFFObjectFile.cpp
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@ -240,59 +240,10 @@ std::error_code COFFObjectFile::getSymbolSize(DataRefImpl Ref,
uint64_t &Result) const {
COFFSymbolRef Symb = getCOFFSymbol(Ref);
if (Symb.isAnyUndefined()) {
Result = UnknownAddressOrSize;
return object_error::success;
}
if (Symb.isCommon()) {
if (Symb.isCommon())
Result = Symb.getValue();
return object_error::success;
}
// Let's attempt to get the size of the symbol by looking at the address of
// the symbol after the symbol in question.
uint64_t SymbAddr;
if (std::error_code EC = getSymbolAddress(Ref, SymbAddr))
return EC;
int32_t SectionNumber = Symb.getSectionNumber();
if (COFF::isReservedSectionNumber(SectionNumber)) {
// Absolute and debug symbols aren't sorted in any interesting way.
Result = 0;
return object_error::success;
}
const section_iterator SecEnd = section_end();
uint64_t AfterAddr = UnknownAddressOrSize;
for (const symbol_iterator SymbI : symbols()) {
section_iterator SecI = SecEnd;
if (std::error_code EC = SymbI->getSection(SecI))
return EC;
// Check the symbol's section, skip it if it's in the wrong section.
// First, make sure it is in any section.
if (SecI == SecEnd)
continue;
// Second, make sure it is in the same section as the symbol in question.
if (!sectionContainsSymbol(SecI->getRawDataRefImpl(), Ref))
continue;
uint64_t Addr;
if (std::error_code EC = SymbI->getAddress(Addr))
return EC;
// We want to compare our symbol in question with the closest possible
// symbol that comes after.
if (AfterAddr > Addr && Addr > SymbAddr)
AfterAddr = Addr;
}
if (AfterAddr == UnknownAddressOrSize) {
// No symbol comes after this one, assume that everything after our symbol
// is part of it.
const coff_section *Section = nullptr;
if (std::error_code EC = getSection(SectionNumber, Section))
return EC;
Result = Section->SizeOfRawData - Symb.getValue();
} else {
// Take the difference between our symbol and the symbol that comes after
// our symbol.
Result = AfterAddr - SymbAddr;
}
else
Result = UnknownAddressOrSize;
return object_error::success;
}

52
llvm/lib/Object/MachOObjectFile.cpp
View File

@ -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]);
}

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llvm/test/Object/Inputs/macho-invalid-getsection-index
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llvm/test/Object/Inputs/macho64-invalid-getsection-index
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9
llvm/test/Object/macho-invalid.test
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@ -28,13 +28,6 @@ RUN: | FileCheck -check-prefix NAME-PAST-EOF %s
RUN: not llvm-nm %p/Inputs/macho-invalid-section-index-getSectionRawName 2>&1 \
RUN: | FileCheck -check-prefix INVALID-SECTION-IDX-SYMBOL-SEC %s
RUN: not llvm-objdump -t %p/Inputs/macho-invalid-getsection-index 2>&1 \
RUN: | FileCheck -check-prefix INVALID-SECTION-IDX-GETSECT %s
RUN: not llvm-objdump -t %p/Inputs/macho64-invalid-getsection-index 2>&1 \
RUN: | FileCheck -check-prefix INVALID-SECTION-IDX-GETSECT64 %s
SMALL-LOADC-SIZE: Load command with size < 8 bytes
SMALL-SEGLOADC-SIZE: Segment load command size is too small
INCOMPLETE-LOADC: Malformed MachO file
@ -43,5 +36,3 @@ BAD-SYMBOL: Requested symbol index is out of range
NAME-PAST-EOF: Symbol name entry points before beginning or past end of file
INVALID-SECTION-IDX-SYMBOL-SEC: getSymbolSection: Invalid section index
INVALID-SECTION-IDX-GETSECT: getSection: Invalid section index
INVALID-SECTION-IDX-GETSECT64: getSection64: Invalid section index

2
llvm/test/Object/objdump-symbol-table.test
View File

@ -30,7 +30,7 @@ ELF-i386: 00000000 *UND* 00000000 puts
macho-i386: trivial-object-test.macho-i386: file format Mach-O 32-bit i386
macho-i386: SYMBOL TABLE:
macho-i386: 00000000 g F __TEXT,__text 00000024 _main
macho-i386: 00000000 g F __TEXT,__text 00000000 _main
macho-i386: 00000000 *UND* 00000000 _SomeOtherFunction
macho-i386: 00000000 *UND* 00000000 _puts

8
llvm/test/tools/llvm-objdump/X86/macho-symbol-table.test
View File

@ -1,8 +1,8 @@
RUN: llvm-objdump -macho -t %p/Inputs/hello.obj.macho-x86_64 | FileCheck %s
CHECK: SYMBOL TABLE:
CHECK: 000000000000003b l F __TEXT,__cstring 0000000d L_.str
CHECK: 0000000000000068 l F __TEXT,__eh_frame 00000018 EH_frame0
CHECK: 0000000000000000 g F __TEXT,__text 0000003b _main
CHECK: 0000000000000080 g F __TEXT,__eh_frame 00000028 _main.eh
CHECK: 000000000000003b l F __TEXT,__cstring 00000000 L_.str
CHECK: 0000000000000068 l F __TEXT,__eh_frame 00000000 EH_frame0
CHECK: 0000000000000000 g F __TEXT,__text 00000000 _main
CHECK: 0000000000000080 g F __TEXT,__eh_frame 00000000 _main.eh
CHECK: 0000000000000000 *UND* 00000000 _printf