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Don't modify archive members unless really needed.

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For whatever reason ld64 requires that member headers (not the member
themselves) should be aligned. The only way to do that is to edit the
previous member so that it ends at an aligned boundary.

Since modifying data put in an archive is an undesirable property,
llvm-ar should only do it when it is absolutely necessary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@295765 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2017-02-21 20:40:54 +00:00
parent 2c0dd61dd0
commit 13f0c80b28
6 changed files with 80 additions and 29 deletions
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1
include/llvm/Object/Archive.h
View File

@ -212,6 +212,7 @@ public:
K_GNU,
K_MIPS64,
K_BSD,
K_DARWIN,
K_DARWIN64,
K_COFF
};

49
lib/Object/ArchiveWriter.cpp
View File

@ -122,12 +122,26 @@ static void printWithSpacePadding(raw_fd_ostream &OS, T Data, unsigned Size,
}
}
static bool isBSDLike(object::Archive::Kind Kind) {
switch (Kind) {
case object::Archive::K_GNU:
return false;
case object::Archive::K_BSD:
case object::Archive::K_DARWIN:
return true;
case object::Archive::K_MIPS64:
case object::Archive::K_DARWIN64:
case object::Archive::K_COFF:
llvm_unreachable("not supported for writting");
}
}
static void print32(raw_ostream &Out, object::Archive::Kind Kind,
uint32_t Val) {
if (Kind == object::Archive::K_GNU)
support::endian::Writer<support::big>(Out).write(Val);
else
if (isBSDLike(Kind))
support::endian::Writer<support::little>(Out).write(Val);
else
support::endian::Writer<support::big>(Out).write(Val);
}
static void printRestOfMemberHeader(
@ -178,7 +192,7 @@ printMemberHeader(raw_fd_ostream &Out, object::Archive::Kind Kind, bool Thin,
std::vector<unsigned>::iterator &StringMapIndexIter,
const sys::TimePoint<std::chrono::seconds> &ModTime,
unsigned UID, unsigned GID, unsigned Perms, unsigned Size) {
if (Kind == object::Archive::K_BSD)
if (isBSDLike(Kind))
return printBSDMemberHeader(Out, Name, ModTime, UID, GID, Perms, Size);
if (!useStringTable(Thin, Name))
return printGNUSmallMemberHeader(Out, Name, ModTime, UID, GID, Perms, Size);
@ -285,10 +299,10 @@ writeSymbolTable(raw_fd_ostream &Out, object::Archive::Kind Kind,
if (!HeaderStartOffset) {
HeaderStartOffset = Out.tell();
if (Kind == object::Archive::K_GNU)
printGNUSmallMemberHeader(Out, "", now(Deterministic), 0, 0, 0, 0);
else
if (isBSDLike(Kind))
printBSDMemberHeader(Out, "__.SYMDEF", now(Deterministic), 0, 0, 0, 0);
else
printGNUSmallMemberHeader(Out, "", now(Deterministic), 0, 0, 0, 0);
BodyStartOffset = Out.tell();
print32(Out, Kind, 0); // number of entries or bytes
}
@ -307,7 +321,7 @@ writeSymbolTable(raw_fd_ostream &Out, object::Archive::Kind Kind,
return EC;
NameOS << '\0';
MemberOffsetRefs.push_back(MemberNum);
if (Kind == object::Archive::K_BSD)
if (isBSDLike(Kind))
print32(Out, Kind, NameOffset);
print32(Out, Kind, 0); // member offset
}
@ -318,12 +332,12 @@ writeSymbolTable(raw_fd_ostream &Out, object::Archive::Kind Kind,
// ld64 prefers the cctools type archive which pads its string table to a
// boundary of sizeof(int32_t).
if (Kind == object::Archive::K_BSD)
if (isBSDLike(Kind))
for (unsigned P = OffsetToAlignment(NameOS.tell(), sizeof(int32_t)); P--;)
NameOS << '\0';
StringRef StringTable = NameOS.str();
if (Kind == object::Archive::K_BSD)
if (isBSDLike(Kind))
print32(Out, Kind, StringTable.size()); // byte count of the string table
Out << StringTable;
@ -342,10 +356,10 @@ writeSymbolTable(raw_fd_ostream &Out, object::Archive::Kind Kind,
// Patch up the number of symbols.
Out.seek(BodyStartOffset);
unsigned NumSyms = MemberOffsetRefs.size();
if (Kind == object::Archive::K_GNU)
print32(Out, Kind, NumSyms);
else
if (isBSDLike(Kind))
print32(Out, Kind, NumSyms * 8);
else
print32(Out, Kind, NumSyms);
Out.seek(Pos);
return BodyStartOffset + 4;
@ -357,8 +371,7 @@ llvm::writeArchive(StringRef ArcName,
bool WriteSymtab, object::Archive::Kind Kind,
bool Deterministic, bool Thin,
std::unique_ptr<MemoryBuffer> OldArchiveBuf) {
assert((!Thin || Kind == object::Archive::K_GNU) &&
"Only the gnu format has a thin mode");
assert((!Thin || !isBSDLike(Kind)) && "Only the gnu format has a thin mode");
SmallString<128> TmpArchive;
int TmpArchiveFD;
if (auto EC = sys::fs::createUniqueFile(ArcName + ".temp-archive-%%%%%%%.a",
@ -388,7 +401,7 @@ llvm::writeArchive(StringRef ArcName,
}
std::vector<unsigned> StringMapIndexes;
if (Kind != object::Archive::K_BSD)
if (!isBSDLike(Kind))
writeStringTable(Out, ArcName, NewMembers, StringMapIndexes, Thin);
std::vector<unsigned>::iterator StringMapIndexIter = StringMapIndexes.begin();
@ -404,7 +417,7 @@ llvm::writeArchive(StringRef ArcName,
// least 4-byte aligned for 32-bit content. Opt for the larger encoding
// uniformly. This matches the behaviour with cctools and ensures that ld64
// is happy with archives that we generate.
if (Kind == object::Archive::K_BSD)
if (Kind == object::Archive::K_DARWIN)
Padding = OffsetToAlignment(M.Buf->getBufferSize(), 8);
printMemberHeader(Out, Kind, Thin,
@ -424,7 +437,7 @@ llvm::writeArchive(StringRef ArcName,
if (MemberReferenceOffset) {
Out.seek(MemberReferenceOffset);
for (unsigned MemberNum : MemberOffsetRefs) {
if (Kind == object::Archive::K_BSD)
if (isBSDLike(Kind))
Out.seek(Out.tell() + 4); // skip over the string offset
print32(Out, Kind, MemberOffset[MemberNum]);
}

6
test/Object/archive-extract.test
View File

@ -43,10 +43,10 @@
CHECK-GNU: 1465 2004-11-19 03:01:31.000000000 very_long_bytecode_file_name.bc
; RUN: rm -f %t.a
; RUN: llvm-ar -format bsd rcU %t.a very_long_bytecode_file_name.bc
; RUN: env TZ=GMT llvm-ar tv %t.a | FileCheck %s -check-prefix CHECK-BSD
; RUN: llvm-ar -format darwin rcU %t.a very_long_bytecode_file_name.bc
; RUN: env TZ=GMT llvm-ar tv %t.a | FileCheck %s -check-prefix CHECK-DARWIN
CHECK-BSD: 1472 2004-11-19 03:01:31.000000000 very_long_bytecode_file_name.bc
CHECK-DARWIN: 1472 2004-11-19 03:01:31.000000000 very_long_bytecode_file_name.bc
RUN: not llvm-ar x %p/Inputs/GNU.a foo.o 2>&1 | FileCheck --check-prefix=NOTFOUND %s
NOTFOUND: foo.o was not found

19
test/Object/archive-format.test
View File

@ -32,12 +32,23 @@ RUN: llvm-ar --format=bsd rc %t.a 0123456789abcde 0123456789abcdef
RUN: cat %t.a | FileCheck -strict-whitespace --check-prefix=BSD %s
BSD: !<arch>
BSD-NEXT: #1/20 0 0 0 644 28 `
BSD-NEXT: #1/20 0 0 0 644 24 `
BSD-NEXT: 0123456789abcde{{.....}}bar.
BSD-SAME: #1/16 0 0 0 644 20 `
BSD-NEXT: 0123456789abcdefzed.
RUN: rm -f %t.a
RUN: llvm-ar --format=darwin rc %t.a 0123456789abcde 0123456789abcdef
RUN: cat %t.a | FileCheck -strict-whitespace --check-prefix=DARWIN %s
DARWIN: !<arch>
DARWIN-NEXT: #1/20 0 0 0 644 28 `
Each [[:space:]] matches a newline. We explicitly match 3 newlines, as the
fourth newline is implicitly consumed by FileCheck and cannot be matched.
BSD-NEXT: 0123456789abcde{{.....}}bar.{{[[:space:]][[:space:]][[:space:]]}}
BSD-NEXT: #1/20 0 0 0 644 28 `
BSD-NEXT: 0123456789abcdef{{....}}zed.
DARWIN-NEXT: 0123456789abcde{{.....}}bar.{{[[:space:]][[:space:]][[:space:]]}}
DARWIN-NEXT: #1/20 0 0 0 644 28 `
DARWIN-NEXT: 0123456789abcdef{{....}}zed.
RUN: rm -f test.a
RUN: llvm-ar --format=gnu rcT test.a 0123456789abcde 0123456789abcdef

19
test/Object/archive-pad.test Normal file
View File

@ -0,0 +1,19 @@
Test that only the darwin format needs to modify archive members to
avoid a ld64 bug.
RUN: echo foo > %t.o
RUN: rm -f %t.a
RUN: llvm-ar -format=bsd rc %t.a %t.o
RUN: llvm-ar p %t.a > %bsd.o
RUN: cmp %bsd.o %t.o
RUN: rm -f %t.a
RUN: llvm-ar -format=gnu rc %t.a %t.o
RUN: llvm-ar p %t.a > %gnu.o
RUN: cmp %gnu.o %t.o
RUN: rm -f %t.a
RUN: llvm-ar -format=darwin rc %t.a %t.o
RUN: llvm-ar p %t.a > %darwin.o
RUN: not cmp %darwin.o %t.o

15
tools/llvm-ar/llvm-ar.cpp
View File

@ -87,13 +87,14 @@ static cl::opt<bool> MRI("M", cl::desc(""));
static cl::opt<std::string> Plugin("plugin", cl::desc("plugin (ignored for compatibility"));
namespace {
enum Format { Default, GNU, BSD };
enum Format { Default, GNU, BSD, DARWIN };
}
static cl::opt<Format>
FormatOpt("format", cl::desc("Archive format to create"),
cl::values(clEnumValN(Default, "default", "default"),
clEnumValN(GNU, "gnu", "gnu"),
clEnumValN(DARWIN, "darwin", "darwin"),
clEnumValN(BSD, "bsd", "bsd")));
static std::string Options;
@ -623,8 +624,9 @@ computeNewArchiveMembers(ArchiveOperation Operation,
}
static object::Archive::Kind getDefaultForHost() {
return Triple(sys::getProcessTriple()).isOSDarwin() ? object::Archive::K_BSD
: object::Archive::K_GNU;
return Triple(sys::getProcessTriple()).isOSDarwin()
? object::Archive::K_DARWIN
: object::Archive::K_GNU;
}
static object::Archive::Kind getKindFromMember(const NewArchiveMember &Member) {
@ -633,7 +635,7 @@ static object::Archive::Kind getKindFromMember(const NewArchiveMember &Member) {
if (OptionalObject)
return isa<object::MachOObjectFile>(**OptionalObject)
? object::Archive::K_BSD
? object::Archive::K_DARWIN
: object::Archive::K_GNU;
// squelch the error in case we had a non-object file
@ -672,6 +674,11 @@ performWriteOperation(ArchiveOperation Operation,
fail("Only the gnu format has a thin mode");
Kind = object::Archive::K_BSD;
break;
case DARWIN:
if (Thin)
fail("Only the gnu format has a thin mode");
Kind = object::Archive::K_DARWIN;
break;
}
std::pair<StringRef, std::error_code> Result =