forked from OSchip/llvm-project
[lld-macho] Fix TLV data initialization
We were mishandling the case where both `__tbss` and `__thread_data` sections were present. TLVP relocations should be encoded as offsets from the start of `__thread_data`, even if the symbol is actually located in `__thread_bss`. Previously, we were writing the offset from the start of the containing section, which doesn't really make sense since there's no way `tlv_get_addr()` can know which section a given `tlv$init` symbol is in at runtime. In addition, this patch ensures that we place `__thread_data` immediately before `__thread_bss`. This is what ld64 does, likely for performance reasons. Zerofill sections must also be at the end of their segments; we were already doing this, but now we ensure that `__thread_bss` occurs before `__bss`, so that it's always possible to have it contiguous with `__thread_data`. Fixes llvm.org/PR48657. Reviewed By: #lld-macho, thakis Differential Revision: https://reviews.llvm.org/D94329
This commit is contained in:
Jez Ng
parent
756dd70766
commit
daaaed6bb8
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@ -11,6 +11,7 @@
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#include "OutputSegment.h"
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#include "Symbols.h"
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#include "Target.h"
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#include "Writer.h"
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#include "lld/Common/Memory.h"
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#include "llvm/Support/Endian.h"
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@ -45,11 +46,12 @@ void InputSection::writeTo(uint8_t *buf) {
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target->resolveSymbolVA(buf + r.offset, *referentSym, r.type);
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if (isThreadLocalVariables(flags)) {
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// References from thread-local variable sections are treated
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// as offsets relative to the start of the referent section,
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// instead of as absolute addresses.
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// References from thread-local variable sections are treated as offsets
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// relative to the start of the thread-local data memory area, which
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// is initialized via copying all the TLV data sections (which are all
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// contiguous).
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if (auto *defined = dyn_cast<Defined>(referentSym))
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referentVA -= defined->isec->parent->addr;
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referentVA -= firstTLVDataSection->addr;
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}
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} else if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {
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referentVA = referentIsec->getVA();
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@ -60,13 +60,22 @@ public:
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std::vector<Reloc> relocs;
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};
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inline uint8_t sectionType(uint32_t flags) {
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return flags & llvm::MachO::SECTION_TYPE;
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}
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inline bool isZeroFill(uint32_t flags) {
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return llvm::MachO::isVirtualSection(flags & llvm::MachO::SECTION_TYPE);
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return llvm::MachO::isVirtualSection(sectionType(flags));
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}
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inline bool isThreadLocalVariables(uint32_t flags) {
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return (flags & llvm::MachO::SECTION_TYPE) ==
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llvm::MachO::S_THREAD_LOCAL_VARIABLES;
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return sectionType(flags) == llvm::MachO::S_THREAD_LOCAL_VARIABLES;
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}
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// These sections contain the data for initializing thread-local variables.
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inline bool isThreadLocalData(uint32_t flags) {
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return sectionType(flags) == llvm::MachO::S_THREAD_LOCAL_REGULAR ||
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sectionType(flags) == llvm::MachO::S_THREAD_LOCAL_ZEROFILL;
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}
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inline bool isDebugSection(uint32_t flags) {
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@ -557,6 +557,24 @@ static int sectionOrder(OutputSection *osec) {
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.Case(section_names::unwindInfo, std::numeric_limits<int>::max() - 1)
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.Case(section_names::ehFrame, std::numeric_limits<int>::max())
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.Default(0);
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} else if (segname == segment_names::data) {
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// For each thread spawned, dyld will initialize its TLVs by copying the
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// address range from the start of the first thread-local data section to
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// the end of the last one. We therefore arrange these sections contiguously
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// to minimize the amount of memory used. Additionally, since zerofill
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// sections must be at the end of their segments, and since TLV data
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// sections can be zerofills, we end up putting all TLV data sections at the
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// end of the segment.
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switch (sectionType(osec->flags)) {
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case S_THREAD_LOCAL_REGULAR:
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return std::numeric_limits<int>::max() - 2;
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case S_THREAD_LOCAL_ZEROFILL:
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return std::numeric_limits<int>::max() - 1;
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case S_ZEROFILL:
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return std::numeric_limits<int>::max();
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default:
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return 0;
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}
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} else if (segname == segment_names::linkEdit) {
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return StringSwitch<int>(osec->name)
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.Case(section_names::rebase, -8)
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@ -571,7 +589,7 @@ static int sectionOrder(OutputSection *osec) {
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}
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// ZeroFill sections must always be the at the end of their segments,
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// otherwise subsequent sections may get overwritten with zeroes at runtime.
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if (isZeroFill(osec->flags))
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if (sectionType(osec->flags) == S_ZEROFILL)
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return std::numeric_limits<int>::max();
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return 0;
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}
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@ -600,6 +618,9 @@ static void sortSegmentsAndSections() {
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if (!osec->isHidden())
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osec->index = ++sectionIndex;
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if (!firstTLVDataSection && isThreadLocalData(osec->flags))
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firstTLVDataSection = osec;
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if (!isecPriorities.empty()) {
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if (auto *merged = dyn_cast<MergedOutputSection>(osec)) {
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llvm::stable_sort(merged->inputs,
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@ -777,3 +798,5 @@ void macho::createSyntheticSections() {
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in.stubHelper = make<StubHelperSection>();
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in.imageLoaderCache = make<ImageLoaderCacheSection>();
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}
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OutputSection *macho::firstTLVDataSection = nullptr;
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@ -14,6 +14,8 @@
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namespace lld {
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namespace macho {
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class OutputSection;
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class LoadCommand {
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public:
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virtual ~LoadCommand() = default;
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@ -25,6 +27,8 @@ void writeResult();
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void createSyntheticSections();
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extern OutputSection *firstTLVDataSection;
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} // namespace macho
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} // namespace lld
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@ -3,8 +3,11 @@
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# RUN: %lld -o %t %t.o
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# RUN: llvm-readobj --section-headers --macho-segment %t | FileCheck %s
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## Check that __bss takes up zero file size, is at file offset zero, and
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## appears at the end of its segment.
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## Check that __bss takes up zero file size, is at file offset zero, and appears
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## at the end of its segment. Also check that __tbss is placed immediately
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## before it.
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## Zerofill sections in other segments (i.e. not __DATA) should also be placed
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## at the end.
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# CHECK: Index: 1
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# CHECK-NEXT: Name: __data
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@ -23,6 +26,22 @@
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# CHECK-NEXT: Reserved3: 0x0
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# CHECK: Index: 2
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# CHECK-NEXT: Name: __thread_bss
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# CHECK-NEXT: Segment: __DATA
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# CHECK-NEXT: Address:
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# CHECK-NEXT: Size: 0x4
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# CHECK-NEXT: Offset: 0
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# CHECK-NEXT: Alignment: 0
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# CHECK-NEXT: RelocationOffset: 0x0
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# CHECK-NEXT: RelocationCount: 0
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# CHECK-NEXT: Type: ThreadLocalZerofill (0x12)
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# CHECK-NEXT: Attributes [ (0x0)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Reserved1: 0x0
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# CHECK-NEXT: Reserved2: 0x0
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# CHECK-NEXT: Reserved3: 0x0
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# CHECK: Index: 3
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# CHECK-NEXT: Name: __bss
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# CHECK-NEXT: Segment: __DATA
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# CHECK-NEXT: Address:
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@ -38,16 +57,32 @@
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# CHECK-NEXT: Reserved2: 0x0
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# CHECK-NEXT: Reserved3: 0x0
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# CHECK: Index: 3
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# CHECK-NEXT: Name: __thread_bss
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# CHECK-NEXT: Segment: __DATA
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# CHECK-NEXT: Address: 0x100001010
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# CHECK-NEXT: Size: 0x4
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# CHECK: Index: 4
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# CHECK-NEXT: Name: foo
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# CHECK-NEXT: Segment: FOO
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# CHECK-NEXT: Address:
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# CHECK-NEXT: Size: 0x8
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# CHECK-NEXT: Offset: 8192
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# CHECK-NEXT: Alignment: 0
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# CHECK-NEXT: RelocationOffset: 0x0
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# CHECK-NEXT: RelocationCount: 0
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# CHECK-NEXT: Type: Regular (0x0)
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# CHECK-NEXT: Attributes [ (0x0)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Reserved1: 0x0
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# CHECK-NEXT: Reserved2: 0x0
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# CHECK-NEXT: Reserved3: 0x0
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# CHECK: Index: 5
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# CHECK-NEXT: Name: bss
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# CHECK-NEXT: Segment: FOO
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# CHECK-NEXT: Address:
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# CHECK-NEXT: Size: 0x8
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# CHECK-NEXT: Offset: 0
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# CHECK-NEXT: Alignment: 0
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# CHECK-NEXT: RelocationOffset: 0x0
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# CHECK-NEXT: RelocationCount: 0
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# CHECK-NEXT: Type: ThreadLocalZerofill (0x12)
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# CHECK-NEXT: Type: ZeroFill (0x1)
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# CHECK-NEXT: Attributes [ (0x0)
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# CHECK-NEXT: ]
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# CHECK-NEXT: Reserved1: 0x0
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@ -61,6 +96,13 @@
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# CHECK-NEXT: fileoff:
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# CHECK-NEXT: filesize: 8
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# CHECK: Name: FOO
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# CHECK-NEXT: Size:
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# CHECK-NEXT: vmaddr:
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# CHECK-NEXT: vmsize: 0x10
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# CHECK-NEXT: fileoff:
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# CHECK-NEXT: filesize: 8
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.globl _main
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.text
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@ -76,3 +118,8 @@ _main:
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.data
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.quad 0x1234
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.zerofill FOO,bss,_zero_foo,0x8
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.section FOO,foo
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.quad 123
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@ -1,53 +1,75 @@
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# REQUIRES: x86
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# RUN: mkdir -p %t
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# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %s -o %t/test.o
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# RUN: rm -rf %t; split-file %s %t
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# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/regular.s -o %t/regular.o
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# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-darwin %t/tbss.s -o %t/tbss.o
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# RUN: %lld -lSystem -o %t/test %t/test.o
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# RUN: llvm-readobj --file-headers %t/test | FileCheck %s --check-prefix=HEADER
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# RUN: llvm-objdump -D --bind --rebase %t/test | FileCheck %s
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# RUN: %lld -lSystem -no_pie -o %t/regular %t/regular.o
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# RUN: llvm-readobj --file-headers %t/regular | FileCheck %s --check-prefix=HEADER
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# RUN: llvm-objdump -d --bind --rebase %t/regular | FileCheck %s --check-prefixes=REG,LINKEDIT
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# RUN: llvm-objdump --macho --section=__DATA,__thread_vars %t/regular | \
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# RUN: FileCheck %s --check-prefix=REG-TLVP
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# RUN: %lld -lSystem -pie -o %t/test %t/test.o
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# RUN: llvm-readobj --file-headers %t/test | FileCheck %s --check-prefix=HEADER
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# RUN: llvm-objdump -D --bind --rebase %t/test | FileCheck %s
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# RUN: %lld -lSystem -pie %t/regular.o -o %t/regular-pie
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# RUN: llvm-readobj --file-headers %t/regular-pie | FileCheck %s --check-prefix=HEADER
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# RUN: llvm-objdump -d --bind --rebase %t/regular-pie | FileCheck %s --check-prefixes=REG,LINKEDIT
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# RUN: llvm-objdump --macho --section=__DATA,__thread_vars %t/regular-pie | \
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# RUN: FileCheck %s --check-prefix=REG-TLVP
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# RUN: %lld -lSystem %t/tbss.o -o %t/tbss -e _f
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# RUN: llvm-objdump -d --bind --rebase %t/tbss | FileCheck %s --check-prefixes=TBSS,LINKEDIT
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# RUN: llvm-objdump --macho --section=__DATA,__thread_vars %t/tbss | \
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# RUN: FileCheck %s --check-prefix=TBSS-TLVP
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# RUN: %lld -lSystem %t/regular.o %t/tbss.o -o %t/regular-and-tbss
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# RUN: llvm-objdump -d --bind --rebase %t/regular-and-tbss | FileCheck %s --check-prefixes=REG,TBSS,LINKEDIT
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# RUN: llvm-objdump --macho --section=__DATA,__thread_vars %t/regular-and-tbss | \
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# RUN: FileCheck %s --check-prefix=REG-TBSS-TLVP
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# RUN: llvm-objdump --section-headers %t/regular-and-tbss | FileCheck %s --check-prefix=SECTION-ORDER
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## Check that we always put __thread_bss immediately after __thread_data,
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## regardless of the order of the input files.
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# RUN: %lld -lSystem %t/tbss.o %t/regular.o -o %t/regular-and-tbss
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# RUN: llvm-objdump --section-headers %t/regular-and-tbss | FileCheck %s --check-prefix=SECTION-ORDER
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# HEADER: MH_HAS_TLV_DESCRIPTORS
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# CHECK: Disassembly of section __TEXT,__text:
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# CHECK-EMPTY:
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# CHECK-NEXT: <_main>:
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# CHECK-NEXT: leaq {{.*}}(%rip), %rax # {{.*}} <_foo>
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# CHECK-NEXT: leaq {{.*}}(%rip), %rax # {{.*}} <_bar>
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# CHECK-NEXT: retq
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# CHECK-EMPTY:
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# CHECK-NEXT: Disassembly of section __DATA,__thread_data:
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# CHECK-EMPTY:
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# CHECK-NEXT: <_foo$tlv$init>:
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# CHECK-NEXT: 00 00
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# CHECK-NEXT: 00 00
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# CHECK-EMPTY:
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# CHECK-NEXT: <_bar$tlv$init>:
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# CHECK-NEXT: 00 00
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# CHECK-NEXT: 00 00
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# CHECK-EMPTY:
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# CHECK-NEXT: Disassembly of section __DATA,__thread_vars:
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# CHECK-EMPTY:
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# CHECK-NEXT: <_foo>:
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# CHECK-NEXT: ...
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# CHECK-EMPTY:
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# CHECK-NEXT: <_bar>:
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# CHECK-NEXT: ...
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# CHECK-NEXT: 04 00
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# CHECK-NEXT: 00 00
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# CHECK-NEXT: 00 00
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# CHECK-NEXT: 00 00
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# REG: <_main>:
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# REG-NEXT: leaq {{.*}}(%rip), %rax # {{.*}} <_foo>
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# REG-NEXT: leaq {{.*}}(%rip), %rax # {{.*}} <_bar>
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# REG-NEXT: retq
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# TBSS: <_f>:
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# TBSS-NEXT: leaq {{.*}}(%rip), %rax # {{.*}} <_baz>
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# TBSS-NEXT: leaq {{.*}}(%rip), %rax # {{.*}} <_qux>
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# TBSS-NEXT: retq
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# REG-TLVP: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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# REG-TLVP-NEXT: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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# REG-TLVP-NEXT: 00 00 00 00 00 00 00 00 08 00 00 00 00 00 00 00
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# TBSS-TLVP: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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# TBSS-TLVP-NEXT: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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# TBSS-TLVP-NEXT: 00 00 00 00 00 00 00 00 08 00 00 00 00 00 00 00
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# REG-TBSS-TLVP: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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# REG-TBSS-TLVP-NEXT: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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# REG-TBSS-TLVP-NEXT: 00 00 00 00 00 00 00 00 08 00 00 00 00 00 00 00
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# REG-TBSS-TLVP-NEXT: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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# REG-TBSS-TLVP-NEXT: 10 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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# REG-TBSS-TLVP-NEXT: 00 00 00 00 00 00 00 00 18 00 00 00 00 00 00 00
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## Make sure we don't emit rebase opcodes for relocations in __thread_vars.
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# CHECK: Rebase table:
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# CHECK-NEXT: segment section address type
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# CHECK-NEXT: Bind table:
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# CHECK: __DATA __thread_vars 0x{{[0-9a-f]*}} pointer 0 libSystem __tlv_bootstrap
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# CHECK: __DATA __thread_vars 0x{{[0-9a-f]*}} pointer 0 libSystem __tlv_bootstrap
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# LINKEDIT: Rebase table:
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# LINKEDIT-NEXT: segment section address type
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# LINKEDIT-NEXT: Bind table:
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# LINKEDIT: __DATA __thread_vars 0x{{[0-9a-f]*}} pointer 0 libSystem __tlv_bootstrap
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# LINKEDIT: __DATA __thread_vars 0x{{[0-9a-f]*}} pointer 0 libSystem __tlv_bootstrap
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# SECTION-ORDER: __thread_data
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# SECTION-ORDER: more_thread_data
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# SECTION-ORDER-NEXT: __thread_bss
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#--- regular.s
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.globl _main
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_main:
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mov _foo@TLVP(%rip), %rax
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@ -56,9 +78,11 @@ _main:
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.section __DATA,__thread_data,thread_local_regular
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_foo$tlv$init:
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.space 4
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.quad 123
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.section __DATA,more_thread_data,thread_local_regular
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_bar$tlv$init:
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.space 4
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.quad 123
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.section __DATA,__thread_vars,thread_local_variables
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.globl _foo, _bar
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@ -70,3 +94,24 @@ _bar:
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.quad __tlv_bootstrap
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.quad 0
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.quad _bar$tlv$init
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#--- tbss.s
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.globl _f
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_f:
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mov _baz@TLVP(%rip), %rax
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mov _qux@TLVP(%rip), %rax
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ret
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.tbss _baz$tlv$init, 8, 3
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.tbss _qux$tlv$init, 8, 3
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.section __DATA,__thread_vars,thread_local_variables
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_baz:
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.quad __tlv_bootstrap
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.quad 0
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.quad _baz$tlv$init
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_qux:
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.quad __tlv_bootstrap
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.quad 0
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.quad _qux$tlv$init
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