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Don't declare all text sections at the start of the .s

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The code this patch removes was there to make sure the text sections went
before the dwarf sections. That is necessary because MachO uses offsets
relative to the start of the file, so adding a section can change relaxations.

The dwarf sections were being printed at the start just to produce symbols
pointing at the start of those sections.

The underlying issue was fixed in r231898. The dwarf sections are now printed
when they are about to be used, which is after we printed the text sections.

To make sure we don't regress, the patch makes the MachO streamer assert
if CodeGen puts anything unexpected after the DWARF sections.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232842 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2015-03-20 20:00:01 +00:00
parent e9994ab8a7
commit d80979b25d
14 changed files with 108 additions and 127 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/llvm/MC/MCObjectStreamer.h
View File

@ -85,6 +85,8 @@ protected:
/// fragment is not a data fragment.
MCDataFragment *getOrCreateDataFragment();
bool changeSectionImpl(const MCSection *Section, const MCExpr *Subsection);
public:
void visitUsedSymbol(const MCSymbol &Sym) override;

20
include/llvm/Support/TargetRegistry.h
View File

@ -65,7 +65,8 @@ namespace llvm {
bool RelaxAll);
MCStreamer *createMachOStreamer(MCContext &Ctx, MCAsmBackend &TAB,
raw_ostream &OS, MCCodeEmitter *CE,
bool RelaxAll, bool LabelSections = false);
bool RelaxAll, bool DWARFMustBeAtTheEnd,
bool LabelSections = false);
MCRelocationInfo *createMCRelocationInfo(StringRef TT, MCContext &Ctx);
@ -138,11 +139,9 @@ namespace llvm {
MCAsmBackend &TAB, raw_ostream &OS,
MCCodeEmitter *Emitter,
bool RelaxAll);
typedef MCStreamer *(*MachOStreamerCtorTy)(MCContext &Ctx,
MCAsmBackend &TAB,
raw_ostream &OS,
MCCodeEmitter *Emitter,
bool RelaxAll);
typedef MCStreamer *(*MachOStreamerCtorTy)(
MCContext &Ctx, MCAsmBackend &TAB, raw_ostream &OS,
MCCodeEmitter *Emitter, bool RelaxAll, bool DWARFMustBeAtTheEnd);
typedef MCStreamer *(*COFFStreamerCtorTy)(MCContext &Ctx, MCAsmBackend &TAB,
raw_ostream &OS,
MCCodeEmitter *Emitter,
@ -444,7 +443,8 @@ namespace llvm {
MCAsmBackend &TAB, raw_ostream &OS,
MCCodeEmitter *Emitter,
const MCSubtargetInfo &STI,
bool RelaxAll) const {
bool RelaxAll,
bool DWARFMustBeAtTheEnd) const {
MCStreamer *S;
switch (T.getObjectFormat()) {
default:
@ -455,9 +455,11 @@ namespace llvm {
break;
case Triple::MachO:
if (MachOStreamerCtorFn)
S = MachOStreamerCtorFn(Ctx, TAB, OS, Emitter, RelaxAll);
S = MachOStreamerCtorFn(Ctx, TAB, OS, Emitter, RelaxAll,
DWARFMustBeAtTheEnd);
else
S = createMachOStreamer(Ctx, TAB, OS, Emitter, RelaxAll);
S = createMachOStreamer(Ctx, TAB, OS, Emitter, RelaxAll,
DWARFMustBeAtTheEnd);
break;
case Triple::ELF:
if (ELFStreamerCtorFn)

6
lib/CodeGen/LLVMTargetMachine.cpp
View File

@ -202,7 +202,8 @@ bool LLVMTargetMachine::addPassesToEmitFile(PassManagerBase &PM,
Triple T(getTargetTriple());
AsmStreamer.reset(getTarget().createMCObjectStreamer(
T, *Context, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll));
T, *Context, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll,
/*DWARFMustBeAtTheEnd*/ true));
break;
}
case CGFT_Null:
@ -253,7 +254,8 @@ bool LLVMTargetMachine::addPassesToEmitMC(PassManagerBase &PM,
Triple T(getTargetTriple());
const MCSubtargetInfo &STI = *getMCSubtargetInfo();
std::unique_ptr<MCStreamer> AsmStreamer(getTarget().createMCObjectStreamer(
T, *Ctx, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll));
T, *Ctx, *MAB, Out, MCE, STI, Options.MCOptions.MCRelaxAll,
/*DWARFMustBeAtTheEnd*/ true));
// Create the AsmPrinter, which takes ownership of AsmStreamer if successful.
FunctionPass *Printer =

49
lib/MC/MCMachOStreamer.cpp
View File

@ -40,6 +40,9 @@ private:
/// need for local relocations. False by default.
bool LabelSections;
bool DWARFMustBeAtTheEnd;
bool CreatedADWARFSection;
/// HasSectionLabel - map of which sections have already had a non-local
/// label emitted to them. Used so we don't emit extraneous linker local
/// labels in the middle of the section.
@ -52,9 +55,9 @@ private:
public:
MCMachOStreamer(MCContext &Context, MCAsmBackend &MAB, raw_ostream &OS,
MCCodeEmitter *Emitter, bool label)
: MCObjectStreamer(Context, MAB, OS, Emitter),
LabelSections(label) {}
MCCodeEmitter *Emitter, bool DWARFMustBeAtTheEnd, bool label)
: MCObjectStreamer(Context, MAB, OS, Emitter), LabelSections(label),
DWARFMustBeAtTheEnd(DWARFMustBeAtTheEnd), CreatedADWARFSection(false) {}
/// state management
void reset() override {
@ -120,10 +123,43 @@ public:
} // end anonymous namespace.
static bool canGoAfterDWARF(const MCSectionMachO &MSec) {
// These sections are created by the assembler itself after the end of
// the .s file.
StringRef SegName = MSec.getSegmentName();
StringRef SecName = MSec.getSectionName();
if (SegName == "__LD" && SecName == "__compact_unwind")
return true;
if (SegName == "__IMPORT") {
if (SecName == "__jump_table")
return true;
if (SecName == "__pointers")
return true;
}
if (SegName == "__TEXT" && SecName == "__eh_frame")
return true;
if (SegName == "__DATA" && SecName == "__nl_symbol_ptr")
return true;
return false;
}
void MCMachOStreamer::ChangeSection(const MCSection *Section,
const MCExpr *Subsection) {
// Change the section normally.
MCObjectStreamer::ChangeSection(Section, Subsection);
bool Created = MCObjectStreamer::changeSectionImpl(Section, Subsection);
const MCSectionMachO &MSec = *cast<MCSectionMachO>(Section);
StringRef SegName = MSec.getSegmentName();
if (SegName == "__DWARF")
CreatedADWARFSection = true;
else if (Created && DWARFMustBeAtTheEnd && !canGoAfterDWARF(MSec))
assert(!CreatedADWARFSection && "Creating regular section after DWARF");
// Output a linker-local symbol so we don't need section-relative local
// relocations. The linker hates us when we do that.
if (LabelSections && !HasSectionLabel[Section]) {
@ -456,9 +492,10 @@ void MCMachOStreamer::FinishImpl() {
MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
raw_ostream &OS, MCCodeEmitter *CE,
bool RelaxAll,
bool RelaxAll, bool DWARFMustBeAtTheEnd,
bool LabelSections) {
MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE, LabelSections);
MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE,
DWARFMustBeAtTheEnd, LabelSections);
if (RelaxAll)
S->getAssembler().setRelaxAll(true);
return S;

9
lib/MC/MCObjectStreamer.cpp
View File

@ -182,10 +182,16 @@ void MCObjectStreamer::EmitWeakReference(MCSymbol *Alias,
void MCObjectStreamer::ChangeSection(const MCSection *Section,
const MCExpr *Subsection) {
changeSectionImpl(Section, Subsection);
}
bool MCObjectStreamer::changeSectionImpl(const MCSection *Section,
const MCExpr *Subsection) {
assert(Section && "Cannot switch to a null section!");
flushPendingLabels(nullptr);
CurSectionData = &getAssembler().getOrCreateSectionData(*Section);
bool Created;
CurSectionData = &getAssembler().getOrCreateSectionData(*Section, &Created);
int64_t IntSubsection = 0;
if (Subsection &&
@ -195,6 +201,7 @@ void MCObjectStreamer::ChangeSection(const MCSection *Section,
report_fatal_error("Subsection number out of range");
CurInsertionPoint =
CurSectionData->getSubsectionInsertionPoint(unsigned(IntSubsection));
return Created;
}
void MCObjectStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {

4
lib/Target/AArch64/MCTargetDesc/AArch64MCTargetDesc.cpp
View File

@ -131,8 +131,10 @@ static MCStreamer *createELFStreamer(const Triple &T, MCContext &Ctx,
static MCStreamer *createMachOStreamer(MCContext &Ctx, MCAsmBackend &TAB,
raw_ostream &OS, MCCodeEmitter *Emitter,
bool RelaxAll) {
bool RelaxAll,
bool DWARFMustBeAtTheEnd) {
return createMachOStreamer(Ctx, TAB, OS, Emitter, RelaxAll,
DWARFMustBeAtTheEnd,
/*LabelSections*/ true);
}

59
lib/Target/ARM/ARMAsmPrinter.cpp
View File

@ -435,65 +435,6 @@ void ARMAsmPrinter::emitInlineAsmEnd(const MCSubtargetInfo &StartInfo,
void ARMAsmPrinter::EmitStartOfAsmFile(Module &M) {
Triple TT(TM.getTargetTriple());
if (TT.isOSBinFormatMachO()) {
Reloc::Model RelocM = TM.getRelocationModel();
if (RelocM == Reloc::PIC_ || RelocM == Reloc::DynamicNoPIC) {
// Declare all the text sections up front (before the DWARF sections
// emitted by AsmPrinter::doInitialization) so the assembler will keep
// them together at the beginning of the object file. This helps
// avoid out-of-range branches that are due a fundamental limitation of
// the way symbol offsets are encoded with the current Darwin ARM
// relocations.
const TargetLoweringObjectFileMachO &TLOFMacho =
static_cast<const TargetLoweringObjectFileMachO &>(
getObjFileLowering());
// Collect the set of sections our functions will go into.
SetVector<const MCSection *, SmallVector<const MCSection *, 8>,
SmallPtrSet<const MCSection *, 8> > TextSections;
// Default text section comes first.
TextSections.insert(TLOFMacho.getTextSection());
// Now any user defined text sections from function attributes.
for (Module::iterator F = M.begin(), e = M.end(); F != e; ++F)
if (!F->isDeclaration() && !F->hasAvailableExternallyLinkage())
TextSections.insert(TLOFMacho.SectionForGlobal(F, *Mang, TM));
// Now the coalescable sections.
TextSections.insert(TLOFMacho.getTextCoalSection());
TextSections.insert(TLOFMacho.getConstTextCoalSection());
// Emit the sections in the .s file header to fix the order.
for (unsigned i = 0, e = TextSections.size(); i != e; ++i)
OutStreamer.SwitchSection(TextSections[i]);
if (RelocM == Reloc::DynamicNoPIC) {
const MCSection *sect =
OutContext.getMachOSection("__TEXT", "__symbol_stub4",
MachO::S_SYMBOL_STUBS,
12, SectionKind::getText());
OutStreamer.SwitchSection(sect);
} else {
const MCSection *sect =
OutContext.getMachOSection("__TEXT", "__picsymbolstub4",
MachO::S_SYMBOL_STUBS,
16, SectionKind::getText());
OutStreamer.SwitchSection(sect);
}
const MCSection *StaticInitSect =
OutContext.getMachOSection("__TEXT", "__StaticInit",
MachO::S_REGULAR |
MachO::S_ATTR_PURE_INSTRUCTIONS,
SectionKind::getText());
OutStreamer.SwitchSection(StaticInitSect);
}
// Compiling with debug info should not affect the code
// generation. Ensure the cstring section comes before the
// optional __DWARF secion. Otherwise, PC-relative loads would
// have to use different instruction sequences at "-g" in order to
// reach global data in the same object file.
OutStreamer.SwitchSection(getObjFileLowering().getCStringSection());
}
// Use unified assembler syntax.
OutStreamer.EmitAssemblerFlag(MCAF_SyntaxUnified);

6
lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp
View File

@ -307,9 +307,9 @@ static MCStreamer *createELFStreamer(const Triple &T, MCContext &Ctx,
static MCStreamer *createARMMachOStreamer(MCContext &Ctx, MCAsmBackend &MAB,
raw_ostream &OS,
MCCodeEmitter *Emitter,
bool RelaxAll) {
return createMachOStreamer(Ctx, MAB, OS, Emitter, false);
MCCodeEmitter *Emitter, bool RelaxAll,
bool DWARFMustBeAtTheEnd) {
return createMachOStreamer(Ctx, MAB, OS, Emitter, false, DWARFMustBeAtTheEnd);
}
static MCInstPrinter *createARMMCInstPrinter(const Target &T,

21
test/CodeGen/ARM/darwin-section-order.ll
View File

@ -1,21 +0,0 @@
; RUN: llc < %s -mtriple=armv7-apple-darwin | FileCheck %s
; CHECK: .section __TEXT,__text,regular,pure_instructions
; CHECK: .section __TEXT,myprecious
; CHECK: .section __TEXT,__textcoal_nt,coalesced,pure_instructions
; CHECK: .section __TEXT,__const_coal,coalesced
; CHECK: .section __TEXT,__picsymbolstub4,symbol_stubs,none,16
; CHECK: .section __TEXT,__StaticInit,regular,pure_instructions
define void @normal() nounwind readnone {
; CHECK: .section __TEXT,__text,regular,pure_instructions
; CHECK: _normal:
ret void
}
define void @special() nounwind readnone section "__TEXT,myprecious" {
; CHECK: .section __TEXT,myprecious
; CHECK: _special:
ret void
}

5
test/CodeGen/ARM/none-macho.ll
View File

@ -2,11 +2,6 @@
; RUN: llc -mtriple=thumbv7m-none-macho -O0 %s -o - -relocation-model=pic -disable-fp-elim | FileCheck %s
; RUN: llc -mtriple=thumbv7m-none-macho -filetype=obj %s -o /dev/null
; Bare-metal should probably "declare" segments just like normal MachO
; CHECK: __picsymbolstub4
; CHECK: __StaticInit
; CHECK: __text
@var = external global i32
define i32 @test_litpool() minsize {

30
test/DebugInfo/ARM/header.ll Normal file
View File

@ -0,0 +1,30 @@
; RUN: llc -mtriple armv7-apple-darwin < %s | FileCheck %s
; Test that we don't pollute the start of the file with debug sections.
; This is particularly important on ARM MachO as a change in section order can
; cause a change the relaxation of the instructions used.
; CHECK: .section __TEXT,__text,regular,pure_instructions
; CHECK-NEXT: .syntax unified
; CHECK-NEXT: .globl _f
; CHECK-NEXT: .align 2
; CHECK-NEXT: _f: @ @f
; CHECK: .section __DWARF,__debug_str,regular,debug
define void @f() {
ret void, !dbg !9
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!7, !8}
!0 = !MDCompileUnit(language: DW_LANG_C99, file: !1, producer: "foo", isOptimized: true, runtimeVersion: 0, emissionKind: 1, enums: !2, retainedTypes: !2, subprograms: !3, globals: !2, imports: !2)
!1 = !MDFile(filename: "/foo/test.c", directory: "/foo")
!2 = !{}
!3 = !{!4}
!4 = !MDSubprogram(name: "f", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, function: void ()* @f, variables: !2)
!5 = !MDSubroutineType(types: !6)
!6 = !{null}
!7 = !{i32 2, !"Dwarf Version", i32 4}
!8 = !{i32 2, !"Debug Info Version", i32 3}
!9 = !MDLocation(line: 1, column: 15, scope: !4)

18
test/DebugInfo/ARM/sectionorder.ll
View File

@ -1,18 +0,0 @@
; RUN: llc -filetype=asm %s -o - | FileCheck %s
; Verifies that the DWARF* sections come _after_ the __TEXT sections.
; rdar://problem/15623193
; CHECK: .section __TEXT,__text,
; CHECK-NOT: __DWARF,__debug
; CHECK: .section __TEXT,__cstring,cstring_literals
target triple = "thumbv7-apple-ios"
!llvm.module.flags = !{!3, !4}
!llvm.dbg.cu = !{!0}
!0 = !MDCompileUnit(language: DW_LANG_C99, producer: "LLVM", isOptimized: true, file: !5, enums: !1, retainedTypes: !1, subprograms: !1, globals: !1)
!1 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 2}
!4 = !{i32 1, !"Debug Info Version", i32 3}
!5 = !MDFile(filename: "test.c", directory: "/Volumes/Data/radar/15623193")

3
tools/dsymutil/DwarfLinker.cpp
View File

@ -511,7 +511,8 @@ bool DwarfStreamer::init(Triple TheTriple, StringRef OutputFilename) {
return error(Twine(OutputFilename) + ": " + EC.message(), Context);
MS = TheTarget->createMCObjectStreamer(TheTriple, *MC, *MAB, *OutFile, MCE,
*MSTI, false);
*MSTI, false,
/*DWARFMustBeAtTheEnd*/ false);
if (!MS)
return error("no object streamer for target " + TripleName, Context);

3
tools/llvm-mc/llvm-mc.cpp
View File

@ -472,7 +472,8 @@ int main(int argc, char **argv) {
MCCodeEmitter *CE = TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx);
MCAsmBackend *MAB = TheTarget->createMCAsmBackend(*MRI, TripleName, MCPU);
Str.reset(TheTarget->createMCObjectStreamer(TheTriple, Ctx, *MAB, FOS, CE,
*STI, RelaxAll));
*STI, RelaxAll,
/*DWARFMustBeAtTheEnd*/ false));
if (NoExecStack)
Str->InitSections(true);
}