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Dont emit Mapping symbols for sections that contain only data. 

Summary:
Dont emit mapping symbols for sections that contain only data.

Patched by Shankar Easwaran <shankare@codeaurora.org>

Reviewers: rengolin, peter.smith, weimingz, kparzysz, t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, llvm-commits

Differential Revision: https://reviews.llvm.org/D30724

llvm-svn: 298901
This commit is contained in:
Weiming Zhao 2017-03-28 05:40:36 +00:00
parent 6a8518086a
commit 320848458b
18 changed files with 177 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
llvm/include/llvm/MC/MCELFStreamer.h
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@ -42,6 +42,7 @@ public:
void InitSections(bool NoExecStack) override;
void ChangeSection(MCSection *Section, const MCExpr *Subsection) override;
void EmitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
void EmitLabel(MCSymbol *Symbol, SMLoc Loc, MCFragment *F) override;
void EmitAssemblerFlag(MCAssemblerFlag Flag) override;
void EmitThumbFunc(MCSymbol *Func) override;
void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) override;

1
llvm/include/llvm/MC/MCObjectStreamer.h
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@ -90,6 +90,7 @@ public:
/// @{
void EmitLabel(MCSymbol *Symbol, SMLoc Loc = SMLoc()) override;
virtual void EmitLabel(MCSymbol *Symbol, SMLoc Loc, MCFragment *F);
void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) override;
void EmitValueImpl(const MCExpr *Value, unsigned Size,
SMLoc Loc = SMLoc()) override;

10
llvm/lib/MC/MCELFStreamer.cpp
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@ -103,6 +103,16 @@ void MCELFStreamer::EmitLabel(MCSymbol *S, SMLoc Loc) {
Symbol->setType(ELF::STT_TLS);
}
void MCELFStreamer::EmitLabel(MCSymbol *S, SMLoc Loc, MCFragment *F) {
auto *Symbol = cast<MCSymbolELF>(S);
MCObjectStreamer::EmitLabel(Symbol, Loc, F);
const MCSectionELF &Section =
static_cast<const MCSectionELF &>(*getCurrentSectionOnly());
if (Section.getFlags() & ELF::SHF_TLS)
Symbol->setType(ELF::STT_TLS);
}
void MCELFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
// Let the target do whatever target specific stuff it needs to do.
getAssembler().getBackend().handleAssemblerFlag(Flag);

18
llvm/lib/MC/MCObjectStreamer.cpp
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@ -171,6 +171,16 @@ void MCObjectStreamer::EmitLabel(MCSymbol *Symbol, SMLoc Loc) {
}
}
void MCObjectStreamer::EmitLabel(MCSymbol *Symbol, SMLoc Loc, MCFragment *F) {
MCStreamer::EmitLabel(Symbol, Loc);
getAssembler().registerSymbol(*Symbol);
auto *DF = dyn_cast_or_null<MCDataFragment>(F);
if (DF)
Symbol->setFragment(F);
else
PendingLabels.push_back(Symbol);
}
void MCObjectStreamer::EmitULEB128Value(const MCExpr *Value) {
int64_t IntValue;
if (Value->evaluateAsAbsolute(IntValue, getAssembler())) {
@ -491,8 +501,8 @@ void MCObjectStreamer::EmitGPRel32Value(const MCExpr *Value) {
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
Value, FK_GPRel_4));
DF->getFixups().push_back(
MCFixup::create(DF->getContents().size(), Value, FK_GPRel_4));
DF->getContents().resize(DF->getContents().size() + 4, 0);
}
@ -501,8 +511,8 @@ void MCObjectStreamer::EmitGPRel64Value(const MCExpr *Value) {
MCDataFragment *DF = getOrCreateDataFragment();
flushPendingLabels(DF, DF->getContents().size());
DF->getFixups().push_back(MCFixup::create(DF->getContents().size(),
Value, FK_GPRel_4));
DF->getFixups().push_back(
MCFixup::create(DF->getContents().size(), Value, FK_GPRel_4));
DF->getContents().resize(DF->getContents().size() + 8, 0);
}

82
llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
View File

@ -464,13 +464,14 @@ public:
void emitUnwindRaw(int64_t Offset, const SmallVectorImpl<uint8_t> &Opcodes);
void ChangeSection(MCSection *Section, const MCExpr *Subsection) override {
// We have to keep track of the mapping symbol state of any sections we
// use. Each one should start off as EMS_None, which is provided as the
// default constructor by DenseMap::lookup.
LastMappingSymbols[getPreviousSection().first] = LastEMS;
LastEMS = LastMappingSymbols.lookup(Section);
LastMappingSymbols[getPreviousSection().first] = std::move(LastEMSInfo);
MCELFStreamer::ChangeSection(Section, Subsection);
auto LastMappingSymbol = LastMappingSymbols.find(Section);
if (LastMappingSymbol != LastMappingSymbols.end()) {
LastEMSInfo = std::move(LastMappingSymbol->second);
return;
}
LastEMSInfo.reset(new ElfMappingSymbolInfo(SMLoc(), nullptr, 0));
}
/// This function is the one used to emit instruction data into the ELF
@ -532,6 +533,14 @@ public:
MCELFStreamer::EmitBytes(Data);
}
void FlushPendingMappingSymbol() {
if (!LastEMSInfo->hasInfo())
return;
ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
EmitMappingSymbol("$d", EMS->Loc, EMS->F, EMS->Offset);
EMS->resetInfo();
}
/// This is one of the functions used to emit data into an ELF section, so the
/// ARM streamer overrides it to add the appropriate mapping symbol ($d) if
/// necessary.
@ -573,22 +582,54 @@ private:
EMS_Data
};
struct ElfMappingSymbolInfo {
explicit ElfMappingSymbolInfo(SMLoc Loc, MCFragment *F, uint64_t O)
: Loc(Loc), F(F), Offset(O), State(EMS_None) {}
void resetInfo() {
F = nullptr;
Offset = 0;
}
bool hasInfo() { return F != nullptr; }
SMLoc Loc;
MCFragment *F;
uint64_t Offset;
ElfMappingSymbol State;
};
void EmitDataMappingSymbol() {
if (LastEMS == EMS_Data) return;
if (LastEMSInfo->State == EMS_Data)
return;
else if (LastEMSInfo->State == EMS_None) {
// This is a tentative symbol, it won't really be emitted until it's
// actually needed.
ElfMappingSymbolInfo *EMS = LastEMSInfo.get();
auto *DF = dyn_cast_or_null<MCDataFragment>(getCurrentFragment());
if (!DF)
return;
EMS->Loc = SMLoc();
EMS->F = getCurrentFragment();
EMS->Offset = DF->getContents().size();
LastEMSInfo->State = EMS_Data;
return;
}
EmitMappingSymbol("$d");
LastEMS = EMS_Data;
LastEMSInfo->State = EMS_Data;
}
void EmitThumbMappingSymbol() {
if (LastEMS == EMS_Thumb) return;
if (LastEMSInfo->State == EMS_Thumb)
return;
FlushPendingMappingSymbol();
EmitMappingSymbol("$t");
LastEMS = EMS_Thumb;
LastEMSInfo->State = EMS_Thumb;
}
void EmitARMMappingSymbol() {
if (LastEMS == EMS_ARM) return;
if (LastEMSInfo->State == EMS_ARM)
return;
FlushPendingMappingSymbol();
EmitMappingSymbol("$a");
LastEMS = EMS_ARM;
LastEMSInfo->State = EMS_ARM;
}
void EmitMappingSymbol(StringRef Name) {
@ -601,6 +642,17 @@ private:
Symbol->setExternal(false);
}
void EmitMappingSymbol(StringRef Name, SMLoc Loc, MCFragment *F,
uint64_t Offset) {
auto *Symbol = cast<MCSymbolELF>(getContext().getOrCreateSymbol(
Name + "." + Twine(MappingSymbolCounter++)));
EmitLabel(Symbol, Loc, F);
Symbol->setType(ELF::STT_NOTYPE);
Symbol->setBinding(ELF::STB_LOCAL);
Symbol->setExternal(false);
Symbol->setOffset(Offset);
}
void EmitThumbFunc(MCSymbol *Func) override {
getAssembler().setIsThumbFunc(Func);
EmitSymbolAttribute(Func, MCSA_ELF_TypeFunction);
@ -626,8 +678,10 @@ private:
bool IsThumb;
int64_t MappingSymbolCounter = 0;
DenseMap<const MCSection *, ElfMappingSymbol> LastMappingSymbols;
ElfMappingSymbol LastEMS = EMS_None;
DenseMap<const MCSection *, std::unique_ptr<ElfMappingSymbolInfo>>
LastMappingSymbols;
std::unique_ptr<ElfMappingSymbolInfo> LastEMSInfo;
// ARM Exception Handling Frame Information
MCSymbol *ExTab;

3
llvm/test/MC/ARM/Inputs/1.s Normal file
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@ -0,0 +1,3 @@
.section .foobar,"ax",%progbits
nop
.word 32

3
llvm/test/MC/ARM/Inputs/2.s Normal file
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@ -0,0 +1,3 @@
.section .foobar,"",%progbits
nop
.word 32

3
llvm/test/MC/ARM/Inputs/3.s Normal file
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@ -0,0 +1,3 @@
.section .foobar,"aw",%progbits
nop
.word 32

2
llvm/test/MC/ARM/Inputs/4.s Normal file
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@ -0,0 +1,2 @@
.section .foobar,"",%progbits
.word 32

2
llvm/test/MC/ARM/Inputs/5.s Normal file
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@ -0,0 +1,2 @@
.section .foobar,"aw",%progbits
.word 32

12
llvm/test/MC/ARM/Inputs/6.s Normal file
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@ -0,0 +1,12 @@
.section .foo
.word 30
.word 31
.word 32
.word 33
nop
.word 34
.word 35
.word 36
.word 37
.word 38
nop

3
llvm/test/MC/ARM/Inputs/7.s Normal file
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@ -0,0 +1,3 @@
.section .foobar,"aw",%progbits
.word 32
nop

5
llvm/test/MC/ARM/Inputs/attr.s Normal file
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@ -0,0 +1,5 @@
.text
.syntax unified
.eabi_attribute 67, "2.09" @ Tag_conformance
.cpu arm7tdmi
.eabi_attribute 6, 2 @ Tag_CPU_arch

1
llvm/test/MC/ARM/Inputs/ident.s Normal file
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@ -0,0 +1 @@
.ident "LLVM ARM Compiler"

17
llvm/test/MC/ARM/data-in-code.ll
View File

@ -60,23 +60,6 @@ exit:
;; ARM-NEXT: Other:
;; ARM-NEXT: Section: [[MIXED_SECT]]
;; ARM: Symbol {
;; ARM: Name: $d
;; ARM-NEXT: Value: 0x0
;; ARM-NEXT: Size: 0
;; ARM-NEXT: Binding: Local (0x0)
;; ARM-NEXT: Type: None (0x0)
;; ARM-NEXT: Other: 0
;; ARM-NEXT: Section: .ARM.exidx
;; ARM-NEXT: }
;; ARM: Symbol {
;; ARM: Name: $d
;; ARM-NEXT: Value: 0
;; ARM-NEXT: Size: 0
;; ARM-NEXT: Binding: Local
;; ARM-NEXT: Type: None
;; ARM-NOT: ${{[atd]}}
;; TMB: Symbol {

48
llvm/test/MC/ARM/mappingsymbols.s Normal file
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@ -0,0 +1,48 @@
# Check section containing code and data with permission executable for the section.
@ RUN: llvm-mc -triple armv7-none-linux -filetype=obj -o %t.o %p/Inputs/1.s
@ RUN: llvm-readobj -elf-output-style=GNU -symbols %t.o | FileCheck %s
# Check section containing code and data with no permissions for the section.
@ RUN: llvm-mc -triple armv7-none-linux -filetype=obj -o %t.o %p/Inputs/2.s
@ RUN: llvm-readobj -elf-output-style=GNU -symbols %t.o | FileCheck %s
# Check section containing code and data with read/write permissions for the section.
@ RUN: llvm-mc -triple armv7-none-linux -filetype=obj -o %t.o %p/Inputs/3.s
@ RUN: llvm-readobj -elf-output-style=GNU -symbols %t.o | FileCheck %s
# Check section containing data with no permissions for the section.
@ RUN: llvm-mc -triple armv7-none-linux -filetype=obj -o %t.o %p/Inputs/4.s
@ RUN: llvm-readobj -elf-output-style=GNU -symbols %t.o | FileCheck %s -check-prefix=MAPPINGSYMBOLS
# Check section containing only data with read/write permissions for the section.
@ RUN: llvm-mc -triple armv7-none-linux -filetype=obj -o %t.o %p/Inputs/5.s
@ RUN: llvm-readobj -elf-output-style=GNU -symbols %t.o | FileCheck %s -check-prefix=MAPPINGSYMBOLS
# Check section containing the ident string with no permissions for the section.
@ RUN: llvm-mc -triple armv7-none-linux -filetype=obj -o %t.o %p/Inputs/ident.s
@ RUN: llvm-readobj -elf-output-style=GNU -symbols %t.o | FileCheck %s -check-prefix=MAPPINGSYMBOLS
# Check section containing the attributes with no permissions for the section.
@ RUN: llvm-mc -triple armv7-none-linux -filetype=obj -o %t.o %p/Inputs/attr.s
@ RUN: llvm-readobj -elf-output-style=GNU -symbols %t.o | FileCheck %s -check-prefix=MAPPINGSYMBOLS
# Check section containing code and data with no permissions for the section.
# data comes before code.
@ RUN: llvm-mc -triple armv7-none-linux -filetype=obj -o %t.o %p/Inputs/6.s
@ RUN: llvm-readobj -elf-output-style=GNU -symbols %t.o | FileCheck %s -check-prefix=MIX
# Check section containing code and data with no permissions for the section.
# data comes before code.
@ RUN: llvm-mc -triple armv7-none-linux -filetype=obj -o %t.o %p/Inputs/7.s
@ RUN: llvm-readobj -elf-output-style=GNU -symbols %t.o | FileCheck %s
#CHECK: $a
#CHECK: $d
#MIX: $a
#MIX: $a
#MIX: $d
#MIX: $d
#MAPPINGSYMBOLS-NOT: $a
#MAPPINGSYMBOLS-NOT: $d

1
llvm/test/MC/ARM/multi-section-mapping.s
View File

@ -29,7 +29,6 @@
@ CHECK: 00000000 .text 00000000 $a
@ CHECK-NEXT: 00000000 .wibble 00000000 $a
@ CHECK-NEXT: 00000000 .starts_data 00000000 $d
@ CHECK-NEXT: 00000000 .starts_thumb 00000000 $t
@ CHECK-NOT: ${{[adt]}}

1
llvm/test/Object/ARM/nm-mapping-symbol.s
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@ -9,3 +9,4 @@
.section .foobar,"",%progbits
.asciz "foo"
nop