[llvm] r204544 - ARM IAS: properly handle function entries in .thumb
NAKAMURA Takumi
geek4civic at gmail.com
Tue Apr 15 06:18:01 PDT 2014
2014-03-23 4:26 GMT+09:00 Saleem Abdulrasool <compnerd at compnerd.org>:
> Author: compnerd
> Date: Sat Mar 22 14:26:18 2014
> New Revision: 204544
>
> URL: http://llvm.org/viewvc/llvm-project?rev=204544&view=rev
> Log:
> ARM IAS: properly handle function entries in .thumb
>
> When a label is parsed, check if there is type information available for the
> label. If so, check if the symbol is a function. If the symbol is a function
> and we are in thumb mode and no explicit thumb_func has been emitted, adjust the
> symbol data to indicate that the function definition is a thumb function.
>
> The application of this inferencing is improved value handling in the object
> file (the required thumb bit is set on symbols which are thumb functions). It
> also helps improve compatibility with binutils.
>
> The one complication that arises from this handling is the MCAsmStreamer. The
> default implementation of getOrCreateSymbolData in MCStreamer does not support
> tracking the symbol data. In order to support the semantics of thumb functions,
> track symbol data in assembly streamer. Although O(n) in number of labels in
> the TU, this is already done in various other streamers and as such the memory
> overhead is not a practical concern in this scenario.
>
> Added:
> llvm/trunk/test/MC/ARM/thumb-types.s
> Modified:
> llvm/trunk/lib/MC/MCAsmStreamer.cpp
> llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
> llvm/trunk/test/MC/ARM/thumb_set.s
>
> Modified: llvm/trunk/lib/MC/MCAsmStreamer.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCAsmStreamer.cpp?rev=204544&r1=204543&r2=204544&view=diff
> ==============================================================================
> --- llvm/trunk/lib/MC/MCAsmStreamer.cpp (original)
> +++ llvm/trunk/lib/MC/MCAsmStreamer.cpp Sat Mar 22 14:26:18 2014
> @@ -57,6 +57,8 @@ private:
> EHPrivateExtern = 1 << 2 };
> DenseMap<const MCSymbol*, unsigned> FlagMap;
>
> + DenseMap<const MCSymbol*, MCSymbolData*> SymbolMap;
> +
> bool needsSet(const MCExpr *Value);
>
> void EmitRegisterName(int64_t Register);
> @@ -252,6 +254,8 @@ public:
> void EmitRawTextImpl(StringRef String) override;
>
> void FinishImpl() override;
> +
> + virtual MCSymbolData &getOrCreateSymbolData(const MCSymbol *Symbol) override;
> };
>
> } // end anonymous namespace.
> @@ -1417,6 +1421,15 @@ void MCAsmStreamer::FinishImpl() {
> EmitFrames(AsmBackend.get(), false);
> }
>
> +MCSymbolData &MCAsmStreamer::getOrCreateSymbolData(const MCSymbol *Symbol) {
> + MCSymbolData *&Entry = SymbolMap[Symbol];
> +
> + if (!Entry)
> + Entry = new MCSymbolData(*Symbol, 0, 0, 0);
It leaks. See http://lab.llvm.org:8011/builders/llvm-x86_64-linux-vg_leak
> +
> + return *Entry;
> +}
> +
> MCStreamer *llvm::createAsmStreamer(MCContext &Context,
> formatted_raw_ostream &OS,
> bool isVerboseAsm, bool useCFI,
>
> Modified: llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp?rev=204544&r1=204543&r2=204544&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp (original)
> +++ llvm/trunk/lib/Target/ARM/AsmParser/ARMAsmParser.cpp Sat Mar 22 14:26:18 2014
> @@ -25,7 +25,9 @@
> #include "llvm/MC/MCAssembler.h"
> #include "llvm/MC/MCContext.h"
> #include "llvm/MC/MCDisassembler.h"
> +#include "llvm/MC/MCELF.h"
> #include "llvm/MC/MCELFStreamer.h"
> +#include "llvm/MC/MCELFSymbolFlags.h"
> #include "llvm/MC/MCExpr.h"
> #include "llvm/MC/MCInst.h"
> #include "llvm/MC/MCInstrDesc.h"
> @@ -8085,6 +8087,7 @@ bool ARMAsmParser::parseDirectiveThumb(S
>
> if (!isThumb())
> SwitchMode();
> +
> getParser().getStreamer().EmitAssemblerFlag(MCAF_Code16);
> return false;
> }
> @@ -8105,6 +8108,7 @@ bool ARMAsmParser::parseDirectiveARM(SML
>
> if (isThumb())
> SwitchMode();
> +
> getParser().getStreamer().EmitAssemblerFlag(MCAF_Code32);
> return false;
> }
> @@ -8113,6 +8117,32 @@ void ARMAsmParser::onLabelParsed(MCSymbo
> if (NextSymbolIsThumb) {
> getParser().getStreamer().EmitThumbFunc(Symbol);
> NextSymbolIsThumb = false;
> + return;
> + }
> +
> + if (!isThumb())
> + return;
> +
> + const MCObjectFileInfo::Environment Format =
> + getContext().getObjectFileInfo()->getObjectFileType();
> + switch (Format) {
> + case MCObjectFileInfo::IsCOFF: {
> + const MCSymbolData &SD =
> + getParser().getStreamer().getOrCreateSymbolData(Symbol);
> + char Type = COFF::IMAGE_SYM_DTYPE_FUNCTION << COFF::SCT_COMPLEX_TYPE_SHIFT;
> + if (SD.getFlags() & (Type << COFF::SF_TypeShift))
> + getParser().getStreamer().EmitThumbFunc(Symbol);
> + break;
> + }
> + case MCObjectFileInfo::IsELF: {
> + const MCSymbolData &SD =
> + getParser().getStreamer().getOrCreateSymbolData(Symbol);
Who manages SD?
> + if (MCELF::GetType(SD) & (ELF::STT_FUNC << ELF_STT_Shift))
> + getParser().getStreamer().EmitThumbFunc(Symbol);
> + break;
> + }
> + case MCObjectFileInfo::IsMachO:
> + break;
> }
> }
>
>
> Added: llvm/trunk/test/MC/ARM/thumb-types.s
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/thumb-types.s?rev=204544&view=auto
> ==============================================================================
> --- llvm/trunk/test/MC/ARM/thumb-types.s (added)
> +++ llvm/trunk/test/MC/ARM/thumb-types.s Sat Mar 22 14:26:18 2014
> @@ -0,0 +1,82 @@
> +@ RUN: llvm-mc -triple armv7-elf -filetype obj -o - %s | llvm-readobj -t \
> +@ RUN: | FileCheck %s
> +
> + .syntax unified
> +
> + .thumb
> +
> + .type implicit_function,%function
> +implicit_function:
> + nop
> +
> + .type implicit_data,%object
> +implicit_data:
> + .long 0
> +
> + .arm
> + .type arm_function,%function
> +arm_function:
> + nop
> +
> + .thumb
> +
> + .text
> +
> +untyped_text_label:
> + nop
> +
> + .type explicit_function,%function
> +explicit_function:
> + nop
> +
> + .data
> +
> +untyped_data_label:
> + nop
> +
> + .type explicit_data,%object
> +explicit_data:
> + .long 0
> +
> +@ CHECK: Symbol {
> +@ CHECK: Name: arm_function
> +@ CHECK: Value: 0x6
> +@ CHECK: Type: Function
> +@ CHECK: }
> +
> +@ CHECK: Symbol {
> +@ CHECK: Name: explicit_data
> +@ CHECK: Value: 0x2
> +@ CHECK: Type: Object
> +@ CHECK: }
> +
> +@ CHECK: Symbol {
> +@ CHECK: Name: explicit_function
> +@ CHECK: Value: 0xD
> +@ CHECK: Type: Function
> +@ CHECK: }
> +
> +@ CHECK: Symbol {
> +@ CHECK: Name: implicit_data
> +@ CHECK: Value: 0x2
> +@ CHECK: Type: Object
> +@ CHECK: }
> +
> +@ CHECK: Symbol {
> +@ CHECK: Name: implicit_function
> +@ CHECK: Value: 0x1
> +@ CHECK: Type: Function
> +@ CHECK: }
> +
> +@ CHECK: Symbol {
> +@ CHECK: Name: untyped_data_label
> +@ CHECK: Value: 0x0
> +@ CHECK: Type: None
> +@ CHECK: }
> +
> +@ CHECK: Symbol {
> +@ CHECK: Name: untyped_text_label
> +@ CHECK: Value: 0xA
> +@ CHECK: Type: None
> +@ CHECK: }
> +
>
> Modified: llvm/trunk/test/MC/ARM/thumb_set.s
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ARM/thumb_set.s?rev=204544&r1=204543&r2=204544&view=diff
> ==============================================================================
> --- llvm/trunk/test/MC/ARM/thumb_set.s (original)
> +++ llvm/trunk/test/MC/ARM/thumb_set.s Sat Mar 22 14:26:18 2014
> @@ -79,8 +79,7 @@ beta:
>
> @ CHECK: Symbol {
> @ CHECK: Name: alpha
> -@ CHECK: Value: 0x6
> -@ XFAIL-CHECK: Value: 0x7
> +@ CHECK: Value: 0x7
> @ CHECK: Type: Function
> @ CHECK: }
>
>
>
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