[llvm-commits] [llvm] r170279 - in /llvm/trunk: include/llvm/MC/ lib/CodeGen/AsmPrinter/ lib/MC/ lib/Target/Mips/MCTargetDesc/ test/CodeGen/Mips/ tools/lto/
Eli Friedman
eli.friedman at gmail.com
Mon Dec 17 15:56:12 PST 2012
On Sat, Dec 15, 2012 at 8:00 PM, Reed Kotler <rkotler at mips.com> wrote:
> Author: rkotler
> Date: Sat Dec 15 22:00:45 2012
> New Revision: 170279
>
> URL: http://llvm.org/viewvc/llvm-project?rev=170279&view=rev
> Log:
> This patch is needed to make c++ exceptions work for mips16.
>
> Mips16 is really a processor decoding mode (ala thumb 1) and in the same
> program, mips16 and mips32 functions can exist and can call each other.
>
> If a jal type instruction encounters an address with the lower bit set, then
> the processor switches to mips16 mode (if it is not already in it). If the
> lower bit is not set, then it switches to mips32 mode.
>
> The linker knows which functions are mips16 and which are mips32.
> When relocation is performed on code labels, this lower order bit is
> set if the code label is a mips16 code label.
>
> In general this works just fine, however when creating exception handling
> tables and dwarf, there are cases where you don't want this lower order
> bit added in.
>
> This has been traditionally distinguished in gas assembly source by using a
> different syntax for the label.
>
> lab1: ; this will cause the lower order bit to be added
> lab2=. ; this will not cause the lower order bit to be added
>
> In some cases, it does not matter because in dwarf and debug tables
> the difference of two labels is used and in that case the lower order
> bits subtract each other out.
>
> To fix this, I have added to mcstreamer the notion of a debuglabel.
> The default is for label and debug label to be the same. So calling
> EmitLabel and EmitDebugLabel produce the same result.
>
> For various reasons, there is only one set of labels that needs to be
> modified for the mips exceptions to work. These are the "$eh_func_beginXXX"
> labels.
>
> Mips overrides the debug label suffix from ":" to "=." .
>
> This initial patch fixes exceptions. More changes most likely
> will be needed to DwarfCFException to make all of this work
> for actual debugging. These changes will be to emit debug labels in some
> places where a simple label is emitted now.
>
> Some historical discussion on this from gcc can be found at:
> http://gcc.gnu.org/ml/gcc-patches/2008-08/msg00623.html
> http://gcc.gnu.org/ml/gcc-patches/2008-11/msg01273.html
>
>
> Added:
> llvm/trunk/test/CodeGen/Mips/mips16ex.ll
> Modified:
> llvm/trunk/include/llvm/MC/MCAsmInfo.h
> llvm/trunk/include/llvm/MC/MCELFStreamer.h
> llvm/trunk/include/llvm/MC/MCObjectStreamer.h
> llvm/trunk/include/llvm/MC/MCStreamer.h
> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
> llvm/trunk/lib/MC/MCAsmInfo.cpp
> llvm/trunk/lib/MC/MCAsmStreamer.cpp
> llvm/trunk/lib/MC/MCELFStreamer.cpp
> llvm/trunk/lib/MC/MCMachOStreamer.cpp
> llvm/trunk/lib/MC/MCNullStreamer.cpp
> llvm/trunk/lib/MC/MCObjectStreamer.cpp
> llvm/trunk/lib/MC/MCPureStreamer.cpp
> llvm/trunk/lib/MC/MCStreamer.cpp
> llvm/trunk/lib/MC/WinCOFFStreamer.cpp
> llvm/trunk/lib/Target/Mips/MCTargetDesc/MipsMCAsmInfo.cpp
> llvm/trunk/tools/lto/LTOModule.cpp
>
> Modified: llvm/trunk/include/llvm/MC/MCAsmInfo.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCAsmInfo.h?rev=170279&r1=170278&r2=170279&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/MC/MCAsmInfo.h (original)
> +++ llvm/trunk/include/llvm/MC/MCAsmInfo.h Sat Dec 15 22:00:45 2012
> @@ -102,6 +102,9 @@
> /// LabelSuffix - This is appended to emitted labels.
> const char *LabelSuffix; // Defaults to ":"
>
> + /// LabelSuffix - This is appended to emitted labels.
> + const char *DebugLabelSuffix; // Defaults to ":"
> +
> /// GlobalPrefix - If this is set to a non-empty string, it is prepended
> /// onto all global symbols. This is often used for "_" or ".".
> const char *GlobalPrefix; // Defaults to ""
> @@ -426,6 +429,11 @@
> const char *getLabelSuffix() const {
> return LabelSuffix;
> }
> +
> + const char *getDebugLabelSuffix() const {
> + return DebugLabelSuffix;
> + }
> +
> const char *getGlobalPrefix() const {
> return GlobalPrefix;
> }
>
> Modified: llvm/trunk/include/llvm/MC/MCELFStreamer.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCELFStreamer.h?rev=170279&r1=170278&r2=170279&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/MC/MCELFStreamer.h (original)
> +++ llvm/trunk/include/llvm/MC/MCELFStreamer.h Sat Dec 15 22:00:45 2012
> @@ -47,6 +47,7 @@
> virtual void InitSections();
> virtual void ChangeSection(const MCSection *Section);
> virtual void EmitLabel(MCSymbol *Symbol);
> + virtual void EmitDebugLabel(MCSymbol *Symbol);
> virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
> virtual void EmitThumbFunc(MCSymbol *Func);
> virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol);
>
> Modified: llvm/trunk/include/llvm/MC/MCObjectStreamer.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCObjectStreamer.h?rev=170279&r1=170278&r2=170279&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/MC/MCObjectStreamer.h (original)
> +++ llvm/trunk/include/llvm/MC/MCObjectStreamer.h Sat Dec 15 22:00:45 2012
> @@ -69,6 +69,7 @@
> /// @{
>
> virtual void EmitLabel(MCSymbol *Symbol);
> + virtual void EmitDebugLabel(MCSymbol *Symbol);
> virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
> virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,
> unsigned AddrSpace);
>
> Modified: llvm/trunk/include/llvm/MC/MCStreamer.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCStreamer.h?rev=170279&r1=170278&r2=170279&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/MC/MCStreamer.h (original)
> +++ llvm/trunk/include/llvm/MC/MCStreamer.h Sat Dec 15 22:00:45 2012
> @@ -244,6 +244,8 @@
> /// used in an assignment.
> virtual void EmitLabel(MCSymbol *Symbol);
>
> + virtual void EmitDebugLabel(MCSymbol *Symbol);
> +
> virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
> MCSymbol *EHSymbol);
>
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp?rev=170279&r1=170278&r2=170279&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp Sat Dec 15 22:00:45 2012
> @@ -122,8 +122,9 @@
> const MCSymbol *Sym = TLOF.getCFIPersonalitySymbol(Per, Asm->Mang, MMI);
> Asm->OutStreamer.EmitCFIPersonality(Sym, PerEncoding);
>
> - Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("eh_func_begin",
> - Asm->getFunctionNumber()));
> + Asm->OutStreamer.EmitDebugLabel
> + (Asm->GetTempSymbol("eh_func_begin",
> + Asm->getFunctionNumber()));
>
> // Provide LSDA information.
> if (!shouldEmitLSDA)
>
> Modified: llvm/trunk/lib/MC/MCAsmInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCAsmInfo.cpp?rev=170279&r1=170278&r2=170279&view=diff
> ==============================================================================
> --- llvm/trunk/lib/MC/MCAsmInfo.cpp (original)
> +++ llvm/trunk/lib/MC/MCAsmInfo.cpp Sat Dec 15 22:00:45 2012
> @@ -37,6 +37,7 @@
> CommentColumn = 40;
> CommentString = "#";
> LabelSuffix = ":";
> + DebugLabelSuffix = ":";
> GlobalPrefix = "";
> PrivateGlobalPrefix = ".";
> LinkerPrivateGlobalPrefix = "";
>
> Modified: llvm/trunk/lib/MC/MCAsmStreamer.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCAsmStreamer.cpp?rev=170279&r1=170278&r2=170279&view=diff
> ==============================================================================
> --- llvm/trunk/lib/MC/MCAsmStreamer.cpp (original)
> +++ llvm/trunk/lib/MC/MCAsmStreamer.cpp Sat Dec 15 22:00:45 2012
> @@ -135,6 +135,8 @@
> }
>
> virtual void EmitLabel(MCSymbol *Symbol);
> + virtual void EmitDebugLabel(MCSymbol *Symbol);
> +
> virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
> MCSymbol *EHSymbol);
> virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
> @@ -345,6 +347,14 @@
> EmitEOL();
> }
>
> +void MCAsmStreamer::EmitDebugLabel(MCSymbol *Symbol) {
> + assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
> + MCStreamer::EmitDebugLabel(Symbol);
> +
> + OS << *Symbol << MAI.getDebugLabelSuffix();
> + EmitEOL();
> +}
> +
> void MCAsmStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
> switch (Flag) {
> case MCAF_SyntaxUnified: OS << "\t.syntax unified"; break;
>
> Modified: llvm/trunk/lib/MC/MCELFStreamer.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCELFStreamer.cpp?rev=170279&r1=170278&r2=170279&view=diff
> ==============================================================================
> --- llvm/trunk/lib/MC/MCELFStreamer.cpp (original)
> +++ llvm/trunk/lib/MC/MCELFStreamer.cpp Sat Dec 15 22:00:45 2012
> @@ -86,6 +86,10 @@
> MCELF::SetType(SD, ELF::STT_TLS);
> }
>
> +void MCELFStreamer::EmitDebugLabel(MCSymbol *Symbol) {
> + EmitLabel(Symbol);
> +}
This doesn't look right: shouldn't we have to do something different
for both object emission as well as asm emission?
-Eli
More information about the llvm-commits
mailing list