[PATCH] D39625: Attribute nonlazybind should not affect calls to functions with hidden visibility

Sriraman Tallam via llvm-commits llvm-commits at lists.llvm.org
Tue Nov 7 10:49:22 PST 2017


On Tue, Nov 7, 2017 at 10:46 AM, Rafael Avila de Espindola <
rafael.espindola at gmail.com> wrote:

> LGTM
>

Thanks, Could you also explicitly accept the revision.

>
> Sriraman Tallam via Phabricator <reviews at reviews.llvm.org> writes:
>
> > tmsriram updated this revision to Diff 121930.
> > tmsriram added a comment.
> >
> > Fix comment as suggested.
> >
> >
> > https://reviews.llvm.org/D39625
> >
> > Files:
> >   lib/Target/TargetMachine.cpp
> >   lib/Target/X86/X86Subtarget.cpp
> >   test/CodeGen/X86/no-plt.ll
> >
> >
> > Index: test/CodeGen/X86/no-plt.ll
> > ===================================================================
> > --- test/CodeGen/X86/no-plt.ll
> > +++ test/CodeGen/X86/no-plt.ll
> > @@ -6,18 +6,25 @@
> >  define i32 @main() #0 {
> >  ; X64: callq *_Z3foov at GOTPCREL(%rip)
> >  ; X64: callq _Z3barv
> > +; X64: callq _Z3bazv
> >
> >  entry:
> >    %retval = alloca i32, align 4
> >    store i32 0, i32* %retval, align 4
> >    %call1 = call i32 @_Z3foov()
> >    %call2 = call i32 @_Z3barv()
> > +  %call3 = call i32 @_Z3bazv()
> >    ret i32 0
> >  }
> >
> >  ; Function Attrs: nonlazybind
> >  declare i32 @_Z3foov() #1
> >
> >  declare i32 @_Z3barv() #2
> >
> > +; Function Attrs: nonlazybind
> > +declare hidden i32 @_Z3bazv() #3
> > +
> > +
> >  attributes #1 = { nonlazybind }
> > +attributes #3 = { nonlazybind }
> > Index: lib/Target/X86/X86Subtarget.cpp
> > ===================================================================
> > --- lib/Target/X86/X86Subtarget.cpp
> > +++ lib/Target/X86/X86Subtarget.cpp
> > @@ -144,15 +144,6 @@
> >  unsigned char
> >  X86Subtarget::classifyGlobalFunctionReference(const GlobalValue *GV,
> >                                                const Module &M) const {
> > -  const Function *F = dyn_cast_or_null<Function>(GV);
> > -
> > -  // Do not use the PLT when explicitly told to do so for ELF 64-bit
> > -  // target.
> > -  if (isTargetELF() && is64Bit() && F &&
> > -      F->hasFnAttribute(Attribute::NonLazyBind) &&
> > -      GV->isDeclarationForLinker())
> > -    return X86II::MO_GOTPCREL;
> > -
> >    if (TM.shouldAssumeDSOLocal(M, GV))
> >      return X86II::MO_NO_FLAG;
> >
> > @@ -162,12 +153,16 @@
> >      return X86II::MO_DLLIMPORT;
> >    }
> >
> > +  const Function *F = dyn_cast_or_null<Function>(GV);
> > +
> >    if (isTargetELF()) {
> >      if (is64Bit() && F && (CallingConv::X86_RegCall ==
> F->getCallingConv()))
> >        // According to psABI, PLT stub clobbers XMM8-XMM15.
> >        // In Regcall calling convention those registers are used for
> passing
> >        // parameters. Thus we need to prevent lazy binding in Regcall.
> >        return X86II::MO_GOTPCREL;
> > +    if (F && F->hasFnAttribute(Attribute::NonLazyBind) && is64Bit())
> > +      return X86II::MO_GOTPCREL;
> >      return X86II::MO_PLT;
> >    }
> >
> > Index: lib/Target/TargetMachine.cpp
> > ===================================================================
> > --- lib/Target/TargetMachine.cpp
> > +++ lib/Target/TargetMachine.cpp
> > @@ -167,6 +167,13 @@
> >      if (GV && !GV->isDeclarationForLinker())
> >        return true;
> >
> > +    // A symbol marked nonlazybind should not be accessed with a plt.
> If the
> > +    // symbol turns out to be external, the linker will convert a direct
> > +    // access to an access via the plt, so don't assume it is local.
> > +    const Function *F = dyn_cast_or_null<Function>(GV);
> > +    if (F && F->hasFnAttribute(Attribute::NonLazyBind))
> > +      return false;
> > +
> >      bool IsTLS = GV && GV->isThreadLocal();
> >      bool IsAccessViaCopyRelocs =
> >          Options.MCOptions.MCPIECopyRelocations && GV &&
> isa<GlobalVariable>(GV);
> >
> >
> > Index: test/CodeGen/X86/no-plt.ll
> > ===================================================================
> > --- test/CodeGen/X86/no-plt.ll
> > +++ test/CodeGen/X86/no-plt.ll
> > @@ -6,18 +6,25 @@
> >  define i32 @main() #0 {
> >  ; X64: callq *_Z3foov at GOTPCREL(%rip)
> >  ; X64: callq _Z3barv
> > +; X64: callq _Z3bazv
> >
> >  entry:
> >    %retval = alloca i32, align 4
> >    store i32 0, i32* %retval, align 4
> >    %call1 = call i32 @_Z3foov()
> >    %call2 = call i32 @_Z3barv()
> > +  %call3 = call i32 @_Z3bazv()
> >    ret i32 0
> >  }
> >
> >  ; Function Attrs: nonlazybind
> >  declare i32 @_Z3foov() #1
> >
> >  declare i32 @_Z3barv() #2
> >
> > +; Function Attrs: nonlazybind
> > +declare hidden i32 @_Z3bazv() #3
> > +
> > +
> >  attributes #1 = { nonlazybind }
> > +attributes #3 = { nonlazybind }
> > Index: lib/Target/X86/X86Subtarget.cpp
> > ===================================================================
> > --- lib/Target/X86/X86Subtarget.cpp
> > +++ lib/Target/X86/X86Subtarget.cpp
> > @@ -144,15 +144,6 @@
> >  unsigned char
> >  X86Subtarget::classifyGlobalFunctionReference(const GlobalValue *GV,
> >                                                const Module &M) const {
> > -  const Function *F = dyn_cast_or_null<Function>(GV);
> > -
> > -  // Do not use the PLT when explicitly told to do so for ELF 64-bit
> > -  // target.
> > -  if (isTargetELF() && is64Bit() && F &&
> > -      F->hasFnAttribute(Attribute::NonLazyBind) &&
> > -      GV->isDeclarationForLinker())
> > -    return X86II::MO_GOTPCREL;
> > -
> >    if (TM.shouldAssumeDSOLocal(M, GV))
> >      return X86II::MO_NO_FLAG;
> >
> > @@ -162,12 +153,16 @@
> >      return X86II::MO_DLLIMPORT;
> >    }
> >
> > +  const Function *F = dyn_cast_or_null<Function>(GV);
> > +
> >    if (isTargetELF()) {
> >      if (is64Bit() && F && (CallingConv::X86_RegCall ==
> F->getCallingConv()))
> >        // According to psABI, PLT stub clobbers XMM8-XMM15.
> >        // In Regcall calling convention those registers are used for
> passing
> >        // parameters. Thus we need to prevent lazy binding in Regcall.
> >        return X86II::MO_GOTPCREL;
> > +    if (F && F->hasFnAttribute(Attribute::NonLazyBind) && is64Bit())
> > +      return X86II::MO_GOTPCREL;
> >      return X86II::MO_PLT;
> >    }
> >
> > Index: lib/Target/TargetMachine.cpp
> > ===================================================================
> > --- lib/Target/TargetMachine.cpp
> > +++ lib/Target/TargetMachine.cpp
> > @@ -167,6 +167,13 @@
> >      if (GV && !GV->isDeclarationForLinker())
> >        return true;
> >
> > +    // A symbol marked nonlazybind should not be accessed with a plt.
> If the
> > +    // symbol turns out to be external, the linker will convert a direct
> > +    // access to an access via the plt, so don't assume it is local.
> > +    const Function *F = dyn_cast_or_null<Function>(GV);
> > +    if (F && F->hasFnAttribute(Attribute::NonLazyBind))
> > +      return false;
> > +
> >      bool IsTLS = GV && GV->isThreadLocal();
> >      bool IsAccessViaCopyRelocs =
> >          Options.MCOptions.MCPIECopyRelocations && GV &&
> isa<GlobalVariable>(GV);
>
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