r240653 - Fix #pragma redefine_extname when there is a local variable of the same name. The local should not be renamed, only the externally-available declaration should be.

[Richard Smith]

On Thu, Jun 25, 2015 at 8:37 AM, Aaron Ballman <aaron at aaronballman.com>
wrote:

> Author: aaronballman
> Date: Thu Jun 25 10:37:16 2015
> New Revision: 240653
>
> URL: http://llvm.org/viewvc/llvm-project?rev=240653&view=rev
> Log:
> Fix #pragma redefine_extname when there is a local variable of the same
> name. The local should not be renamed, only the externally-available
> declaration should be.
>
> Patch by Andrey Bokhanko!
>
> Modified:
>     cfe/trunk/lib/Sema/SemaDecl.cpp
>     cfe/trunk/test/CodeGen/redefine_extname.c
>     cfe/trunk/test/CodeGenCXX/redefine_extname.cpp
>
> Modified: cfe/trunk/lib/Sema/SemaDecl.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDecl.cpp?rev=240653&r1=240652&r2=240653&view=diff
>
> ==============================================================================
> --- cfe/trunk/lib/Sema/SemaDecl.cpp (original)
> +++ cfe/trunk/lib/Sema/SemaDecl.cpp Thu Jun 25 10:37:16 2015
> @@ -5525,6 +5525,19 @@ bool Sema::adjustContextForLocalExternDe
>    return true;
>  }
>
> +/// \brief Returns true if given declaration is TU-scoped and externally
> +/// visible.
> +static bool isDeclTUScopedExternallyVisible(const Decl *D) {
> +  if (auto *FD = dyn_cast<FunctionDecl>(D))
> +    return (FD->getDeclContext()->isTranslationUnit() || FD->isExternC())
> &&
> +           FD->hasExternalFormalLinkage();
>

Hmm, should non-extern-C functions get this behavior at all in C++? My
understanding is that redefine_extname is supposed to have the semantics of
"search and replace on the generated assembly", so it should only apply to
names that don't get mangled.


> +  else if (auto *VD = dyn_cast<VarDecl>(D))
> +    return (VD->getDeclContext()->isTranslationUnit() || VD->isExternC())
> &&
> +           VD->hasExternalFormalLinkage();
> +
> +  llvm_unreachable("Unknown type of decl!");
> +}
> +
>  NamedDecl *
>  Sema::ActOnVariableDeclarator(Scope *S, Declarator &D, DeclContext *DC,
>                                TypeSourceInfo *TInfo, LookupResult
> &Previous,
> @@ -5949,7 +5962,8 @@ Sema::ActOnVariableDeclarator(Scope *S,
>
>      NewVD->addAttr(::new (Context) AsmLabelAttr(SE->getStrTokenLoc(0),
>                                                  Context, Label, 0));
> -  } else if (!ExtnameUndeclaredIdentifiers.empty()) {
> +  } else if (!ExtnameUndeclaredIdentifiers.empty() &&
> +             isDeclTUScopedExternallyVisible(NewVD)) {
>      llvm::DenseMap<IdentifierInfo*,AsmLabelAttr*>::iterator I =
>        ExtnameUndeclaredIdentifiers.find(NewVD->getIdentifier());
>      if (I != ExtnameUndeclaredIdentifiers.end()) {
> @@ -7471,7 +7485,8 @@ Sema::ActOnFunctionDeclarator(Scope *S,
>      StringLiteral *SE = cast<StringLiteral>(E);
>      NewFD->addAttr(::new (Context) AsmLabelAttr(SE->getStrTokenLoc(0),
> Context,
>                                                  SE->getString(), 0));
> -  } else if (!ExtnameUndeclaredIdentifiers.empty()) {
> +  } else if (!ExtnameUndeclaredIdentifiers.empty() &&
> +             isDeclTUScopedExternallyVisible(NewFD)) {
>      llvm::DenseMap<IdentifierInfo*,AsmLabelAttr*>::iterator I =
>        ExtnameUndeclaredIdentifiers.find(NewFD->getIdentifier());
>      if (I != ExtnameUndeclaredIdentifiers.end()) {
>
> Modified: cfe/trunk/test/CodeGen/redefine_extname.c
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/redefine_extname.c?rev=240653&r1=240652&r2=240653&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/CodeGen/redefine_extname.c (original)
> +++ cfe/trunk/test/CodeGen/redefine_extname.c Thu Jun 25 10:37:16 2015
> @@ -13,3 +13,14 @@ int fish() { return fake() + __PRAGMA_RE
>  // CHECK:   call i32 @real()
>  // Check that this also works with variables names
>  // CHECK:   load i32, i32* @alias
> +
> +// This is a case when redefenition is deferred *and* we have a local of
> the
> +// same name. PR23923.
> +#pragma redefine_extname foo bar
> +int f() {
> +  int foo = 0;
> +  return foo;
> +}
> +extern int foo() { return 1; }
> +// CHECK: define i32 @bar()
> +
>
> Modified: cfe/trunk/test/CodeGenCXX/redefine_extname.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/redefine_extname.cpp?rev=240653&r1=240652&r2=240653&view=diff
>
> ==============================================================================
> --- cfe/trunk/test/CodeGenCXX/redefine_extname.cpp (original)
> +++ cfe/trunk/test/CodeGenCXX/redefine_extname.cpp Thu Jun 25 10:37:16 2015
> @@ -8,7 +8,7 @@ extern "C" {
>    int statvfs64(struct statvfs64 *);
>  }
>
> -void foo() {
> +void some_func() {
>    struct statvfs64 st;
>    statvfs64(&st);
>  // Check that even if there is a structure with redefined name before the
> @@ -16,3 +16,15 @@ void foo() {
>  // CHECK:  call i32 @statvfs(%struct.statvfs64* %st)
>  }
>
> +// This is a case when redefenition is deferred *and* we have a local of
> the
> +// same name. PR23923.
> +#pragma redefine_extname foo bar
> +int f() {
> +  int foo = 0;
> +  return foo;
> +}
> +extern "C" {
> +  int foo() { return 1; }
> +// CHECK: define i32 @bar()
> +}
> +
>
>
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