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.

[Aaron Ballman]

On Thu, Jun 25, 2015 at 5:43 PM, Richard Smith <richard at metafoo.co.uk> wrote:
> 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.

Possibly. Andrey, what do you think?

~Aaron

>
>>
>> +  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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>
>