Commit d437fba8 authored by serge-sans-paille's avatar serge-sans-paille
Browse files

Reapply Allow system header to provide their own implementation of some builtin 

This reverts commit 3d210ed3.

See https://reviews.llvm.org/D71082 for the patch and discussion that make it
possible to reapply this patch.
parent 6b840834

clang/include/clang/AST/Decl.h

+3 −0
Original line number Diff line number Diff line
@@ -2309,6 +2309,9 @@ public: 
  /// true through IsAligned.

  bool isReplaceableGlobalAllocationFunction(bool *IsAligned = nullptr) const;



  /// Determine if this function provides an inline implementation of a builtin.

  bool isInlineBuiltinDeclaration() const;



  /// Determine whether this is a destroying operator delete.

  bool isDestroyingOperatorDelete() const;

clang/lib/AST/Decl.cpp

+8 −0
Original line number Diff line number Diff line
@@ -3046,6 +3046,14 @@ bool FunctionDecl::isReplaceableGlobalAllocationFunction(bool *IsAligned) const 
  return Params == FPT->getNumParams();

}



bool FunctionDecl::isInlineBuiltinDeclaration() const {

  if (!getBuiltinID())

    return false;



  const FunctionDecl *Definition;

  return hasBody(Definition) && Definition->isInlineSpecified();

}



bool FunctionDecl::isDestroyingOperatorDelete() const {

  // C++ P0722:

  //   Within a class C, a single object deallocation function with signature

clang/lib/CodeGen/CGExpr.cpp

+8 −1
Original line number Diff line number Diff line
@@ -4621,7 +4621,14 @@ RValue CodeGenFunction::EmitSimpleCallExpr(const CallExpr *E, 
}



static CGCallee EmitDirectCallee(CodeGenFunction &CGF, const FunctionDecl *FD) {



  if (auto builtinID = FD->getBuiltinID()) {

    // Replaceable builtin provide their own implementation of a builtin. Unless

    // we are in the builtin implementation itself, don't call the actual

    // builtin. If we are in the builtin implementation, avoid trivial infinite

    // recursion.

    if (!FD->isInlineBuiltinDeclaration() ||

        CGF.CurFn->getName() == FD->getName())

      return CGCallee::forBuiltin(builtinID, FD);

  }

clang/lib/CodeGen/CodeGenModule.cpp

+5 −0
Original line number Diff line number Diff line
@@ -1840,6 +1840,11 @@ void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F, 
  else if (const auto *SA = FD->getAttr<SectionAttr>())

     F->setSection(SA->getName());



  if (FD->isInlineBuiltinDeclaration()) {

    F->addAttribute(llvm::AttributeList::FunctionIndex,

                    llvm::Attribute::NoBuiltin);

  }



  if (FD->isReplaceableGlobalAllocationFunction()) {

    // A replaceable global allocation function does not act like a builtin by

    // default, only if it is invoked by a new-expression or delete-expression.

clang/test/CodeGen/memcpy-nobuiltin.c

0 → 100644
+15 −0
Original line number Diff line number Diff line 
// RUN: %clang_cc1 -verify -S -emit-llvm -o- %s -isystem %S -DWITH_DECL | FileCheck --check-prefix=CHECK-WITH-DECL %s

// RUN: %clang_cc1 -verify -S -emit-llvm -o- %s -isystem %S -UWITH_DECL | FileCheck --check-prefix=CHECK-NO-DECL %s

// RUN: %clang_cc1 -verify -S -emit-llvm -o- %s -isystem %S -DWITH_SELF_REFERENCE_DECL | FileCheck --check-prefix=CHECK-SELF-REF-DECL %s

//

// CHECK-WITH-DECL-NOT: @llvm.memcpy

// CHECK-NO-DECL: @llvm.memcpy

// CHECK-SELF-REF-DECL: @llvm.memcpy

//

#include <memcpy-nobuiltin.inc>

void test(void *dest, void const *from, size_t n) {

  memcpy(dest, from, n);



  static char buffer[1];

  memcpy(buffer, from, 2); // expected-warning {{'memcpy' will always overflow; destination buffer has size 1, but size argument is 2}}

}