nicolas/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

C++1y sized deallocation: if we have a use, but not a definition, of a sized

Browse Source 
deallocation function (and the corresponding unsized deallocation function has
been declared), emit a weak discardable definition of the function that
forwards to the corresponding unsized deallocation.

This allows a C++ standard library implementation to provide both a sized and
an unsized deallocation function, where the unsized one does not just call the
sized one, for instance by putting both in the same object file within an
archive.

llvm-svn: 194055
This commit is contained in:
Richard Smith
2013-11-05 09:12:18 +00:00
parent 2d1d3ca1cc
commit b47c36f8e1
10 changed files with 87 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
clang/lib/CodeGen/CodeGenFunction.cpp
View File

@@ -643,13 +643,12 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
DI->EmitLocation(Builder, StartLoc);
}
void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) {
const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl());
assert(FD->getBody());
if (const CompoundStmt *S = dyn_cast<CompoundStmt>(FD->getBody()))
void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args,
const Stmt *Body) {
if (const CompoundStmt *S = dyn_cast<CompoundStmt>(Body))
EmitCompoundStmtWithoutScope(*S);
else
EmitStmt(FD->getBody());
EmitStmt(Body);
}
/// Tries to mark the given function nounwind based on the
@@ -672,6 +671,17 @@ static void TryMarkNoThrow(llvm::Function *F) {
F->setDoesNotThrow();
}
static void EmitSizedDeallocationFunction(CodeGenFunction &CGF,
const FunctionDecl *UnsizedDealloc) {
// This is a weak discardable definition of the sized deallocation function.
CGF.CurFn->setLinkage(llvm::Function::LinkOnceAnyLinkage);
// Call the unsized deallocation function and forward the first argument
// unchanged.
llvm::Constant *Unsized = CGF.CGM.GetAddrOfFunction(UnsizedDealloc);
CGF.Builder.CreateCall(Unsized, &*CGF.CurFn->arg_begin());
}
void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
const CGFunctionInfo &FnInfo) {
const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
@@ -726,9 +736,15 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
// Implicit copy-assignment gets the same special treatment as implicit
// copy-constructors.
emitImplicitAssignmentOperatorBody(Args);
}
else
EmitFunctionBody(Args);
} else if (Stmt *Body = FD->getBody()) {
EmitFunctionBody(Args, Body);
} else if (FunctionDecl *UnsizedDealloc =
FD->getCorrespondingUnsizedGlobalDeallocationFunction()) {
// Global sized deallocation functions get an implicit weak definition if
// they don't have an explicit definition.
EmitSizedDeallocationFunction(*this, UnsizedDealloc);
} else
llvm_unreachable("no definition for emitted function");
// C++11 [stmt.return]p2:
// Flowing off the end of a function [...] results in undefined behavior in