I forgot to include the Phabricator URL for the patch in question. It is here:
https://reviews.llvm.org/D38473 Thanks, -michael On Mon, Oct 2, 2017 at 3:19 PM, Michael Ferguson <mpfe...@gmail.com> wrote: > This change adds a new function, CodeGen::getFieldNumber, that > enables a user of clang's code generation to get the field number > in a generated LLVM IR struct that corresponds to a particular field > in a C struct. > > It is important to expose this information in Clang's code generation > interface because there is no reasonable way for users of Clang's code > generation to get this information. In particular: > > 1. LLVM struct types do not include field names. > 2. Clang adds a non-trivial amount of logic to the code generation of > LLVM IR types for structs, in particular to handle padding and bit > fields. > > This in some ways is a philosophical continuation of > https://reviews.llvm.org/D35180 . > > I'm working on a programming language that uses Clang to create > seamless C interoperability. One of the language features is to create > "extern records", which are just structs that have a definition in C > code. The language needs to be able to code generate element access to > particular structure fields by name, and without this patch, I need to > use clang-internal headers to do so. > > > > diff --git a/include/clang/CodeGen/CodeGenABITypes.h > b/include/clang/CodeGen/CodeGenABITypes.h > index 615e55c8b6..f4fa28da1b 100644 > --- a/include/clang/CodeGen/CodeGenABITypes.h > +++ b/include/clang/CodeGen/CodeGenABITypes.h > @@ -78,6 +78,10 @@ llvm::FunctionType > *convertFreeFunctionType(CodeGenModule &CGM, > > llvm::Type *convertTypeForMemory(CodeGenModule &CGM, QualType T); > > +// Returns a field number for a struct suitable for GEP'ing > +unsigned getFieldNumber(CodeGenModule &CGM, > + const RecordDecl *RD, const FieldDecl *FD); > + > } // end namespace CodeGen > } // end namespace clang > > diff --git a/lib/CodeGen/CodeGenABITypes.cpp b/lib/CodeGen/CodeGenABITypes.cpp > index 0735a9c3df..759ad75897 100644 > --- a/lib/CodeGen/CodeGenABITypes.cpp > +++ b/lib/CodeGen/CodeGenABITypes.cpp > @@ -17,6 +17,7 @@ > > //===----------------------------------------------------------------------===// > > #include "clang/CodeGen/CodeGenABITypes.h" > +#include "CGRecordLayout.h" > #include "CodeGenModule.h" > #include "clang/CodeGen/CGFunctionInfo.h" > #include "clang/Frontend/CodeGenOptions.h" > @@ -80,3 +81,8 @@ llvm::Type * > CodeGen::convertTypeForMemory(CodeGenModule &CGM, QualType T) { > return CGM.getTypes().ConvertTypeForMem(T); > } > + > +unsigned CodeGen::getFieldNumber(CodeGenModule &CGM, > + const RecordDecl *RD, const FieldDecl *FD) { > + return CGM.getTypes().getCGRecordLayout(RD).getLLVMFieldNo(FD); > +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
