[llvm-dev] [Help] Add custom pragma (original) (raw)

Vedant Kumar via llvm-dev llvm-dev at lists.llvm.org
Tue Oct 25 16:22:05 PDT 2016

Yes. I checked that file, but I wasn't sure whether that is right one to look at.

It seems promising. I imagine you'd want something like the LoopHint attr.

What is *.td extension btw?

The llvm project uses that extension to identify TableGen inputs (http://llvm.org/docs/TableGen/).

vedant

On Oct 25, 2016, at 4:12 PM, Sunghyun Park <sunggg at umich.edu> wrote:

Yes. I checked that file, but I wasn't sure whether that is right one to look at. What is *.td extension btw? When I google it, it says this is for Windows Debug Simulator. Why clang use this extension, which is limited to Windows environment? On Tue, Oct 25, 2016 at 7:00 PM, Vedant Kumar <vsk at apple.com> wrote: That file is generated by the clang-tblgen tool: COMMAND = cd /Users/vk/Desktop/llvm/DA-NoModules/tools/clang/include/clang/Sema && /Users/vk/Desktop/llvm/DA-NoModules/bin/clang-tblgen -gen-clang-attr-parsed-attr-list -I /Users/vk/Desktop/llvm/tools/clang/include/clang/Sema/../../ -I /Users/vk/Desktop/llvm/tools/clang/include/clang/Sema -I /Users/vk/Desktop/llvm/lib/Target -I /Users/vk/Desktop/llvm/include /Users/vk/Desktop/llvm/tools/clang/include/clang/Sema/../Basic/Attr.td -o /Users/vk/Desktop/llvm/DA-NoModules/tools/clang/include/clang/Sema/AttrParsedAttrList.inc.tmp Try looking include/clang/Basic/Attr.td? best, vedant > On Oct 25, 2016, at 2:54 PM, Sunghyun Park via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Hi, all. > I want to give programmer ability to tell LLVM that certain region of code is expected to get specialized optimization. > So, I'm trying to make custom pragma to mark certain region of code and pass this information to LLVM, in the similar way that '#pragma clang loop unrollcount(N)' works. > > By tracking the framework of loop unroll pragma, I found out it works in the way below. > (1) Detect pragma at lexer, parser. > (2) Create AttributeList and push it into AST. > (3) Once AST is built, consume AST and generate LLVM IR at CodeGeneration > (4) If attribute for loop unroll is found, put tag on LLVM IR with Meta data which indicates whether to unroll loop. > > Now I can detect my own pragma and figured it out how to create and tag custom metadata. > The problem is that creating custom AttributeList is somewhat hard to follow. > > As far as I know, the attribute for loop unroll pragma gets serviced at ProcessSmtAttrbute Function @ tools/clang/lib/Sema/SemaStmtAttr.cpp. > It contains switch statement like below. > > ProcessSmtAttrbute @ tools/clang/lib/Sema/SemaStmtAttr.cpp > // A : AttributeList - passed by argument > switch( A.getKind() ) { > case AttributeList::UnknownAttribute: > ~ > case AttributeList::ATFallThrough: > return ~ > case AttributeList::ATLoopHint: > return handleLoopHintAttr( ~ ) > case AttributeList::ATOpenCLUnrollHint: > ~ > ... > } > > As I want to define new attribute, I've tried to find where the definitions for ATLoopHint, ATFallThrough are done. This is what I found. > > class AttributeList @ tools/clang/include/clang/Sema/AttributeList.h > > enum Kind{ > #define PARSED ATTR(NAME) AT##NAME, > #include "clang/Sema/AttrParsedAttrList.inc" > #undef PARSEDATTR > IgnoredAttribute, > UnkownAttribute > }; > > It looks like those are defined at this enum, but there's no such file, "clang/Sema/AttrParsedAttrList.inc". > > Anyone knows how those definitions are defined and how the kind of attributes are decided? > Thank you for your valuable time! > > -- > Best, Sung _> ________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

-- Best, Sung

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