Re: perf tools: LIBCLANGLLVM=1 build broken with llvm 7/clang 6

[Yonghong Song <yhs@fb.com>]

On 6/16/18 5:26 AM, Arnaldo Carvalho de Melo wrote:
> Hi Wang, Yogong,
> 
> 	While reviewing the BTF patches for pahole, I updated llvm/clang
> to HEAD and then building perf with clang embedded I noticed this, will
> investigate, posting here to document the regression, maybe this is
> something you came across in other scenario:
> 
>   $ make LIBCLANGLLVM=1 -C tools/perf/
>   <SNIP>
>    CC       /tmp/tmp.t53Qo38zci/tests/kmod-path.o
> util/c++/clang.cpp: In function ‘std::unique_ptr<llvm::SmallVectorImpl<char> > perf::getBPFObjectFromModule(llvm::Module*)’:
> util/c++/clang.cpp:150:43: error: no matching function for call to ‘llvm::TargetMachine::addPassesToEmitFile(llvm::legacy::PassManager&, llvm::raw_svector_ostream&, llvm::TargetMachine::CodeGenFileType)’
>               TargetMachine::CGFT_ObjectFile)) {
>                                             ^
> In file included from util/c++/clang.cpp:25:0:
> /usr/local/include/llvm/Target/TargetMachine.h:254:16: note: candidate: virtual bool llvm::TargetMachine::addPassesToEmitFile(llvm::legacy::PassManagerBase&, llvm::raw_pwrite_stream&, llvm::raw_pwrite_stream*, llvm::TargetMachine::CodeGenFileType, bool, llvm::MachineModuleInfo*)
>     virtual bool addPassesToEmitFile(PassManagerBase &, raw_pwrite_stream &,
>                  ^~~~~~~~~~~~~~~~~~~
> /usr/local/include/llvm/Target/TargetMachine.h:254:16: note:   candidate expects 6 arguments, 3 provided
> mv: cannot stat '/tmp/tmp.t53Qo38zci/util/c++/.clang.o.tmp': No such file or directory
> make[7]: *** [/home/acme/git/perf/tools/build/Makefile.build:101: /tmp/tmp.t53Qo38zci/util/c++/clang.o] Error 1
> make[6]: *** [/home/acme/git/perf/tools/build/Makefile.build:139: c++] Error 2
> make[5]: *** [/home/acme/git/perf/tools/build/Makefile.build:139: util] Error 2
> make[5]: *** Waiting for unfinished jobs....
>    CC       /tmp/tmp.t53Qo38zci/tests/thread-map.o

There is an interface change in llvm 7.0 (trunk) for function 
llvm::TargetMachine::addPassesToEmitFile. The following patch
should fix the problem.

-bash-4.2$ git diff
diff --git a/tools/perf/util/c++/clang.cpp b/tools/perf/util/c++/clang.cpp
index bf31cea..11dee58 100644
--- a/tools/perf/util/c++/clang.cpp
+++ b/tools/perf/util/c++/clang.cpp
@@ -146,8 +146,15 @@ getBPFObjectFromModule(llvm::Module *Module)
         raw_svector_ostream ostream(*Buffer);

         legacy::PassManager PM;
-       if (TargetMachine->addPassesToEmitFile(PM, ostream,
- 
TargetMachine::CGFT_ObjectFile)) {
+       bool NotAdded;
+#if CLANG_VERSION_MAJOR < 7
+       NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream,
+ 
TargetMachine::CGFT_ObjectFile);
+#else
+       NotAdded = TargetMachine->addPassesToEmitFile(PM, ostream, nullptr,
+ 
TargetMachine::CGFT_ObjectFile);
+#endif
+       if (!NotAdded) {
                 llvm::errs() << "TargetMachine can't emit a file of 
this type\n";
                 return 
std::unique_ptr<llvm::SmallVectorImpl<char>>(nullptr);;
         }
-bash-4.2$

Will submit a formal patch soon.

> 
> - Arnaldo
>