Add missing header for InstructionCombining.cpp, in order to export LLVMInitializeInstCombine as extern "C"

[brenton]

Summary

Getting this error:

"Undefined symbols for architecture x86_64:
  \"_LLVMInitializeInstCombine\", referenced from:
      _LLVMLink_LLVMInitializeInstCombine_Wrapper in llvmc60.cpp.o
     (maybe you meant: _LLVMLink_LLVMInitializeInstCombine_Wrapper)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see \
invocation)
make[2]: *** [LLVMLink.dylib] Error 1
make[1]: *** [CMakeFiles/LLVMLink.dir/all] Error 2
make: *** [all] Error 2
"

LLVMInitializeInstCombine is declared extern "C" in the LLVM-C header Initialization.h, but not declared extern "C" surrounding the definition for the function in lib/Transforms/InstCombine/InstructionCombining.cpp.

This fixes 35947
https://bugs.llvm.org/show_bug.cgi?id=35947

[Eugene.Zelenko]

Please run Clang-fromat. If I'm not mistaken, llvm-c/Initialization.h should be after InstCombineInternal.h.

[brenton]

You are correct. I ran clang-format on it.

clang-format also formatted the rest of the file and changed it, but I did not want to make those changes in this revision.

[brenton]

I cannot commit this patch myself. I do not have permissions.

I was wondering about including this in the first bug release of 6.0. How would I ensure this?

[Eugene.Zelenko]

In D44140#1028627, @brenton wrote:

I cannot commit this patch myself. I do not have permissions.

I'll try to do this later today.

I was wondering about including this in the first bug release of 6.0. How would I ensure this?

You'll need to create bug report in http://bugs.llvm.org, but I'm not sure was meta-report for 6.0.1 created or not.

[nmgeek]

This bug seems to be in the mainstream, stable, LTS Ubuntu apt repository as version 1:6.0-1ubuntu2~16.04.1. It breaks the llvmlite python package and, by extension, the python numba package. Conda works around it by compiling llvm from source and repackaging. What is the recommended workaround for Ubuntu 16 when not using Conda?

llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp

 //    5. add X, X is represented as (X*2) => (X << 1)
 //    6. Multiplies with a power-of-two constant argument are transformed into
 //       shifts.
 //   ... etc.
 //
 //===----------------------------------------------------------------------===//
 
 #include "InstCombineInternal.h"
+#include "llvm-c/Initialization.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/None.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/TinyPtrVector.h"