[llvm-dev] How to profile the LLVm JITed Code

[张建 via llvm-dev]

I'm using llvm 3.3,which was built with the options below:

../llvm-3.3.src/configure
> --prefix=/home/admin/jianzhang.zj/llvm/llvm-install-2/
> --with-gcc-toolchain=/home/admin/jianzhang.zj/gcc-4.8.2-install/
> --enable-optimized --enable-debug-runtime --enable-debug-symbols
> --disable-assertions
> --with-oprofile=/home/admin/jianzhang.zj/oprofile-0.9.9-install/
> --enable-profiling --with-intel-jitevents


The oprofile's version is 0.99

I'm using the following Makefile to build the Fibonacci examples in the
llvm source code:

LLVM_CONFIG=/home/admin/jianzhang.zj/llvm/llvm-install-2/bin/llvm-config
> CLANG=/home/admin/jianzhang.zj/llvm/llvm-install-2/bin/clang
> SRC_IDR=$(PWD)
> LLVM_FLAGS=$(shell $(LLVM_CONFIG) --cxxflags --cppflags --ldflags
> --ldflags --libs )
> COMMON_FLAGS= -DTEST -DMCJIT -g -rdynamic -O3 -lpthread -ldl
> SRC_DIR = .
> INCLUDE = -I/home/admin/jianzhang.zj/llvm/llvm-install-2/include/
> CXX=g++
> PROGRAM= fibonacci
> all: clean output
> output: $(PROGRAM)
> $(PROGRAM):
> $(CXX) $@.cpp $(INCLUDE) -o $@ $(COMMON_FLAGS) $(LLVM_FLAGS) -fexceptions
> clean:
> rm -f $(PROGRAM)  *.o *LOG*


then I use the operf command to sampling:

$ /home/admin/jianzhang.zj/oprofile-0.9.9-install/bin/operf ./fibonacci 40
> operf: Profiler started
> verifying... OK
> We just constructed this LLVM module:
> ---------
> ; ModuleID = 'test'
> define i32 @fib(i32 %AnArg) {
> EntryBlock:
>   %cond = icmp sle i32 %AnArg, 2
>   br i1 %cond, label %return, label %recurse
> return:                                           ; preds = %EntryBlock
>   ret i32 1
> recurse:                                          ; preds = %EntryBlock
>   %arg = sub i32 %AnArg, 1
>   %fibx1 = tail call i32 @fib(i32 %arg)
>   %arg1 = sub i32 %AnArg, 2
>   %fibx2 = tail call i32 @fib(i32 %arg1)
>   %addresult = add i32 %fibx1, %fibx2
>   ret i32 %addresult
> }
> ---------
> starting fibonacci(40) with JIT...
> Result: 102334155
> Profiling done.


then use opreport:

$ /home/admin/jianzhang.zj/oprofile-0.9.9-install/bin/opreport
> Using
> /apsarapangu/disk8/jianzhang.zj/llvm/llvm-3.3.src/examples/Fibonacci/oprofile_data/samples/
> for samples directory.
> CPU: Intel Sandy Bridge microarchitecture, speed 2199.75 MHz (estimated)
> Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit
> mask of 0x00 (No unit mask) count 100000
> CPU_CLK_UNHALT...|
>   samples|      %|
> ------------------
>     16252 100.000 fibonacci
> CPU_CLK_UNHALT...|
>  samples|      %|
> ------------------
>    15368 94.5607 anon (tgid:60546 range:0x7faa17b40000-0x7faa17bbffff)
>      656  4.0364 no-vmlinux
>      139  0.8553 libc-2.5.so
>       54  0.3323 fibonacci
>       33  0.2031 ld-2.5.so
>        2  0.0123 libstdc++.so.6.0.8


here the '*anon (tgid:60546 range:0x7faa17b40000-0x7faa17bbffff)*' isn't
the result I expected, so I think there must be something wrong and I use
the ldd command to check the dependencies:

$ ldd fibonacci
> linux-vdso.so.1 =>  (0x00007fffcd1ba000)
> libpthread.so.0 => /lib64/libpthread.so.0 (0x00000031edc00000)
> libdl.so.2 => /lib64/libdl.so.2 (0x00000031ed800000)
> libz.so.1 => /lib64/libz.so.1 (0x00000031ee400000)
> librt.so.1 => /lib64/librt.so.1 (0x00000031ef000000)
> libopagent.so.1 =>
> /home/admin/jianzhang.zj/oprofile-0.9.9-install//lib/oprofile/libopagent.so.1
> (0x00007fb835b86000)
> libm.so.6 => /lib64/libm.so.6 (0x00000031ee000000)
> libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00000031f3000000)
> libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00000031f0800000)
> libc.so.6 => /lib64/libc.so.6 (0x00000031ed400000)
> /lib64/ld-linux-x86-64.so.2 (0x00000031ed000000)
> libbfd-2.24.so => /home/admin/jianzhang.zj/binutils-2.24-install/lib/
> libbfd-2.24.so (0x00007fb83587b000)
> libiberty.so =>
> /home/admin/jianzhang.zj/binutils-2.24-install/lib/libiberty.so
> (0x00007fb83563e000)
>
> $ ldd -u fibonacci
> Unused direct dependencies:
>
> /lib64/libdl.so.2
> /lib64/libz.so.1
> /lib64/librt.so.1
>
> /home/admin/jianzhang.zj/oprofile-0.9.9-install//lib/oprofile/libopagent.so.1


can anyone tell me how to profile the llvm JITed code or which step was
wrong ?

thanks very much.
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