[llvm-commits] Initial OProfile symbolization support

[Jeffrey Yasskin]

OProfile provides a library to tell it about JIT output, described at
http://oprofile.sourceforge.net/doc/devel/jit-interface.html. This
patch tells OProfile about function ranges, but not line numbers. It
adds a --with-oprofile=<prefix> flag to configure, but I don't know
how to do the equivalent to cmake.

Problems:
1. Because oprofile installs its libraries to <prefix>/lib/oprofile,
we need an -rpath option to let the loader find them. We could
probably link the oprofile library statically to avoid this (but
how?).
2. llvm-config doesn't include the required -L and -rpath flags in its
--ldflags output, even though it includes -lopagent.
3. cmake support is missing, as mentioned above.

I've tested this by running the attached fib.c under lli. Let me know
if you can think of an automated way to test it.



The output from opreport follows:

Before:

$ opreport -l ~/opensource/llvm/trunk/dbg/Debug/bin/lli

CPU: Core 2, speed 1998 MHz (estimated)

Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask
of 0x00 (Unhalted core cycles) count 100000

samples  %        image name               symbol name

48182    98.9729  anon (tgid:19412 range:0x7f12ccaab000-0x7f12cdaab000) anon
(tgid:19412 range:0x7f12ccaab000-0x7f12cdaab000)

11        0.0226  libstdc++.so.6.0.9       /usr/lib/libstdc++.so.6.0.9

10        0.0205  lli                      llvm::MachineOperand::isReg() const

...


After:

$ opreport -l ~/opensource/llvm/oprof/dbg/Debug/bin/lli
CPU: Core 2, speed 1998 MHz (estimated)

Counted CPU_CLK_UNHALTED events (Clock cycles when not halted) with a unit mask
of 0x00 (Unhalted core cycles) count 100000

samples  %        image name               symbol name

24565    60.7308  19814.jo                 fib_left

15365    37.9861  19814.jo                 fib_right

22        0.0544  ld-2.7.so                do_lookup_x

10        0.0247  lli                      llvm::MachineOperand::isReg() const

8         0.0198  ld-2.7.so                _dl_relocate_object

8         0.0198  lli                      std::vector<llvm::MachineOperand,
std::allocator<llvm::MachineOperand> >::size() const
...
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