[LLVMdev] size of generated machine code ?

[Chris Lattner]

On Wed, 21 Jun 2006, Simon Burton wrote:
>> To be specific, this is the number of bytes of machine code JIT'd.  Thus,
>> this only includes the stuff reachable from main, for example.  To see
>> specifically what functions it is compiling and how big they are, use:
>>
>> lli -debug-only=jit foo.bc <args>
>
> This does not seem to be available in my build (1.7 release-asserts).

Right, release-asserts builds have no debug stuff in them.

> Another question: does lli actually run the program ?

Yup.

> I've cooked up a main function that would probably segfault it.
> And what i'm seeing (with strace) is that something does segfault (a child thread?) and
> lli is waiting on a futex:

Right. lli is the JIT, which dynamically compiles code as it goes.  If 
you're just curious about code size, why not use size on .o file?

-Chris

> access("dump.bc", F_OK)                 = 0
> open("dump.bc", O_RDONLY)               = 3
> fstat64(3, {st_mode=S_IFREG|0600, st_size=22744, ...}) = 0
> mmap2(NULL, 24576, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7fe3000
> mmap2(NULL, 16777216, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6d9c000
> mmap2(0xb7d9c000, 1048576, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6c9c000
> mmap2(0xb6d9c000, 1048576, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6b9c000
> futex(0xb7fbb1b4, FUTEX_WAKE, 2147483647) = 0
> brk(0)                                  = 0x8562000
> brk(0x8583000)                          = 0x8583000
> brk(0)                                  = 0x8583000
> brk(0x85a4000)                          = 0x85a4000
> brk(0)                                  = 0x85a4000
> brk(0x85c5000)                          = 0x85c5000
> brk(0)                                  = 0x85c5000
> brk(0x85e6000)                          = 0x85e6000
> brk(0)                                  = 0x85e6000
> brk(0x8609000)                          = 0x8609000
> brk(0)                                  = 0x8609000
> brk(0x862b000)                          = 0x862b000
> brk(0)                                  = 0x862b000
> brk(0x864c000)                          = 0x864c000
> --- SIGSEGV (Segmentation fault) @ 0 (0) ---
> pipe([4, 5])                            = 0
> futex(0xb7ecf900, FUTEX_WAIT, 2, NULL
> <unfinished ...>
>
> dump.bc attached.
>
> Simon.
>
>

-Chris

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