[LLVMbugs] [Bug 177] [JIT] Functions pointed to by global variables should be lazily compiled!

[bugzilla-daemon at zion.cs.uiuc.edu]

http://llvm.cs.uiuc.edu/bugs/show_bug.cgi?id=177

sabre at nondot.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED



------- Additional Comments From sabre at nondot.org  2003-12-12 01:18 -------
These patches implement this (for X86.  Sparc needs a small patch to implement
the new hook):
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20031208/010113.html
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20031208/010114.html
http://mail.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20031208/010115.html

Fixing this speeds up "ll-tblgen --help" from 4.55s to 2.36s, and "ll-opt
--help" goes from 18.85s to 7.30s.  We now "only" compile 111413 bytes of
machine code, instead of 284680 bytes for ll-tblgen.  Fixing Bug 135 would also
provide another HUGE speedup, because we are initializing 4.23Mbytes of global
variables (vtables, rtti info, ...), though they are presumably all completely
unreferenced in such a short run.

For the testcase in the PR, I now get this, which is what we want:

$ lli -debug-only=jit test.o 
Global 'P1' -> 0x84e44a8
Global 'P2' -> 0x84e44b8
Finished CodeGen of [0x4018dffa] Function stub for: bar: 6 bytes of text
Finished CodeGen of [0x4018dff4] Function stub for: baz: 6 bytes of text
Finished CodeGen of [0x4018e000] Function: main: 57 bytes of text
WARNING: Cannot resolve fn '__main' using a dummy noop function instead!

[zion ~]$ lli -debug-only=jit test.o x
Global 'P1' -> 0x84e44a8
Global 'P2' -> 0x84e44b8
Finished CodeGen of [0x4018dffa] Function stub for: bar: 6 bytes of text
Finished CodeGen of [0x4018dff4] Function stub for: baz: 6 bytes of text
Finished CodeGen of [0x4018e000] Function: main: 57 bytes of text
WARNING: Cannot resolve fn '__main' using a dummy noop function instead!
Finished CodeGen of [0x4018e03c] Function: qux: 16 bytes of text
Finished CodeGen of [0x4018e04c] Function: baz: 7 bytes of text

-Chris



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