[LLVMdev] global symbols converted to local symbols
Frits van Bommel
fvbommel at wxs.nl
Thu Oct 30 03:52:08 PDT 2008
Ryan M. Lefever wrote:
> Ryan M. Lefever wrote:
>> I have a bitcode file x.bc. When I run llmv-nm on x.bc, it shows that a
>> function f(), that I've written, is defined as a global function (text)
>> object, i.e., llvm-nm shows it marked with a 'T'. I have converted x.bc
>> to an executable with the following command: llvm-ld -native -o x.exe
>> x.bc When I run nm on x.exe, it shows that f is now a local function
>> (text) object, i.e., nm shows it marked with a 't'. Why is llvm-ld
>> converting f() from a global function object to a local function object.
> As a follow up, if I first convert x.bc to a c file using llc -march=c
> -o x.c x.bc, and then I use normal gcc to convert x.c to an executable,
> f() remains a global symbol. Is llvm-nm incorrectly converting the
> global symbols to local symbols?
I believe your problem may be that llvm-ld by default runs the
'internalize' pass before running any other optimizations. What that
pass does is mark any functions other than 'main' (or functions
explicitly specified by the user) as 'internal'. This is done to allow
other optimizations to modify the function signatures; many
interprocedural optimizations refuse to touch non-internal functions.
If you want to disable this behavior entirely, pass
-disable-internalize' to llvm-ld. If you want to disable it only for
specific functions (recommended if you want to optimize your code) try
If you use either of the latter two, make sure to put 'main' on the list
as well; it doesn't look like 'internalize' does that automatically
anymore if it's passed an explicit list.
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