llvm dev - Nov 2005 - [LLVMdev] Runtime optimization and other doubts

Hi ,

Regarding my previous help on LLVM Instrumentation , gdb helped me out.

Your docs on Writing an LLVM Pass - Using gdb with dynamically loaded 

passes was very useful.

I've done some instrumentation and collected profiles during runtime using 

library routines in a separate pass with opt tool.

I used :

In the tools/lli/Makefile , I included the following line 

TOOLLINKOPTS := -lpthread

$opt -load ../../../mypass.so -myoption test.bc > test1.bc

$lli -load ../../../mypass.so test1.bc

using JIT and it worked perfectly.

Now I am trying to generate static native code generation and then execute the 

native code program as:

$opt -load ../../../mypass.so -myoption test.bc > test1.bc

$llc -load ../../../mypass.so test1.bc -o test1.s

$gcc test1.s -o test1.native -lpthread

but now I get the following error

/tmp/cc8ilAEp.o(.text+0x251): In function `main':

: undefined reference to `llvm_profile_init'

/tmp/cc8ilAEp.o(.text+0x26d): In function `main':

: undefined reference to `llvm_method_entry'

/tmp/cc8ilAEp.o(.text+0x39e): In function `main':

: undefined reference to `llvm_method_exit'

/tmp/cc8ilAEp.o(.text+0x3a3): In function `main':

: undefined reference to `llvm_profile_display'

collect2: ld returned 1 exit status

$

I also tried with various gcc options like -shared , -shared-libgcc , -L

to link my library mypass.so ,but nothing worked.How can I do this?

I am also interested in knowing more about profile driven runtime optimizations 

on LLVM1.5.Is it already available ? If so where can I find it? If not any hint

on how/where to start .

I found that optimizations of FunctionPass or MachineFunctionPass when used with

JIT are executed only once for each function. Am I wright ?

Is there any pass which will be executed each time a function is called or 

whenever it is needed i.e. during runtime ? 

Is it possible to inline/ clone the function after the machine code is generated
?

 

Thanks in advance for any help,

Sandra

 

 


		
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On Wed, 2 Nov 2005, Sandra Johnson wrote:
> $lli -load ../../../mypass.so test1.bc
> using JIT and it worked perfectly.
> Now I am trying to generate static native code generation and then execute
the
> native code program as:
> $opt -load ../../../mypass.so -myoption test.bc > test1.bc
> $llc -load ../../../mypass.so test1.bc -o test1.s
> $gcc test1.s -o test1.native -lpthread
> but now I get the following error
> /tmp/cc8ilAEp.o(.text+0x251): In function `main':
> : undefined reference to `llvm_profile_init'
Try

gcc test1.s -o test1.native -lpthread ../../../mypass.so

Make sure that ../../.. is in your LD_LIBRARY_PATH when running your 
program.
> I am also interested in knowing more about profile driven runtime
optimizations
There is one profile driven optimization (basic block layout), it does not 
run at runtime though, and is not enabled by default.
> I found that optimizations of FunctionPass or MachineFunctionPass when 
> used with JIT are executed only once for each function. Am I wright ?
Yes.
> Is there any pass which will be executed each time a function is called 
> or whenever it is needed i.e. during runtime ?
No.  You could use a function pass that inserts a function call into each 
function though, that would give you control every time each function is 
entered.
> Is it possible to inline/ clone the function after the machine code is 
> generated ?
No, not currently.  High-level optimizations like inlining are best 
performed on the LLVM IR level, not the machine code level.

-Chris

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