From cTuning.org
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=== Work flow === | === Work flow === | ||
| - | For each cgraph node, we check whether it | + | For each cgraph node, we check whether it needs to be cloned. |
If yes, clone it using cgraph_function_version, apply options for each clone, and insert selection mechanism into original function. | If yes, clone it using cgraph_function_version, apply options for each clone, and insert selection mechanism into original function. | ||
Revision as of 08:50, 12 August 2009
Google Summer of Code 2009: Generic function cloning.
Liang Peng (ICT, China)
Based on Run-time Function Adaptation for Statically-Compiled Programs based on function multiversioning and FunctionSpecificOpt, we enabled generic function cloning with low-overhead program behavior monitoring routines. It will enable fine-grain self-tuning binaries and libraries and will increase performance and portability of the static code which is particularly important for rapidly evolving hardware and virtual enviroments.
Contents |
Key data structures
Information from xml files for function cloning and instrumentation through ICI plugin.
Defined in both gcc/highlev-plugin-internal.h and gcc/highlev-plugin.h:
typedef struct {
/* number of function to clone. */
int numofclonefun;
/* function name list. */
char **clone_function_list;
/* corresponding filename of function. */
char **function_filename_list;
/* corresponding number of clones. */
int *clones;
/* corresponding function name extension for clone. */
char **clone_extension;
/* corresponding adaptation function name for current function . */
char **adaptation_function;
/* option list for clone . */
char **clone_option;
/* corresponding external libraries. */
char *external_libraries;
} cloneinfo ;
typedef struct {
/* number of function to instrument. */
int numofinstrfun;
/* function name list. */
char **instrument_function_list;
/* corresponding filename of function. */
char **function_filename_list;
/* name of function instrument at the begin of function. */
char **timer1;
/* name of function instrument at the end of function. */
char **timer2;
/* flag list whether function is cloned. */
char *cloned;
} instrinfo ;
New ICI event
ICI event "load_clone_config"
This event is called at the very beginning of function cloning pass.
- Call back function: load_clone_config () Defined in ICI plugin adapt.c
- It gets the current main input filename first using get_feature ("main_input_filename"), then read information from corresponding xml file into datastruct cloneinfo using Mini-XML library.
- ICI event parameter: clone_info A pointer to datastruct cloneinfo
ICI event “load_instr_config”
This event is called at the very beginning of function instrumentation pass.
- Call back function : load_instr_config () Defined in ICI plugin adapt.c
- It gets the current main input filename first using get_feature ("main_input_filename"), then read information from corresponding xml file into datastruct instrinfo using Mini-XML library.
- ICI event parameter: clone_info A pointer to datastruct instrinfo
Function cloning
Description
SIMPLE_IPA_PASS "generic_cloning"
This pass performs generic function cloning. It has the ability to create any number of clones for a given function on demand, and aply different fine-grain optimizations for a given clone, also provide mechanism to select different clones at run-time based on optimization scenarios. It's placed before pass_early_local_passes, and we are trying to put it more earlier.
It can be triggered by GCC option -fapi-clone-function and ICI adaptation framework. The information come from xml files through ICI.
Primary functions
- exec_clone_functions (void)
- This is the execute function for gimple_opt_pass pass_clone_functions. It calls event "load_instr_config" to load information needed by cloning, and clone functions that is in the clone list using cgraph_function_versioning, and insert selection mechanism at last.
- add_call_to_clones (struct cgraph_node *orig, int nid)
- This function insert selection mechanism, which includes call to clones, call to adaptation function, and build switch statement.
- get_arguments (tree tree_list)
- This function get the arguments of original function into tree argv.
- parse_arguments (char *text, unsigned int *argc)
- This function parse a option string, and return the number of argument and argument vector.
- For example parse string "-O3 -fici -fapi-clone-functions", to int argc=3, char **argv={"-O3","-fici","-fapi-clone-functions"}
- find_clone_options (char *funcname, int *nid)
- This function trys to find a option for clone according to clone's name in clone_option list, also records the id.
- is_in_clone_list (const char *func_name, const char *file_name, int *nid)
- This function check whether function:func_name in file:file_name needs to clone, return true if yes, false if no, nid records the id in the list.
- is_it_clonable (struct cgraph_node *cg_func)
- check whether cgraph_node:cg_func is clonable.
- is_it_main (struct cgraph_node *cg_func)
- check whether cgraph_node:cg_func is a cgraph node of main/MAIN__.
Work flow
For each cgraph node, we check whether it needs to be cloned.
If yes, clone it using cgraph_function_version, apply options for each clone, and insert selection mechanism into original function.
Applying different optimization to clone
Selection mechanism and overhead
Instrumentation
Description
SIMPLE_IPA_PASS "Instrumentation"
This pass performs function instrumentation. Currently, it has only ability to add function calls and selection mechanism to choose clones based on the external library monitoring routines. We also have the ability to link external libraries transparently withou Makefile modifications. This pass also can be triggered by GCC option fapi-instrument-functions and ICI adaptation framework. The information come from xml files through ICI.
Primary functions
exec_instrument_functions (void)
add_timer_begin (struct cgraph_node *cg_func, char *funname, int cloned)
add_timer_end (struct cgraph_node *cg_func, char *funname)
freeinstrinfo (instrinfo idi)
is_in_instrument_list (const char *func_name, const char *file_name, int *nid)
is_it_instrumentable (struct cgraph_node *cg_func)
Work flow
ICI Adaptation
Work flow
Three steps compilation:
Scripts
adaptutil.py