GCC Middle and Back End API Reference
tm_log_entry Struct Reference
Collaboration diagram for tm_log_entry:

Data Fields

tree addr
basic_block entry_block
vec< gimple * > stmts
tree save_var

Detailed Description

Instead of instrumenting thread private memory, we save the
addresses in a log which we later use to save/restore the addresses
upon transaction start/restart.

The log is keyed by address, where each element contains individual
statements among different code paths that perform the store.

This log is later used to generate either plain save/restore of the
addresses upon transaction start/restart, or calls to the ITM_L*
logging functions.

So for something like:

    struct large { int x[1000]; };
    struct large lala = { 0 };
    __transaction {
      lala.x[i] = 123;

We can either save/restore:

    lala = { 0 };
    trxn = _ITM_startTransaction ();
    if (trxn & a_saveLiveVariables)
      tmp_lala1 = lala.x[i];
    else if (a & a_restoreLiveVariables)
      lala.x[i] = tmp_lala1;

or use the logging functions:

    lala = { 0 };
    trxn = _ITM_startTransaction ();
    _ITM_LU4 (&lala.x[i]);

Obviously, if we use _ITM_L* to log, we prefer to call _ITM_L* as
far up the dominator tree to shadow all of the writes to a given
location (thus reducing the total number of logging calls), but not
so high as to be called on a path that does not perform a
One individual log entry.  We may have multiple statements for the
same location if neither dominate each other (on different
execution paths).   

Field Documentation

◆ addr

◆ entry_block

◆ save_var

tree tm_log_entry::save_var

◆ stmts

vec<gimple *> tm_log_entry::stmts

The documentation for this struct was generated from the following file: