| Message ID | CAO2gOZVs-YERrXhJYgWUe-2+xDZeCH56kAH8yak_SMJfJbb=TQ@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
ok. David On Tue, Oct 15, 2013 at 10:58 AM, Dehao Chen <dehao@google.com> wrote: > This patch add a new flag to let user to tell compiler that the > AutoFDO profile is accurate. So the compiler will assume function > without any sample is UNLIKELY_EXECUTED. This could save 10%~20% text > section size. > > Bootstrapped and passed regression test. > > OK for google-4_8 branch? > > Thanks, > Dehao > > Index: gcc/common.opt > =================================================================== > --- gcc/common.opt (revision 203546) > +++ gcc/common.opt (working copy) > @@ -942,6 +942,10 @@ Common Joined RejectNegative Var(auto_profile_file > Use sample profile information for call graph node weights. The profile > file is specified in the argument. > > +fauto-profile-accurate > +Common Report Var(flag_auto_profile_accurate) Optimization > +Whether to assume the sample profile is accurate. > + > ; -fcheck-bounds causes gcc to generate array bounds checks. > ; For C, C++ and ObjC: defaults off. > ; For Java: defaults to on. > Index: gcc/predict.c > =================================================================== > --- gcc/predict.c (revision 203546) > +++ gcc/predict.c (working copy) > @@ -2866,7 +2866,9 @@ compute_function_frequency (void) > || (flag_auto_profile && profile_status == PROFILE_GUESSED)) > { > int flags = flags_from_decl_or_type (current_function_decl); > - if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl)) > + if (profile_info && flag_auto_profile_accurate) > + node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; > + else if (lookup_attribute ("cold", DECL_ATTRIBUTES > (current_function_decl)) > != NULL) > node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; > else if (lookup_attribute ("hot", DECL_ATTRIBUTES > (current_function_decl))
Index: gcc/common.opt =================================================================== --- gcc/common.opt (revision 203546) +++ gcc/common.opt (working copy) @@ -942,6 +942,10 @@ Common Joined RejectNegative Var(auto_profile_file Use sample profile information for call graph node weights. The profile file is specified in the argument. +fauto-profile-accurate +Common Report Var(flag_auto_profile_accurate) Optimization +Whether to assume the sample profile is accurate. + ; -fcheck-bounds causes gcc to generate array bounds checks. ; For C, C++ and ObjC: defaults off. ; For Java: defaults to on. Index: gcc/predict.c =================================================================== --- gcc/predict.c (revision 203546) +++ gcc/predict.c (working copy) @@ -2866,7 +2866,9 @@ compute_function_frequency (void) || (flag_auto_profile && profile_status == PROFILE_GUESSED)) { int flags = flags_from_decl_or_type (current_function_decl); - if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl)) + if (profile_info && flag_auto_profile_accurate) + node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED; + else if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl)) != NULL) node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED;
This patch add a new flag to let user to tell compiler that the AutoFDO profile is accurate. So the compiler will assume function without any sample is UNLIKELY_EXECUTED. This could save 10%~20% text section size. Bootstrapped and passed regression test. OK for google-4_8 branch? Thanks, Dehao else if (lookup_attribute ("hot", DECL_ATTRIBUTES (current_function_decl))