A regular IPA pass is a pass derived from ipa_opt_pass_d that
is executed in WHOPR compilation. Regular IPA passes may have summary
hooks implemented in any of the LGEN, WPA or LTRANS stages (see Using summary information in IPA passes).
This pass performs various optimizations involving symbol visibility
with -fwhole-program, including symbol privatization,
discovering local functions, and dismantling comdat groups. It is
located in ipa-visibility.cc and is described by
pass_ipa_whole_program_visibility.
The IPA profile pass propagates profiling frequencies across the call
graph. It is located in ipa-profile.cc and is described by
pass_ipa_profile.
This is the inter-procedural identical code folding pass.
The goal of this transformation is to discover functions
and read-only variables that have exactly the same semantics. It is
located in ipa-icf.cc and is described by pass_ipa_icf.
This pass performs speculative devirtualization based on the type
inheritance graph. When a polymorphic call has only one likely target
in the unit, it is turned into a speculative call. It is located in
ipa-devirt.cc and is described by pass_ipa_devirt.
The goal of this pass is to discover functions that are always invoked
with some arguments with the same known constant values and to modify
the functions accordingly. It can also do partial specialization and
type-based devirtualization. It is located in ipa-cp.cc and is
described by pass_ipa_cp.
This pass can replace an aggregate parameter with a set of other parameters
representing part of the original, turning those passed by reference
into new ones which pass the value directly. It also removes unused
function return values and unused function parameters. This pass is
located in ipa-sra.cc and is described by pass_ipa_sra.
This pass merges multiple constructors and destructors for static
objects into single functions. It’s only run at LTO time unless the
target doesn’t support constructors and destructors natively. The
pass is located in ipa.cc and is described by
pass_ipa_cdtor_merge.
This pass provides function analysis for inter-procedural passes.
It collects estimates of function body size, execution time, and frame
size for each function. It also estimates information about function
calls: call statement size, time and how often the parameters change
for each call. It is located in ipa-fnsummary.cc and is
described by pass_ipa_fn_summary.
The IPA inline pass handles function inlining with whole-program
knowledge. Small functions that are candidates for inlining are
ordered in increasing badness, bounded by unit growth parameters.
Unreachable functions are removed from the call graph. Functions called
once and not exported from the unit are inlined. This pass is located in
ipa-inline.cc and is described by pass_ipa_inline.
This pass marks functions as being either const (TREE_READONLY) or
pure (DECL_PURE_P). The per-function information is produced
by pure_const_generate_summary, then the global information is computed
by performing a transitive closure over the call graph. It is located in
ipa-pure-const.cc and is described by pass_ipa_pure_const.
This pass is a regular IPA pass when argument small_p is false.
It releases inline function summaries and call summaries.
It is located in ipa-fnsummary.cc and is described by
pass_ipa_free_fn_summary.
This pass gathers information about how variables whose scope is
confined to the compilation unit are used. It is located in
ipa-reference.cc and is described by pass_ipa_reference.
This pass checks whether variables are used by a single function.
It is located in ipa.cc and is described by
pass_ipa_single_use.
This pass looks for static symbols that are used exclusively
within one comdat group, and moves them into that comdat group. It is
located in ipa-comdats.cc and is described by
pass_ipa_comdats.