9.4.1 Small IPA passes

A small IPA pass is a pass derived from simple_ipa_opt_pass. As described in IPA, it does everything at once and defines only the Execute stage. During this stage it accesses and modifies the function bodies. No generate_summary, read_summary, or write_summary hooks are defined.

• IPA free lang data

  This pass frees resources that are used by the front end but are not needed once it is done. It is located in tree.c and is described by pass_ipa_free_lang_data.

• IPA function and variable visibility

  This is a local function pass handling visibilities of all symbols. This happens before LTO streaming, so -fwhole-program should be ignored at this level. It is located in ipa-visibility.c and is described by pass_ipa_function_and_variable_visibility.

• IPA remove symbols

  This pass performs reachability analysis and reclaims all unreachable nodes. It is located in passes.c and is described by pass_ipa_remove_symbols.

• IPA OpenACC

  This is a pass group for OpenACC processing. It is located in tree-ssa-loop.c and is described by pass_ipa_oacc.

• IPA points-to analysis

  This is a tree-based points-to analysis pass. The idea behind this analyzer is to generate set constraints from the program, then solve the resulting constraints in order to generate the points-to sets. It is located in tree-ssa-structalias.c and is described by pass_ipa_pta.

• IPA OpenACC kernels

  This is a pass group for processing OpenACC kernels regions. It is a subpass of the IPA OpenACC pass group that runs on offloaded functions containing OpenACC kernels loops. It is located in tree-ssa-loop.c and is described by pass_ipa_oacc_kernels.

• Target clone

  This is a pass for parsing functions with multiple target attributes. It is located in multiple_target.c and is described by pass_target_clone.

• IPA auto profile

  This pass uses AutoFDO profiling data to annotate the control flow graph. It is located in auto-profile.c and is described by pass_ipa_auto_profile.

• IPA tree profile

  This pass does profiling for all functions in the call graph. It calculates branch probabilities and basic block execution counts. It is located in tree-profile.c and is described by pass_ipa_tree_profile.

• IPA free function summary

  This pass is a small IPA pass when argument small_p is true. It releases inline function summaries and call summaries. It is located in ipa-fnsummary.c and is described by pass_ipa_free_free_fn_summary.

• IPA increase alignment

  This pass increases the alignment of global arrays to improve vectorization. It is located in tree-vectorizer.c and is described by pass_ipa_increase_alignment.

• IPA transactional memory

  This pass is for transactional memory support. It is located in trans-mem.c and is described by pass_ipa_tm.

• IPA lower emulated TLS

  This pass lowers thread-local storage (TLS) operations to emulation functions provided by libgcc. It is located in tree-emutls.c and is described by pass_ipa_lower_emutls.