Compilation passes

Compilation goes through several transformations phases of the original source until the assembly is generated:

How to observe the internals

To observe all passes at once, use:

gcc -fdump-tree-all -fdump-ipa-all -fdump-rtl-all

This generates several files with names of type:

<original file>.<id><dump>.<extension>

e.g.:

atomic.cpp.001t.tu
atomic.cpp.002t.class
atomic.cpp.166r.expand

where each one represents one pass.

<dump> is one letter that depends on the dump type: t for tree and r for rtl

The most interesting stages are:

.gimple:
.s.gkd: -fdump-final-insns: the very last representation before conversion to assembly

Non obvious ones:

.tu, from -fdump-translation-unit. The output is huge as it contains all includes.
.original, from -fdump-tree-original
.omplower and .lower, from TODO?
.eh, TODO. Likely liked to the eh_frame sections.
.cfg, control flow graph

Dump with -fdump-tree-gimple to a .gimple file.

Part of GIMPLE.

Part of RTL.