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Diffstat (limited to 'gcc/doc/passes.texi')
| -rw-r--r-- | gcc/doc/passes.texi | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/gcc/doc/passes.texi b/gcc/doc/passes.texi index daeaf9520e1..9004dd763ec 100644 --- a/gcc/doc/passes.texi +++ b/gcc/doc/passes.texi @@ -841,6 +841,28 @@ Global register allocation. This pass allocates hard registers for the remaining pseudo registers (those whose life spans are not contained in one basic block). The pass is located in @file{global.c}. +@item +The optional integrated register allocator (@acronym{IRA}). It can be +used instead of the local and global allocator. It is called +integrated because coalescing, register live range splitting, and hard +register preferencing are done on-the-fly during coloring. It also +has better integration with the reload pass. Pseudo-registers spilled +by the allocator or the reload have still a chance to get +hard-registers if the reload evicts some pseudo-registers from +hard-registers. The allocator helps to choose better pseudos for +spilling based on their live ranges and to coalesce stack slots +allocated for the spilled pseudo-registers. IRA is a regional +register allocator which is transformed into Chaitin-Briggs allocator +if there is one region. By default, IRA chooses regions using +register pressure but the user can force it to use one region or +regions corresponding to all loops. + +Source files of the allocator are @file{ira.c}, @file{ira-build.c}, +@file{ira-costs.c}, @file{ira-conflicts.c}, @file{ira-color.c}, +@file{ira-emit.c}, @file{ira-lives}, plus header files @file{ira.h} +and @file{ira-int.h} used for the communication between the allocator +and the rest of the compiler and between the IRA files. + @cindex reloading @item Reloading. This pass renumbers pseudo registers with the hardware |