[UNIX]
Interprocess Communication
ctime(3)の最後には改行文字が付く
[GCC]
The Inner Working of GCC
URL: http://www.redhat.com/magazine/002dec04/features/gcc/
[ Various Optimization ]
- Algebraic simplifications
i + 1 -i -> 1
[ Constant folding ]
4 + 3 - 8 -> -1
[ Redundancy Elimination ]
[ (1)Loop-invariant code motion ]
while{ i = 1; hogehoge; } -> i = 1; while{ hogehoge; }
[ (2)Common sub-expression elimination ]
i = func(2); j = func(2); -> i = func(2); j = i;
[ (3)Partial redundancy elimination ]
(1), (2)を1 expressionだけでなくもっと広範囲に適用する。
コンパイラってこんなこともしてたんか、すげ。
Figure : Existing Compilation Process in GCC
Fiture : GCC's Compilation Process with Tree SSA
- GENERIC addresses the lack of a common tree representation among the various front ends.
- GIMPLE solves the complexity problems that facilitate the discovery of data and control flow in the program.
GENERIC and GIMPLE
Although some Front Ends share the same tree representation, there is no single representation used by all GCC Front Ends. Every Front End is responsible from translating its own parse trees directly into RTL. To address this problem, we have introduced a new representation, named GENERIC, that is merely a superset of all the existing tree representations in GCC. Instead of generating RTL, every Front End is responsible for converting its own parse trees into GENERIC trees. Since GENERIC trees are language-independent, all the semantics of the input language must be explicitly described by each Front End. Some of these semantics are translated in the "genericize" pass, while others are translated in the "gimplification" pass.
GCC 4.0からはProgrammingLanguage -> GENERIC -> GIMPLE -> RTL -> MachineCodeの流れになるのか。
Red Hat Magazine( http://www.redhat.com/magazine/ )なんてモノが有ったんですね。
[ Various Optimization ]
- Algebraic simplifications
i + 1 -i -> 1
[ Constant folding ]
4 + 3 - 8 -> -1
[ Redundancy Elimination ]
[ (1)Loop-invariant code motion ]
while{ i = 1; hogehoge; } -> i = 1; while{ hogehoge; }
[ (2)Common sub-expression elimination ]
i = func(2); j = func(2); -> i = func(2); j = i;
[ (3)Partial redundancy elimination ]
(1), (2)を1 expressionだけでなくもっと広範囲に適用する。
コンパイラってこんなこともしてたんか、すげ。
Figure : Existing Compilation Process in GCC
Fiture : GCC's Compilation Process with Tree SSA
- GENERIC addresses the lack of a common tree representation among the various front ends.
- GIMPLE solves the complexity problems that facilitate the discovery of data and control flow in the program.
GENERIC and GIMPLE
Although some Front Ends share the same tree representation, there is no single representation used by all GCC Front Ends. Every Front End is responsible from translating its own parse trees directly into RTL. To address this problem, we have introduced a new representation, named GENERIC, that is merely a superset of all the existing tree representations in GCC. Instead of generating RTL, every Front End is responsible for converting its own parse trees into GENERIC trees. Since GENERIC trees are language-independent, all the semantics of the input language must be explicitly described by each Front End. Some of these semantics are translated in the "genericize" pass, while others are translated in the "gimplification" pass.
GCC 4.0からはProgrammingLanguage -> GENERIC -> GIMPLE -> RTL -> MachineCodeの流れになるのか。
Red Hat Magazine( http://www.redhat.com/magazine/ )なんてモノが有ったんですね。