GCC的中间语言及后端信息的转换

The Intermediate Language and theBack-End Information Translation in GCC

ＧＣＣ是一个成功地支持多种高级语言和多种机器平台的系统，分析其中间语言ＲＴＬ是扩充其前端和移植ＧＣＣ的前提。ＧＣＣ的后端信息ＭＤ使用ＲＴＬ的外部形式书写，主要用于定义机器的指令集、功能部件、延迟特性等。ＧＣＣ提供一套ＭＤ的转换程序ｇｅｎ＊来生成一套Ｃ文件ｉｎｓｎ－＊，供编译体更有效地获取与机器有关的信息；可以把ｇｅｎ＊看作是ＭＤ的编译器。

GCC is a successful system which supports a few high level languagesas well as many machines. Before adding something to its front end or making it runn onsome other system,analysis of its intermediate language RTL becomes a prerequisite.The back end information MDs in GCC are written in textual form of RTL,MDs areused to define instruction sets ,function units,delay slots,etc. GCC uses a set of pro-grams gen * to produce a set of C files inse-*, which give the machine information tothe complier in GCC directly. Gen* can be considered as the complier of MD.