These new tree formats are called GENERIC and GIMPLE. Recently, two new forms of language-independent trees have been introduced. Confusingly, the meaning of a tree was somewhat different for different language front-ends, and front-ends could provide their own tree codes.

Until recently, the tree representation of the program was not fully independent of the processor being targeted. Some parsers use a YACC-type grammar specification, and the others are hand-coded recursive descent parsers. Nearly all of GCC is written in C, although much of the Ada frontend is written in Ada.įrontends vary internally, having to produce trees that can be handled by the backend. All have a common internal structure a per-language front end that parses the languages and produces an abstract syntax tree ('tree' for short), and a back end that converts the trees to GCC's Register Transfer Language (RTL), runs various compiler optimizations, then produces assembly language using architecture-specific pattern matching originally based on an algorithm of Jack Davidson and Chris Fraser's. Users invoke a driver program named gcc, which interprets command arguments, decides which language compilers to use for each input file, runs the assembler on their output, and then possibly runs the linker to produce a complete program.Įach of the language compilers is a separate program that takes in source code and produces assembly language. GCC's external interface is generally standard for a Unix compiler. Additional processors, such as the D10V, PDP-10, and Z8000, have been supported by GCC versions maintained separately from the FSF version. Lesser-known target processors supported in the standard release have included A29K, ARC, Atmel AVR, C4x, CRIS, D30V, DSP16xx, FR-30, FR-V, Intel i960, IP2000, M32R, 68HC11, MCORE, MMIX, MN10200, MN10300, NS32K, ROMP, Stormy16, V850, and Xtensa. GCC target processors (as of version 3.2) include: Pascal, Modula-2, Modula-3, Mercury, VHDL, PL/I and Objective-C++ frontends also exist. The G77 front end was dropped in favour of the new GFortran frontend that supports Fortran 95. As of version 4.0.0 (released on ), the standard compiler release includes front ends for:Ī front end for CHILL was previously included, but has been dropped owing to a lack of maintenance.

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