| 3 | | = GHC Commentary: What the hell is a {{{.cmm}}} file? = |
| | 3 | = GHC Commentary: What the hell is a `.cmm` file? = |
| | 4 | |
| | 5 | A `.cmm` file is rather like C--. The syntax is almost C-- (a few constructs are missing), and it is augmented with some macros that are expanded by GHC's code generator (eg. `INFO_TABLE()`). A `.cmm` file is compiled by GHC itself: the syntax is parsed by [[GhcFile(compiler/cmm/CmmParse.y)]] and [[GhcFile(compiler/cmm/CmmLex.x)]] into the [wiki:Commentary/Compiler/CmmType Cmm] data type, where it is then passed through one of the [wiki:Commentary/Compiler/Backends back-ends]. |
| | 6 | |
| | 7 | We use the C preprocessor on `.cmm` files, making extensive use of macros to make writing this low-level code a bit less tedious and error-prone. Most of our C-- macros are in [[GhcFile(includes/Cmm.h)]]. |
