git://gcc.gnu.org / gcc.git / blame
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1 | This file describes the implementation notes of the GNU C Compiler for |
| 2 | the Texas Instruments Floating Point Digital Signal Processor | |
| 3 | families, TMS320C3x and TMS320C4x (including the C30, C31, C32, C40, | |
| 4 | and C44 chips). | |
| 5 | ||
| 6 | ||
| 7 | Currently, only two code variants are generated---those for the C3x | |
| 8 | and C4x architectures. Note that the new operand combinations for | |
| 9 | parallel instructions, included in newer silicon revisions, are not | |
| 10 | yet supported. These should be trivial to add for someone with the | |
| 11 | newer chips and the inclination. | |
| 12 | ||
| 13 | ||
| 14 | While the generated assembly code is fairly similar to that recognised | |
| 15 | by the TI assembler, there are a few differences (currently the machine | |
| 16 | option -mti, designed to enfore compatibility, is not fully | |
| 17 | implemented). The major difference is the use of the ^ operator to | |
| 18 | load the 16 MSBs of an address or constant for the C4x. | |
| 19 | ||
| 20 | ||
| 21 | The generated assembly code requires the GNU assembler (GAS). This is | |
| 22 | not currently included as part of the binutils package, due to the | |
| 23 | many hacks required to be compatible with TI's kludged COFF | |
| 24 | implementation, and the binutils not being designed for 32-bit bytes. | |
| 25 | Patches against binutils-2.7.2 can be obtained from | |
| 26 | ftp://ongaonga.chch.cri.nz/pub/c4x. This site also has patches for | |
| 27 | the GNU debugger (GDB), incoporating a cycle accurate simulator that | |
| 28 | can display profiles and histories of code execution, detailing | |
| 29 | pipeline conflicts etc. | |
| 30 | ||
| 31 | ||
| 32 | GCC can be configured as a cross compiler for both the C3x and C4x | |
| 33 | architectures on the same system. Use `configure --target=c4x' to | |
| 34 | configure GCC for both the C3x and C4x. Then use the -m30 option to | |
| 35 | generate code for the C30 or -m40 (the default) for the C40. | |
| 36 | ||
| 37 | ||
| 38 | Further installation notes and other optimization patches for GCC can | |
| 39 | also be obtained from ftp://ongaonga.chch.cri.nz/pub/c4x. | |
| 40 | ||
| 41 | ||
| 42 | A Majordomo mailing list, gcc_c40@atlantek.com.au, exists to discuss | |
| 43 | related issues and suggestions for further optimizations. To | |
| 44 | subscribe send a message with `subscribe gcc_c40' in the body to | |
| 45 | majordomo@atlantek.com.au. | |
| 46 | ||
| 47 | ||
| 48 | Michael Hayes, 16 Sep 98 |