Hi Richard, Last few weeks I have been working on cleaning up ARC port for further reviewing.
In the context of the decoder, if I recall well, your observation was that a linear search was not Ok. Your suggestion was not to reinvent the wheel and generate decodetree to create the decoder. We started to do that and in the process we realize that the approach would bring us yet another encoding language description to maintain. Also that decodetree alone would not allow us to properly disassembly code, still requiring to keep the initial structure. Taking in consideration that we do all the other toolchain tools for ARC and that the decoder structure is already upstreamed in binutils we would definitely prefer to keep that structure and optimize the surroundings for proper decoding speeds. So far, we did the following: - converted opcodes.def to macros instead of table entries. - created a script that reads those entries and outputs macros that directly translate to a switch/case decision tree (example below), just like the ones produced by decodetree. The difference is that the switch will return the enum entry for the proper decoder structure instead of calling a translation function. - the script can either be contributed in C or python language as it is based on a simple recursive algorithm. As you have been the one giving attention to our target, I seek for your early feedback and to make sure that the solution is still inline with your expectations. Looking forward for your feedback. Regards, Cupertino PS: Would it be asking too much if we could have a call, just to get to meet each other. Unfortunately, no one now is able to do it any other way. I miss the traveling and conferences. Example1 (first few lines of the file): MATCH_PATTERN(0xf8000000) /* 11111000000000000000000000000000 */ MATCH_VALUE(0x0) /* 0 */ MATCH_PATTERN(0x10000) /* 10000000000000000 */ MATCH_VALUE(0x0) /* 0 */ RETURN_MATCH(OPCODE_ARCv2HS_b_0x00000000_0xF8010000_BRANCH_OP_SIMM21_A16_5) /* 00000ssssssssss0SSSSSSSSSSNQQQQQ */ END_MATCH_VALUE(0x0) /* 0 */ MATCH_VALUE(0x10000) /* 10000000000000000 */ RETURN_MATCH(OPCODE_ARCv2HS_b_0x00010000_0xF8010000_BRANCH_OP_SIMM25_A16_5) /* 00000ssssssssss1SSSSSSSSSSNRtttt */ END_MATCH_VALUE(0x10000) /* 10000000000000000 */ END_MATCH_PATTERN(0x10000) /* 10000000000000000 */ END_MATCH_VALUE(0x0) /* 0 */ MATCH_VALUE(0x8000000) /* 1000000000000000000000000000 */ MATCH_PATTERN(0x10000) /* 10000000000000000 */ MATCH_VALUE(0x0) /* 0 */ MATCH_PATTERN(0x20000) /* 100000000000000000 */ MATCH_VALUE(0x0) /* 0 */ RETURN_MATCH(OPCODE_ARCv2HS_bl_0x08000000_0xF8030000_BRANCH_OP_SIMM21_A32_5) /* 00001sssssssss00SSSSSSSSSSNQQQQQ */ END_MATCH_VALUE(0x0) /* 0 */ MATCH_VALUE(0x20000) /* 100000000000000000 */ RETURN_MATCH(OPCODE_ARCv2HS_bl_0x08020000_0xF8030000_BRANCH_OP_SIMM25_A32_5) /* 00001sssssssss10SSSSSSSSSSNRtttt */ END_MATCH_VALUE(0x20000) /* 100000000000000000 */ END_MATCH_PATTERN(0x20000) /* 100000000000000000 */ END_MATCH_VALUE(0x0) /* 0 */ MATCH_VALUE(0x10000) /* 10000000000000000 */ MATCH_PATTERN(0x17) /* 10111 */ MATCH_VALUE(0x0) /* 0 */ MULTI_MATCH(OPCODE_ARCv2HS_breq_0x08010000_0xF8010017_BRCC_OP_RB_RC_SIMM9_A16_8) /* 00001bbbsssssss1SBBBCCCCCCN0Y000 */ MULTI_MATCH(OPCODE_ARCv2HS_breq_0x08010F80_0xF8010FF7_BRCC_OP_RB_LIMM_SIMM9_A16_8) /* 00001bbbsssssss1SBBB11111000Y000 */ MULTI_MATCH(OPCODE_ARCv2HS_breq_0x0E017000_0xFF017037_BRCC_OP_LIMM_RC_SIMM9_A16_8) /* 00001110sssssss1S111CCCCCC00Y000 */ MULTI_MATCH(OPCODE_ARCv2HS_breq_0x0E017F80_0xFF017FF7_BRCC_OP_LIMM_LIMMdup_SIMM9_A16_8) /* 00001110sssssss1S11111111000Y000 */ END_MATCH_VALUE(0x0) /* 0 */
