Improved Lightrec Debug #351
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When set, Lightrec will be built with the debug log level, the built-in disassembler for PSX code and JIT code (requires binutils), and support outputing data to the big-ass debugger (if the proper environment variables are set). Signed-off-by: Paul Cercueil <[email protected]>
These optimizations cause Lightrec's interpreter and dynarec to have different behaviours. Signed-off-by: Paul Cercueil <[email protected]>
This debugger has this name because it doesn't even try to be suttle - it will run the dynarec and interpreter versions of Lightrec in parallel, comparing their behaviour at every exit point, and returning any issue as soon as they appear. By default, the emulator will print a checksum of the registers after each exit point. When a mismatch is found, it is advised to re-start the debugging setting the LIGHTREC_VERY_DEBUG=1 environment variable, and to set the LIGHTREC_BEGIN_CYCLES environment variable to the cycle value of the last known state. When the "very debug" mode is used, the interpreter and dynarec will exit after each single block, and the emulator will compute a checksum of the whole RAM and scratchpad and print all registers. This two-level debugging allows to find a mismatch point very fast, and then fine-tune until the exact breaking point is found. Signed-off-by: Paul Cercueil <[email protected]>
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Allow to compile with LIGHTREC_DEBUG=1, which will set Lightrec's log level to debug mode, enable its built-in PSX code disassembler, the JIT disassembler, and enable support for the "big-ass debugger".
The latter will run the standalone build of PCSX in parallel with Lightrec's interpreter vs. its dynarec, and periodically compare their behaviour.
By default, the emulator will print a checksum of the registers after each exit point. When a mismatch is found, it is advised to re-start the debugging setting the LIGHTREC_VERY_DEBUG=1 environment variable, and to set the LIGHTREC_BEGIN_CYCLES environment variable to the cycle value of the last known state. When the "very debug" mode is used, the interpreter and dynarec will exit after each single block, and the emulator will compute a checksum of the whole RAM and scratchpad and print all registers. This two-level debugging allows to find a mismatch point very fast, and then fine-tune until the exact breaking point is found.
This is porting some code from my old pcsx_rearmed fork, which is just way too old to allow me to debug anything anymore. While it does not necesarily need to be in upstream pcsx_rearmed, it would make my life easier.