fix: ARM64 JIT crashes, visual corruption, and 64-bit pointer safety (#1766)#1824
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fix: ARM64 JIT crashes, visual corruption, and 64-bit pointer safety (#1766)#1824
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…1766) Fix 12 root-cause bugs in the ARM64 JIT compiler that caused crashes, visual corruption, and stalls across various Amiga configurations. Crashes & stalls: - Inter-block dont_care_flags: flush_flags() before dont_care_flags() to prevent stale NZCV on interpreter fallback path - FBcc branch target truncation: avoid set_const() for 64-bit host pointers on non-PC_P registers in FPU conditional branches - BSR.L/Bcc.L sign extension: cast comp_get_ilong() to (uae_s32) for 32-bit displacements in 32 branch handlers + generator - Bus error recovery: setjmp/longjmp in m68k_run_jit() with SIGBUS handler integration for JIT code accessing unmapped memory Visual corruption (A4000 AGA wallpaper): - ADDX_b/w MOVN_xi initialization: move register init outside the FLAG_Z guard since it serves dual purpose (Z-flag base AND byte-packing padding for ADCS carry chain) - ADDX/SUBX Z-flag semantics: implement M68K "only clears" behavior with proper sticky-Z via UBFX/CMP/SET_xxZflag/CSEL/AND 64-bit pointer safety: - arm_ADD_l/arm_ADD_l_ri: sign-extend 32-bit M68K displacements when destination is PC_P (the only 64-bit virtual register) - set_const: mask non-PC_P registers to 32 bits - All pc_p store/load paths use 64-bit operations - MOVE16: use ADD_xxx (64-bit) for natmem pointer arithmetic Memory subsystem: - natmem_reserved_size upgraded to size_t (was uae_u32, overflowed) - ARM64 gets 4GB natmem reservation - commit_natmem_gaps() fills unmapped regions with read-only pages Performance optimizations: - Two-pass liveflags: use successor block needed_flags for better flag elimination (+2.3% with R_REGSTRUCT range optimization) - R_REGSTRUCT range-based offset: regflags uses fast 1-instruction STR_wXi instead of 4-5 instruction LOAD_U64 path - ADDX/SUBX Z-flag skip: wrap Z handling in needed_flags check - Guard infrastructure fully removed (was diagnostic-only) - setjmp placed outside inner dispatch loop (~2% cost) Tested: Lightwave-NoRAM.uae (boots), Lightwave.uae (app stable), A4000.uae (clean AGA wallpaper), SysInfo.uae (~7391 MIPS).
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…rm zero-fill skip - sigsegv_handler.cpp: longjmp value 3 (address error) → 2 (bus error) for unmapped memory faults from unrecognized JIT instructions - amiberry_mem.cpp: remove #ifndef _WIN32 guard around zero-fill skip since Windows VirtualAlloc(MEM_COMMIT) also zero-fills pages
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Summary
Fixes 12 root-cause bugs in the ARM64 JIT compiler that caused crashes, visual corruption, and stalls across various Amiga configurations. All fixes are root-cause — no guards or bandaids.
dont_care_flags()stale flag bug, FBcc 64-bit branch target truncation, BSR.L/Bcc.L sign extension for backward branches, bus error recovery viasetjmp/longjmpMOVN_xidual-purpose bug), ADDX/SUBX Z-flag M68K "only clears" semanticsarm_ADD_l/arm_ADD_l_risign extension,set_const32-bit masking, 64-bitpc_pstore/load paths, MOVE16 pointer arithmeticsize_tfor natmem sizes, 4GB ARM64 reservation,commit_natmem_gaps()read-only gap pagesTest Results
Files Changed (16 source + 3 skill docs)
JIT Core (6 files)
compemu_support_arm.cpp— Inter-block fix, two-pass liveflags, cleanupcodegen_arm64.cpp— R_REGSTRUCT range optimization, 64-bit pc_p pathscompemu_midfunc_arm64.cpp— Sign-extension fixes, set_const maskingcompemu_midfunc_arm64_2.cpp— ADDX/SUBX Z-flag + MOVN_xi fix, MOVE16compemu_fpp_arm.cpp— FBcc branch target truncation fixcompemu.h—jit_in_compiled_codeexternRuntime (4 files)
newcpu.cpp— setjmp/bus error recovery, dispatch loopsigsegv_handler.cpp— SIGBUS/longjmp handlerm68k.h— FLAGBIT_X=0, SET_XFLG/GET_XFLG bit 0Memory (6 files)
amiberry_mem.cpp—commit_natmem_gaps(), 4GB ARM64, size_tmemory.cpp/memory.h— Gap commit call, size_t declarationsvm.h/vm.cpp— size_t function signatures throughoutmain.cpp,ram.cpp,expansion.cpp— size_t, cleanupCloses #1766