This is interesting: https://github.com/zherczeg/sljit/blob/master/sljit_src/sljitLir.h https://github.com/zherczeg/sljit/blob/master/sljit_src/slji... (Lines

This is interesting: https://github.com/zherczeg/sljit/blob/master/sljit_src/sljitLir.h https://github.com/zherczeg/sljit/blob/master/sljit_src/slji... (Lines 167-205): // Scratch registers. #define SLJIT_R0 1 #define SLJIT_R1 2 #define SLJIT_R2 3 // Note: on x86-32, R3 - R6 (same as S3 - S6) are emulated (they are allocated on the stack). These registers are called virtual and cannot be used for memory addressing (cannot be part of any SLJIT_MEM1, SLJIT_MEM2 construct). There is no such limitation on other CPUs. See sljit_get_register_index(). #define SLJIT_R3 4 [...] #define SLJIT_R9 10 [...] /* Saved registers. */ #define SLJIT_S0 (SLJIT_NUMBER_OF_REGISTERS) #define SLJIT_S1 (SLJIT_NUMBER_OF_REGISTERS - 1) #define SLJIT_S2 (SLJIT_NUMBER_OF_REGISTERS - 2) // Note: on x86-32, S3 - S6 (same as R3 - R6) are emulated (they are allocated on the stack). These registers are called virtual and cannot be used for memory addressing (cannot be part of any SLJIT_MEM1, SLJIT_MEM2 construct). There is no such limitation on other CPUs. See sljit_get_register_index(). #define SLJIT_S3 (SLJIT_NUMBER_OF_REGISTERS - 3) [...] #define SLJIT_S9 (SLJIT_NUMBER_OF_REGISTERS - 9) Anyway, this is a cool technique... Emulating additional registers on machines that don't have them via the Stack, so that the assembly-like LIR can run on those machines too! Very nice!