nx_x86_64_branch_test.nx

nx_x86_64_branch_test.nx -- session 3 smoke for cmp/setcc/branch. Builds a program that exercises every cmp/branch primitive: rax := 5 rcx := 5 cmpq %rcx, %rax ; rax - rcx == 0 sete %al ; al = 1 movzbq %al, %rax ; rax = 1 testq %rax, %rax ; flags from rax (non-zero) jne .Leq ; branch taken write 'N' and exit (should NOT reach) .Leq: write 'Y' (means: equality compare worked) rax := 3 rcx := 7 cmpq %rcx, %rax ; rax - rcx == -4 < 0 jl .Llt ; signed less-than (cmpq operand order: ; AT&T `cmpq src1, src2` is src2 - src1, ; so jl jumps when src2 < src1 -- here ; rax (3) < rcx (7) yes) write 'B' and exit (should NOT reach) .Llt: write 'L' (means: signed-less-than branch worked) jmp .Ldone .Ldone: exit 0 Expected stdout: "YL" (2 bytes hex 59 4C).