https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118328
--- Comment #7 from Ken Jin <kenjin4096 at gmail dot com> --- The files are too big to upload here, so I've uploaded them to https://github.com/Fidget-Spinner/debugging-dump. They correspond to the main interpreter loop of CPython https://github.com/python/cpython/blob/e1988942ca26440a0df6f3949e93ddc0dbd1e57e/Python/ceval.c . Compiled with /home/ken/GCC-15.0-trunk/bin/gcc -c -fno-strict-overflow -Wsign-compare -DNDEBUG -g -O3 -Wall -std=c11 -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wstrict-prototypes -Werror=implicit-function-declaration -fvisibility=hidden -I./Include/internal -I./Include/internal/mimalloc -I. -I./Include -DPy_BUILD_CORE --save-temps -o Python/ceval.o Python/ceval.c Specifically, zoom in on the function _TAIL_CALL_YIELD_VALUE, it produces on GCC 15 (note the assembly here might be slightly different than the one in .s file, because it's from a different build but same flags passed): pushq %rbx movq -24(%rdi), %rax addq $2, %rcx subl $2, %r9d movq -8(%rsi), %r8 subq $8, %rsi movb %r9b, -5(%rdi) movq %rcx, 56(%rdi) movq %rsi, 64(%rdi) movq %rax, 120(%rdx) movq 8(%rdi), %rax movq $0, -24(%rdi) movq 56(%rax), %rcx movq 64(%rax), %rsi movq %rax, 72(%rdx) addl $1, 44(%rdx) movzwl 4(%rcx), %r9d movq $0, 8(%rdi) addq $4, %rcx addq $8, %rsi movq $0, 64(%rax) movl %r9d, %ebx movzbl %r9b, %edi movq %r8, -8(%rsi) movzbl %bh, %ebx movq INSTRUCTION_TABLE(,%rdi,8), %r10 movq %rdi, %r8 movq %rax, %rdi movl %ebx, %r9d popq %rbx jmp *%r10 .string "ENTER_EXECUTOR is not supported in this build" On Clang-19.1, it produces: movq %r15, 56(%r12) movq -8(%r13), %rcx addq $-8, %r13 addq $2, %r15 movq %r15, 56(%r12) addb $-2, %sil movb %sil, -5(%r12) movq %r13, 64(%r12) movq -24(%r12), %rax movq %rax, 120(%r14) movq $0, -24(%r12) incl 44(%r14) movq 8(%r12), %rax movq %rax, 72(%r14) movq $0, 8(%r12) movq 56(%rax), %r15 movq 64(%rax), %r13 movq $0, 64(%rax) movq %rcx, (%r13) addq $8, %r13 movzwl 4(%r15), %esi addq $4, %r15 movzbl %sil, %edi shrl $8, %esi leaq INSTRUCTION_TABLE(%rip), %rcx movq %rax, %r12 jmpq *(%rcx,%rdi,8)
