from zephyr.c:122
static const struct stack_register_offset arm_cpu_saved[] = {
{ ARMV7M_R0, 0, 32 },
{ ARMV7M_R1, 4, 32 },
{ ARMV7M_R2, 8, 32 },
{ ARMV7M_R3, 12, 32 },
{ ARMV7M_R4, -1, 32 },
{ ARMV7M_R5, -1, 32 },
{ ARMV7M_R6, -1, 32 },
{ ARMV7M_R7, -1, 32 },
{ ARMV7M_R8, -1, 32 },
{ ARMV7M_R9, -1, 32 },
{ ARMV7M_R10, -1, 32 },
{ ARMV7M_R11, -1, 32 },
{ ARMV7M_R12, 16, 32 },
{ ARMV7M_R13, -2, 32 },
{ ARMV7M_R14, 20, 32 },
{ ARMV7M_PC, 24, 32 },
{ ARMV7M_XPSR, 28, 32 },
};