diff options
Diffstat (limited to 'py')
| -rw-r--r-- | py/asmthumb.c | 41 |
1 files changed, 35 insertions, 6 deletions
diff --git a/py/asmthumb.c b/py/asmthumb.c index c0ba6222c..fda0f5270 100644 --- a/py/asmthumb.c +++ b/py/asmthumb.c @@ -499,6 +499,7 @@ void asm_thumb_store_reg_reg_offset(asm_thumb_t *as, uint reg_src, uint reg_base #define OP_BW_HI(byte_offset) (0xf000 | (((byte_offset) >> 12) & 0x07ff)) #define OP_BW_LO(byte_offset) (0xb800 | (((byte_offset) >> 1) & 0x07ff)) +// In Thumb1 mode, this may clobber r1. void asm_thumb_b_label(asm_thumb_t *as, uint label) { mp_uint_t dest = get_label_dest(as, label); mp_int_t rel = dest - as->base.code_offset; @@ -518,19 +519,40 @@ void asm_thumb_b_label(asm_thumb_t *as, uint label) { if (asm_thumb_allow_armv7m(as)) { asm_thumb_op32(as, OP_BW_HI(rel), OP_BW_LO(rel)); } else { + // this code path has to be the same instruction size irrespective of the value of rel + bool need_align = as->base.code_offset & 2u; if (SIGNED_FIT12(rel)) { - // this code path has to be the same number of instructions irrespective of rel asm_thumb_op16(as, OP_B_N(rel)); - } else { asm_thumb_op16(as, ASM_THUMB_OP_NOP); - if (dest != (mp_uint_t)-1) { - // we have an actual branch > 12 bits; this is not handled yet - mp_raise_NotImplementedError(MP_ERROR_TEXT("native method too big")); + asm_thumb_op16(as, ASM_THUMB_OP_NOP); + asm_thumb_op16(as, ASM_THUMB_OP_NOP); + if (need_align) { + asm_thumb_op16(as, ASM_THUMB_OP_NOP); } + } else { + // do a large jump using: + // (nop) + // ldr r1, [pc, _data] + // add pc, r1 + // _data: .word rel + // + // note: can't use r0 as a temporary because native code can have the return value + // in that register and use a large jump to get to the exit point of the function + + rel -= 2; // account for the "ldr r1, [pc, _data]" + if (need_align) { + asm_thumb_op16(as, ASM_THUMB_OP_NOP); + rel -= 2; // account for this nop + } + asm_thumb_ldr_rlo_pcrel_i8(as, ASM_THUMB_REG_R1, 0); + asm_thumb_add_reg_reg(as, ASM_THUMB_REG_R15, ASM_THUMB_REG_R1); + asm_thumb_op16(as, rel & 0xffff); + asm_thumb_op16(as, rel >> 16); } } } +// In Thumb1 mode, this may clobber r1. void asm_thumb_bcc_label(asm_thumb_t *as, int cond, uint label) { mp_uint_t dest = get_label_dest(as, label); mp_int_t rel = dest - as->base.code_offset; @@ -551,8 +573,15 @@ void asm_thumb_bcc_label(asm_thumb_t *as, int cond, uint label) { asm_thumb_op32(as, OP_BCC_W_HI(cond, rel), OP_BCC_W_LO(rel)); } else { // reverse the sense of the branch to jump over a longer branch - asm_thumb_op16(as, OP_BCC_N(cond ^ 1, 0)); + size_t code_offset_start = as->base.code_offset; + byte *c = asm_thumb_get_cur_to_write_bytes(as, 2); asm_thumb_b_label(as, label); + size_t bytes_to_skip = as->base.code_offset - code_offset_start; + uint16_t op = OP_BCC_N(cond ^ 1, bytes_to_skip - 4); + if (c != NULL) { + c[0] = op; + c[1] = op >> 8; + } } } |