diff options
Diffstat (limited to 'gcc/combine.c')
| -rw-r--r-- | gcc/combine.c | 18 |
1 files changed, 9 insertions, 9 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 6ffa387a95c..6b7bdd0f687 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -9895,18 +9895,17 @@ reg_nonzero_bits_for_combine (const_rtx x, machine_mode mode, (DF_LR_IN (ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb), REGNO (x))))) { - unsigned HOST_WIDE_INT mask = rsp->last_set_nonzero_bits; - - if (GET_MODE_PRECISION (rsp->last_set_mode) < GET_MODE_PRECISION (mode)) - /* We don't know anything about the upper bits. */ - mask |= GET_MODE_MASK (mode) ^ GET_MODE_MASK (rsp->last_set_mode); - - *nonzero &= mask; + /* Note that, even if the precision of last_set_mode is lower than that + of mode, record_value_for_reg invoked nonzero_bits on the register + with nonzero_bits_mode (because last_set_mode is necessarily integral + and HWI_COMPUTABLE_MODE_P in this case) so bits in nonzero_bits_mode + are all valid, hence in mode too since nonzero_bits_mode is defined + to the largest HWI_COMPUTABLE_MODE_P mode. */ + *nonzero &= rsp->last_set_nonzero_bits; return NULL; } tem = get_last_value (x); - if (tem) { if (SHORT_IMMEDIATES_SIGN_EXTEND) @@ -9915,7 +9914,8 @@ reg_nonzero_bits_for_combine (const_rtx x, machine_mode mode, return tem; } - else if (nonzero_sign_valid && rsp->nonzero_bits) + + if (nonzero_sign_valid && rsp->nonzero_bits) { unsigned HOST_WIDE_INT mask = rsp->nonzero_bits; |