diff options
Diffstat (limited to 'gcc/reload1.c')
| -rw-r--r-- | gcc/reload1.c | 46 |
1 files changed, 41 insertions, 5 deletions
diff --git a/gcc/reload1.c b/gcc/reload1.c index c86b2bd429f..c469fb07618 100644 --- a/gcc/reload1.c +++ b/gcc/reload1.c @@ -2548,6 +2548,30 @@ eliminate_regs_1 (rtx x, enum machine_mode mem_mode, rtx insn, case POST_INC: case PRE_DEC: case POST_DEC: + /* We do not support elimination of a register that is modified. + elimination_effects has already make sure that this does not + happen. */ + return x; + + case PRE_MODIFY: + case POST_MODIFY: + /* We do not support elimination of a register that is modified. + elimination_effects has already make sure that this does not + happen. The only remaining case we need to consider here is + that the increment value may be an eliminable register. */ + if (GET_CODE (XEXP (x, 1)) == PLUS + && XEXP (XEXP (x, 1), 0) == XEXP (x, 0)) + { + rtx new = eliminate_regs_1 (XEXP (XEXP (x, 1), 1), mem_mode, + insn, true); + + if (new != XEXP (XEXP (x, 1), 1)) + return gen_rtx_fmt_ee (code, GET_MODE (x), XEXP (x, 0), + gen_rtx_PLUS (GET_MODE (x), + XEXP (x, 0), new)); + } + return x; + case STRICT_LOW_PART: case NEG: case NOT: case SIGN_EXTEND: case ZERO_EXTEND: @@ -2743,6 +2767,14 @@ elimination_effects (rtx x, enum machine_mode mem_mode) case POST_DEC: case POST_MODIFY: case PRE_MODIFY: + /* If we modify the source of an elimination rule, disable it. */ + for (ep = reg_eliminate; ep < ®_eliminate[NUM_ELIMINABLE_REGS]; ep++) + if (ep->from_rtx == XEXP (x, 0)) + ep->can_eliminate = 0; + + /* If we modify the target of an elimination rule by adding a constant, + update its offset. If we modify the target in any other way, we'll + have to disable the rule as well. */ for (ep = reg_eliminate; ep < ®_eliminate[NUM_ELIMINABLE_REGS]; ep++) if (ep->to_rtx == XEXP (x, 0)) { @@ -2757,11 +2789,15 @@ elimination_effects (rtx x, enum machine_mode mem_mode) ep->offset += size; else if (code == PRE_INC || code == POST_INC) ep->offset -= size; - else if ((code == PRE_MODIFY || code == POST_MODIFY) - && GET_CODE (XEXP (x, 1)) == PLUS - && XEXP (x, 0) == XEXP (XEXP (x, 1), 0) - && CONSTANT_P (XEXP (XEXP (x, 1), 1))) - ep->offset -= INTVAL (XEXP (XEXP (x, 1), 1)); + else if (code == PRE_MODIFY || code == POST_MODIFY) + { + if (GET_CODE (XEXP (x, 1)) == PLUS + && XEXP (x, 0) == XEXP (XEXP (x, 1), 0) + && CONST_INT_P (XEXP (XEXP (x, 1), 1))) + ep->offset -= INTVAL (XEXP (XEXP (x, 1), 1)); + else + ep->can_eliminate = 0; + } } /* These two aren't unary operators. */ |