On 10/27/2014 12:49 AM, Zhenqiang Chen wrote:
> + {AARCH64_CC_Z, 0}, /* EQ, Z == 1. */
> + {0, AARCH64_CC_Z}, /* NE, Z == 0. */
> + {AARCH64_CC_C, 0}, /* CS, C == 1. */
> + {0, AARCH64_CC_C}, /* CC, C == 0. */
> + {0, 0}, /* MI, not supported*/
> + {0, 0}, /* PL, not supported*/
> + {0, 0}, /* VS, not supported*/
> + {0, 0}, /* VC, not supported*/
Why not go ahead and fill out the table? You know what needs to go in these
slots, after all.
> + {AARCH64_CC_C, AARCH64_CC_Z}, /* HI, C ==1 && Z == 0. */
> + {AARCH64_CC_Z, AARCH64_CC_C}, /* LS, !(C == 1 && Z == 0). */
> + {AARCH64_CC_N | AARCH64_CC_V, AARCH64_CC_N}, /* GE, N == V. */
> + {AARCH64_CC_N, AARCH64_CC_N | AARCH64_CC_V}, /* LT, N != V. */
> + {AARCH64_CC_N | AARCH64_CC_V, AARCH64_CC_Z}, /* GT, Z == 0 && N == V. */
> + {AARCH64_CC_Z, AARCH64_CC_N | AARCH64_CC_V}, /* LE, !(Z == 0 && N == V).
> */
Perhaps it's me, but does it make things clearer to reduce these?
That is, for the compound conditions, we need not make both sub-conditions be
false, only one of them. E.g.
{AARCH64_CC_C, 0} /* HI, C ==1 && Z == 0. */
{0, AARCH64_CC_C} /* LS, !(C ==1 && Z == 0) */
{0, AARCH64_CC_V} /* GE, N == V */
{AARCH64_CC_V, 0} /* LT, N != V */
{0, AARCH64_CC_Z} /* GT, Z == 0 && N == V */
{AARCH64_CC_Z, 0} /* LE, !(Z == 0 && N == V) */
At which point it becomes blindingly obvious that while we can't compress the
table with ~nczv, we can index it with reverse_comparison instead.
> + case 'k':
> + {
> + int cond_code;
> + rtx op0 = XEXP (x, 0);
> + enum rtx_code mode_code;
> + /* Print a condition (eq, ne, etc) of ccmp. */
> +
> + if (!COMPARISON_P (x) || !ccmp_cc_register (op0, GET_MODE (op0)))
> + {
> + output_operand_lossage ("invalid operand for '%%%c'", code);
> + return;
> + }
> +
> + mode_code = aarch64_ccmp_mode_to_code (GET_MODE (op0));
> + cond_code = aarch64_get_condition_code_1 (CCmode, mode_code);
> + gcc_assert (cond_code >= 0);
> + fputs (aarch64_condition_codes[cond_code], f);
> + }
Is there a branch with all the patches applied? I can't look back at the
modified aarch64_get_condition_code_1, but off-hand I can't think of why %m/%M
wouldn't work. Surely
aarch64_get_condition_code_1 (GET_MODE (op0), GET_CODE (x))
will yield the correct cond_code. If it didn't, then surely branches wouldn't
work at all.
These are not some magic new kind of conditions; they're exactly the same.
r~
