diff options
Diffstat (limited to 'gcc/optabs.c')
| -rw-r--r-- | gcc/optabs.c | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/gcc/optabs.c b/gcc/optabs.c index 48a3406..bdbb88c 100644 --- a/gcc/optabs.c +++ b/gcc/optabs.c @@ -3711,18 +3711,24 @@ prepare_cmp_insn (rtx *px, rtx *py, enum rtx_code *pcomparison, rtx size, result = emit_library_call_value (libfunc, NULL_RTX, LCT_CONST_MAKE_BLOCK, word_mode, 2, x, mode, y, mode); + /* There are two kinds of comparison routines. Biased routines + return 0/1/2, and unbiased routines return -1/0/1. Other parts + of gcc expect that the comparison operation is equivalent + to the modified comparison. For signed comparisons compare the + result against 1 in the biased case, and zero in the unbiased + case. For unsigned comparisons always compare against 1 after + biasing the unbased result by adding 1. This gives us a way to + represent LTU. */ *px = result; *pmode = word_mode; - if (TARGET_LIB_INT_CMP_BIASED) - /* Integer comparison returns a result that must be compared - against 1, so that even if we do an unsigned compare - afterward, there is still a value that can represent the - result "less than". */ - *py = const1_rtx; - else + *py = const1_rtx; + + if (!TARGET_LIB_INT_CMP_BIASED) { - *py = const0_rtx; - *punsignedp = 1; + if (*punsignedp) + *px = plus_constant (result, 1); + else + *py = const0_rtx; } return; } |