diff options
Diffstat (limited to 'gcc/simplify-rtx.c')
| -rw-r--r-- | gcc/simplify-rtx.c | 17 |
1 files changed, 13 insertions, 4 deletions
diff --git a/gcc/simplify-rtx.c b/gcc/simplify-rtx.c index 19d664b..0298b79e 100644 --- a/gcc/simplify-rtx.c +++ b/gcc/simplify-rtx.c @@ -449,14 +449,23 @@ simplify_unary_operation (code, mode, op, op_mode) case CLZ: arg0 &= GET_MODE_MASK (mode); - val = GET_MODE_BITSIZE (mode) - floor_log2 (arg0) - 1; + if (arg0 == 0 && CLZ_DEFINED_VALUE_AT_ZERO (mode, val)) + ; + else + val = GET_MODE_BITSIZE (mode) - floor_log2 (arg0) - 1; break; case CTZ: arg0 &= GET_MODE_MASK (mode); - val = arg0 == 0 - ? GET_MODE_BITSIZE (mode) - : exact_log2 (arg0 & -arg0); + if (arg0 == 0) + { + /* Even if the value at zero is undefined, we have to come + up with some replacement. Seems good enough. */ + if (! CTZ_DEFINED_VALUE_AT_ZERO (mode, val)) + val = GET_MODE_BITSIZE (mode); + } + else + val = exact_log2 (arg0 & -arg0); break; case POPCOUNT: |