| Message ID | eeb7e8bf-3d4d-aecc-7f23-f20c14c59d57@linux.ibm.com |
|---|---|
| State | New |
| Headers | show |
| Series | [S390] Avoid LA with base and index on z13 | expand |
On 07/16/2018 01:02 PM, Robin Dapp wrote: >> But on zEC12 LA works pretty much the same as on z13/z14, it is >> indeed not cracked, but still a 2-cycle instruction when using >> an index register. So I guess the change really should apply >> to zEC12 as well, and this could be as simple as changing the >> above line to: >> >> if (addr.indx && s390_tune >= PROCESSOR_2817_Z196) >> >> (Note that "addr.base && addr.indx" is the same as just checking >> for addr.indx, since s390_decompose_address will never fill in >> *just* an index.) > > Good point, I adapted the patch and changed the comment. > > Regards > Robin > > -- > > gcc/ChangeLog: > > 2018-07-16 Robin Dapp <rdapp@linux.ibm.com> > > * config/s390/s390.c (preferred_la_operand_p): Do not use > LA with index register on z196 or later. > Ok to apply. Thanks! Andreas
diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c index 23c3f3db621..d8b47c6fe67 100644 --- a/gcc/config/s390/s390.c +++ b/gcc/config/s390/s390.c @@ -4623,11 +4623,11 @@ preferred_la_operand_p (rtx op1, rtx op2) if (addr.indx && !REGNO_OK_FOR_INDEX_P (REGNO (addr.indx))) return false; - /* Avoid LA instructions with index register on z196; it is - preferable to use regular add instructions when possible. - Starting with zEC12 the la with index register is "uncracked" - again. */ - if (addr.indx && s390_tune == PROCESSOR_2817_Z196) + /* Avoid LA instructions with index (and base) register on z196 or + later; it is preferable to use regular add instructions when + possible. Starting with zEC12 the la with index register is + "uncracked" again but still slower than a regular add. */ + if (addr.indx && s390_tune >= PROCESSOR_2817_Z196) return false; if (!TARGET_64BIT && !addr.pointer)