Hi,
"Kewen.Lin" <li...@linux.ibm.com> writes:
> Hi Jeff,
>
> on 2022/9/7 15:08, Jiufu Guo via Gcc-patches wrote:
>> Hi,
>>
>> As the issue in PR106460, a rtx 'high:DI (symbol_ref:DI ("var_48")' is tried
>> to store into constant pool and ICE occur. But actually, this rtx represents
>> partial address and can not be put into a .rodata section.
>>
>> This patch updates rs6000_cannot_force_const_mem to return true for rtx(s)
>> with
>> HIGH code, because these rtx(s) indicate part of address and are not ok for
>> constant pool.
>>
>> Below are some examples:
>> (high:DI (const:DI (plus:DI (symbol_ref:DI ("xx") (const_int 12 [0xc])))))
>> (high:DI (symbol_ref:DI ("var_1")..)))
>>
>> This patch updated the previous patch, and drafted an test case which ICE
>> without the patch, and assoicated with one PR.
>> https://gcc.gnu.org/pipermail/gcc-patches/2022-July/597712.html
>> This patch also updated the message for previous patch V2.
>>
>> I would ask help to review this patch one more time.
>>
>> Bootstrap and regtest pass on ppc64 and ppc64le.
>> Is this ok for trunk.
>>
>> BR,
>> Jeff(Jiufu)
>>
>> PR target/106460
>>
>> gcc/ChangeLog:
>>
>> * config/rs6000/rs6000.cc (rs6000_cannot_force_const_mem): Return true
>> for HIGH code rtx.
>>
>> gcc/testsuite/ChangeLog:
>>
>> * gcc.target/powerpc/pr106460.c: New test.
>> ---
>> gcc/config/rs6000/rs6000.cc | 7 +++++--
>> gcc/testsuite/gcc.target/powerpc/pr106460.c | 11 +++++++++++
>> 2 files changed, 16 insertions(+), 2 deletions(-)
>> create mode 100644 gcc/testsuite/gcc.target/powerpc/pr106460.c
>>
>> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
>> index 2f3146e56f8..04e3a393147 100644
>> --- a/gcc/config/rs6000/rs6000.cc
>> +++ b/gcc/config/rs6000/rs6000.cc
>> @@ -9643,8 +9643,11 @@ rs6000_init_stack_protect_guard (void)
>> static bool
>> rs6000_cannot_force_const_mem (machine_mode mode ATTRIBUTE_UNUSED, rtx x)
>> {
>> - if (GET_CODE (x) == HIGH
>> - && GET_CODE (XEXP (x, 0)) == UNSPEC)
>> + /* If GET_CODE (x) is HIGH, the 'X' represets the high part of a
>> symbol_ref.
>> + It indicates partial address, which can not be put into a constant
>> pool.
>> + e.g. (high:DI (unspec:DI [(symbol_ref/u:DI ("*.LC0")..)
>> + (high:DI (symbol_ref:DI ("var")..)). */
>
> Nit: Maybe it's good to align these two "(high:DI ... ?
OK, thanks!
>
>> + if (GET_CODE (x) == HIGH)
>> return true;
>>
>> /* A TLS symbol in the TOC cannot contain a sum. */
>> diff --git a/gcc/testsuite/gcc.target/powerpc/pr106460.c
>> b/gcc/testsuite/gcc.target/powerpc/pr106460.c
>> new file mode 100644
>> index 00000000000..dfaffcb6e28
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.target/powerpc/pr106460.c
>> @@ -0,0 +1,11 @@
>
> Need a power10_ok effective target here.
>
> /* { dg-require-effective-target power10_ok } */
OK, will add this.
>
>> +/* { dg-options "-O1 -mdejagnu-cpu=power10" } */
>
> Nit: As Segher's review on one of my patches, O2 is preferred against O1 if it
> still works for this issue. The point is to avoid some related optimization
> (routines or passes) to be disabled at O1 one day and this becomes
> ineffective.
>
Yeap. While, for this case, the ICE is not reproduciable with -O2.
So, -O1 is used here.
BR,
Jeff (Jiufu)
> BR,
> Kewen
