On Fri, 9 Jun 2023, Richard Sandiford wrote: > guojiufu <guoji...@linux.ibm.com> writes: > > Hi, > > > > On 2023-06-09 16:00, Richard Biener wrote: > >> On Fri, 9 Jun 2023, Jiufu Guo wrote: > >> > >>> Hi, > >>> > >>> As checking the code, there is a "gcc_assert (SCALAR_INT_MODE_P > >>> (mode))" > >>> in "try_const_anchors". > >>> This assert seems correct because the function try_const_anchors cares > >>> about integer values currently, and modes other than SCALAR_INT_MODE_P > >>> are not needed to support. > >>> > >>> This patch makes sure SCALAR_INT_MODE_P when calling > >>> try_const_anchors. > >>> > >>> This patch is raised when drafting below one. > >>> https://gcc.gnu.org/pipermail/gcc-patches/2022-October/603530.html. > >>> With that patch, "{[%1:DI]=0;} stack_tie" with BLKmode runs into > >>> try_const_anchors, and hits the assert/ice. > >>> > >>> Boostrap and regtest pass on ppc64{,le} and x86_64. > >>> Is this ok for trunk? > >> > >> Iff the correct fix at all (how can a CONST_INT have BLKmode?) then > >> I suggest to instead fix try_const_anchors to change > >> > >> /* CONST_INT is used for CC modes, but we should leave those alone. > >> */ > >> if (GET_MODE_CLASS (mode) == MODE_CC) > >> return NULL_RTX; > >> > >> gcc_assert (SCALAR_INT_MODE_P (mode)); > >> > >> to > >> > >> /* CONST_INT is used for CC modes, leave any non-scalar-int mode > >> alone. */ > >> if (!SCALAR_INT_MODE_P (mode)) > >> return NULL_RTX; > >> > > > > This is also able to fix this issue. there is a "Punt on CC modes" > > patch > > to return NULL_RTX in try_const_anchors. > > > >> but as said I wonder how we arrive at a BLKmode CONST_INT and whether > >> we should have fended this off earlier. Can you share more complete > >> RTL of that stack_tie? > > > > > > (insn 15 14 16 3 (parallel [ > > (set (mem/c:BLK (reg/f:DI 1 1) [1 A8]) > > (const_int 0 [0])) > > ]) "/home/guojiufu/temp/gdb.c":13:3 922 {stack_tie} > > (nil)) > > > > It is "set (mem/c:BLK (reg/f:DI 1 1) (const_int 0 [0])". > > I'm not convinced this is correct RTL. (unspec:BLK [(const_int 0)] ...) > would be though. It's arguably more accurate too, since the effect > on the stack locations is unspecified rather than predictable.
powerpc seems to be the only port with a stack_tie that's not using an UNSPEC RHS. > Thanks, > Richard
