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. Thanks, Richard
