Hi,
Richard Biener <rguent...@suse.de> writes: > 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. In rs6000.md, it is ; This is to explain that changes to the stack pointer should ; not be moved over loads from or stores to stack memory. (define_insn "stack_tie" [(match_parallel 0 "tie_operand" [(set (mem:BLK (reg 1)) (const_int 0))])] "" "" [(set_attr "length" "0")]) This would be just an placeholder insn, and acts as the comments. UNSPEC_ would works like other targets. While, I'm wondering the concerns on "set (mem:BLK (reg 1)) (const_int 0)". MODEs between SET_DEST and SET_SRC? Thanks for comments! BR, Jeff (Jiufu Guo) > >> Thanks, >> Richard
