https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111754
--- Comment #6 from prathamesh3492 at gcc dot gnu.org --- (In reply to rguent...@suse.de from comment #4) > On Tue, 10 Oct 2023, prathamesh3492 at gcc dot gnu.org wrote: > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111754 > > > > --- Comment #3 from prathamesh3492 at gcc dot gnu.org --- > > The issue is that we only support integral vector types in > > fold_vec_perm_cst, > > but fail to check for the same before calling it from fold_vec_perm. > > The following tweak fixes the ICE: > > > > diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc > > index 4f8561509ff..a29a8af6d2f 100644 > > --- a/gcc/fold-const.cc > > +++ b/gcc/fold-const.cc > > @@ -10801,7 +10801,8 @@ fold_vec_perm (tree type, tree arg0, tree arg1, > > const > > vec_perm_indices &sel) > > return NULL_TREE; > > > > if (TREE_CODE (arg0) == VECTOR_CST > > - && TREE_CODE (arg1) == VECTOR_CST) > > + && TREE_CODE (arg1) == VECTOR_CST > > + && INTEGRAL_TYPE_P (TREE_TYPE (type))) > > return fold_vec_perm_cst (type, arg0, arg1, sel); > > Huh, that looks wrong. I fail to see how the element type matters > at all. IIUC, the element type matters for VLA folding when sel has a stepped sequence because in that case we need to derive elements from the encoding using vector_cst_elt / vector_cst_int_elt, and it gets enforced for VLS vectors too because they are handled in unified manner in fold_vec_perm_cst. Another possible approach is to use "VLS exception" in fold_vec_perm_cst to encode all the elements: res_npatterns = res_nelts; res_nelts_per_patterns = 1 just like we do if valid_mask_for_fold_vec_perm_cst_p returns false. Does the following fix look OK instead ? diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc index 4f8561509ff..356eb052fbc 100644 --- a/gcc/fold-const.cc +++ b/gcc/fold-const.cc @@ -10642,6 +10642,11 @@ valid_mask_for_fold_vec_perm_cst_p (tree arg0, tree arg1, if (sel_nelts_per_pattern < 3) return true; + /* If SEL contains stepped sequence, ensure that we are dealing with + integral vector_cst. */ + if (!INTEGRAL_TYPE_P (TREE_TYPE (arg0))) + return false; + for (unsigned pattern = 0; pattern < sel_npatterns; pattern++) { poly_uint64 a1 = sel[pattern + sel_npatterns];
