Message ID | 20220201091849.GT2646553@tucnak |
---|---|
State | New |
Headers | show |
Series | veclower: Fix up -fcompare-debug issue in expand_vector_comparison [PR104307] | expand |
On Tue, 1 Feb 2022, Jakub Jelinek wrote: > Hi! > > The following testcase fails -fcompare-debug, because expand_vector_comparison > since r11-1786-g1ac9258cca8030745d3c0b8f63186f0adf0ebc27 sets > vec_cond_expr_only when it sees some use other than VEC_COND_EXPR that uses > the lhs in its condition. > Obviously we should ignore debug stmts when doing so, e.g. by not pushing > them to uses. > That would be a 2 liner change, but while looking at it, I'm also worried > about VEC_COND_EXPRs that would use the lhs in more than one operand, > like VEC_COND_EXPR <lhs, lhs, something> or VEC_COND_EXPR <lhs, something, lhs> > (sure, they ought to be folded, but what if they weren't). Because if > something like that happens, then FOR_EACH_IMM_USE_FAST would push the same > stmt multiple times and expand_vector_condition can return true even when > it modifies it (for vector bool masking). > And lastly, it seems quite wasteful to safe_push statements that will just > cause vec_cond_expr_only = false; and break; in the second loop, both for > cases like 1000 immediate non-VEC_COND_EXPR uses and for cases like > 999 VEC_COND_EXPRs with lhs in cond followed by a single non-VEC_COND_EXPR > use. So this patch only pushes VEC_COND_EXPRs there. As > expand_vector_condition modifies the IL, it checks the condition again as > before. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? So I think it's all fine besides the handling of VEC_COND_EXPRs where the use is in rhs1 and rhs2 and/or rhs3 - I don't really understand your worry here but shouldn't the stmt end up on the vector at least once? You can use gimple_assign_rhs1_ptr to see whether the use is the rhs1 use comparing that with USE_PTR IIRC. Btw, if you never push VEC_COND_EXPRs with such double-use it's not necessary to check again in the second loop? That said, the other changes look reasonable. Thanks, Richard. > 2022-02-01 Jakub Jelinek <jakub@redhat.com> > > PR middle-end/104307 > * tree-vect-generic.cc (expand_vector_comparison): Don't push debug > stmts to uses vector, just set vec_cond_expr_only to false for > non-VEC_COND_EXPRs instead of pushing them into uses. Treat > VEC_COND_EXPRs that use lhs not just in rhs1, but rhs2 or rhs3 too > like non-VEC_COND_EXPRs. > > * gcc.target/i386/pr104307.c: New test. > > --- gcc/tree-vect-generic.cc.jj 2022-01-20 11:30:45.641577244 +0100 > +++ gcc/tree-vect-generic.cc 2022-01-31 18:01:29.062568721 +0100 > @@ -436,29 +436,43 @@ expand_vector_comparison (gimple_stmt_it > feeding a VEC_COND_EXPR statement. */ > auto_vec<gimple *> uses; > FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs) > - uses.safe_push (USE_STMT (use_p)); > - > - for (unsigned i = 0; i < uses.length (); i ++) > { > - gassign *use = dyn_cast<gassign *> (uses[i]); > - if (use != NULL > + gimple *use = USE_STMT (use_p); > + if (is_gimple_debug (use)) > + continue; > + if (is_gimple_assign (use) > && gimple_assign_rhs_code (use) == VEC_COND_EXPR > - && gimple_assign_rhs1 (use) == lhs) > - { > - gimple_stmt_iterator it = gsi_for_stmt (use); > - if (!expand_vector_condition (&it, dce_ssa_names)) > - { > - vec_cond_expr_only = false; > - break; > - } > - } > + && gimple_assign_rhs1 (use) == lhs > + && gimple_assign_rhs2 (use) != lhs > + && gimple_assign_rhs3 (use) != lhs) > + uses.safe_push (use); > else > - { > - vec_cond_expr_only = false; > - break; > - } > + vec_cond_expr_only = false; > } > > + if (vec_cond_expr_only) > + for (gimple *use : uses) > + { > + if (is_gimple_assign (use) > + && gimple_assign_rhs_code (use) == VEC_COND_EXPR > + && gimple_assign_rhs1 (use) == lhs > + && gimple_assign_rhs2 (use) != lhs > + && gimple_assign_rhs3 (use) != lhs) > + { > + gimple_stmt_iterator it = gsi_for_stmt (use); > + if (!expand_vector_condition (&it, dce_ssa_names)) > + { > + vec_cond_expr_only = false; > + break; > + } > + } > + else > + { > + vec_cond_expr_only = false; > + break; > + } > + } > + > if (!uses.is_empty () && vec_cond_expr_only) > return NULL_TREE; > > --- gcc/testsuite/gcc.target/i386/pr104307.c.jj 2022-01-31 17:34:42.163145798 +0100 > +++ gcc/testsuite/gcc.target/i386/pr104307.c 2022-01-31 17:35:14.111696698 +0100 > @@ -0,0 +1,6 @@ > +/* PR middle-end/104307 */ > +/* { dg-do compile } */ > +/* { dg-require-effective-target int128 } */ > +/* { dg-options "-O2 -mavx512f -fcompare-debug " } */ > + > +#include "pr78669.c" > > Jakub > >
On Tue, Feb 01, 2022 at 10:29:03AM +0100, Richard Biener wrote: > So I think it's all fine besides the handling of VEC_COND_EXPRs where > the use is in rhs1 and rhs2 and/or rhs3 - I don't really understand > your worry here but shouldn't the stmt end up on the vector at least > once? You can use gimple_assign_rhs1_ptr to see whether the My worry is that FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs) uses.safe_push (USE_STMT (use_p)); for a stmt with multiple uses of lhs pushes the same stmt multiple times. And then if (a_is_comparison) a = gimplify_build2 (gsi, code, type, a1, a2); a1 = gimplify_build2 (gsi, BIT_AND_EXPR, type, a, b); a2 = gimplify_build1 (gsi, BIT_NOT_EXPR, type, a); a2 = gimplify_build2 (gsi, BIT_AND_EXPR, type, a2, c); a = gimplify_build2 (gsi, BIT_IOR_EXPR, type, a1, a2); gimple_assign_set_rhs_from_tree (gsi, a); update_stmt (gsi_stmt (*gsi)); will modify it (though the above at least will not remove the stmt and update it in place I think) and then it won't be a VEC_COND_EXPR anymore. To me the non-cond uses in VEC_COND_EXPR conceptually look like any other unhandled uses that the second loop clears vec_cond_expr_only on. But I don't have a testcase, dunno if it is even possible. > use is the rhs1 use comparing that with USE_PTR IIRC. Btw, if you > never push VEC_COND_EXPRs with such double-use it's not necessary > to check again in the second loop? I was just trying to be extra cautious in case expand_vector_comparison modifies some other stmts, but maybe it is just expand_vector_comparison in veclower and no other function that modifies anything but the current stmt (+ pushes some new preparation statements and follow-up statements). So perhaps indeed: + if (vec_cond_expr_only) + for (gimple *use : uses) + { + gimple_stmt_iterator it = gsi_for_stmt (use); + if (!expand_vector_condition (&it, dce_ssa_names)) + { + vec_cond_expr_only = false; + break; + } + } for the second loop is enough. But sure, if you prefer all I can do: FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs) - uses.safe_push (USE_STMT (use_p)); + if (!is_gimple_debug (USE_STMT (use_p))) + uses.safe_push (USE_STMT (use_p)); and keep the rest for GCC 13. Jakub
On Tue, 1 Feb 2022, Jakub Jelinek wrote: > On Tue, Feb 01, 2022 at 10:29:03AM +0100, Richard Biener wrote: > > So I think it's all fine besides the handling of VEC_COND_EXPRs where > > the use is in rhs1 and rhs2 and/or rhs3 - I don't really understand > > your worry here but shouldn't the stmt end up on the vector at least > > once? You can use gimple_assign_rhs1_ptr to see whether the > > My worry is that > FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs) > uses.safe_push (USE_STMT (use_p)); > for a stmt with multiple uses of lhs pushes the same > stmt multiple times. > And then > if (a_is_comparison) > a = gimplify_build2 (gsi, code, type, a1, a2); > a1 = gimplify_build2 (gsi, BIT_AND_EXPR, type, a, b); > a2 = gimplify_build1 (gsi, BIT_NOT_EXPR, type, a); > a2 = gimplify_build2 (gsi, BIT_AND_EXPR, type, a2, c); > a = gimplify_build2 (gsi, BIT_IOR_EXPR, type, a1, a2); > gimple_assign_set_rhs_from_tree (gsi, a); > update_stmt (gsi_stmt (*gsi)); > will modify it (though the above at least will not remove the > stmt and update it in place I think) and then it won't be > a VEC_COND_EXPR anymore. Ah, OK. Sure, pushing the stmt multiple times looks bogus and indeed if we see we'll visit it a second time for a rhs{2,3} use there's no point in pushing it in the first place. > To me the non-cond uses in VEC_COND_EXPR conceptually look like > any other unhandled uses that the second loop clears > vec_cond_expr_only on. But I don't have a testcase, dunno if it is even > possible. > > > use is the rhs1 use comparing that with USE_PTR IIRC. Btw, if you > > never push VEC_COND_EXPRs with such double-use it's not necessary > > to check again in the second loop? > > I was just trying to be extra cautious in case expand_vector_comparison > modifies some other stmts, but maybe it is just expand_vector_comparison > in veclower and no other function that modifies anything but the > current stmt (+ pushes some new preparation statements and follow-up > statements). > So perhaps indeed: > + if (vec_cond_expr_only) > + for (gimple *use : uses) > + { > + gimple_stmt_iterator it = gsi_for_stmt (use); > + if (!expand_vector_condition (&it, dce_ssa_names)) > + { > + vec_cond_expr_only = false; > + break; > + } > + } > for the second loop is enough. Yes, I think so. > But sure, if you prefer all I can do: > FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs) > - uses.safe_push (USE_STMT (use_p)); > + if (!is_gimple_debug (USE_STMT (use_p))) > + uses.safe_push (USE_STMT (use_p)); > > and keep the rest for GCC 13. No, I think the change is fine with the second loop adjusted. Thanks, Richard.
--- gcc/tree-vect-generic.cc.jj 2022-01-20 11:30:45.641577244 +0100 +++ gcc/tree-vect-generic.cc 2022-01-31 18:01:29.062568721 +0100 @@ -436,29 +436,43 @@ expand_vector_comparison (gimple_stmt_it feeding a VEC_COND_EXPR statement. */ auto_vec<gimple *> uses; FOR_EACH_IMM_USE_FAST (use_p, iterator, lhs) - uses.safe_push (USE_STMT (use_p)); - - for (unsigned i = 0; i < uses.length (); i ++) { - gassign *use = dyn_cast<gassign *> (uses[i]); - if (use != NULL + gimple *use = USE_STMT (use_p); + if (is_gimple_debug (use)) + continue; + if (is_gimple_assign (use) && gimple_assign_rhs_code (use) == VEC_COND_EXPR - && gimple_assign_rhs1 (use) == lhs) - { - gimple_stmt_iterator it = gsi_for_stmt (use); - if (!expand_vector_condition (&it, dce_ssa_names)) - { - vec_cond_expr_only = false; - break; - } - } + && gimple_assign_rhs1 (use) == lhs + && gimple_assign_rhs2 (use) != lhs + && gimple_assign_rhs3 (use) != lhs) + uses.safe_push (use); else - { - vec_cond_expr_only = false; - break; - } + vec_cond_expr_only = false; } + if (vec_cond_expr_only) + for (gimple *use : uses) + { + if (is_gimple_assign (use) + && gimple_assign_rhs_code (use) == VEC_COND_EXPR + && gimple_assign_rhs1 (use) == lhs + && gimple_assign_rhs2 (use) != lhs + && gimple_assign_rhs3 (use) != lhs) + { + gimple_stmt_iterator it = gsi_for_stmt (use); + if (!expand_vector_condition (&it, dce_ssa_names)) + { + vec_cond_expr_only = false; + break; + } + } + else + { + vec_cond_expr_only = false; + break; + } + } + if (!uses.is_empty () && vec_cond_expr_only) return NULL_TREE; --- gcc/testsuite/gcc.target/i386/pr104307.c.jj 2022-01-31 17:34:42.163145798 +0100 +++ gcc/testsuite/gcc.target/i386/pr104307.c 2022-01-31 17:35:14.111696698 +0100 @@ -0,0 +1,6 @@ +/* PR middle-end/104307 */ +/* { dg-do compile } */ +/* { dg-require-effective-target int128 } */ +/* { dg-options "-O2 -mavx512f -fcompare-debug " } */ + +#include "pr78669.c"