| Message ID | 20170206193002.GM1849@tucnak |
|---|---|
| State | New |
| Headers | show |
OK. On Mon, Feb 6, 2017 at 2:30 PM, Jakub Jelinek <jakub@redhat.com> wrote: > Hi! > > #pragma GCC ivdep can make it through into potential_constant_expression_1 > as the following testcase shows. As it is just a hint to the compiler, > I think it isn't needed to make loops with that pragma non-constexpr, so > the patch just ignores the hint for determination of what is a potential > constant expression and ditto in cxx_eval_constant_expression. The pragma > is represented by ANNOTATE_EXPR with first operand being the condition > of the loop and second operand annot_expr_ivdep_kind. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? > > 2017-02-06 Jakub Jelinek <jakub@redhat.com> > > PR c++/79379 > * constexpr.c (cxx_eval_constant_expression): Handle ANNOTATE_EXPR. > (potential_constant_expression_1): Likewise. > > * g++.dg/cpp1y/constexpr-79379.C: New test. > > --- gcc/cp/constexpr.c.jj 2017-02-03 23:35:37.000000000 +0100 > +++ gcc/cp/constexpr.c 2017-02-06 16:00:21.903921006 +0100 > @@ -4518,6 +4518,14 @@ cxx_eval_constant_expression (const cons > *non_constant_p = true; > return t; > > + case ANNOTATE_EXPR: > + gcc_assert (tree_to_uhwi (TREE_OPERAND (t, 1)) == annot_expr_ivdep_kind); > + r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0), > + lval, > + non_constant_p, overflow_p, > + jump_target); > + break; > + > default: > if (STATEMENT_CODE_P (TREE_CODE (t))) > { > @@ -5689,6 +5697,10 @@ potential_constant_expression_1 (tree t, > return false; > } > > + case ANNOTATE_EXPR: > + gcc_assert (tree_to_uhwi (TREE_OPERAND (t, 1)) == annot_expr_ivdep_kind); > + return RECUR (TREE_OPERAND (t, 0), rval); > + > default: > if (objc_is_property_ref (t)) > return false; > --- gcc/testsuite/g++.dg/cpp1y/constexpr-79379.C.jj 2017-02-06 16:09:30.457863715 +0100 > +++ gcc/testsuite/g++.dg/cpp1y/constexpr-79379.C 2017-02-06 16:08:49.000000000 +0100 > @@ -0,0 +1,19 @@ > +// PR c++/79379 > +// { dg-do compile { target c++14 } } > +// { dg-options "-O2" } > + > +template <int N> > +constexpr int > +foo (int x) > +{ > + int q[64] = { 0 }, r = 0; > +#pragma GCC ivdep > + for (int i = 0; i < x; ++i) > + q[i] += 2; > + for (int i = 0; i < x; ++i) > + r += q[i]; > + return r + N; > +} > + > +constexpr int a = foo<0> (17); > +static_assert (a == 34, ""); > > Jakub
--- gcc/cp/constexpr.c.jj 2017-02-03 23:35:37.000000000 +0100 +++ gcc/cp/constexpr.c 2017-02-06 16:00:21.903921006 +0100 @@ -4518,6 +4518,14 @@ cxx_eval_constant_expression (const cons *non_constant_p = true; return t; + case ANNOTATE_EXPR: + gcc_assert (tree_to_uhwi (TREE_OPERAND (t, 1)) == annot_expr_ivdep_kind); + r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0), + lval, + non_constant_p, overflow_p, + jump_target); + break; + default: if (STATEMENT_CODE_P (TREE_CODE (t))) { @@ -5689,6 +5697,10 @@ potential_constant_expression_1 (tree t, return false; } + case ANNOTATE_EXPR: + gcc_assert (tree_to_uhwi (TREE_OPERAND (t, 1)) == annot_expr_ivdep_kind); + return RECUR (TREE_OPERAND (t, 0), rval); + default: if (objc_is_property_ref (t)) return false; --- gcc/testsuite/g++.dg/cpp1y/constexpr-79379.C.jj 2017-02-06 16:09:30.457863715 +0100 +++ gcc/testsuite/g++.dg/cpp1y/constexpr-79379.C 2017-02-06 16:08:49.000000000 +0100 @@ -0,0 +1,19 @@ +// PR c++/79379 +// { dg-do compile { target c++14 } } +// { dg-options "-O2" } + +template <int N> +constexpr int +foo (int x) +{ + int q[64] = { 0 }, r = 0; +#pragma GCC ivdep + for (int i = 0; i < x; ++i) + q[i] += 2; + for (int i = 0; i < x; ++i) + r += q[i]; + return r + N; +} + +constexpr int a = foo<0> (17); +static_assert (a == 34, "");