| Message ID | 20190911211527.GM14737@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | C++ PATCH for c++/91740 - ICE with constexpr call and ?: in ARRAY_REF | expand |
Hi, On 11/09/19 23:15, Marek Polacek wrote: > --- gcc/cp/pt.c > +++ gcc/cp/pt.c > @@ -26709,7 +26709,7 @@ build_non_dependent_expr (tree expr) > if (TREE_CODE (expr) == COND_EXPR) > return build3 (COND_EXPR, > TREE_TYPE (expr), > - TREE_OPERAND (expr, 0), > + build_non_dependent_expr (TREE_OPERAND (expr, 0)), > (TREE_OPERAND (expr, 1) > ? build_non_dependent_expr (TREE_OPERAND (expr, 1)) > : build_non_dependent_expr (TREE_OPERAND (expr, 0))), Looks like we would end up unnecessarily calling build_non_dependent_expr three times instead of two: probably is very cheap, probably the code is cleaner this way but I'm a little annoyed at this anyway, for the record ;) Cheers, Paolo.
Hi again, On 12/09/19 11:03, Paolo Carlini wrote: > Hi, > > On 11/09/19 23:15, Marek Polacek wrote: >> --- gcc/cp/pt.c >> +++ gcc/cp/pt.c >> @@ -26709,7 +26709,7 @@ build_non_dependent_expr (tree expr) >> if (TREE_CODE (expr) == COND_EXPR) >> return build3 (COND_EXPR, >> TREE_TYPE (expr), >> - TREE_OPERAND (expr, 0), >> + build_non_dependent_expr (TREE_OPERAND (expr, 0)), >> (TREE_OPERAND (expr, 1) >> ? build_non_dependent_expr (TREE_OPERAND (expr, 1)) >> : build_non_dependent_expr (TREE_OPERAND (expr, 0))), > > Looks like we would end up unnecessarily calling > build_non_dependent_expr three times instead of two: probably is very > cheap, probably the code is cleaner this way but I'm a little annoyed > at this anyway, for the record ;) Sorry, I misread the code: normally TREE_OPERAND (expr, 1) isn't NULL_TREE thus we are fine. Paolo.
On Thu, Sep 12, 2019 at 11:08:43AM +0200, Paolo Carlini wrote: > Hi again, > > On 12/09/19 11:03, Paolo Carlini wrote: > > Hi, > > > > On 11/09/19 23:15, Marek Polacek wrote: > > > --- gcc/cp/pt.c > > > +++ gcc/cp/pt.c > > > @@ -26709,7 +26709,7 @@ build_non_dependent_expr (tree expr) > > > if (TREE_CODE (expr) == COND_EXPR) > > > return build3 (COND_EXPR, > > > TREE_TYPE (expr), > > > - TREE_OPERAND (expr, 0), > > > + build_non_dependent_expr (TREE_OPERAND (expr, 0)), > > > (TREE_OPERAND (expr, 1) > > > ? build_non_dependent_expr (TREE_OPERAND (expr, 1)) > > > : build_non_dependent_expr (TREE_OPERAND (expr, 0))), > > > > Looks like we would end up unnecessarily calling > > build_non_dependent_expr three times instead of two: probably is very > > cheap, probably the code is cleaner this way but I'm a little annoyed at > > this anyway, for the record ;) > > Sorry, I misread the code: normally TREE_OPERAND (expr, 1) isn't NULL_TREE > thus we are fine. And I forgot to mention that build_x_conditional_expr has 6743 ifexp = build_non_dependent_expr (ifexp); 6744 if (op1) 6745 op1 = build_non_dependent_expr (op1); 6746 op2 = build_non_dependent_expr (op2); which means my fix should make more sense. -- Marek Polacek • Red Hat, Inc. • 300 A St, Boston, MA
On 9/11/19 4:15 PM, Marek Polacek wrote: > This ICEs since r267272 - more location wrapper nodes, but not because we can't > cope with new location wrappers, but because that commit introduced a call to > maybe_constant_value in cp_build_array_ref. In this testcase we call it with > > f (VIEW_CONVERT_EXPR<const char[4]>("BAR")) ? 1 : 0 > > argument and that crashes in fold_convert because we end up trying to convert > "BAR" of type const char[4] to const char * when evaluating the call. At this > point, decay_conversion hasn't turned the argument into (const char *) "BAR" > yet. > > The ICE doesn't occur without :?, because then the call will be wrapped in > NON_DEPENDENT_EXPR and constexpr throws its hands (I'm anthropomorphizing) up > when it encounters such an expression. > > I noticed that build_non_dependent_expr doesn't wrap op0 of ?: in N_D_E. This > is so since r70606 -- Nathan, is there a reason not to do it? Doing it fixes > this problem. > > Bootstrapped/regtested on x86_64-linux, ok for trunk? > > 2019-09-11 Marek Polacek <polacek@redhat.com> > > PR c++/91740 - ICE with constexpr call and ?: in ARRAY_REF. > * pt.c (build_non_dependent_expr): Call build_non_dependent_expr for > the first operand. > > * g++.dg/cpp1y/var-templ63.C: New test. > > diff --git gcc/cp/pt.c gcc/cp/pt.c > index c5915a5ecd0..775389d8245 100644 > --- gcc/cp/pt.c > +++ gcc/cp/pt.c > @@ -26709,7 +26709,7 @@ build_non_dependent_expr (tree expr) > if (TREE_CODE (expr) == COND_EXPR) > return build3 (COND_EXPR, > TREE_TYPE (expr), > - TREE_OPERAND (expr, 0), > + build_non_dependent_expr (TREE_OPERAND (expr, 0)), > (TREE_OPERAND (expr, 1) > ? build_non_dependent_expr (TREE_OPERAND (expr, 1)) > : build_non_dependent_expr (TREE_OPERAND (expr, 0))), OK. I wonder why this code copies op0 for the ?: extension rather than leave it null? Jason
diff --git gcc/cp/pt.c gcc/cp/pt.c index c5915a5ecd0..775389d8245 100644 --- gcc/cp/pt.c +++ gcc/cp/pt.c @@ -26709,7 +26709,7 @@ build_non_dependent_expr (tree expr) if (TREE_CODE (expr) == COND_EXPR) return build3 (COND_EXPR, TREE_TYPE (expr), - TREE_OPERAND (expr, 0), + build_non_dependent_expr (TREE_OPERAND (expr, 0)), (TREE_OPERAND (expr, 1) ? build_non_dependent_expr (TREE_OPERAND (expr, 1)) : build_non_dependent_expr (TREE_OPERAND (expr, 0))), diff --git gcc/testsuite/g++.dg/cpp1y/var-templ63.C gcc/testsuite/g++.dg/cpp1y/var-templ63.C new file mode 100644 index 00000000000..a65f53b2963 --- /dev/null +++ gcc/testsuite/g++.dg/cpp1y/var-templ63.C @@ -0,0 +1,5 @@ +// PR c++/91740 - ICE with constexpr call and ?: in ARRAY_REF. +// { dg-do compile { target c++14 } } + +constexpr bool f(const char*) { return true; } +template<typename T> const char c = "FOO"[f("BAR") ? 1 : 0];
This ICEs since r267272 - more location wrapper nodes, but not because we can't cope with new location wrappers, but because that commit introduced a call to maybe_constant_value in cp_build_array_ref. In this testcase we call it with f (VIEW_CONVERT_EXPR<const char[4]>("BAR")) ? 1 : 0 argument and that crashes in fold_convert because we end up trying to convert "BAR" of type const char[4] to const char * when evaluating the call. At this point, decay_conversion hasn't turned the argument into (const char *) "BAR" yet. The ICE doesn't occur without :?, because then the call will be wrapped in NON_DEPENDENT_EXPR and constexpr throws its hands (I'm anthropomorphizing) up when it encounters such an expression. I noticed that build_non_dependent_expr doesn't wrap op0 of ?: in N_D_E. This is so since r70606 -- Nathan, is there a reason not to do it? Doing it fixes this problem. Bootstrapped/regtested on x86_64-linux, ok for trunk? 2019-09-11 Marek Polacek <polacek@redhat.com> PR c++/91740 - ICE with constexpr call and ?: in ARRAY_REF. * pt.c (build_non_dependent_expr): Call build_non_dependent_expr for the first operand. * g++.dg/cpp1y/var-templ63.C: New test.