Message ID | 51E1DBE2.3070801@redhat.com |
---|---|
State | New |
Headers | show |
Hi Jason, > From: gcc-patches-owner@gcc.gnu.org [mailto:gcc-patches- > owner@gcc.gnu.org] On Behalf Of Jason Merrill > Sent: 14 July 2013 00:00 > To: Joseph S. Myers > Cc: Eric Botcazou; gcc-patches@gcc.gnu.org; Richard Biener > Subject: PATCH (c,c++) for c++/57793 > > On 07/10/2013 01:24 AM, Eric Botcazou wrote: > > The idea behind the existing trick is that the reference is within the > bounds > > of the base object, i.e. the global offset (offset<<3 + bitpos) is > positive, > > but the bitpos part is negative, so we rearrange it into ((offset- > c>>3)<<3 + > > (bitpos+c)). Here the global offset is negative because it has > overflowed so > > I'm not sure the rearrangement makes any sense. > > I thought the idea of the trick was that when offset<<3 is too big, we > can use offset as a byte offset and then use bitpos separately in order > to avoid the overflowing operation. But I guess I was wrong; we end up > with a negative number in the assembly output. > > So here's a patch that just complains about the class being too big. > Tested x86_64-pc-linux-gnu, applying to trunk. Joseph, I'm assuming the > change makes sense for C as well; let me know if you disagree. With this patch we now get PASS->FAIL: gcc.dg/pr42611.c, because the error message now appears on the line of the definition of the struct. This patch fixes the testcase. Ok to apply to trunk? Thanks, Kyrill 2013-07-17 Kyrylo Tkachov <kyrylo.tkachov@arm.com> * gcc.dg/pr42611.c: Move dg-error to correct line.
On 07/17/2013 04:50 AM, Kyrylo Tkachov wrote: > With this patch we now get PASS->FAIL: gcc.dg/pr42611.c, because the error > message now appears on the line of the definition of the struct. This patch > fixes the testcase. > Ok to apply to trunk? Please. Jason
commit b3639b7c7ebca9ee1e2f1adf1b9a41451cbfbe22 Author: Jason Merrill <jason@redhat.com> Date: Fri Jul 12 17:45:59 2013 -0700 PR c++/57793 c/ * c-decl.c (finish_struct): Check for too-large class. cp/ * class.c (layout_class_type): Check for too-large class. diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c index 8170a80..f7ae648 100644 --- a/gcc/c/c-decl.c +++ b/gcc/c/c-decl.c @@ -7210,6 +7210,12 @@ finish_struct (location_t loc, tree t, tree fieldlist, tree attributes, layout_type (t); + if (TYPE_SIZE_UNIT (t) + && TREE_CODE (TYPE_SIZE_UNIT (t)) == INTEGER_CST + && !TREE_OVERFLOW (TYPE_SIZE_UNIT (t)) + && !valid_constant_size_p (TYPE_SIZE_UNIT (t))) + error ("type %qT is too large", t); + /* Give bit-fields their proper types. */ { tree *fieldlistp = &fieldlist; diff --git a/gcc/cp/class.c b/gcc/cp/class.c index e516632..45652a6 100644 --- a/gcc/cp/class.c +++ b/gcc/cp/class.c @@ -6237,6 +6237,12 @@ layout_class_type (tree t, tree *virtuals_p) /* Let the back end lay out the type. */ finish_record_layout (rli, /*free_p=*/true); + if (TYPE_SIZE_UNIT (t) + && TREE_CODE (TYPE_SIZE_UNIT (t)) == INTEGER_CST + && !TREE_OVERFLOW (TYPE_SIZE_UNIT (t)) + && !valid_constant_size_p (TYPE_SIZE_UNIT (t))) + error ("type %qT is too large", t); + /* Warn about bases that can't be talked about due to ambiguity. */ warn_about_ambiguous_bases (t); diff --git a/gcc/testsuite/c-c++-common/pr57793.c b/gcc/testsuite/c-c++-common/pr57793.c new file mode 100644 index 0000000..d66fada --- /dev/null +++ b/gcc/testsuite/c-c++-common/pr57793.c @@ -0,0 +1,23 @@ +/* PR c++/57793 */ + +struct A { unsigned a : 1; unsigned b : 1; }; +struct B /* { dg-error "type .B. is too large" "" { target { c++ && ilp32 } } } */ +{ + unsigned char c[0x40000000]; + unsigned char d[0x40000ff0]; + struct A e; +}; /* { dg-error "type .struct B. is too large" "" { target { c && ilp32 } } } */ + +void *foo (struct B *p) +{ + if (p->e.a) + return (void *) 0; + p->e.b = 1; + return p->c; +} + +void +bar (struct B *p) +{ + foo (p); +}