more on Solaris internal compiler error

[Joe Buck <jbuck at synopsys dot com>]

Earlier I reported an internal compiler error that seems to make vectors
of class objects unusable on Solaris.  I reduced the problem still more,
down to the file that appears at the end of this message.  I made a stab
at debugging it, and to make my life easier decided to build a cc1plus
with the old gcc (2.7.2.1) and CFLAGS=-g for easier debugging and
Purify'ing.  But the resulting compiler behaves differently than the
bootstrapped, optimized compiler.  The debug compiler gives

foo3.cxx:31: internal error--insn does not satisfy its constraints:
(insn 166 162 167 (set (reg/v:SI 8 %o0)
        (reg/v:SI 107)) 111 {*movsi_insn} (nil)
    (expr_list:REG_DEAD (reg/v:SI 107)
        (nil)))
foo3.cxx:31: confused by earlier errors, bailing out

But the optimized compiler gives

foo3.cxx: In function `struct SomeClass * proc(const struct SomeClass *,
const struct SomeClass *, struct SomeClass *, struct __false_type)':
foo3.cxx:31: Internal compiler error.
foo3.cxx:31: Please submit a full bug report to `egcs-bugs@cygnus.com'.

The actual crash is a SIGBUS in reload_cse_noop_set_p .

So it occurred to me that there may be some memory access problem
(a UMR giving different behavior in optimization).

I ran the debug executable through Purify.

Sure enough, I found what looks like a serious problem in reload1.c.
The first error is a UMR in exactly the function where the crash occurs.
Now, I don't quite understand it (it looks like x has a value)
, but here's what I get:

****  Purify instrumented gnu/src/egcs-971105/gcc/cc1plus (pid 20786)  ****
UMR: Uninitialized memory read:
  * This is occurring while in:
	reload_cse_noop_set_p [reload1.c:8036]
	reload_cse_regs [reload1.c:7874]
	rest_of_compilation [toplev.c:3541]
	finish_function [decl.c:12332]
	yyparse        [parse.y:552]
	compile_file   [toplev.c:2513]
  * Reading 4 bytes from 0xefffe414 on the stack.
  * Address 0xefffe414 is local variable "x" in function reload_cse_noop_set_p.

****  Purify instrumented gnu/src/egcs-971105/gcc/cc1plus (pid 20786)  ****
UMR: Uninitialized memory read:
  * This is occurring while in:
	reload_cse_record_set [reload1.c:8292]
	reload_cse_regs [reload1.c:7885]
	rest_of_compilation [toplev.c:3541]
	finish_function [decl.c:12332]
	yyparse        [parse.y:552]
	compile_file   [toplev.c:2513]
  * Reading 4 bytes from 0xefffe414 on the stack.
  * Address 0xefffe414 is local variable "i" in function reload_cse_record_set.

The test case follows.
----------------
struct SomeClass {
    int data;
};

typedef unsigned int size_t;

inline void *operator new(size_t, void *place) throw() { return place; }

struct __false_type {
};

inline void destroy(SomeClass* first, SomeClass* last)
{
    for (; first < last; ++first)
	first->~SomeClass();
}

SomeClass*
proc(const SomeClass* first, const SomeClass* last,
     SomeClass* result, __false_type) {
  SomeClass* cur = result;
  try {
    for ( ; first != last; ++first, ++cur)
      new(cur) SomeClass(*first);
    return cur;
  }
  catch(...) {
    destroy(result, cur);
    throw;
  }
}