Incorrect optimized code generated by current CVS snapshot

[James A. Bednar]

Using the g++ from the 20000504 CVS snapshot RPMs obtained from
http://www.codesourcery.com/gcc-snapshots.html , the following code
prints garbage when compiled using "-O2" but works fine in all other
C++ compiler cases tested: "-O1", no optimization, other g++ versions,
other C++ compilers, etc.:

  #include <stdio.h>
  
  void F(const char **sp)
  {  printf("%s\n",*sp);  }
  
  void G(const char* s)
  {  F(&s);  }
  
  int main(int, char)
  {  G("TestString");  } 

Here's the output from a working compiler on a Pentium III:

  linux> /usr/bin/g++ -v
  Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/2.95.2/specs
  gcc version 2.95.2 19991024 (release)

  linux> /usr/bin/g++ -O2 bug12.c 
  linux> ./a.out
  TestString

Here's the output from the current snapshot on the same machine:

  linux> /usr/local/bin/g++ -v
  Reading specs from /usr/local/bin/../lib/gcc-lib/i386-pc-linux-gnu/2.96/specs
  gcc version 2.96 20000504 (experimental)

  linux> /usr/local/bin/g++ -O2 bug12.c 
  linux> ./a.out
  ????$\227^D^H^A

I've transliterated the garbage output above into how it appears in an
Emacs buffer; the output consists of binary characters, so it would
have printed differently on different terminals and wouldn't have
survived email anyway.

Here's the output from the snapshot's C compiler on the same machine:

  linux> /usr/local/bin/gcc -v
  Reading specs from /usr/local/bin/../lib/gcc-lib/i386-pc-linux-gnu/2.96/specs
  gcc version 2.96 20000504 (experimental)
  
  linux> /usr/local/bin/gcc -O2 bug12.c  
  bug12.c: In function `main':
  bug12.c:9: parameter name omitted
  bug12.c:9: parameter name omitted
  
  linux> ./a.out
  ????$\227^D^H^A

Oddly, the garbage disappears if I add names for the main()
parameters, which is why I present the g++ output, since in C++ it
should be legal to omit the names of these unused parameters.

In case this code proves useful as a test case, I hereby place it into
the public domain for anyone to use for any purpose whatsoever.

Jim Bednar