[Bug optimization/11457] New:

["gcc-bugzilla at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11457

           Product: gcc
           Version: 3.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: user42 at zip dot com dot au
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i386-pc-linux-gnu
  GCC host triplet: i386-pc-linux-gnu
GCC target triplet: i386-pc-linux-gnu

When presented with tests like "n>=0" followed by "n==0", two i386
"test" instructions are generated, where one would suffice.  This is
apparently a regression from some point, since for instance gcc 2.95.4
generates only one.

Environment:
System: Linux blah 2.2.15 #1 Tue Apr 25 17:13:48 EST 2000 i586 unknown unknown GNU/Linux
Architecture: i586
	<machine, os, target, libraries (multiple lines)>
host: i386-pc-linux-gnu
build: i386-pc-linux-gnu
target: i386-pc-linux-gnu
configured with: ../src/configure -v --enable-languages=c,c++,java,f77,pascal,objc,ada,treelang --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-gxx-include-dir=/usr/include/c++/3.3 --enable-shared --with-system-zlib --enable-nls --without-included-gettext --enable-__cxa_atexit --enable-clocale=gnu --enable-debug --enable-java-gc=boehm --enable-java-awt=xlib --enable-objc-gc i386-linux

How-To-Repeat:
A file foo.c containing

	void
	foo (int n)
	{
	  if (n >= 0)
	    {
	      if (n == 0)
	        zero ();
	      else
	        non_negative ();
	    }
	  else
	    negative ();
	}

compiled with

	gcc -O2 -S foo.c

produces foo.s containing the sequence

        testl   %eax, %eax
        js      .L2
        testl   %eax, %eax
        jne     .L3

I think the second "testl" is unnecessary, and that the code would be
smaller and probably faster if it was omitted.

It seems this was done in the past, for instance a recent Debian
packaged gcc 2.95.4 does it,

        testl %eax,%eax
        jl .L3
        jne .L4