Bug#106866: gcc-3.0: Optimisation: [i386] pointless jump before a call

[<herbert@gondor.apana.org.au>]

Package: gcc-3.0
Version: 1:3.0.1-0pre010723
Severity: normal

I was playing with the noreturn flag when I noticed the following pointless
jump into a call instruction:

  86:   a1 00 00 00 00          mov    0x0,%eax
                        87: R_386_32    intpending
  8b:   85 c0                   test   %eax,%eax
  8d:   74 c9                   je     58 <evalsubshell+0x58>
  8f:   eb 3b                   jmp    cc <evalsubshell+0xcc>
  91:   8d 76 00                lea    0x0(%esi),%esi

...

  c8:   eb d4                   jmp    9e <evalsubshell+0x9e>
  ca:   89 f6                   mov    %esi,%esi
  cc:   e8 fc ff ff ff          call   cd <evalsubshell+0xcd>
                        cd: R_386_PC32  doint
  d1:   8d 76 00                lea    0x0(%esi),%esi

There are no other jumps to cc.  That costed me 8 bytes and a pointless
jump.

The source that generated this can be fetched from

http://gondor.apana.org.au/~herbert/bugs/gcc-bug-1.tar.bz2

To reproduce, do:

gcc-3.0 -g -O2 -DUSE_DOINT -c eval.c

-- System Information
Debian Release: testing/unstable
Kernel Version: Linux gondolin 2.4.7-686-smp #1 SMP Sun Jul 22 14:00:21 EST 2001 i686 unknown

Versions of the packages gcc-3.0 depends on:
ii  binutils       2.11.90.0.24-1 The GNU assembler, linker and binary utiliti
ii  cpp-3.0        3.0.1-0pre0107 The GNU C preprocessor.
ii  gcc-3.0-base   3.0.1-0pre0107 The GNU Compiler Collection (base package).
ii  libc6          2.2.3-7        GNU C Library: Shared libraries and Timezone
ii  libgcc1        3.0.1-0pre0107 GCC support library.