[Bug c++/43965] New: doubled code (x86)

["hartmut dot schirmer at arcormail dot de" <gcc-bugzilla@gcc.gnu.org>]

On this test case

---
struct Vector
{
   int size( void ) const
   {
      return mSize ? *mSize : 0 ;
   }
   int* mSize;
};

int diff(const Vector& a, const Vector& b)

{
   if (a.size() != b.size())
   {
      return a.size() - b.size();
   }

   return 0;
}
---

gcc omits the following code:

__Z4diffRK6VectorS1_:
        pushl   %ebp     #
        movl    %esp, %ebp       #,
        pushl   %esi     #
        xorl    %esi, %esi       # D.2130
        pushl   %ebx     #
        movl    8(%ebp), %eax    # a, a
        movl    (%eax), %ecx     # a_2(D)->mSize, D.2131
        testl   %ecx, %ecx       # D.2131
        je      L2       #,
        movl    (%ecx), %esi     #* D.2131, D.2130
L2:
        movl    12(%ebp), %eax   # b, b
        xorl    %ebx, %ebx       # D.2134
        movl    (%eax), %edx     # b_4(D)->mSize, D.2135
        testl   %edx, %edx       # D.2135
        je      L3       #,
        movl    (%edx), %ebx     #* D.2135, D.2134
L3:
        xorl    %eax, %eax       # D.2116
        cmpl    %ebx, %esi       # D.2134, D.2130
        je      L4       #,
        testl   %ecx, %ecx       # D.2131
        je      L5       #,
        movl    (%ecx), %eax     #* D.2131, D.2138
L5:
        xorl    %ecx, %ecx       # D.2142
        testl   %edx, %edx       # D.2135
        je      L6       #,
        movl    (%edx), %ecx     #* D.2135, D.2142
L6:
        subl    %ecx, %eax       # D.2142, D.2116
L4:
        popl    %ebx     #
        popl    %esi     #
        popl    %ebp     #
        ret

Basicly code following the cmpl after L3 up to L6 is needless,
subl could operate on same values as cmpl did

 # GNU C++ (GCC) version 4.5.0 (mingw32)
 #      compiled by GNU C version 4.5.0, GMP version 5.0.1, MPFR version 2.4.1,
MPC version 0.8.1
 # GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
 # options passed:  -fpreprocessed yy4.ii -march=atom -O2 -fverbose-asm


-- 
           Summary: doubled code (x86)
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: hartmut dot schirmer at arcormail dot de
 GCC build triplet: i686-pc-mingw32
  GCC host triplet: i686-pc-mingw32
GCC target triplet: i686-pc-mingw32


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43965