[Bug target/40670] New: Load floating point constant 0 directly

[carrot at google dot com]

Compile following function with options -Os -mthumb -march=armv5te

float return_zero()
{
  return 0;
}

Gcc generates:

        ldr     r0, .L2
        bx      lr
.L3:
        .align  2
.L2:
        .word   0

Floating point 0 is also integer 0. So the function body can be simplified as

       mov r0, 0
       bx  lr

Now we can remove the memory load and constant pool. The result code is smaller
and faster.

The memory load and constant pool is expanded in pass machine_reorg.


-- 
           Summary: Load floating point constant 0 directly
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: carrot at google dot com
 GCC build triplet: i686-linux
  GCC host triplet: i686-linux
GCC target triplet: arm-eabi


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40670