[Bug target/48085] New: [x32] Unnecessary zero-extension

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48085

           Summary: [x32] Unnecessary zero-extension
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: hjl.to...@gmail.com


[hjl@gnu-6 ilp32-31]$ cat y.c 
int
foo (int *p)
{
  return *p;
}
[hjl@gnu-6 ilp32-31]$ make y.s
/export/build/gnu/gcc-x32/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc-x32/build-x86_64-linux/gcc/ -S -o y.s -mx32
-funroll-all-loops -O3 -dp  y.c
[hjl@gnu-6 ilp32-31]$ cat y.s
    .file    "y.c"
    .text
    .p2align 4,,15
    .globl    foo
    .type    foo, @function
foo:
.LFB0:
    .cfi_startproc
    mov    %edi, %edi    # 2    *zero_extendsidi2_rex64/1    [length = 2]
    movl    (%rdi), %eax    # 6    *movsi_internal/1    [length = 2]
    ret    # 20    return_internal    [length = 1]
    .cfi_endproc
.LFE0:
    .size    foo, .-foo
    .ident    "GCC: (GNU) 4.6.0 20110311 (experimental)"
    .section    .note.GNU-stack,"",@progbits
[hjl@gnu-6 ilp32-31]$ 

We don't need to zero-extend 32bit pointer in EDI to RDI.