[Bug target/53219] inline function erroneously clobbers %i0 register on 64 bit sparc compile of perls regcomp.c

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53219

--- Comment #7 from Martin Husemann <martin at netbsd dot org> 2012-05-06 10:59:19 UTC ---
Created attachment 27324
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27324
gcc -S output for the miscompiled function

The original report showed the disassembler output from gdb; here is the
original compiler output (stripped to the function in question, I can provide
the full output if needed).

The crash happens in the section starting at line 521:

.LLBB1732:
        .loc 1 4563 0
        ldx     [%i0+624], %g1 
        add     %fp, 1695, %o0
        mov     0, %o1
        call    __sigsetjmp14, 0
         stx    %g1, [%fp+1687]
.LLVL2000:
        add     %fp, 1687, %g1
        st      %o0, [%fp+1815]
.LLBE1732:
        .loc 1 4567 0
        andcc   %o0, 0xff, %o1
.LLBB1733:
        .loc 1 4563 0
        stx     %g1, [%i0+624]


on return from the sigsetjmp %i0 is zero and we crash in the last line cited
above.

I think the register %i0 is left as zero after (post first call to sigsetjmp)
when going throught he code starting at line 77:

.LLVL1968:
.LL2453:
.LLBB1694:
.LLBB1695:
        .loc 3 77 0  
        ldx     [%fp+2191], %i0
.LLVL1969: 
.LL2734:  
        and     %i0, 224, %g1
        srl     %g1, 5, %g1
.LLVL1970:  
.LLBE1695:
.LLBE1694:
        .loc 1 4617 0 
        cmp     %g1, 1

This register value later gets saved to the on-stack copy of the register
window, from where it is restored on siglongjmp.