Bug#945414: (no subject)

[Gregor Riepl]

I replaced the aliased pointers with memcpy.
This makes the issues go away on sparc64 and probably other architectures
where the accessed memory may not be 64-bit aligned.
It had no visible impact on the amd64 build.

Aside from the 3 library functions that had issues, I also had to change a
number of unit tests.

On amd64, the two most crucial functions compile into the same assembly code:

With pointer aliasing:
Dump of assembler code for function gck_value_to_ulong:
   0x0000000000013700 <+0>:     test   %rdi,%rdi
   0x0000000000013703 <+3>:     je     0x13720 <gck_value_to_ulong+32>
   0x0000000000013705 <+5>:     cmp    $0x8,%rsi
   0x0000000000013709 <+9>:     jne    0x13720 <gck_value_to_ulong+32>
   0x000000000001370b <+11>:    mov    $0x1,%eax
   0x0000000000013710 <+16>:    test   %rdx,%rdx
   0x0000000000013713 <+19>:    je     0x13722 <gck_value_to_ulong+34>
   0x0000000000013715 <+21>:    mov    (%rdi),%rcx
   0x0000000000013718 <+24>:    mov    %rcx,(%rdx)
   0x000000000001371b <+27>:    retq
   0x000000000001371c <+28>:    nopl   0x0(%rax)
   0x0000000000013720 <+32>:    xor    %eax,%eax
   0x0000000000013722 <+34>:    retq
With memcpy:
Dump of assembler code for function gck_value_to_ulong:
   0x0000000000013730 <+0>:     test   %rdi,%rdi
   0x0000000000013733 <+3>:     je     0x13750 <gck_value_to_ulong+32>
   0x0000000000013735 <+5>:     cmp    $0x8,%rsi
   0x0000000000013739 <+9>:     jne    0x13750 <gck_value_to_ulong+32>
   0x000000000001373b <+11>:    mov    $0x1,%eax
   0x0000000000013740 <+16>:    test   %rdx,%rdx
   0x0000000000013743 <+19>:    je     0x13752 <gck_value_to_ulong+34>
   0x0000000000013745 <+21>:    mov    (%rdi),%rcx
   0x0000000000013748 <+24>:    mov    %rcx,(%rdx)
   0x000000000001374b <+27>:    retq
   0x000000000001374c <+28>:    nopl   0x0(%rax)
   0x0000000000013750 <+32>:    xor    %eax,%eax
   0x0000000000013752 <+34>:    retq

With pointer aliasing:
Dump of assembler code for function gck_value_to_boolean:
   0x0000000000013730 <+0>:     test   %rdi,%rdi
   0x0000000000013733 <+3>:     je     0x13750 <gck_value_to_boolean+32>
   0x0000000000013735 <+5>:     cmp    $0x1,%rsi
   0x0000000000013739 <+9>:     jne    0x13750 <gck_value_to_boolean+32>
   0x000000000001373b <+11>:    mov    $0x1,%eax
   0x0000000000013740 <+16>:    test   %rdx,%rdx
   0x0000000000013743 <+19>:    je     0x13752 <gck_value_to_boolean+34>
   0x0000000000013745 <+21>:    xor    %ecx,%ecx
   0x0000000000013747 <+23>:    cmpb   $0x0,(%rdi)
   0x000000000001374a <+26>:    setne  %cl
   0x000000000001374d <+29>:    mov    %ecx,(%rdx)
   0x000000000001374f <+31>:    retq
   0x0000000000013750 <+32>:    xor    %eax,%eax
   0x0000000000013752 <+34>:    retq
With memcpy:
Dump of assembler code for function gck_value_to_boolean:
   0x0000000000013760 <+0>:     test   %rdi,%rdi
   0x0000000000013763 <+3>:     je     0x13780 <gck_value_to_boolean+32>
   0x0000000000013765 <+5>:     cmp    $0x1,%rsi
   0x0000000000013769 <+9>:     jne    0x13780 <gck_value_to_boolean+32>
   0x000000000001376b <+11>:    mov    $0x1,%eax
   0x0000000000013770 <+16>:    test   %rdx,%rdx
   0x0000000000013773 <+19>:    je     0x13782 <gck_value_to_boolean+34>
   0x0000000000013775 <+21>:    xor    %ecx,%ecx
   0x0000000000013777 <+23>:    cmpb   $0x0,(%rdi)
   0x000000000001377a <+26>:    setne  %cl
   0x000000000001377d <+29>:    mov    %ecx,(%rdx)
   0x000000000001377f <+31>:    retq
   0x0000000000013780 <+32>:    xor    %eax,%eax
   0x0000000000013782 <+34>:    retq

On sparc64, gck_value_to_boolean doesn't change, but gck_value_to_ulong gets a
memcpy call to avoid the misaligned memory access:

Dump of assembler code for function gck_value_to_ulong:
   0x0000000000016338 <+0>:     save  %sp, -176, %sp
   0x000000000001633c <+4>:     xor  %i1, 8, %i1
   0x0000000000016340 <+8>:     clr  %g2
   0x0000000000016344 <+12>:    clr  %g1
   0x0000000000016348 <+16>:    movre  %i0, 1, %g2
   0x000000000001634c <+20>:    movrne  %i1, 1, %g1
   0x0000000000016350 <+24>:    orcc  %g2, %g1, %g0
   0x0000000000016354 <+28>:    bne,pn   %icc, 0x16374 <gck_value_to_ulong+60>
   0x0000000000016358 <+32>:    clr  %i5
   0x000000000001635c <+36>:    brz,pn   %i2, 0x16374 <gck_value_to_ulong+60>
   0x0000000000016360 <+40>:    mov  1, %i5
   0x0000000000016364 <+44>:    mov  8, %o2
   0x0000000000016368 <+48>:    mov  %i0, %o1
   0x000000000001636c <+52>:    call  0x134780 <memcpy at got.plt>
   0x0000000000016370 <+56>:    mov  %i2, %o0
   0x0000000000016374 <+60>:    return  %i7 + 8
   0x0000000000016378 <+64>:    sra  %o5, 0, %o0
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