Rename to skein_block_asm.s to .S, to use Clang's integrated assembler

[tsoome]

Seems ok for me, assuming its tested and compiler driver does build it properly:)

[emaste]

This doesn't actually build with the integrated assembler today -- see https://bugs.llvm.org/show_bug.cgi?id=33405

[emaste]

rebase

[cem]

lib/libmd/Makefile

122 ↗

(On Diff #72728)

I might keep the comment explaining the constant (if accurate)

126 ↗

(On Diff #72728)

Hm, did we not kill ripemd yet?

sys/modules/crypto/Makefile

35 ↗

(On Diff #72728)

Do we want these in the other make file?

[emaste]

lib/libmd/Makefile

121 ↗

(On Diff #72728)

strip-local-absolute in LLVM:
https://bugs.llvm.org/show_bug.cgi?id=27201

[tsoome]

Looks good.

[emaste]

We assemble skein_block_asm.S four times - once for sys/modules/crypto, and three times for lib/libmd (.o, .pico, .po). All four instances have the same change when assembled with Clang IAS vs. GNU as 2.17.50:

│ │ ├── objdump --line-numbers --disassemble --demangle --reloc --section=.text {}
│ │ │ @@ -1884,17 +1884,17 @@
│ │ │      1b8f:        00
│ │ │      1b90:        48 89 bd a8 00 00 00    mov    %rdi,0xa8(%rbp)
│ │ │      1b97:        48 89 b5 b0 00 00 00    mov    %rsi,0xb0(%rbp)
│ │ │      1b9e:        48 89 95 b8 00 00 00    mov    %rdx,0xb8(%rbp)
│ │ │      1ba5:        48 89 8d c0 00 00 00    mov    %rcx,0xc0(%rbp)
│ │ │      1bac:        4c 8b 4f 18             mov    0x18(%rdi),%r9
│ │ │      1bb0:        eb 0e                   jmp    1bc0 <Skein1024_block_loop>
│ │ │ -    1bb2:        66 66 2e 0f 1f 84 00    data16 nopw %cs:0x0(%rax,%rax,1)
│ │ │ -    1bb9:        00 00 00 00
│ │ │ -    1bbd:        0f 1f 00                nopl   (%rax)
│ │ │ +    1bb2:        66 2e 0f 1f 84 00 00    nopw   %cs:0x0(%rax,%rax,1)
│ │ │ +    1bb9:        00 00 00
│ │ │ +    1bbc:        0f 1f 40 00             nopl   0x0(%rax)
│ │ │
│ │ │  0000000000001bc0 <Skein1024_block_loop>:
│ │ │  Skein1024_block_loop():
│ │ │      1bc0:        4c 8b 47 10             mov    0x10(%rdi),%r8
│ │ │      1bc4:        4c 03 85 c0 00 00 00    add    0xc0(%rbp),%r8
│ │ │      1bcb:        4d 89 ca                mov    %r9,%r10
│ │ │      1bce:        4d 31 c2                xor    %r8,%r10

That is, for padding GNU as emits an 11 byte NOP followed by a 3 byte NOP, while IAS emits a 10 byte NOP followed by a 4 byte NOP.

[arichardson]

Clang will accept -defsym SKEIN_LOOP=0 (single dash). But using the C preprocessor also seems fine to me.

[allanjude]

Reviewed By: allanjude