Closed
Description
rlibc's memcpy get miscompiled with -O --target=x86_64-sun-solaris -C target-feature=-mmx,-sse,-sse2
At 0x18 lea esi, [rsi+0] zeroes the upper 32-bits of rsi which is a 64-bit pointer.
Curiously some targets has the loop unrolled. I don't see any reason for this.
Assembler output of various targets:
x86_64-rumprun-netbsd:
x86_64-sun-solaris:
.text.memcpy:0000000000000010 memcpy proc near
.text.memcpy:0000000000000010 test rdx, rdx
.text.memcpy:0000000000000013 jz short loc_2F
.text.memcpy:0000000000000015 mov rax, rdi
.text.memcpy:0000000000000018 lea esi, [rsi+0]
.text.memcpy:000000000000001F nop
.text.memcpy:0000000000000020
.text.memcpy:0000000000000020 loc_20: ; CODE XREF: memcpy+1D�j
.text.memcpy:0000000000000020 mov cl, [rsi]
.text.memcpy:0000000000000022 mov [rax], cl
.text.memcpy:0000000000000024 inc rax
.text.memcpy:0000000000000027 inc rsi
.text.memcpy:000000000000002A dec rdx
.text.memcpy:000000000000002D jnz short loc_20
.text.memcpy:000000000000002F
.text.memcpy:000000000000002F loc_2F: ; CODE XREF: memcpy+3�j
.text.memcpy:000000000000002F mov rax, rdi
.text.memcpy:0000000000000032 retn
.text.memcpy:0000000000000032 memcpy endp
x86_64-unknown-linux-gnu:
x86_64-unknown-linux-musl:
x86_64-unknown-freebsd:
.text.memcpy:0000000000000010 public memcpy
.text.memcpy:0000000000000010 memcpy proc near
.text.memcpy:0000000000000010 test rdx, rdx
.text.memcpy:0000000000000013 jz loc_A4
.text.memcpy:0000000000000019 lea r8, [rdx-1]
.text.memcpy:000000000000001D xor ecx, ecx
.text.memcpy:000000000000001F test dl, 7
.text.memcpy:0000000000000022 jz short loc_3E
.text.memcpy:0000000000000024 mov r9d, edx
.text.memcpy:0000000000000027 and r9d, 7
.text.memcpy:000000000000002B xor ecx, ecx
.text.memcpy:000000000000002D nop dword ptr [rax]
.text.memcpy:0000000000000030
.text.memcpy:0000000000000030 loc_30: ; CODE XREF: memcpy+2C�j
.text.memcpy:0000000000000030 mov al, [rsi+rcx]
.text.memcpy:0000000000000033 mov [rdi+rcx], al
.text.memcpy:0000000000000036 inc rcx
.text.memcpy:0000000000000039 cmp r9, rcx
.text.memcpy:000000000000003C jnz short loc_30
.text.memcpy:000000000000003E
.text.memcpy:000000000000003E loc_3E: ; CODE XREF: memcpy+12�j
.text.memcpy:000000000000003E cmp r8, 7
.text.memcpy:0000000000000042 jb short loc_A4
.text.memcpy:0000000000000044 sub rdx, rcx
.text.memcpy:0000000000000047 lea r8, [rdi+rcx+7]
.text.memcpy:000000000000004C lea rcx, [rsi+rcx+7]
.text.memcpy:0000000000000051 db 66h, 66h, 66h, 66h, 66h, 66h, 2Eh
.text.memcpy:0000000000000051 nop dword ptr [rax+rax+00000000h]
.text.memcpy:0000000000000060
.text.memcpy:0000000000000060 loc_60: ; CODE XREF: memcpy+92�j
.text.memcpy:0000000000000060 mov al, [rcx-7]
.text.memcpy:0000000000000063 mov [r8-7], al
.text.memcpy:0000000000000067 mov al, [rcx-6]
.text.memcpy:000000000000006A mov [r8-6], al
.text.memcpy:000000000000006E mov al, [rcx-5]
.text.memcpy:0000000000000071 mov [r8-5], al
.text.memcpy:0000000000000075 mov al, [rcx-4]
.text.memcpy:0000000000000078 mov [r8-4], al
.text.memcpy:000000000000007C mov al, [rcx-3]
.text.memcpy:000000000000007F mov [r8-3], al
.text.memcpy:0000000000000083 mov al, [rcx-2]
.text.memcpy:0000000000000086 mov [r8-2], al
.text.memcpy:000000000000008A mov al, [rcx-1]
.text.memcpy:000000000000008D mov [r8-1], al
.text.memcpy:0000000000000091 mov al, [rcx]
.text.memcpy:0000000000000093 mov [r8], al
.text.memcpy:0000000000000096 add r8, 8
.text.memcpy:000000000000009A add rcx, 8
.text.memcpy:000000000000009E add rdx, 0FFFFFFFFFFFFFFF8h
.text.memcpy:00000000000000A2 jnz short loc_60
.text.memcpy:00000000000000A4
.text.memcpy:00000000000000A4 loc_A4: ; CODE XREF: memcpy+3�j
.text.memcpy:00000000000000A4 ; memcpy+32�j
.text.memcpy:00000000000000A4 mov rax, rdi
.text.memcpy:00000000000000A7 retn
.text.memcpy:00000000000000A7 memcpy endp
.text.memcpy:00000000000000A7
.text.memcpy:00000000000000A7 _text_memcpy ends
.text.memcpy