Passing c_chars to C/C++ results in random gibberish #4
Comments
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Can you provide some sample code that shows this off? |
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@steveklabnik I am not sure this is easily reproduceable, I'll try to whip something up |
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yeah, totally understand. 😄 |
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@steveklabnik sorry I haven't uploaded a demo yet. I swear that it doesn't work with my library. I'll see what I can do this week and also update my rustc. If that doesn't work, I'll just upload the library code. Thanks for understanding :) |
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No worries. I'm going to give this a close until then, but if you can give me a reproduction, we'll reopen! |
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I just tested it with an updated rustc, it definitely is still the same. Still need time to write a demo though :( |
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@steveklabnik I've successfully written a demo that shows how arguments are passed incorrectly https://github.com/boghison/rust-wrong-argument-demo |
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When I run it, I see no output, and you're not printing anything. What's the expected here? |
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@boghison it looks like Rust/C++ disagree on the signatures of the |
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Ahh, nice look. |
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@alexcrichton I need to pass a struct to C++, so what should I do? @steveklabnik a cpp.txt file will be created and written in the dir where you run it. |
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You probably want to change the signature in Rust to: extern {
fn c_call(rust_struct: *mut VoidStruct,
char1: *const c_char,
char2: *const c_char,
char3: *const c_char,
char4: *const c_char,
char5: *const c_char,
char6: *const c_char);
}(note the |
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@alexcrichton Thanks a lot :) BTW, is this actually documented anywhere, I was banging my head against this for a long time, I also tried declaring it as a struct in C++, that didn't work either :( |
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Glad I could help! |
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@alexcrichton So I guess it isn't documented then :/ *const works as well btw |
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…ust-lang#425) * Work arounds for LLVM6 code-gen bugs in all/any reductions This commit adds workarounds for the mask reductions: `all` and `any`. 64-bit wide mask types (`m8x8`, `m16x4`, `m32x2`) `x86_64` with `MMX` enabled ```asm all_8x8: push rbp mov rbp, rsp movzx eax, byte, ptr, [rdi, +, 7] movd xmm0, eax movzx eax, byte, ptr, [rdi, +, 6] movd xmm1, eax punpcklwd xmm1, xmm0 movzx eax, byte, ptr, [rdi, +, 5] movd xmm0, eax movzx eax, byte, ptr, [rdi, +, 4] movd xmm2, eax punpcklwd xmm2, xmm0 punpckldq xmm2, xmm1 movzx eax, byte, ptr, [rdi, +, 3] movd xmm0, eax movzx eax, byte, ptr, [rdi, +, 2] movd xmm1, eax punpcklwd xmm1, xmm0 movzx eax, byte, ptr, [rdi, +, 1] movd xmm0, eax movzx eax, byte, ptr, [rdi] movd xmm3, eax punpcklwd xmm3, xmm0 punpckldq xmm3, xmm1 punpcklqdq xmm3, xmm2 movdqa xmm0, xmmword, ptr, [rip, +, LCPI9_0] pand xmm3, xmm0 pcmpeqw xmm3, xmm0 pshufd xmm0, xmm3, 78 pand xmm0, xmm3 pshufd xmm1, xmm0, 229 pand xmm1, xmm0 movdqa xmm0, xmm1 psrld xmm0, 16 pand xmm0, xmm1 movd eax, xmm0 and al, 1 pop rbp ret any_8x8: push rbp mov rbp, rsp movzx eax, byte, ptr, [rdi, +, 7] movd xmm0, eax movzx eax, byte, ptr, [rdi, +, 6] movd xmm1, eax punpcklwd xmm1, xmm0 movzx eax, byte, ptr, [rdi, +, 5] movd xmm0, eax movzx eax, byte, ptr, [rdi, +, 4] movd xmm2, eax punpcklwd xmm2, xmm0 punpckldq xmm2, xmm1 movzx eax, byte, ptr, [rdi, +, 3] movd xmm0, eax movzx eax, byte, ptr, [rdi, +, 2] movd xmm1, eax punpcklwd xmm1, xmm0 movzx eax, byte, ptr, [rdi, +, 1] movd xmm0, eax movzx eax, byte, ptr, [rdi] movd xmm3, eax punpcklwd xmm3, xmm0 punpckldq xmm3, xmm1 punpcklqdq xmm3, xmm2 movdqa xmm0, xmmword, ptr, [rip, +, LCPI8_0] pand xmm3, xmm0 pcmpeqw xmm3, xmm0 pshufd xmm0, xmm3, 78 por xmm0, xmm3 pshufd xmm1, xmm0, 229 por xmm1, xmm0 movdqa xmm0, xmm1 psrld xmm0, 16 por xmm0, xmm1 movd eax, xmm0 and al, 1 pop rbp ret ``` After this PR for `m8x8`, `m16x4`, `m32x2`: ```asm all_8x8: push rbp mov rbp, rsp movq mm0, qword, ptr, [rdi] pmovmskb eax, mm0 cmp eax, 255 sete al pop rbp ret any_8x8: push rbp mov rbp, rsp movq mm0, qword, ptr, [rdi] pmovmskb eax, mm0 test eax, eax setne al pop rbp ret ``` x86` with `MMX` enabled Before this PR: ```asm all_8x8: call L9$pb L9$pb: pop eax mov ecx, dword, ptr, [esp, +, 4] movzx edx, byte, ptr, [ecx, +, 7] movd xmm0, edx movzx edx, byte, ptr, [ecx, +, 6] movd xmm1, edx punpcklwd xmm1, xmm0 movzx edx, byte, ptr, [ecx, +, 5] movd xmm0, edx movzx edx, byte, ptr, [ecx, +, 4] movd xmm2, edx punpcklwd xmm2, xmm0 punpckldq xmm2, xmm1 movzx edx, byte, ptr, [ecx, +, 3] movd xmm0, edx movzx edx, byte, ptr, [ecx, +, 2] movd xmm1, edx punpcklwd xmm1, xmm0 movzx edx, byte, ptr, [ecx, +, 1] movd xmm0, edx movzx ecx, byte, ptr, [ecx] movd xmm3, ecx punpcklwd xmm3, xmm0 punpckldq xmm3, xmm1 punpcklqdq xmm3, xmm2 movdqa xmm0, xmmword, ptr, [eax, +, LCPI9_0-L9$pb] pand xmm3, xmm0 pcmpeqw xmm3, xmm0 pshufd xmm0, xmm3, 78 pand xmm0, xmm3 pshufd xmm1, xmm0, 229 pand xmm1, xmm0 movdqa xmm0, xmm1 psrld xmm0, 16 pand xmm0, xmm1 movd eax, xmm0 and al, 1 ret any_8x8: call L8$pb L8$pb: pop eax mov ecx, dword, ptr, [esp, +, 4] movzx edx, byte, ptr, [ecx, +, 7] movd xmm0, edx movzx edx, byte, ptr, [ecx, +, 6] movd xmm1, edx punpcklwd xmm1, xmm0 movzx edx, byte, ptr, [ecx, +, 5] movd xmm0, edx movzx edx, byte, ptr, [ecx, +, 4] movd xmm2, edx punpcklwd xmm2, xmm0 punpckldq xmm2, xmm1 movzx edx, byte, ptr, [ecx, +, 3] movd xmm0, edx movzx edx, byte, ptr, [ecx, +, 2] movd xmm1, edx punpcklwd xmm1, xmm0 movzx edx, byte, ptr, [ecx, +, 1] movd xmm0, edx movzx ecx, byte, ptr, [ecx] movd xmm3, ecx punpcklwd xmm3, xmm0 punpckldq xmm3, xmm1 punpcklqdq xmm3, xmm2 movdqa xmm0, xmmword, ptr, [eax, +, LCPI8_0-L8$pb] pand xmm3, xmm0 pcmpeqw xmm3, xmm0 pshufd xmm0, xmm3, 78 por xmm0, xmm3 pshufd xmm1, xmm0, 229 por xmm1, xmm0 movdqa xmm0, xmm1 psrld xmm0, 16 por xmm0, xmm1 movd eax, xmm0 and al, 1 ret ``` After this PR: ```asm all_8x8: mov eax, dword, ptr, [esp, +, 4] movq mm0, qword, ptr, [eax] pmovmskb eax, mm0 cmp eax, 255 sete al ret any_8x8: mov eax, dword, ptr, [esp, +, 4] movq mm0, qword, ptr, [eax] pmovmskb eax, mm0 test eax, eax setne al ret ``` `aarch64` Before this PR: ```asm all_8x8: ldr d0, [x0] umov w8, v0.b[0] umov w9, v0.b[1] tst w8, #0xff umov w10, v0.b[2] cset w8, ne tst w9, #0xff cset w9, ne tst w10, #0xff umov w10, v0.b[3] and w8, w8, w9 cset w9, ne tst w10, #0xff umov w10, v0.b[4] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[5] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[6] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[7] and w8, w9, w8 cset w9, ne tst w10, #0xff and w8, w9, w8 cset w9, ne and w0, w9, w8 ret any_8x8: ldr d0, [x0] umov w8, v0.b[0] umov w9, v0.b[1] orr w8, w8, w9 umov w9, v0.b[2] orr w8, w8, w9 umov w9, v0.b[3] orr w8, w8, w9 umov w9, v0.b[4] orr w8, w8, w9 umov w9, v0.b[5] orr w8, w8, w9 umov w9, v0.b[6] orr w8, w8, w9 umov w9, v0.b[7] orr w8, w8, w9 tst w8, #0xff cset w0, ne ret ``` After this PR: ```asm all_8x8: ldr d0, [x0] mov v0.d[1], v0.d[0] uminv b0, v0.16b fmov w8, s0 tst w8, #0xff cset w0, ne ret any_8x8: ldr d0, [x0] mov v0.d[1], v0.d[0] umaxv b0, v0.16b fmov w8, s0 tst w8, #0xff cset w0, ne ret ``` `ARMv7` + `neon` Before this PR: ```asm all_8x8: vmov.i8 d0, #0x1 vldr d1, [r0] vtst.8 d0, d1, d0 vext.8 d1, d0, d0, rust-lang#4 vand d0, d0, d1 vext.8 d1, d0, d0, rust-lang#2 vand d0, d0, d1 vdup.8 d1, d0[1] vand d0, d0, d1 vmov.u8 r0, d0[0] and r0, r0, rust-lang#1 bx lr any_8x8: vmov.i8 d0, #0x1 vldr d1, [r0] vtst.8 d0, d1, d0 vext.8 d1, d0, d0, rust-lang#4 vorr d0, d0, d1 vext.8 d1, d0, d0, rust-lang#2 vorr d0, d0, d1 vdup.8 d1, d0[1] vorr d0, d0, d1 vmov.u8 r0, d0[0] and r0, r0, rust-lang#1 bx lr ``` After this PR: ```asm all_8x8: vldr d0, [r0] b <m8x8 as All>::all <m8x8 as All>::all: vpmin.u8 d16, d0, d16 vpmin.u8 d16, d16, d16 vpmin.u8 d0, d16, d16 b m8x8::extract any_8x8: vldr d0, [r0] b <m8x8 as Any>::any <m8x8 as Any>::any: vpmax.u8 d16, d0, d16 vpmax.u8 d16, d16, d16 vpmax.u8 d0, d16, d16 b m8x8::extract ``` (note: inlining does not work properly on ARMv7) 128-bit wide mask types (`m8x16`, `m16x8`, `m32x4`, `m64x2`) `x86_64` with SSE2 enabled Before this PR: ```asm all_8x16: push rbp mov rbp, rsp movdqa xmm0, xmmword, ptr, [rip, +, LCPI9_0] movdqa xmm1, xmmword, ptr, [rdi] pand xmm1, xmm0 pcmpeqb xmm1, xmm0 pmovmskb eax, xmm1 xor ecx, ecx cmp eax, 65535 mov eax, -1 cmovne eax, ecx and al, 1 pop rbp ret any_8x16: push rbp mov rbp, rsp movdqa xmm0, xmmword, ptr, [rip, +, LCPI8_0] movdqa xmm1, xmmword, ptr, [rdi] pand xmm1, xmm0 pcmpeqb xmm1, xmm0 pmovmskb eax, xmm1 neg eax sbb eax, eax and al, 1 pop rbp ret ``` After this PR: ```asm all_8x16: push rbp mov rbp, rsp movdqa xmm0, xmmword, ptr, [rdi] pmovmskb eax, xmm0 cmp eax, 65535 sete al pop rbp ret any_8x16: push rbp mov rbp, rsp movdqa xmm0, xmmword, ptr, [rdi] pmovmskb eax, xmm0 test eax, eax setne al pop rbp ret ``` `aarch64` Before this PR: ```asm all_8x16: ldr q0, [x0] umov w8, v0.b[0] umov w9, v0.b[1] tst w8, #0xff umov w10, v0.b[2] cset w8, ne tst w9, #0xff cset w9, ne tst w10, #0xff umov w10, v0.b[3] and w8, w8, w9 cset w9, ne tst w10, #0xff umov w10, v0.b[4] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[5] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[6] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[7] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[8] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[9] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[10] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[11] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[12] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[13] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[14] and w8, w9, w8 cset w9, ne tst w10, #0xff umov w10, v0.b[15] and w8, w9, w8 cset w9, ne tst w10, #0xff and w8, w9, w8 cset w9, ne and w0, w9, w8 ret any_8x16: ldr q0, [x0] umov w8, v0.b[0] umov w9, v0.b[1] orr w8, w8, w9 umov w9, v0.b[2] orr w8, w8, w9 umov w9, v0.b[3] orr w8, w8, w9 umov w9, v0.b[4] orr w8, w8, w9 umov w9, v0.b[5] orr w8, w8, w9 umov w9, v0.b[6] orr w8, w8, w9 umov w9, v0.b[7] orr w8, w8, w9 umov w9, v0.b[8] orr w8, w8, w9 umov w9, v0.b[9] orr w8, w8, w9 umov w9, v0.b[10] orr w8, w8, w9 umov w9, v0.b[11] orr w8, w8, w9 umov w9, v0.b[12] orr w8, w8, w9 umov w9, v0.b[13] orr w8, w8, w9 umov w9, v0.b[14] orr w8, w8, w9 umov w9, v0.b[15] orr w8, w8, w9 tst w8, #0xff cset w0, ne ret ``` After this PR: ```asm all_8x16: ldr q0, [x0] uminv b0, v0.16b fmov w8, s0 tst w8, #0xff cset w0, ne ret any_8x16: ldr q0, [x0] umaxv b0, v0.16b fmov w8, s0 tst w8, #0xff cset w0, ne ret ``` `ARMv7` + `neon` Before this PR: ```asm all_8x16: vmov.i8 q0, #0x1 vld1.64 {d2, d3}, [r0] vtst.8 q0, q1, q0 vext.8 q1, q0, q0, rust-lang#8 vand q0, q0, q1 vext.8 q1, q0, q0, rust-lang#4 vand q0, q0, q1 vext.8 q1, q0, q0, rust-lang#2 vand q0, q0, q1 vdup.8 q1, d0[1] vand q0, q0, q1 vmov.u8 r0, d0[0] and r0, r0, rust-lang#1 bx lr any_8x16: vmov.i8 q0, #0x1 vld1.64 {d2, d3}, [r0] vtst.8 q0, q1, q0 vext.8 q1, q0, q0, rust-lang#8 vorr q0, q0, q1 vext.8 q1, q0, q0, rust-lang#4 vorr q0, q0, q1 vext.8 q1, q0, q0, rust-lang#2 vorr q0, q0, q1 vdup.8 q1, d0[1] vorr q0, q0, q1 vmov.u8 r0, d0[0] and r0, r0, rust-lang#1 bx lr ``` After this PR: ```asm all_8x16: vld1.64 {d0, d1}, [r0] b <m8x16 as All>::all <m8x16 as All>::all: vpmin.u8 d0, d0, d b <m8x8 as All>::all any_8x16: vld1.64 {d0, d1}, [r0] b <m8x16 as Any>::any <m8x16 as Any>::any: vpmax.u8 d0, d0, d1 b <m8x8 as Any>::any ``` The inlining problems are pretty bad on ARMv7 + NEON. 256-bit wide mask types (`m8x32`, `m16x16`, `m32x8`, `m64x4`) With SSE2 enabled Before this PR: ```asm all_8x32: push rbp mov rbp, rsp movdqa xmm0, xmmword, ptr, [rip, +, LCPI17_0] movdqa xmm1, xmmword, ptr, [rdi] pand xmm1, xmm0 movdqa xmm2, xmmword, ptr, [rdi, +, 16] pand xmm2, xmm0 pcmpeqb xmm2, xmm0 pcmpeqb xmm1, xmm0 pand xmm1, xmm2 pmovmskb eax, xmm1 xor ecx, ecx cmp eax, 65535 mov eax, -1 cmovne eax, ecx and al, 1 pop rbp ret any_8x32: push rbp mov rbp, rsp movdqa xmm0, xmmword, ptr, [rdi] por xmm0, xmmword, ptr, [rdi, +, 16] movdqa xmm1, xmmword, ptr, [rip, +, LCPI16_0] pand xmm0, xmm1 pcmpeqb xmm0, xmm1 pmovmskb eax, xmm0 neg eax sbb eax, eax and al, 1 pop rbp ret ``` After this PR: ```asm all_8x32: push rbp mov rbp, rsp movdqa xmm0, xmmword, ptr, [rdi] pmovmskb eax, xmm0 cmp eax, 65535 jne LBB17_1 movdqa xmm0, xmmword, ptr, [rdi, +, 16] pmovmskb ecx, xmm0 mov al, 1 cmp ecx, 65535 je LBB17_3 LBB17_1: xor eax, eax LBB17_3: pop rbp ret any_8x32: push rbp mov rbp, rsp movdqa xmm0, xmmword, ptr, [rdi] pmovmskb ecx, xmm0 mov al, 1 test ecx, ecx je LBB16_1 pop rbp ret LBB16_1: movdqa xmm0, xmmword, ptr, [rdi, +, 16] pmovmskb eax, xmm0 test eax, eax setne al pop rbp ret ``` With AVX enabled Before this PR: ```asm all_8x32: push rbp mov rbp, rsp vmovaps ymm0, ymmword, ptr, [rdi] vandps ymm0, ymm0, ymmword, ptr, [rip, +, LCPI25_0] vextractf128 xmm1, ymm0, 1 vpxor xmm2, xmm2, xmm2 vpcmpeqb xmm1, xmm1, xmm2 vpcmpeqd xmm3, xmm3, xmm3 vpxor xmm1, xmm1, xmm3 vpcmpeqb xmm0, xmm0, xmm2 vpxor xmm0, xmm0, xmm3 vinsertf128 ymm0, ymm0, xmm1, 1 vandps ymm0, ymm0, ymm1 vpermilps xmm1, xmm0, 78 vandps ymm0, ymm0, ymm1 vpermilps xmm1, xmm0, 229 vandps ymm0, ymm0, ymm1 vpsrld xmm1, xmm0, 16 vandps ymm0, ymm0, ymm1 vpsrlw xmm1, xmm0, 8 vandps ymm0, ymm0, ymm1 vpextrb eax, xmm0, 0 and al, 1 pop rbp vzeroupper ret any_8x32: push rbp mov rbp, rsp vmovaps ymm0, ymmword, ptr, [rdi] vandps ymm0, ymm0, ymmword, ptr, [rip, +, LCPI24_0] vextractf128 xmm1, ymm0, 1 vpxor xmm2, xmm2, xmm2 vpcmpeqb xmm1, xmm1, xmm2 vpcmpeqd xmm3, xmm3, xmm3 vpxor xmm1, xmm1, xmm3 vpcmpeqb xmm0, xmm0, xmm2 vpxor xmm0, xmm0, xmm3 vinsertf128 ymm0, ymm0, xmm1, 1 vorps ymm0, ymm0, ymm1 vpermilps xmm1, xmm0, 78 vorps ymm0, ymm0, ymm1 vpermilps xmm1, xmm0, 229 vorps ymm0, ymm0, ymm1 vpsrld xmm1, xmm0, 16 vorps ymm0, ymm0, ymm1 vpsrlw xmm1, xmm0, 8 vorps ymm0, ymm0, ymm1 vpextrb eax, xmm0, 0 and al, 1 pop rbp vzeroupper ret ``` After this PR: ```asm all_8x32: push rbp mov rbp, rsp vmovdqa ymm0, ymmword, ptr, [rdi] vxorps xmm1, xmm1, xmm1 vcmptrueps ymm1, ymm1, ymm1 vptest ymm0, ymm1 setb al pop rbp vzeroupper ret any_8x32: push rbp mov rbp, rsp vmovdqa ymm0, ymmword, ptr, [rdi] vptest ymm0, ymm0 setne al pop rbp vzeroupper ret ``` --- Closes rust-lang#362 . * test avx on all x86 targets * disable assert_instr on avx test * enable all appropriate features * disable assert_instr on x86+avx * the fn_must_use is stable * fix nbody example on armv7 * fixup * fixup * enable 64-bit wide mask MMX optimizations on x86_64 only * remove coresimd dependency on cfg_if * allow wasm to fail * use an env variable to disable assert_instr tests * disable m32x2 mask MMX optimization on macos * move cfg_if to coresimd/macros.rs
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Using CString, I am passing c_chars to a function in C++ (defined with extern "C" of course). I tried debugging and on the Rust side, the strings get printed correctly, while on the C++ side it results in
^X0�;�^? @��D�^?. Sometimes only one argument gets corrupted, sometimes two (like here). The weirdest thing is that after this, the arguments get passed correctly, but not to the right place. So if I have 4 arguments in C and the first 2 get corrupted, the third one will actually be the value of the fist one in Rust.Is this a nul terminator issue? Quoting the CString documentation:
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