ARMv6 architecture support broken in nightly-2019-07-18

[Majkl578]

The support for ARMv6 architecture was broken somewhere between 07e0c36...bc2e84c: nightly-2019-07-16 compiles file while nightly-2019-07-17 produces binary that crashes with Illegal instruction.

More specifically, this is a binary cross-compiled from x86_64-unknown-linux-gnu for arm-unknown-linux-gnueabihf arch, linked with a custom linker for ARMv6.

The hardware is part of Raspberry Pi Zero rev. 1.1, the processor information is as follows:

$ cat /proc/cpuinfo
processor	: 0
model name	: ARMv6-compatible processor rev 7 (v6l)
BogoMIPS	: 697.95
Features	: half thumb fastmult vfp edsp java tls 
CPU implementer	: 0x41
CPU architecture: 7
CPU variant	: 0x0
CPU part	: 0xb76
CPU revision	: 7

Hardware	: BCM2835
Revision	: 9000c1
Serial		: 000000005f455245

[nikic]

Presumably due to LLVM update. Can you determine what the illegal instruction is? (E.g. via gdb and disassemble.)

[flippedoffbit]

did you try compiling code on your raspberry pi 0 ?
this might be issue with gcc cross compiler (code generator part)l/linker rather than Rust

[Majkl578]

Looks like even compilation directly on RPi0 is broken as the compiler/cargo crashes:

 $ cargo build --examples
    Updating crates.io index
Illegal instruction

Running under gdb:

 $ gdb -q --args cargo build
Reading symbols from cargo...done.
(gdb) r
Starting program: /home/pi/.cargo/bin/cargo build
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/arm-linux-gnueabihf/libthread_db.so.1".
process 1600 is executing new program: /home/pi/.rustup/toolchains/nightly-2019-07-20-arm-unknown-linux-gnueabihf/bin/cargo
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/arm-linux-gnueabihf/libthread_db.so.1".
    Updating crates.io index
[New Thread 0xb6d7b2f0 (LWP 1615)]
[Thread 0xb6d7b2f0 (LWP 1615) exited]

Thread 1 "cargo" received signal SIGILL, Illegal instruction.
0x00566c54 in cargo::util::progress::State::tick ()
(gdb) bt full
#0  0x00566c54 in cargo::util::progress::State::tick ()
No symbol table info available.
#1  0xbeff856c in ?? ()
No symbol table info available.
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
   lqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqk
  >x0x566c54 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+124>  vcvt.f64.u32   d16, s0                                                                                                                                                                                x
   x0x566c58 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+128>  vmov   s0, r6                                                                                                                                                                                         x
   x0x566c5c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+132>  vcvt.f64.u32   d17, s0                                                                                                                                                                                x
   x0x566c60 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+136>  ldr    r2, [r4, #140]  ; 0x8c                                                                                                                                                                         x
   x0x566c64 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+140>  add    r2, r2, #1                                                                                                                                                                                     x
   x0x566c68 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+144>  str    r2, [r4, #140]  ; 0x8c                                                                                                                                                                         x
   x0x566c6c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+148>  stmib  sp, {r6, r7}                                                                                                                                                                                   x
   x0x566c70 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+152>  vdiv.f64       d16, d17, d16                                                                                                                                                                          x
   x0x566c74 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+156>  vmov   r0, r1, d16                                                                                                                                                                                    x
   x0x566c78 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+160>  vldr   d17, [pc, #1008]        ; 0x567070 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1176>                                                                      x
   x0x566c7c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+164>  bic    r1, r1, #-2147483648    ; 0x80000000                                                                                                                                                           x
   x0x566c80 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+168>  vmov   d18, r0, r1                                                                                                                                                                                    x
   x0x566c84 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+172>  ldrb   r0, [r9, #12]                                                                                                                                                                                  x
   x0x566c88 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+176>  vcmpe.f64      d18, d17                                                                                                                                                                               x
   x0x566c8c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+180>  vmrs   APSR_nzcv, fpscr                                                                                                                                                                               x
   x0x566c90 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+184>  vmovmi.f64     d8, d16                                                                                                                                                                                x
   x0x566c94 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+188>  cmp    r0, #1                                                                                                                                                                                         x
   x0x566c98 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+192>  bne    0x566cec <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+276>                                                                                                 x
   x0x566c9c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+196>  mov    r1, #2                                                                                                                                                                                         x
   x0x566ca0 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+200>  add    r2, sp, #56     ; 0x38                                                                                                                                                                         x
   x0x566ca4 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+204>  ldr    r0, [pc, #980]  ; 0x567080 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1192>                                                                              x
   mqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqj
multi-thre Thread 0xb6ff0010 ( In: _ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568                                                                                                                                                                      L??   PC: 0x566c54
(gdb) disassemble
Dump of assembler code for function _ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568:
   0x00566bd8 <+0>:     push    {r4, r5, r6, r7, r8, r9, r10, r11, lr}
   0x00566bdc <+4>:     sub     sp, sp, #4
   0x00566be0 <+8>:     vpush   {d8}
   0x00566be4 <+12>:    sub     sp, sp, #72     ; 0x48
   0x00566be8 <+16>:    mov     r9, r0
   0x00566bec <+20>:    ldrb    r0, [r0, #52]   ; 0x34
   0x00566bf0 <+24>:    mov     r4, #0
   0x00566bf4 <+28>:    mov     r5, #0
   0x00566bf8 <+32>:    cmp     r0, #0
   0x00566bfc <+36>:    bne     0x566fd0 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1016>
   0x00566c00 <+40>:    mov     r8, r3
   0x00566c04 <+44>:    mov     r7, r2
   0x00566c08 <+48>:    mov     r6, r1
   0x00566c0c <+52>:    cmp     r1, r2
   0x00566c10 <+56>:    bne     0x566c20 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+72>
   0x00566c14 <+60>:    cmp     r7, #0
   0x00566c18 <+64>:    movne   r0, #1
   0x00566c1c <+68>:    strbne  r0, [r9, #52]   ; 0x34
   0x00566c20 <+72>:    ldr     r4, [r9]
   0x00566c24 <+76>:    ldr     r0, [r4, #140]  ; 0x8c
   0x00566c28 <+80>:    cmp     r0, #0
   0x00566c2c <+84>:    bne     0x566fe8 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1040>
   0x00566c30 <+88>:    ldrb    r0, [r4, #144]  ; 0x90
   0x00566c34 <+92>:    mvn     r1, #0
   0x00566c38 <+96>:    str     r1, [r4, #140]  ; 0x8c
   0x00566c3c <+100>:   cmp     r0, #0
   0x00566c40 <+104>:   ldrbne  r0, [r4, #145]  ; 0x91
   0x00566c44 <+108>:   cmpne   r0, #0
   0x00566c48 <+112>:   bne     0x566dc8 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+496>
   0x00566c4c <+116>:   vmov    s0, r7
   0x00566c50 <+120>:   vldr    d8, [pc, #1008] ; 0x567048 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1136>
=> 0x00566c54 <+124>:   vcvt.f64.u32    d16, s0
   0x00566c58 <+128>:   vmov    s0, r6
(gdb) disassemble
Dump of assembler code for function _ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568:
   0x00566bd8 <+0>:     push    {r4, r5, r6, r7, r8, r9, r10, r11, lr}
   0x00566bdc <+4>:     sub     sp, sp, #4
   0x00566be0 <+8>:     vpush   {d8}
   0x00566be4 <+12>:    sub     sp, sp, #72     ; 0x48
   0x00566be8 <+16>:    mov     r9, r0
   0x00566bec <+20>:    ldrb    r0, [r0, #52]   ; 0x34
   0x00566bf0 <+24>:    mov     r4, #0
   0x00566bf4 <+28>:    mov     r5, #0
   0x00566bf8 <+32>:    cmp     r0, #0
   0x00566bfc <+36>:    bne     0x566fd0 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1016>
   0x00566c00 <+40>:    mov     r8, r3
   0x00566c04 <+44>:    mov     r7, r2
   0x00566c08 <+48>:    mov     r6, r1
   0x00566c0c <+52>:    cmp     r1, r2
   0x00566c10 <+56>:    bne     0x566c20 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+72>
   0x00566c14 <+60>:    cmp     r7, #0
   0x00566c18 <+64>:    movne   r0, #1
   0x00566c1c <+68>:    strbne  r0, [r9, #52]   ; 0x34
   0x00566c20 <+72>:    ldr     r4, [r9]
   0x00566c24 <+76>:    ldr     r0, [r4, #140]  ; 0x8c
   0x00566c28 <+80>:    cmp     r0, #0
   0x00566c2c <+84>:    bne     0x566fe8 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1040>
   0x00566c30 <+88>:    ldrb    r0, [r4, #144]  ; 0x90
   0x00566c34 <+92>:    mvn     r1, #0
   0x00566c38 <+96>:    str     r1, [r4, #140]  ; 0x8c
   0x00566c3c <+100>:   cmp     r0, #0
   0x00566c40 <+104>:   ldrbne  r0, [r4, #145]  ; 0x91
   0x00566c44 <+108>:   cmpne   r0, #0
   0x00566c48 <+112>:   bne     0x566dc8 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+496>
   0x00566c4c <+116>:   vmov    s0, r7
   0x00566c50 <+120>:   vldr    d8, [pc, #1008] ; 0x567048 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1136>
=> 0x00566c54 <+124>:   vcvt.f64.u32    d16, s0
   0x00566c58 <+128>:   vmov    s0, r6
--Type <RET> for more, q to quit, c to continue without paging--
   0x00566c5c <+132>:   vcvt.f64.u32    d17, s0
   0x00566c60 <+136>:   ldr     r2, [r4, #140]  ; 0x8c
   0x00566c64 <+140>:   add     r2, r2, #1
   0x00566c68 <+144>:   str     r2, [r4, #140]  ; 0x8c
   0x00566c6c <+148>:   stmib   sp, {r6, r7}
   0x00566c70 <+152>:   vdiv.f64        d16, d17, d16
   0x00566c74 <+156>:   vmov    r0, r1, d16
   0x00566c78 <+160>:   vldr    d17, [pc, #1008]        ; 0x567070 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1176>
   0x00566c7c <+164>:   bic     r1, r1, #-2147483648    ; 0x80000000
   0x00566c80 <+168>:   vmov    d18, r0, r1
   0x00566c84 <+172>:   ldrb    r0, [r9, #12]
   0x00566c88 <+176>:   vcmpe.f64       d18, d17
   0x00566c8c <+180>:   vmrs    APSR_nzcv, fpscr
   0x00566c90 <+184>:   vmovmi.f64      d8, d16
   0x00566c94 <+188>:   cmp     r0, #1
   0x00566c98 <+192>:   bne     0x566cec <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+276>
   0x00566c9c <+196>:   mov     r1, #2
   0x00566ca0 <+200>:   add     r2, sp, #56     ; 0x38
   0x00566ca4 <+204>:   ldr     r0, [pc, #980]  ; 0x567080 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1192>
   0x00566ca8 <+208>:   str     r1, [sp, #52]   ; 0x34
   0x00566cac <+212>:   str     r2, [sp, #48]   ; 0x30
   0x00566cb0 <+216>:   mov     r2, #0
   0x00566cb4 <+220>:   str     r2, [sp, #44]   ; 0x2c
   0x00566cb8 <+224>:   add     r0, pc, r0
   0x00566cbc <+228>:   str     r2, [sp, #40]   ; 0x28
   0x00566cc0 <+232>:   add     r2, sp, #8
   0x00566cc4 <+236>:   str     r1, [sp, #36]   ; 0x24
   0x00566cc8 <+240>:   ldr     r1, [pc, #948]  ; 0x567084 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1196>
   0x00566ccc <+244>:   ldr     r1, [pc, r1]
   0x00566cd0 <+248>:   str     r1, [sp, #68]   ; 0x44
   0x00566cd4 <+252>:   str     r2, [sp, #64]   ; 0x40
   0x00566cd8 <+256>:   str     r1, [sp, #60]   ; 0x3c
   0x00566cdc <+260>:   add     r1, sp, #4
   0x00566ce0 <+264>:   str     r1, [sp, #56]   ; 0x38
--Type <RET> for more, q to quit, c to continue without paging--
   0x00566ce4 <+268>:   str     r0, [sp, #32]
   0x00566ce8 <+272>:   b       0x566d40 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+360>
   0x00566cec <+276>:   vldr    d16, [pc, #900] ; 0x567078 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1184>
   0x00566cf0 <+280>:   mov     r2, #1
   0x00566cf4 <+284>:   ldr     r0, [pc, #936]  ; 0x5670a4 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1228>
   0x00566cf8 <+288>:   add     r3, sp, #24
   0x00566cfc <+292>:   vmul.f64        d16, d8, d16
   0x00566d00 <+296>:   ldr     r1, [pc, #928]  ; 0x5670a8 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1232>
   0x00566d04 <+300>:   str     r2, [sp, #52]   ; 0x34
   0x00566d08 <+304>:   add     r0, pc, r0
   0x00566d0c <+308>:   str     r3, [sp, #48]   ; 0x30
   0x00566d10 <+312>:   add     r1, pc, r1
   0x00566d14 <+316>:   str     r2, [sp, #44]   ; 0x2c
   0x00566d18 <+320>:   mov     r2, #2
   0x00566d1c <+324>:
        str     r2, [sp, #36]   ; 0x24
   0x00566d20 <+328>:   ldr     r2, [pc, #900]  ; 0x5670ac <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1236>
   0x00566d24 <+332>:   ldr     r2, [pc, r2]
   0x00566d28 <+336>:   str     r2, [sp, #28]
   0x00566d2c <+340>:   add     r2, sp, #56     ; 0x38
   0x00566d30 <+344>:   str     r1, [sp, #40]   ; 0x28
   0x00566d34 <+348>:   str     r2, [sp, #24]
   0x00566d38 <+352>:   str     r0, [sp, #32]
   0x00566d3c <+356>:   vstr    d16, [sp, #56]  ; 0x38
   0x00566d40 <+360>:   add     r0, sp, #12
   0x00566d44 <+364>:   add     r1, sp, #32
   0x00566d48 <+368>:   bl      0xcaac20 <alloc::fmt::format>
   0x00566d4c <+372>:   ldr     r11, [sp, #20]
   0x00566d50 <+376>:   ldr     r4, [r9, #4]
   0x00566d54 <+380>:   ldr     r0, [r9, #8]
   0x00566d58 <+384>:   add     r1, r11, #17
   0x00566d5c <+388>:   cmp     r4, r0
   0x00566d60 <+392>:   movls   r0, r4
   0x00566d64 <+396>:   subs    r7, r0, r1
   0x00566d68 <+400>:   bcs     0x566d98 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+448>
--Type <RET> for more, q to quit, c to continue without paging--
   0x00566d6c <+404>:   ldr     r1, [sp, #16]
   0x00566d70 <+408>:   mov     r4, #0
   0x00566d74 <+412>:   str     r4, [sp, #64]   ; 0x40
   0x00566d78 <+416>:   cmp     r1, #0
   0x00566d7c <+420>:   str     r4, [sp, #60]   ; 0x3c
   0x00566d80 <+424>:   str     r4, [sp, #56]   ; 0x38
   0x00566d84 <+428>:   beq     0x566fcc <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1012>
   0x00566d88 <+432>:   ldr     r0, [sp, #12]
   0x00566d8c <+436>:   mov     r2, #1
   0x00566d90 <+440>:   bl      0x49c8bc <__rust_dealloc>
   0x00566d94 <+444>:   b       0x566fcc <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1012>
   0x00566d98 <+448>:   cmn     r4, #1
   0x00566d9c <+452>:   ble     0x567008 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1072>
   0x00566da0 <+456>:   cmp     r4, #0
   0x00566da4 <+460>:   beq     0x566e00 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+552>
   0x00566da8 <+464>:   mov     r0, r4
   0x00566dac <+468>:   mov     r1, #1
   0x00566db0 <+472>:   bl      0x49c8b8 <__rust_alloc>
   0x00566db4 <+476>:   cmp     r0, #0
   0x00566db8 <+480>:   beq     0x567010 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1080>
   0x00566dbc <+484>:   mov     r1, #0
   0x00566dc0 <+488>:   str     r1, [sp, #40]   ; 0x28
   0x00566dc4 <+492>:   b       0x566e28 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+592>
   0x00566dc8 <+496>:   mov     r1, #19
   0x00566dcc <+500>:   mov     r0, #0
   0x00566dd0 <+504>:   orr     r1, r1, #21504  ; 0x5400
   0x00566dd4 <+508>:   add     r2, sp, #32
   0x00566dd8 <+512>:   str     r0, [sp, #36]   ; 0x24
   0x00566ddc <+516>:   str     r0, [sp, #32]
   0x00566de0 <+520>:   mov     r0, #2
   0x00566de4 <+524>:   bl      0x43bc38 <ioctl@plt>
   0x00566de8 <+528>:   cmn     r0, #1
   0x00566dec <+532>:
        ble     0x566c4c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+116>
   0x00566df0 <+536>:   ldrh    r0, [sp, #34]   ; 0x22
--Type <RET> for more, q to quit, c to continue without paging--
   0x00566df4 <+540>:   cmp     r0, #0
   0x00566df8 <+544>:   strne   r0, [r9, #4]
   0x00566dfc <+548>:   b       0x566c4c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+116>
   0x00566e00 <+552>:   mov     r0, #0
   0x00566e04 <+556>:   mov     r1, #1
   0x00566e08 <+560>:   str     r0, [sp, #40]   ; 0x28
   0x00566e0c <+564>:   mov     r0, #1
   0x00566e10 <+568>:   str     r4, [sp, #36]   ; 0x24
   0x00566e14 <+572>:   mov     r4, #1
   0x00566e18 <+576>:   str     r4, [sp, #32]
   0x00566e1c <+580>:   bl      0x49c8b8 <__rust_alloc>
   0x00566e20 <+584>:   cmp     r0, #0
   0x00566e24 <+588>:   beq     0x567018 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1088>
   0x00566e28 <+592>:   vmov    s0, r7
   0x00566e2c <+596>:   str     r4, [sp, #36]   ; 0x24
   0x00566e30 <+600>:   str     r0, [sp, #32]
   0x00566e34 <+604>:   mov     r1, #91 ; 0x5b
   0x00566e38 <+608>:   vcvt.f64.u32    d16, s0
   0x00566e3c <+612>:   vmul.f64        d16, d8, d16
   0x00566e40 <+616>:   vcvt.u32.f64    s0, d16
   0x00566e44 <+620>:   strb    r1, [r0]
   0x00566e48 <+624>:   mov     r0, #1
   0x00566e4c <+628>:   str     r0, [sp, #40]   ; 0x28
   0x00566e50 <+632>:   vmov    r10, s0
   0x00566e54 <+636>:   cmp     r10, #0
   0x00566e58 <+640>:   beq     0x566ec4 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+748>
   0x00566e5c <+644>:   ldr     r4, [pc, #548]  ; 0x567088 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1200>
   0x00566e60 <+648>:
add     r5, sp, #32
   0x00566e64 <+652>:   mov     r6, r10
   0x00566e68 <+656>:   add     r4, pc, r4
   0x00566e6c <+660>:   subs    r6, r6, #1
   0x00566e70 <+664>:   beq     0x566e88 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+688>
   0x00566e74 <+668>:   mov     r0, r5
   0x00566e78 <+672>:   mov     r1, r4
--Type <RET> for more, q to quit, c to continue without paging--
   0x00566e7c <+676>:   mov     r2, #1
   0x00566e80 <+680>:   bl      0x67a490 <_ZN93_$LT$alloc..vec..Vec$LT$T$GT$$u20$as$u20$core..iter..traits..collect..Extend$LT$$RF$T$GT$$GT$6extend17h135f0dd5c0b278d6E>
   0x00566e84 <+684>:   b       0x566e6c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+660>
   0x00566e88 <+688>:   ldr     r0, [sp, #8]
   0x00566e8c <+692>:   ldr     r1, [sp, #4]
   0x00566e90 <+696>:   cmp     r1, r0
   0x00566e94 <+700>:   bne     0x566eb0 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+728>
   0x00566e98 <+704>:   ldr     r1, [pc, #496]  ; 0x567090 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1208>
   0x00566e9c <+708>:   add     r1, pc, r1
   0x00566ea0 <+712>:   add     r0, sp, #32
   0x00566ea4 <+716>:   mov     r2, #1
   0x00566ea8 <+720>:   bl      0x67a490 <_ZN93_$LT$alloc..vec..Vec$LT$T$GT$$u20$as$u20$core..iter..traits..collect..Extend$LT$$RF$T$GT$$GT$6extend17h135f0dd5c0b278d6E>
   0x00566eac <+724>:   b       0x566ec4 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+748>
   0x00566eb0 <+728>:   ldr     r1, [pc, #468]  ; 0x56708c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1204>
   0x00566eb4 <+732>:   add     r1, pc, r1
   0x00566eb8 <+736>:   add     r0, sp, #32
   0x00566ebc <+740>:   mov     r2, #1
   0x00566ec0 <+744>:   bl      0x67a490 <_ZN93_$LT$alloc..vec..Vec$LT$T$GT$$u20$as$u20$core..iter..traits..collect..Extend$LT$$RF$T$GT$$GT$6extend17h135f0dd5c0b278d6E>
   0x00566ec4 <+748>:   ldr
r4, [pc, #456]  ; 0x567094 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1212>
   0x00566ec8 <+752>:   sub     r6, r7, r10
   0x00566ecc <+756>:   add     r5, sp, #32
   0x00566ed0 <+760>:   mvn     r7, #0
   0x00566ed4 <+764>:   add     r4, pc, r4
   0x00566ed8 <+768>:   add     r7, r7, #1
   0x00566edc <+772>:   cmp     r7, r6
   0x00566ee0 <+776>:   bcs     0x566ef8 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+800>
   0x00566ee4 <+780>:   mov     r0, r5
   0x00566ee8 <+784>:   mov     r1, r4
   0x00566eec <+788>:   mov     r2, #1
   0x00566ef0 <+792>:   bl      0x67a490 <_ZN93_$LT$alloc..vec..Vec$LT$T$GT$$u20$as$u20$core..iter..traits..collect..Extend$LT$$RF$T$GT$$GT$6extend17h135f0dd5c0b278d6E>
   0x00566ef4 <+796>:   b       0x566ed8 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+768>
   0x00566ef8 <+800>:   ldr     r1, [pc, #408]  ; 0x567098 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1216>
   0x00566efc <+804>:   add     r1, pc, r1
   0x00566f00 <+808>:   add     r0, sp, #32
--Type <RET> for more, q to quit, c to continue without paging--
   0x00566f04 <+812>:   mov     r2, #1
   0x00566f08 <+816>:   bl      0x67a490 <_ZN93_$LT$alloc..vec..Vec$LT$T$GT$$u20$as$u20$core..iter..traits..collect..Extend$LT$$RF$T$GT$$GT$6extend17h135f0dd5c0b278d6E>
   0x00566f0c <+820>:   ldr     r4, [sp, #12]
   0x00566f10 <+824>:   add     r0, sp, #32
   0x00566f14 <+828>:   mov     r1, r4
   0x00566f18 <+832>:   mov     r2, r11
   0x00566f1c <+836>:   bl      0x67a490 <_ZN93_$LT$alloc..vec..Vec$LT$T$GT$$u20$as$u20$core..iter..traits..collect..Extend$LT$$RF$T$GT$$GT$6extend17h135f0dd5c0b278d6E>
   0x00566f20 <+840>:   add     r3, sp, #32
   0x00566f24 <+844>:   ldr     r1, [sp, #16]
   0x00566f28 <+848>:   add     r12, sp, #56    ; 0x38
   0x00566f2c <+852>:   ldm     r3, {r0, r2, r3}
   0x00566f30 <+856>:   cmp     r1, #0
   0x00566f34 <+860>:   stm     r12, {r0, r2, r3}
   0x00566f38 <+864>:   beq     0x566f48 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+880>

   0x00566f3c <+868>:   mov     r0, r4
   0x00566f40 <+872>:   mov     r2, #1
   0x00566f44 <+876>:   bl      0x49c8bc <__rust_dealloc>
   0x00566f48 <+880>:   ldr     r0, [sp, #56]   ; 0x38
   0x00566f4c <+884>:   cmp     r0, #0
   0x00566f50 <+888>:   beq     0x566fc8 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1008>
   0x00566f54 <+892>:   ldr     r6, [sp, #56]   ; 0x38
   0x00566f58 <+896>:   ldr     r0, [sp, #60]   ; 0x3c
   0x00566f5c <+900>:   ldr     r2, [sp, #64]   ; 0x40
   0x00566f60 <+904>:   str     r2, [sp, #40]   ; 0x28
   0x00566f64 <+908>:   str     r0, [sp, #36]   ; 0x24
   0x00566f68 <+912>:   str     r6, [sp, #32]
   0x00566f6c <+916>:   ldr     r0, [sp, #120]  ; 0x78
   0x00566f70 <+920>:   mov     r1, r6
   0x00566f74 <+924>:   str     r0, [sp]
   0x00566f78 <+928>:   mov     r0, r9
   0x00566f7c <+932>:   mov     r3, r8
   0x00566f80 <+936>:   bl      0x5670b0 <_ZN5cargo4util8progress5State5print17h6dc31809966badaeE.llvm.6020787217439157568>
   0x00566f84 <+940>:   mov     r4, r0
   0x00566f88 <+944>:   cmp     r0, #0
--Type <RET> for more, q to quit, c to continue without paging--
   0x00566f8c <+948>:   beq     0x566fb0 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+984>
   0x00566f90 <+952>:   mov     r5, r1
   0x00566f94 <+956>:   ldr     r1, [sp, #36]   ; 0x24
   0x00566f98 <+960>:   cmp     r1, #0
   0x00566f9c <+964>:   beq     0x566fd0 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1016>
   0x00566fa0 <+968>:   mov     r0, r6
   0x00566fa4 <+972>:   mov     r2, #1
   0x00566fa8 <+976>:   bl      0x49c8bc <__rust_dealloc>

   0x00566fac <+980>:   b       0x566fd0 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1016>
   0x00566fb0 <+984>:   ldr     r1, [sp, #36]   ; 0x24
   0x00566fb4 <+988>:   cmp     r1, #0
   0x00566fb8 <+992>:   beq     0x566fc8 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1008>
   0x00566fbc <+996>:   mov     r0, r6
   0x00566fc0 <+1000>:  mov     r2, #1
   0x00566fc4 <+1004>:  bl      0x49c8bc <__rust_dealloc>
   0x00566fc8 <+1008>:  mov     r4, #0
   0x00566fcc <+1012>:  mov     r5, #0
   0x00566fd0 <+1016>:  mov     r0, r4
   0x00566fd4 <+1020>:  mov     r1, r5
   0x00566fd8 <+1024>:  add     sp, sp, #72     ; 0x48
   0x00566fdc <+1028>:  vpop    {d8}
   0x00566fe0 <+1032>:  add     sp, sp, #4
   0x00566fe4 <+1036>:  pop     {r4, r5, r6, r7, r8, r9, r10, r11, pc}
   0x00566fe8 <+1040>:  ldr     r0, [pc, #172]  ; 0x56709c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1220>
   0x00566fec <+1044>:  add     r2, sp, #32
   0x00566ff0 <+1048>:  ldr     r3, [pc, #168]  ; 0x5670a0 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1224>
   0x00566ff4 <+1052>:  mov     r1, #16
   0x00566ff8 <+1056>:  add     r0, pc, r0
   0x00566ffc <+1060>:  add     r3, pc, r3



   0x00567000 <+1064>:  bl      0xcb0c9c <core::result::unwrap_failed>
   0x00567004 <+1068>:  udf     #65006  ; 0xfdee
   0x00567008 <+1072>:  bl      0x750194 <_ZN5alloc7raw_vec19RawVec$LT$T$C$A$GT$11allocate_in28_$u7b$$u7b$closure$u7d$$u7d$17hfff8a4b022386362E.llvm.10649790427578084810>
   0x0056700c <+1076>:  udf     #65006  ; 0xfdee
   0x00567010 <+1080>:  mov     r0, r4
--Type <RET> for more, q to quit, c to continue without paging--
   0x00567014 <+1084>:  b       0x56701c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1092>
   0x00567018 <+1088>:
        mov     r0, #1
   0x0056701c <+1092>:  mov     r1, #1
   0x00567020 <+1096>:  bl      0xcaaa24 <alloc::alloc::handle_alloc_error>
   0x00567024 <+1100>:  udf     #65006  ; 0xfdee
   0x00567028 <+1104>:  mov     r4, r0
   0x0056702c <+1108>:  b       0x56705c <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1156>
   0x00567030 <+1112>:  mov     r4, r0
   0x00567034 <+1116>:  add     r0, sp, #32
   0x00567038 <+1120>:  b       0x567060 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1160>
   0x0056703c <+1124>:  b       0x567050 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1144>
   0x00567040 <+1128>:  b       0x567050 <_ZN5cargo4util8progress5State4tick17hfa4ef476c56b997eE.llvm.6020787217439157568+1144>
   0x00567044 <+1132>:  nop                     ; (mov r0, r0)
   0x00567048 <+1136>:  andeq   r0, r0, r0
   0x0056704c <+1140>:  andeq   r0, r0, r0
   0x00567050 <+1144>:  mov     r4, r0
   0x00567054 <+1148>:  add     r0, sp, #32
   0x00567058 <+1152>:  bl      0x541f50 <_ZN4core3ptr18real_drop_in_place17hfc27c23e20d4480aE.llvm.6020787217439157568>
   0x0056705c <+1156>:  add     r0, sp, #12
   0x00567060 <+1160>:  bl      0x541f50 <_ZN4core3ptr18real_drop_in_place17hfc27c23e20d4480aE.llvm.6020787217439157568>
   0x00567064 <+1164>:  mov     r0, r4
   0x00567068 <+1168>:  bl      0x43b65c <_Unwind_Resume@plt>
   0x0056706c <+1172>:  udf     #65006  ; 0xfdee
   0x00567070 <+1176>:  andeq   r0, r0, r0
   0x00567074 <+1180>:  svcvc   0x00f00000      ; IMB
   0x00567078 <+1184>:  andeq   r0, r0, r0
   0x0056707c <+1188>:  subsmi  r0, r9, r0
   0x00567080 <+1192>:  addeq   sp, lr, r12, lsr #7
   0x00567084 <+1196>:  addseq  pc, r0, r8, lsl #6
   0x00567088 <+1200>:
        rsbseq  r5, r6, r4, lsl r12
   0x0056708c <+1204>:  rsbseq  r5, r6, r9, asr #23
   0x00567090 <+1208>:  rsbseq  r5, r6, r0, ror #23
   0x00567094 <+1212>:  rsbseq  r5, r6, sp, lsl #1
   0x00567098 <+1216>:  rsbseq  r5, r6, r2, lsl #23
--Type <RET> for more, q to quit, c to continue without paging--
   0x0056709c <+1220>:  rsbseq  lr, r5, r6, lsr #31
   0x005670a0 <+1224>:  addeq   pc, lr, r0, lsl #6
   0x005670a4 <+1228>:  addeq   sp, lr, r12, ror #6
   0x005670a8 <+1232>:  rsbseq  r5, r6, r8, asr #26
   0x005670ac <+1236>:                  ; <UNDEFINED> instruction: 0x0090eebc
End of assembler dump.

@nikic I'm not sure if this helpful at all, I can send (e-mail) you the coredump or do anything else you need, unfortunately I have basically no experience debugging low-level ASM issues.

[nikic]

The problematic instruction is vcvt.f64.u32, which requires vfp2 and dpvfp. The arm-unknown-linux-gnueabihf target builds with +vfp2.

There were some changes in LLVM 9 around the sp/dp handling on ARM (+fp-only-sp became -fp64), possibly we flipped a default there...

[Majkl578]

According to the ARM1176JZF-S™ Technical Reference Manual (which is the CPU used in Raspberry Pi Zero) it contains a VFP11 coprocessor (VFP2 implementation with full support for single-precision and double-precision math operations).
Maybe VFP11 is somehow slightly different from what LLVM assumes?

ARM refs:

• ARM1176JZF-S™ Technical Reference Manual
• VFP11 ™ VectorFloating-point Coprocessor Technical Reference Manual
  for ARM1136JF-S
• ARM Architecture Reference Manual ARMv7-A and ARMv7-R edition + later ARMv6 architecture releases for ARM11 processors

[nikic]

Thanks for the references. So both vfp2 and fp64 should be supported.

Something I missed before is that the instruction uses the d16 register, while the VFP11 coprocessor only has 16 double-precision registers. To target this CPU -d32 needs to be added to the target features.

It looks like the corresponding armv7 target does disable d32.

Possibly the default flipped here, in which case we should just add -d32 to all the older ARM targets.