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Description
The cross-compiled MIPS host compilers are fine, but stage1 immediately segfaults when asked to do just about anything:
// x.rs
fn main() {
}$ ./build/mips64el-unknown-linux-gnuabi64/stage1/bin/rustc ./x.rs
thread 'rustc' has overflowed its stack
fatal runtime error: stack overflow
[1] 3433 IOT instruction (core dumped) ./build/mips64el-unknown-linux-gnuabi64/stage1/bin/rustc ./x.rs
(gdb) r ./x.rs
Starting program: /opt/store/src/rust/build/mips64el-unknown-linux-gnuabi64/stage1/bin/rustc ./x.rs
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
[New Thread 0xfff353ef10 (LWP 3476)]
Thread 2 "rustc" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xfff353ef10 (LWP 3476)]
0x000000fff57198b8 in __ctzdi2 () from /opt/store/src/rust/build/mips64el-unknown-linux-gnuabi64/stage1/bin/../lib/../lib/librustc_llvm-d0f44aedc4c18d77.so
(gdb) disas
Dump of assembler code for function __ctzdi2:
0x000000fff57198b0 <+0>: daddiu sp,sp,-32
0x000000fff57198b4 <+4>: sll v0,a0,0x0
=> 0x000000fff57198b8 <+8>: sd s0,8(sp)
0x000000fff57198bc <+12>: sltiu s0,v0,1
0x000000fff57198c0 <+16>: sd gp,16(sp)
0x000000fff57198c4 <+20>: dnegu s0,s0
0x000000fff57198c8 <+24>: lui gp,0x96
0x000000fff57198cc <+28>: nor a1,zero,s0
0x000000fff57198d0 <+32>: daddu gp,gp,t9
0x000000fff57198d4 <+36>: dsra32 a0,a0,0x0
0x000000fff57198d8 <+40>: and v1,a0,s0
0x000000fff57198dc <+44>: daddiu gp,gp,18760
0x000000fff57198e0 <+48>: and a0,a1,v0
0x000000fff57198e4 <+52>: ld t9,-32584(gp)
0x000000fff57198e8 <+56>: or a0,v1,a0
0x000000fff57198ec <+60>: dsll32 a0,a0,0x0
0x000000fff57198f0 <+64>: sd ra,24(sp)
0x000000fff57198f4 <+68>: bal 0xfff57198b0 <__ctzdi2>
0x000000fff57198f8 <+72>: dsrl32 a0,a0,0x0
0x000000fff57198fc <+76>: ld ra,24(sp)
0x000000fff5719900 <+80>: andi s0,s0,0x20
0x000000fff5719904 <+84>: addu v0,v0,s0
0x000000fff5719908 <+88>: ld gp,16(sp)
0x000000fff571990c <+92>: ld s0,8(sp)
0x000000fff5719910 <+96>: jr ra
0x000000fff5719914 <+100>: daddiu sp,sp,32
End of assembler dump.
Notice the recursion, which is obviously wrong, and non-existent on stage0:
$ ar x ../../../nightly/2016-11-14/lib/rustlib/mips64el-unknown-linux-gnuabi64/lib/libcompiler_builtins-e428224f6caf212a.rlib
$ objdump -d ctzdi2.o
ctzdi2.o: file format elf64-tradlittlemips
Disassembly of section .text.__ctzdi2:
0000000000000000 <__ctzdi2>:
0: 00041800 sll v1,a0,0x0
4: 2c650001 sltiu a1,v1,1
8: 0005282f dnegu a1,a1
c: 0004203f dsra32 a0,a0,0x0
10: 0065200a movz a0,v1,a1
14: 00041023 negu v0,a0
18: 00822024 and a0,a0,v0
1c: 70842020 clz a0,a0
20: 2402001f li v0,31
24: 00441023 subu v0,v0,a0
28: 30a50020 andi a1,a1,0x20
2c: 03e00008 jr ra
30: 00a21021 addu v0,a1,v0
34: 00000000 nop
This is LLVM bug 11663. Maybe we should incorporate the workaround there as well.
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