Re-enable FastISel for MIPS O32 with LLVM 20 #21215
Description
Zig Version
Steps to Reproduce and Observed Behavior
zig build test -fqemu --glibc-runtimes <...> test-behavior -Dtest-slow-targets -Dtest-target-filter=mips-linux.4.19...6.10.3-gnueabihf.2.28
Program received signal SIGBUS, Bus error.
0x00068bd8 in mem.eqlBytes (a=..., b=...) at /home/alexrp/Source/zig/lib/std/mem.zig:685
685 x |= @as(u32, @bitCast(a[n..][0..4].*)) ^ @as(u32, @bitCast(b[n..][0..4].*));
(gdb) bt
#0 0x00068bd8 in mem.eqlBytes (a=..., b=...) at /home/alexrp/Source/zig/lib/std/mem.zig:685
#1 0x00063748 in mem.eql__anon_1648 (a=..., b=...) at /home/alexrp/Source/zig/lib/std/mem.zig:660
#2 0x0006392c in mem.startsWith__anon_1657 (haystack=..., needle=...) at /home/alexrp/Source/zig/lib/std/mem.zig:2913
#3 0x00055f10 in test_runner.main () at /home/alexrp/Source/zig/lib/compiler/test_runner.zig:38
#4 0x00055674 in start.callMain () at /home/alexrp/Source/zig/lib/std/start.zig:605
#5 start.callMainWithArgs () at /home/alexrp/Source/zig/lib/std/start.zig:574
#6 start.main (c_argc=3, c_argv=0x2b2ab314, c_envp=0x2b2ab324) at /home/alexrp/Source/zig/lib/std/start.zig:589
(gdb) disas $pc-100,$pc+100
Dump of assembler code from 0x68b74 to 0x68c3c:
0x00068b74 <mem.eqlBytes+2068>: sw at,116(s8)
0x00068b78 <mem.eqlBytes+2072>: lw v1,352(s8)
0x00068b7c <mem.eqlBytes+2076>: addu v1,v1,v0
0x00068b80 <mem.eqlBytes+2080>: sw v1,120(s8)
0x00068b84 <mem.eqlBytes+2084>: li v1,4
0x00068b88 <mem.eqlBytes+2088>: addu v0,v0,v1
0x00068b8c <mem.eqlBytes+2092>: sw v0,124(s8)
0x00068b90 <mem.eqlBytes+2096>: sltu at,at,v0
0x00068b94 <mem.eqlBytes+2100>: xori at,at,0x1
0x00068b98 <mem.eqlBytes+2104>: bgtz at,0x68bf0 <mem.eqlBytes+2192>
0x00068b9c <mem.eqlBytes+2108>: nop
0x00068ba0 <mem.eqlBytes+2112>: b 0x68bf8 <mem.eqlBytes+2200>
0x00068ba4 <mem.eqlBytes+2116>: nop
0x00068ba8 <mem.eqlBytes+2120>: b 0x68b4c <mem.eqlBytes+2028>
0x00068bac <mem.eqlBytes+2124>: nop
0x00068bb0 <mem.eqlBytes+2128>: lw a1,136(s8)
0x00068bb4 <mem.eqlBytes+2132>: lw a0,144(s8)
0x00068bb8 <mem.eqlBytes+2136>: lw at,220(s8)
0x00068bbc <mem.eqlBytes+2140>: lw at,-32728(at)
0x00068bc0 <mem.eqlBytes+2144>: addiu t9,at,22496
0x00068bc4 <mem.eqlBytes+2148>: bal 0x557e0 <builtin.panicOutOfBounds>
0x00068bc8 <mem.eqlBytes+2152>: nop
0x00068bcc <mem.eqlBytes+2156>: lw at,132(s8)
0x00068bd0 <mem.eqlBytes+2160>: lw v0,112(s8)
0x00068bd4 <mem.eqlBytes+2164>: lw v1,120(s8)
=> 0x00068bd8 <mem.eqlBytes+2168>: lw v1,0(v1)
0x00068bdc <mem.eqlBytes+2172>: xor v0,v0,v1
0x00068be0 <mem.eqlBytes+2176>: or at,at,v0
0x00068be4 <mem.eqlBytes+2180>: sw at,320(s8)
0x00068be8 <mem.eqlBytes+2184>: b 0x68ac0 <mem.eqlBytes+1888>
0x00068bec <mem.eqlBytes+2188>: nop
0x00068bf0 <mem.eqlBytes+2192>: b 0x68bcc <mem.eqlBytes+2156>
0x00068bf4 <mem.eqlBytes+2196>: nop
0x00068bf8 <mem.eqlBytes+2200>: lw a1,116(s8)
0x00068bfc <mem.eqlBytes+2204>: lw a0,124(s8)
0x00068c00 <mem.eqlBytes+2208>: lw at,220(s8)
0x00068c04 <mem.eqlBytes+2212>: lw at,-32728(at)
0x00068c08 <mem.eqlBytes+2216>: addiu t9,at,22496
0x00068c0c <mem.eqlBytes+2220>: bal 0x557e0 <builtin.panicOutOfBounds>
0x00068c10 <mem.eqlBytes+2224>: nop
0x00068c14 <mem.eqlBytes+2228>: li at,2
0x00068c18 <mem.eqlBytes+2232>: sw at,268(s8)
0x00068c1c <mem.eqlBytes+2236>: li at,3
0x00068c20 <mem.eqlBytes+2240>: sw at,272(s8)
0x00068c24 <mem.eqlBytes+2244>: li at,4
0x00068c28 <mem.eqlBytes+2248>: sw at,276(s8)
0x00068c2c <mem.eqlBytes+2252>: li at,5
0x00068c30 <mem.eqlBytes+2256>: sw at,280(s8)
0x00068c34 <mem.eqlBytes+2260>: lw at,224(s8)
0x00068c38 <mem.eqlBytes+2264>: li v0,0
End of assembler dump.
It looks like an LLVM miscompilation, but not sure yet.
Very oddly, -musleabihf is fine (but note that I haven't upstreamed my branch for that yet).
Expected Behavior
No failure.