GHCi on Windows has had a segfault for while now on x86_64. During the upgrade of GCC in D1123 I noticed that test prog003 was failing with a segfault.

Currently the segfault exist in both versions but on x86 it's particularly easy to trigger.

In my case I can't even start ghci.

$ inplace/bin/GHC-stage2.exe --interactive
GHCi, version 7.11.20151213: http://www.haskell.org/ghc/  :? for help
Segmentation fault/access violation in generated code

The segfault does not seem to happen when linked to the debug rts, and running with +RTS -Ds -RTS doesn't report anything special.

Compiling with devel2 so the rts gets compiled with -g the stack trace is not very useful.

(gdb) run --interactive
Starting program: /home/Tamar/ghc/inplace/bin/ghc-stage2 --interactive
[New Thread 108480.0x1960c]
[New Thread 108480.0x19b2c]
[New Thread 108480.0x19c30]
[New Thread 108480.0x1a0a8]
[New Thread 108480.0x1a93c]
[New Thread 108480.0x13954]
[New Thread 108480.0x14440]
GHCi, version 7.11.20151213: http://www.haskell.org/ghc/  :? for help

Program received signal SIGSEGV, Segmentation fault.
0x06843aa5 in ?? ()
(gdb) bt
#0  0x06843aa5 in ?? ()
#1  0x04b82cfc in ?? ()
#2  0x8d078902 in ?? ()
#3  0xc689fd47 in ?? ()
#4  0xff04c583 in ?? ()
#5  0x83c70065 in ?? ()
#6  0x0000033c in ?? ()
#7  0x00000008 in ?? ()
#8  0x04e9c689 in ?? ()
Backtrace stopped: Cannot access memory at address 0x47c70cc8

And the output of p4

(gdb) p4 0x06843aa5
0x6843ab0:      0x330073
0x6843aac:      0x790073 <c1CgU_info+131>
0x6843aa8:      0x6d005c <c1rsa_info+715>
0x6843aa4:      0x3a0045