Panic in RegisterAlloc

The following code causes a panic when compiling with the NCG (i.e. with -fasm).

stg_ap_0_fast {
    bits32 y, x;
    c7: y = bits32[x];
        goto c7;
}

The panic is

ghc-6.7.20070620: panic! (the 'impossible' happened)
  (GHC version 6.7.20070620 for i386-unknown-linux):
        RegisterAlloc.joinToTargets

I do not know of any code that depends on this yet. I just tripped over it when writting tests for the CPS pass.

Trac metadata

Trac field	Value
Version	6.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler (NCG)
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Multiple
Architecture