Program produces <<loop>> with GHC 9.0/9.2, but not with GHC 8.10

While attempting to upgrade the saw-script project, I have noticed that it will produce a runtime <<loop>> on GHC 9.0 and 9.2 on a program that did not used to <<loop>> with GHC 8.10. I believe this to be a regression, so I am reporting it here. Unfortunately, I have not been able to minimize the issue, but you can perform the following steps:

1. Ensure you have Clang installed. In case it is important, I am using Clang 10.0.0 on 64-bit Ubuntu 20.04:

   $ clang --version
   clang version 10.0.0-4ubuntu1 
   Target: x86_64-pc-linux-gnu
   Thread model: posix
   InstalledDir: /usr/bin

2. Clone https://github.com/GaloisInc/saw-script, enter the saw-script directory, and check out the ghc-9.0-9.2-bug branch:

   $ git clone https://github.com/GaloisInc/saw-script
   $ cd saw-script
   $ git checkout ghc-9.0-9.2-bug

3. Put the following files in the saw-script directory:

   // column.c
   typedef enum {
       ColumnA = 0,
       ColumnB,
   } Column;
   
   int is_column_a(Column c) {
     return c == ColumnA;
   }

   // column.saw

   // bug.saw
   enable_experimental;
   
   env <- heapster_init_env "column" "column.bc";
   
   heapster_define_perm env "int32" " " "llvmptr 32" "exists x:bv 32.eq(llvmword(x))";
   
   heapster_define_perm env "Column" ""
       "llvmptr 32"
       "eq(llvmword(0)) or eq(llvmword(1))";
   
   heapster_typecheck_fun env "is_column_a"
       "().arg0:Column<> -o ret:int32<>";

4. Compile column.c with Clang like so:

   $ clang-10 -emit-llvm -c column.c -o column.bc

5. Run the following command to run saw using GHC 8.10.7, which should succeed:

   $ cabal run exe:saw -w ghc-8.10.7 -- bug.saw
   Resolving dependencies...
   Up to date
   
   
   
   [00:19:37.163] Loading file "/home/ryanglscott/Documents/Hacking/Haskell/saw-script/bug.saw"

6. Now run the same command with GHC 9.0.2 or 9.2.4. These will loop:

   $ cabal run exe:saw -w ghc-9.0.2 -- bug.saw    
   Resolving dependencies...
   Up to date
   
   
   
   [00:21:46.189] Loading file "/home/ryanglscott/Documents/Hacking/Haskell/saw-script/bug.saw"
   [00:21:46.531] <<loop>>

   $ cabal run exe:saw -w ghc-9.2.4 -- bug.saw
   Resolving dependencies...
   Up to date
   
   
   
   [00:22:49.344] Loading file "/home/ryanglscott/Documents/Hacking/Haskell/saw-script/bug.saw"
   [00:22:49.682] <<loop>>

   Note that you should only use GHC 9.2.4 or earlier, not 9.2.5, as GHC 9.2.5 will trigger #22491 (closed).