Temporarily disable common block elimination; fixes #8083 for now

compiler/cmm/CmmPipeline.hs

@@ -68,9 +68,11 @@ cpsTop hsc_env proc =
                                           , do_layout = do_layout }} = h
 
        ----------- Eliminate common blocks -------------------------------------
-       g <- {-# SCC "elimCommonBlocks" #-}
-            condPass Opt_CmmElimCommonBlocks elimCommonBlocks g
-                     Opt_D_dump_cmm_cbe "Post common block elimination"
+       g <- if False -- temporarily disabled: See #8083
+            then {-# SCC "elimCommonBlocks" #-}
+                 condPass Opt_CmmElimCommonBlocks elimCommonBlocks g
+                          Opt_D_dump_cmm_cbe "Post common block elimination"
+            else return g
 
        -- Any work storing block Labels must be performed _after_
        -- elimCommonBlocks