Re: [GHC] #14754: -O1 changes result at runtime

#14754: -O1 changes result at runtime -------------------------------------+------------------------------------- Reporter: Bodigrim | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.4.1 Component: Compiler | Version: 8.4.1-alpha1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ben Gamari ): In [changeset:"50adbd7c5fe5894d3e6e2a58b353ed07e5f8949d/ghc" 50adbd7c/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="50adbd7c5fe5894d3e6e2a58b353ed07e5f8949d" cmm: Revert more aggressive CBE due to #14226 Trac #14226 noted that the C-- CBE pass frequently fails to common up semantically identical blocks due to the differences in local register naming. These patches fixed this by making the pass consider equality up to alpha-renaming. However, the new logic failed to consider the possibility that local register naming *may* matter across multiple blocks. This lead to the regression #14754. I'll need to do a bit of thinking on a proper solution to this but in the meantime I'm reverting all four patches. This reverts commit a27056f9823f8bbe2302f1924b3ab38fd6752e37. This reverts commit 6f990c54f922beae80362fe62426beededc21290. This reverts commit 9aa73892e10e90a1799b9277da593e816a827364. This reverts commit 7920a7d9c53083b234e060a3e72f00b601a46808. }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14754#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler