#14872: Hex Literals in GHC Core -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: (none) Type: feature | Status: new request | Priority: lowest | Milestone: Component: Compiler | Version: 8.2.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Sometimes, when I'm doing stuff that involves twiddling bits, it would be nicer to see integer literals in hexadecimal when I dump core with `-ddump-simpl`. For example, in a project I'm working on, I've got this: {{{ detectNull :: Word -> Word detectNull x = (x - repeatHexZeroOne) .&. complement x .&. repeatHexEightZero detectArtifact :: Word -> Word -> Word detectArtifact x artifact = detectNull (applyArtifact x artifact) applyArtifact :: Word -> Word -> Word applyArtifact = xor repeatHexZeroOne :: Word repeatHexZeroOne = div maxBound 255 repeatHexEightZero :: Word repeatHexEightZero = 128 * (div maxBound 255 :: Word) }}} Once everything gets unboxed and constant-folding happens, in GHC core, the places where I used `repeatHexZeroOne` show `72340172838076673##` (on a 64-bit machine). This is accurate, but it would be nice I could give a flag to make it show `0x0101010101010101##` instead. This would make it easier for me to confirm that the arithmetic I used to generate a bit pattern actually generated what I thought it did. Admittedly, we'd probably want leading zeroes to get chopped off so that small integer literals didn't show up with 15 zeroes in front of them. So, realistically, it might show up as `0x101010101010101##`. Or maybe it could always to padded with leading zeroes until the length was a power of two. Anyway, not important, but I thought it would be nice to have. Possible flag name: `-ddump-hex-literals`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14872 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler