On Fri, May 17, 2013 at 11:49:26AM +0200, Jan Stolarek wrote:
Now here's the tricky part. I'm testing this with test lib/integer/integerConstantFolding in the testsuite and the test fails because rules for quotRemInteger, divModInteger, quotInteger and remInteger don't fire, leaving the constants unfolded. I noticed that if I mark eqInteger with NOINLINE, then these rules fire, but then obviously comparisons like (100012 :: Integer) == 100012 don't get folded and the test fails anyway. I'm analyzing how the function quotInteger and others use eqInteger, but I don't see anything that would be obvious.
If you remove everything but the quotInteger test from integerConstantFolding and compile with -ddump-rule-rewrites then you'll see that the eqInteger rule fires before quotInteger. This is presumably comparing against 0, as the definition of quot for Integer (in GHC.Real) is _ `quot` 0 = divZeroError n `quot` d = n `quotInteger` d
eqIntegerPrimIdKey = mkPreludeMiscIdUnique 70 eqIntegerPrimName = varQual gHC_INTEGER_TYPE (fsLit "eqIntegerPrim") eqIntegerPrimIdKey
Do you also still have eqInteger wired in? It sounds like you might have given them both the same unique? Thanks Ian -- Ian Lynagh, Haskell Consultant Well-Typed LLP, http://www.well-typed.com/