There are various rules for conversions between types that generally work well. However for a patch of mine the rules failed to fire and I saw things like this expression. ``` (case GHC.Num.Integer.$wintegerToWord# (case i_aN8 of { GHC.Types.I# i_a2i7 -> GHC.Num.Integer.IS i_a2i7 }) ``` If integerToWord would be allowed to inline this would still compile to a no-op. Now I wonder if we could run into similar situations with user-defined numeric types. Can these cause rules to fail to fire and can we then end up in the same situation? I don't have code where it does happen (outside of my patch) currently. But I thought @hsyl20 might be able to say if this should be a concern or not without spending too much time on it. ---------- (Edit by @hsyl20) The idea would be to only keep BigNat# primitives opaque but to allow Integer/Natural primitives to inline. List of ghc-bignum primitives that are not inlined: * Natural * [X] naturalFromBigNat# - won't do as it uses BigNat# internals * [ ] naturalToBigNat# - need constant folding for bigNatFromWord# * [ ] naturalToWord# - need constant folding for bigNatIndex# * [x] naturalToWordClamp# - just inline * [x] naturalGe# - need constant folding for bigNatGe# (or just bigNatCompare?) * [x] naturalLe# - need constant folding for bigNatLe# (ditto) * [x] naturalGt# - need constant folding for bigNatGt# (ditto) * [x] naturalLt# - need constant folding for bigNatLt# (ditto) * [x] naturalCompare - need constant folding for bigNatCompare * [ ] naturalPopCount# - need constant folding for bigNatPopCount# * [ ] naturalShiftR# - need constant folding for bigNatShiftR# * [ ] naturalShiftL# - need constant folding for bigNatShiftL# (clz# should already be done) * [ ] naturalAdd - need constant folding for addWordC# (not sure if we have it), bigNatFromWord2#, bigNatAddWord# and bigNatAdd * [ ] naturalSub - need constant folding for bigNatSubWordUnsafe#, subWordC#, bigNatSub * [ ] naturalSubThrow - rewrite using naturalSub * [ ] naturalSubUnsafe - c-f for bigNatSubWordUnsafe#, bigNatSub * [ ] naturalMul - put 0/1 tests in new naturalMulWord#, need constant folding for naturalFromWord2# * [ ] naturalMulWord (new) - need constant folding for bigNatMul, bigNatMulWord# * [x] naturalSignum - just inline * [x] naturalNegate - just inline * [ ] naturalQuotRem - need constant folding for bigNatQuotRemWord#, bigNatQuotRem# * [ ] naturalQuot - need constant folding for bigNatQuotWord#, bigNatQuot * [ ] naturalRem - need constant folding for bigNatRemWord#, bigNatRem * [ ] naturalAnd - need constant folding for bigNatToWord#, bigNatAnd * [ ] naturalAndNot, naturalOr, naturalXor - similar to naturalAnd * [ ] naturalTestBit# - need constant folding for bigNatTestBit# * [ ] naturalBit# - need constant folding for bigNatBit# * [ ] naturalGcd - need constant folding for gcdWord#, bigNatGcdWord#, bigNatGcd * [ ] naturalLcm - need constant folding for bigNatLcmWordWord#, bigNatLcmWord#, bigNatLcm * [ ] naturalLog2# - need constant folding for bigNatLog2 * [ ] naturalLogBaseWord# - need constant folding for wordLogBase#, bigNatLogBaseWord# * [ ] naturalLogBase# - need constant folding for bigNatLogBase# * [ ] naturalPowMod - need constant folding for powModWord#, bigNatPowModWord#, bigNatPowMod * [ ] naturalSizeInBase# - need constant folding for wordLogBase#, bigNatSizeInBase# * [x] naturalToAddr# - just inline and make bigNatToAddrLE/BE# NOINLINE * [x] naturalFromAddr# - just inline and make bigNatFromAddrLE/BE# NOINLINE * [x] naturalToMutableByteArray# - just inline and make bigNatToMutableByteArrayLE/BE# NOINLINE * [x] naturalFromByteArray# - just inline and make bigNatFromByteArrayLE/BE# NOINLINE * Integer * [ ] integerToInt# - need cf bigNatToWord# * [ ] integerFromWord# - need cf for bigNatFromWord# * [ ] integerToWord# - need cf for bigNatToWord# * [ ] integerFromNatural - just inline (relies on integerFromWord#) * [ ] integerToNaturalClamp - need cf for naturalFromBigNat#, naturalFromWord# * [ ] integerToNatural - need cf for naturalFromBigNat#, naturalFromWord# * [ ] integerToNaturalThrow - need cf for naturalFromWord#, naturalFromBigNat# * [x] integerEq# - need cf for bigNatEq# * [x] integerNe# - need cf for bigNatNe# * [x] integerGt#/Le/Lt/Ge - just inline (relies on integerCompare) * [x] integerCompare - merge integerCompare/Compare', just inline, need cf for bigNatCompare * [ ] integerSub - quite big, maybe split fast/slow path. need cf for bigNatSubWordUnsafe#, bigNatSubUnsafe, bigNatAdd, subIntC#, bigNatCompare, bigNatAddWord#... * [ ] integerAdd - ditto * [ ] integerMul - remove CPP (we always build with stage1 which is >= 8.11). maybe split. need cf for bigNatMul, bigNatMulWord#, timesInt2#... * [ ] integerNegate - need cf for bigNatFromWord#, bigNatEqWord# * [ ] integerAbs - just inline * [x] integerSignum[#] - just inline * [ ] integerPopCount# - need cf for popCntI#, bigNatPopCount# * [ ] integerBit# - need cf for bigNatBit# * [ ] integerTestBit# - put negative case in a noinline helper. need cf for bigNatTestBit# * [ ] integerShiftR# - need cf for bigNatShiftR#, bigNatShiftRNeg# * [ ] integerShiftL# - need cf for bigNatShiftL#, relies on integerBit# * [ ] integerOr - add helper integerOrInt#, split negative case?. need cf for bigNatOrWord#, bigNatAndNot, bigNatAddWord#, bigNatSub... * [ ] integerXor, integerAnd - ditto * [ ] integerComplement - need cf for bigNatAddWord#, bigNatSubWordUnsafe# * [ ] integerQuotRem# - need cf for bigNatQuotRemWord#, bigNatQuotRem#. Quite big... * [ ] integerQuot, integerRem - similar to integerQuotRem# * [ ] integerDivMod# - just inline, relies on integerSignum#, integerSub, integerAdd, integerQuotRem# * [ ] integerDiv - just inline, relies in integerQuot, integerDivMod# * [ ] integerMod - ditto, relies on integerRem * [ ] integerGcd - add integerGcdInt# helper to remove recursive call. need cf for bigNatGcd, bigNatGcdWord#, gcdWord#. Relies on integerAbs * [ ] integerLcm - inline, relies on integerAbs, integerQuot, integerGcd, integerMul * [ ] integerFromInt64#, integerFromWord64# - need cf for bigNatFromWord64# * [ ] integerToInt64#, integerToWord64# - need cf for bigNatToWord64# * [ ] integerEncodeDouble#, integerEncodeFloat# - why is that even here? put this in base with bigNatEncodeDouble# and intEncodeDouble#.