Compile-time computations
$ cat Reduce3.hs
module Reduce3
where
foo = 1 + 2
$ cat Reduce4.hs
module Reduce4
where
foo = 3
$ ghc -c -O2 -fforce-recomp -ddump-simpl Reduce3.hs
==================== Tidy Core ====================
Reduce3.lvl :: GHC.Num.Integer
[GlobalId]
[NoCafRefs]
Reduce3.lvl = GHC.Num.S# 1
Reduce3.lvl1 :: GHC.Num.Integer
[GlobalId]
[NoCafRefs]
Reduce3.lvl1 = GHC.Num.S# 2
Reduce3.foo :: GHC.Num.Integer
[GlobalId]
[Str: DmdType]
Reduce3.foo = GHC.Num.plusInteger Reduce3.lvl Reduce3.lvl1
==================== Tidy Core Rules ====================
$ ghc -c -O2 -fforce-recomp -ddump-simpl Reduce4.hs
==================== Tidy Core ====================
Reduce4.foo :: GHC.Num.Integer
[GlobalId]
[NoCafRefs
Str: DmdType]
Reduce4.foo = GHC.Num.S# 3
==================== Tidy Core Rules ====================
It would be nice if GHC could do the addition at compile time (since, after all, the result will always be the same) instead of at runtime.
Trac metadata
Trac field | Value |
---|---|
Version | 6.8.2 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | Unknown |
Architecture | Unknown |