diff options
Diffstat (limited to 'compiler/GHC/Platform/Reg.hs')
| -rw-r--r-- | compiler/GHC/Platform/Reg.hs | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/compiler/GHC/Platform/Reg.hs b/compiler/GHC/Platform/Reg.hs index 5edd39df51..8203b9bbea 100644 --- a/compiler/GHC/Platform/Reg.hs +++ b/compiler/GHC/Platform/Reg.hs @@ -34,7 +34,6 @@ import GHC.Utils.Panic import GHC.Types.Unique import GHC.Builtin.Uniques import GHC.Platform.Reg.Class -import Data.List (intersect) -- | An identifier for a primitive real machine register. type RegNo @@ -173,8 +172,17 @@ regNosOfRealReg rr realRegsAlias :: RealReg -> RealReg -> Bool -realRegsAlias rr1 rr2 - = not $ null $ intersect (regNosOfRealReg rr1) (regNosOfRealReg rr2) +realRegsAlias rr1 rr2 = + -- used to be `not $ null $ intersect (regNosOfRealReg rr1) (regNosOfRealReg rr2)` + -- but that resulted in some gnarly, gnarly, allocating code. So we manually + -- write out all the cases which gives us nice non-allocating code. + case rr1 of + RealRegSingle r1 -> + case rr2 of RealRegPair r2 r3 -> r1 == r2 || r1 == r3 + RealRegSingle r2 -> r1 == r2 + RealRegPair r1 r2 -> + case rr2 of RealRegPair r3 r4 -> r1 == r3 || r1 == r4 || r2 == r3 || r2 == r4 + RealRegSingle r3 -> r1 == r3 || r2 == r3 -------------------------------------------------------------------------------- -- | A register, either virtual or real |