From c9629e9f5e4957c8665fc2497b5e769b769cb7d3 Mon Sep 17 00:00:00 2001 From: Simon Marlow Date: Thu, 10 Feb 2011 11:56:08 +0000 Subject: [PATCH] constant fold (a + N) - M and (a - N) + M --- compiler/cmm/CmmOpt.hs | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/compiler/cmm/CmmOpt.hs b/compiler/cmm/CmmOpt.hs index 0e35cc1..df0555f 100644 --- a/compiler/cmm/CmmOpt.hs +++ b/compiler/cmm/CmmOpt.hs @@ -306,9 +306,18 @@ cmmMachOpFold op [x@(CmmLit _), y] -- PicBaseReg from the corresponding label (or label difference). -- cmmMachOpFold mop1 [CmmMachOp mop2 [arg1,arg2], arg3] - | mop1 == mop2 && isAssociativeMachOp mop1 + | mop2 `associates_with` mop1 && not (isLit arg1) && not (isPicReg arg1) - = cmmMachOpFold mop1 [arg1, cmmMachOpFold mop2 [arg2,arg3]] + = cmmMachOpFold mop2 [arg1, cmmMachOpFold mop1 [arg2,arg3]] + where + MO_Add{} `associates_with` MO_Sub{} = True + mop1 `associates_with` mop2 = + mop1 == mop2 && isAssociativeMachOp mop1 + +-- special case: (a - b) + c ==> a + (c - b) +cmmMachOpFold mop1@(MO_Add{}) [CmmMachOp mop2@(MO_Sub{}) [arg1,arg2], arg3] + | not (isLit arg1) && not (isPicReg arg1) + = cmmMachOpFold mop1 [arg1, cmmMachOpFold mop2 [arg3,arg2]] -- Make a RegOff if we can cmmMachOpFold (MO_Add _) [CmmReg reg, CmmLit (CmmInt n rep)] -- 1.7.10.4