X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FcodeGen%2FStgCmmUtils.hs;h=558b7fdeaa82188ff88e59cc4671183fe160a3da;hp=ad9ebf175c37bb3d67b1eef9419761398d0c5cb5;hb=d9a655dad8e013e41c74dca98fb86c4ed6f29879;hpb=ee5addccd1929a7368a39b2c88d1b77f0bc8fb73

diff --git a/compiler/codeGen/StgCmmUtils.hs b/compiler/codeGen/StgCmmUtils.hs
index ad9ebf1..558b7fd 100644
--- a/compiler/codeGen/StgCmmUtils.hs
+++ b/compiler/codeGen/StgCmmUtils.hs
@@ -23,7 +23,7 @@ module StgCmmUtils (
         callerSaves, callerSaveVolatileRegs, get_GlobalReg_addr,
 
 	cmmAndWord, cmmOrWord, cmmNegate, cmmEqWord, cmmNeWord,
-        cmmUGtWord,
+        cmmUGtWord, cmmSubWord, cmmMulWord, cmmAddWord, cmmUShrWord,
 	cmmOffsetExprW, cmmOffsetExprB,
 	cmmRegOffW, cmmRegOffB,
 	cmmLabelOffW, cmmLabelOffB,
@@ -160,7 +160,8 @@ cmmLoadIndexW base off ty = CmmLoad (cmmOffsetW base off) ty
 
 -----------------------
 cmmULtWord, cmmUGeWord, cmmUGtWord, cmmSubWord,
-  cmmNeWord, cmmEqWord, cmmOrWord, cmmAndWord 
+  cmmNeWord, cmmEqWord, cmmOrWord, cmmAndWord,
+  cmmUShrWord, cmmAddWord, cmmMulWord
   :: CmmExpr -> CmmExpr -> CmmExpr
 cmmOrWord  e1 e2 = CmmMachOp mo_wordOr  [e1, e2]
 cmmAndWord e1 e2 = CmmMachOp mo_wordAnd [e1, e2]
@@ -170,8 +171,10 @@ cmmULtWord e1 e2 = CmmMachOp mo_wordULt [e1, e2]
 cmmUGeWord e1 e2 = CmmMachOp mo_wordUGe [e1, e2]
 cmmUGtWord e1 e2 = CmmMachOp mo_wordUGt [e1, e2]
 --cmmShlWord e1 e2 = CmmMachOp mo_wordShl [e1, e2]
---cmmUShrWord e1 e2 = CmmMachOp mo_wordUShr [e1, e2]
+cmmUShrWord e1 e2 = CmmMachOp mo_wordUShr [e1, e2]
+cmmAddWord e1 e2 = CmmMachOp mo_wordAdd [e1, e2]
 cmmSubWord e1 e2 = CmmMachOp mo_wordSub [e1, e2]
+cmmMulWord e1 e2 = CmmMachOp mo_wordMul [e1, e2]
 
 cmmNegate :: CmmExpr -> CmmExpr
 cmmNegate (CmmLit (CmmInt n rep)) = CmmLit (CmmInt (-n) rep)
@@ -340,22 +343,23 @@ emitRtsCall' res pkg fun args _vols safe
 --  * Regs.h claims that BaseReg should be saved last and loaded first
 --    * This might not have been tickled before since BaseReg is callee save
 --  * Regs.h saves SparkHd, ParkT1, SparkBase and SparkLim
--- EZY: This code is very dodgy, because callerSaves only ever
--- returns true in the current universe for registers NOT in
+--
+-- This code isn't actually used right now, because callerSaves
+-- only ever returns true in the current universe for registers NOT in
 -- system_regs (just do a grep for CALLER_SAVES in
--- includes/stg/MachRegs.h).  Thus, this is all one giant no-op.  What we are
--- actually interested in is saving are the non-system registers, which
--- we is what the old code generator actually does at this point.
--- Unfortunately, we can't do that here either, because we don't
--- liveness information, and thus there's not an easy way to tell which
--- specific global registers need to be saved (the 'vols' argument in
--- the old code generator.)  One possible hack is to save all of them
--- unconditionally, but unless we have very clever dead /memory/
--- elimination (unlikely), this will still leave a dead, unnecessary
--- memory assignment.  And really, we shouldn't be doing the workaround
--- at this point in the pipeline, see Note [Register parameter passing].
--- Right now the workaround is to avoid inlining across unsafe foreign
--- calls in rewriteAssignments.
+-- includes/stg/MachRegs.h).  It's all one giant no-op, and for
+-- good reason: having to save system registers on every foreign call
+-- would be very expensive, so we avoid assigning them to those
+-- registers when we add support for an architecture.
+--
+-- Note that the old code generator actually does more work here: it
+-- also saves other global registers.  We can't (nor want) to do that
+-- here, as we don't have liveness information.  And really, we
+-- shouldn't be doing the workaround at this point in the pipeline, see
+-- Note [Register parameter passing] and the ToDo on CmmCall in
+-- cmm/CmmNode.hs.  Right now the workaround is to avoid inlining across
+-- unsafe foreign calls in rewriteAssignments, but this is strictly
+-- temporary.
 callerSaveVolatileRegs :: (CmmAGraph, CmmAGraph)
 callerSaveVolatileRegs = (caller_save, caller_load)
   where
@@ -549,7 +553,13 @@ mkByteStringCLit bytes
 -------------------------------------------------------------------------
 
 assignTemp :: CmmExpr -> FCode LocalReg
--- Make sure the argument is in a local register
+-- Make sure the argument is in a local register.
+-- We don't bother being particularly aggressive with avoiding
+-- unnecessary local registers, since we can rely on a later
+-- optimization pass to inline as necessary (and skipping out
+-- on things like global registers can be a little dangerous
+-- due to them being trashed on foreign calls--though it means
+-- the optimization pass doesn't have to do as much work)
 assignTemp (CmmReg (CmmLocal reg)) = return reg
 assignTemp e = do { uniq <- newUnique
 		  ; let reg = LocalReg uniq (cmmExprType e)