From: uz Date: Sat, 15 Aug 2009 12:49:15 +0000 (+0000) Subject: Remove unnecessary transfer instructions. X-Git-Tag: V2.13.0rc1~244 X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=14f213cadbb8a1378a244fb021468f25bc70f1f7;p=cc65 Remove unnecessary transfer instructions. git-svn-id: svn://svn.cc65.org/cc65/trunk@4011 b7a2c559-68d2-44c3-8de9-860c34a00d81 --- diff --git a/src/cc65/codeopt.c b/src/cc65/codeopt.c index 18673ebbf..5ff833a19 100644 --- a/src/cc65/codeopt.c +++ b/src/cc65/codeopt.c @@ -1019,6 +1019,7 @@ static OptFunc DOptSub3 = { OptSub3, "OptSub3", 100, 0, static OptFunc DOptTest1 = { OptTest1, "OptTest1", 100, 0, 0, 0, 0, 0 }; static OptFunc DOptTransfers1 = { OptTransfers1, "OptTransfers1", 0, 0, 0, 0, 0, 0 }; static OptFunc DOptTransfers2 = { OptTransfers2, "OptTransfers2", 60, 0, 0, 0, 0, 0 }; +static OptFunc DOptTransfers3 = { OptTransfers3, "OptTransfers3", 65, 0, 0, 0, 0, 0 }; static OptFunc DOptUnusedLoads = { OptUnusedLoads, "OptUnusedLoads", 0, 0, 0, 0, 0, 0 }; static OptFunc DOptUnusedStores = { OptUnusedStores, "OptUnusedStores", 0, 0, 0, 0, 0, 0 }; @@ -1095,6 +1096,7 @@ static OptFunc* OptFuncs[] = { &DOptTest1, &DOptTransfers1, &DOptTransfers2, + &DOptTransfers3, &DOptUnusedLoads, &DOptUnusedStores, }; @@ -1425,6 +1427,7 @@ static unsigned RunOptGroup3 (CodeSeg* S) C += RunOptFunc (S, &DOptDupLoads, 1); C += RunOptFunc (S, &DOptStoreLoad, 1); C += RunOptFunc (S, &DOptTransfers1, 1); + C += RunOptFunc (S, &DOptTransfers3, 1); C += RunOptFunc (S, &DOptStore1, 1); C += RunOptFunc (S, &DOptStore5, 1); C += RunOptFunc (S, &DOptPushPop, 1); diff --git a/src/cc65/coptind.c b/src/cc65/coptind.c index e72f6c28d..abcb9b142 100644 --- a/src/cc65/coptind.c +++ b/src/cc65/coptind.c @@ -6,8 +6,8 @@ /* */ /* */ /* */ -/* (C) 2001-2005, Ullrich von Bassewitz */ -/* Römerstraße 52 */ +/* (C) 2001-2009, Ullrich von Bassewitz */ +/* Roemerstrasse 52 */ /* D-70794 Filderstadt */ /* EMail: uz@cc65.org */ /* */ @@ -1234,6 +1234,169 @@ unsigned OptTransfers2 (CodeSeg* S) +unsigned OptTransfers3 (CodeSeg* S) +/* Replace a register transfer followed by a store of the second register by a + * store of the first register if this is possible. + */ +{ + unsigned Changes = 0; + unsigned Xfer = 0; /* Index of transfer insn */ + unsigned Store = 0; /* Index of store insn */ + CodeEntry* XferEntry = 0; /* Pointer to xfer insn */ + CodeEntry* StoreEntry = 0; /* Pointer to store insn */ + + enum { + Searching, + FoundXfer, + FoundStore + } State = Searching; + + /* Walk over the entries. Look for a xfer instruction that is followed by + * a store later, where the value of the register is not used later. + */ + unsigned I = 0; + while (I < CS_GetEntryCount (S)) { + + /* Get next entry */ + CodeEntry* E = CS_GetEntry (S, I); + + switch (State) { + + case Searching: + if (E->Info & OF_XFR) { + /* Found start of sequence */ + Xfer = I; + XferEntry = E; + State = FoundXfer; + } + break; + + case FoundXfer: + /* If we find a conditional jump, abort the sequence, since + * handling them makes things really complicated. + */ + if (E->Info & OF_CBRA) { + + /* Switch back to searching */ + I = Xfer; + State = Searching; + + /* Does this insn use the target register of the transfer? */ + } else if ((E->Use & XferEntry->Chg) != 0) { + + /* It it's a store instruction, and the block is a basic + * block, proceed. Otherwise restart + */ + if ((E->Info & OF_STORE) != 0 && + CS_IsBasicBlock (S, Xfer, I)) { + Store = I; + StoreEntry = E; + State = FoundStore; + } else { + I = Xfer; + State = Searching; + } + + /* Does this insn change the target register of the transfer? */ + } else if (E->Chg & XferEntry->Chg) { + + /* We *may* add code here to remove the transfer, but I'm + * currently not sure about the consequences, so I won't + * do that and bail out instead. + */ + I = Xfer; + State = Searching; + } + break; + + case FoundStore: + /* We are at the instruction behind the store. If the register + * isn't used later, and we have an address mode match, we can + * replace the transfer by a store and remove the store here. + */ + if ((GetRegInfo (S, I, XferEntry->Chg) & XferEntry->Chg) == 0 && + (StoreEntry->AM == AM65_ABS || StoreEntry->AM == AM65_ZP) && + !MemAccess (S, Xfer+1, Store-1, E->Arg)) { + + /* Generate the replacement store insn */ + CodeEntry* X = 0; + switch (XferEntry->OPC) { + + case OP65_TXA: + X = NewCodeEntry (OP65_STX, + StoreEntry->AM, + StoreEntry->Arg, + 0, + StoreEntry->LI); + break; + + case OP65_TAX: + X = NewCodeEntry (OP65_STA, + StoreEntry->AM, + StoreEntry->Arg, + 0, + StoreEntry->LI); + break; + + case OP65_TYA: + X = NewCodeEntry (OP65_STY, + StoreEntry->AM, + StoreEntry->Arg, + 0, + StoreEntry->LI); + break; + + case OP65_TAY: + X = NewCodeEntry (OP65_STA, + StoreEntry->AM, + StoreEntry->Arg, + 0, + StoreEntry->LI); + break; + + default: + break; + } + + /* If we have a replacement store, change the code */ + if (X) { + /* Insert before the xfer insn */ + CS_InsertEntry (S, X, Xfer); + + /* Remove the xfer instead */ + CS_DelEntry (S, Xfer+1); + + /* Remove the final store */ + CS_DelEntry (S, Store); + + /* Correct I so we continue with the next insn */ + I -= 2; + + /* Remember we had changes */ + ++Changes; + } else { + /* Restart after last xfer insn */ + I = Xfer; + } + } else { + /* Restart after last xfer insn */ + I = Xfer; + } + State = Searching; + break; + + } + + /* Next entry */ + ++I; + } + + /* Return the number of changes made */ + return Changes; +} + + + unsigned OptPushPop (CodeSeg* S) /* Remove a PHA/PLA sequence were A is not used later */ { @@ -1315,6 +1478,9 @@ unsigned OptPushPop (CodeSeg* S) /* Remove the PLA/STA sequence */ CS_DelEntries (S, Pop, 2); + /* Correct I so we continue with the next insn */ + I -= 2; + /* Remember we had changes */ ++Changes; @@ -1324,8 +1490,10 @@ unsigned OptPushPop (CodeSeg* S) /* We can remove the PHA and PLA instructions */ CS_DelEntry (S, Pop); CS_DelEntry (S, Push); + /* Correct I so we continue with the next insn */ I -= 2; + /* Remember we had changes */ ++Changes; diff --git a/src/cc65/coptind.h b/src/cc65/coptind.h index ae72b1fbb..089499a94 100644 --- a/src/cc65/coptind.h +++ b/src/cc65/coptind.h @@ -6,10 +6,10 @@ /* */ /* */ /* */ -/* (C) 2001-2003 Ullrich von Bassewitz */ -/* Römerstrasse 52 */ -/* D-70794 Filderstadt */ -/* EMail: uz@cc65.org */ +/* (C) 2001-2009, Ullrich von Bassewitz */ +/* Roemerstrasse 52 */ +/* D-70794 Filderstadt */ +/* EMail: uz@cc65.org */ /* */ /* */ /* This software is provided 'as-is', without any expressed or implied */ @@ -110,6 +110,11 @@ unsigned OptTransfers2 (CodeSeg* S); * register if possible. */ +unsigned OptTransfers3 (CodeSeg* S); +/* Replace a register transfer followed by a store of the second register by a + * store of the first register if this is possible. + */ + unsigned OptPushPop (CodeSeg* S); /* Remove a PHA/PLA sequence were A is not used later */