X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=src%2Fcc65%2Fcoptind.c;h=80d6c772c65a56647da04e0bc68c03f65915e487;hb=c2b03e02088d2d459ababaef366ae73a6ab8adf4;hp=f4bdecbb126f5cb817bcdf0a1a987bd572427426;hpb=c7490cf060e914ca03cf6586d3ec0c29d4cbe290;p=cc65 diff --git a/src/cc65/coptind.c b/src/cc65/coptind.c index f4bdecbb1..80d6c772c 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 */ /* */ @@ -38,10 +38,10 @@ /* cc65 */ #include "codeent.h" +#include "coptind.h" #include "codeinfo.h" #include "codeopt.h" #include "error.h" -#include "coptind.h" @@ -51,6 +51,79 @@ +static int MemAccess (CodeSeg* S, unsigned From, unsigned To, const CodeEntry* N) +/* Checks a range of code entries if there are any memory accesses to N->Arg */ +{ + /* Get the length of the argument */ + unsigned NLen = strlen (N->Arg); + + /* What to check for? */ + enum { + None = 0x00, + Base = 0x01, /* Check for location without "+1" */ + Word = 0x02, /* Check for location with "+1" added */ + } What = None; + + + /* If the argument of N is a zero page location that ends with "+1", we + * must also check for word accesses to the location without +1. + */ + if (N->AM == AM65_ZP && NLen > 2 && strcmp (N->Arg + NLen - 2, "+1") == 0) { + What |= Base; + } + + /* If the argument is zero page indirect, we must also check for accesses + * to "arg+1" + */ + if (N->AM == AM65_ZP_INDY || N->AM == AM65_ZPX_IND || N->AM == AM65_ZP_IND) { + What |= Word; + } + + /* Walk over all code entries */ + while (From <= To) { + + /* Get the next entry */ + CodeEntry* E = CS_GetEntry (S, From); + + /* Check if there is an argument and if this argument equals Arg in + * some variants. + */ + if (E->Arg[0] != '\0') { + + unsigned ELen; + + if (strcmp (E->Arg, N->Arg) == 0) { + /* Found an access */ + return 1; + } + + ELen = strlen (E->Arg); + if ((What & Base) != 0) { + if (ELen == NLen - 2 && strncmp (E->Arg, N->Arg, NLen-2) == 0) { + /* Found an access */ + return 1; + } + } + + if ((What & Word) != 0) { + if (ELen == NLen + 2 && strncmp (E->Arg, N->Arg, NLen) == 0 && + E->Arg[NLen] == '+' && E->Arg[NLen+1] == '1') { + /* Found an access */ + return 1; + } + } + } + + /* Next entry */ + ++From; + } + + /* Nothing found */ + return 0; +} + + + static int GetBranchDist (CodeSeg* S, unsigned From, CodeEntry* To) /* Get the branch distance between the two entries and return it. The distance * will be negative for backward jumps and positive for forward jumps. @@ -406,17 +479,12 @@ unsigned OptJumpCascades (CodeSeg* S) /* Remember, we had changes */ ++Changes; - /* Done */ - continue; - - } - /* Check if both are conditional branches, and the condition of * the second is the inverse of that of the first. In this case, * the second branch will never be taken, and we may jump directly * to the instruction behind this one. */ - if ((E->Info & OF_CBRA) != 0 && (N->Info & OF_CBRA) != 0) { + } else if ((E->Info & OF_CBRA) != 0 && (N->Info & OF_CBRA) != 0) { CodeEntry* X; /* Instruction behind N */ CodeLabel* LX; /* Label attached to X */ @@ -447,10 +515,6 @@ unsigned OptJumpCascades (CodeSeg* S) /* Remember, we had changes */ ++Changes; - - /* Done */ - continue; - } } @@ -520,7 +584,7 @@ unsigned OptRTS (CodeSeg* S) -unsigned OptJumpTarget (CodeSeg* S) +unsigned OptJumpTarget1 (CodeSeg* S) /* If the instruction preceeding an unconditional branch is the same as the * instruction preceeding the jump target, the jump target may be moved * one entry back. This is a size optimization, since the instruction before @@ -540,12 +604,13 @@ unsigned OptJumpTarget (CodeSeg* S) /* Get next entry */ E2 = CS_GetNextEntry (S, I); - /* Check if we have a jump or branch, and a matching label, which - * is not attached to the jump itself + /* Check if we have a jump or branch without a label attached, and + * a jump target, which is not attached to the jump itself */ - if (E2 != 0 && + if (E2 != 0 && (E2->Info & OF_UBRA) != 0 && - E2->JumpTo && + !CE_HasLabel (E2) && + E2->JumpTo && E2->JumpTo->Owner != E2) { /* Get the entry preceeding the branch target */ @@ -555,6 +620,13 @@ unsigned OptJumpTarget (CodeSeg* S) goto NextEntry; } + /* The entry preceeding the branch target may not be the branch + * insn. + */ + if (T1 == E2) { + goto NextEntry; + } + /* Get the entry preceeding the jump */ E1 = CS_GetEntry (S, I); @@ -599,13 +671,166 @@ NextEntry: +unsigned OptJumpTarget2 (CodeSeg* S) +/* If a bcs jumps to a sec insn or a bcc jumps to clc, skip this insn, since + * it's job is already done. + */ +{ + unsigned Changes = 0; + + /* Walk over the entries */ + unsigned I = 0; + while (I < CS_GetEntryCount (S)) { + + /* OP that may be skipped */ + opc_t OPC; + + /* Jump target insn, old and new */ + CodeEntry* T; + CodeEntry* N; + + /* New jump label */ + CodeLabel* L; + + /* Get next entry */ + CodeEntry* E = CS_GetEntry (S, I); + + /* Check if this is a bcc insn */ + if (E->OPC == OP65_BCC || E->OPC == OP65_JCC) { + OPC = OP65_CLC; + } else if (E->OPC == OP65_BCS || E->OPC == OP65_JCS) { + OPC = OP65_SEC; + } else { + /* Not what we're looking for */ + goto NextEntry; + } + + /* Must have a jump target */ + if (E->JumpTo == 0) { + goto NextEntry; + } + + /* Get the owner insn of the jump target and check if it's the one, we + * will skip if present. + */ + T = E->JumpTo->Owner; + if (T->OPC != OPC) { + goto NextEntry; + } + + /* Get the entry following the branch target */ + N = CS_GetNextEntry (S, CS_GetEntryIndex (S, T)); + if (N == 0) { + /* There is no such entry */ + goto NextEntry; + } + + /* Get the label for the instruction following the jump target. + * This routine will create a new label if the instruction does + * not already have one. + */ + L = CS_GenLabel (S, N); + + /* Change the jump target to point to this new label */ + CS_MoveLabelRef (S, E, L); + + /* Remember that we had changes */ + ++Changes; + +NextEntry: + /* Next entry */ + ++I; + } + + /* Return the number of changes made */ + return Changes; +} + + + +unsigned OptJumpTarget3 (CodeSeg* S) +/* Jumps to load instructions of a register, that do already have the matching + * register contents may skip the load instruction, since it's job is already + * done. + */ +{ + unsigned Changes = 0; + unsigned I; + + /* Generate register info for this step */ + CS_GenRegInfo (S); + + /* Walk over the entries */ + I = 0; + while (I < CS_GetEntryCount (S)) { + + unsigned J, K; + CodeEntry* N; + + /* New jump label */ + CodeLabel* LN = 0; + + /* Get next entry */ + CodeEntry* E = CS_GetEntry (S, I); + + /* Check if this is a load insn with a label */ + if ((E->Info & OF_LOAD) != 0 && + CE_IsConstImm (E) && + CE_HasLabel (E) && + (N = CS_GetNextEntry (S, I)) != 0) { + + /* Walk over all insn that jump here */ + for (J = 0; J < CE_GetLabelCount (E); ++J) { + + /* Get the label */ + CodeLabel* L = CE_GetLabel (E, J); + for (K = 0; K < CL_GetRefCount (L); ++K) { + + /* Get the entry that jumps here */ + CodeEntry* Jump = CL_GetRef (L, K); + + /* Get the register info from this insn */ + short Val = RegVal (E->Chg, &Jump->RI->Out2); + + /* Check if the outgoing value is the one thatr's loaded */ + if (Val == (unsigned char) E->Num) { + + /* Ok, skip the insn. First, generate a label */ + if (LN == 0) { + LN = CS_GenLabel (S, N); + } + + /* Change the jump target to point to this new label */ + CS_MoveLabelRef (S, Jump, LN); + + /* Remember that we had changes */ + ++Changes; + } + } + } + + } + + /* Next entry */ + ++I; + } + + /* Free register info */ + CS_FreeRegInfo (S); + + /* Return the number of changes made */ + return Changes; +} + + + /*****************************************************************************/ /* Optimize conditional branches */ /*****************************************************************************/ -unsigned OptCondBranches (CodeSeg* S) +unsigned OptCondBranches1 (CodeSeg* S) /* Performs several optimization steps: * * - If an immidiate load of a register is followed by a conditional jump that @@ -651,7 +876,7 @@ unsigned OptCondBranches (CodeSeg* S) CS_DelEntry (S, I+1); /* Remember, we had changes */ - ++Changes; + ++Changes; } else if ((BC == BC_EQ && E->Num == 0) || (BC == BC_NE && E->Num != 0) || @@ -668,7 +893,7 @@ unsigned OptCondBranches (CodeSeg* S) } if ((E->Info & OF_CBRA) != 0 && /* It's a conditional branch */ - (L = E->JumpTo) != 0 && /* ..referencing a local label */ + (L = E->JumpTo) != 0 && /* ..referencing a local label */ (N = CS_GetNextEntry (S, I)) != 0 && /* There is a following entry */ (N->Info & OF_UBRA) != 0 && /* ..which is an uncond branch, */ !CE_HasLabel (N) && /* ..has no label attached */ @@ -698,6 +923,62 @@ unsigned OptCondBranches (CodeSeg* S) +unsigned OptCondBranches2 (CodeSeg* S) +/* If on entry to a "rol a" instruction the accu is zero, and a beq/bne follows, + * we can remove the rol and branch on the state of the carry flag. + */ +{ + unsigned Changes = 0; + unsigned I; + + /* Generate register info for this step */ + CS_GenRegInfo (S); + + /* Walk over the entries */ + I = 0; + while (I < CS_GetEntryCount (S)) { + + CodeEntry* N; + + /* Get next entry */ + CodeEntry* E = CS_GetEntry (S, I); + + /* Check if it's a rol insn with A in accu and a branch follows */ + if (E->OPC == OP65_ROL && + E->AM == AM65_ACC && + E->RI->In.RegA == 0 && + !CE_HasLabel (E) && + (N = CS_GetNextEntry (S, I)) != 0 && + (N->Info & OF_ZBRA) != 0 && + !RegAUsed (S, I+1)) { + + /* Replace the branch condition */ + switch (GetBranchCond (N->OPC)) { + case BC_EQ: CE_ReplaceOPC (N, OP65_JCC); break; + case BC_NE: CE_ReplaceOPC (N, OP65_JCS); break; + default: Internal ("Unknown branch condition in OptCondBranches2"); + } + + /* Delete the rol insn */ + CS_DelEntry (S, I); + + /* Remember, we had changes */ + ++Changes; + } + + /* Next entry */ + ++I; + } + + /* Free register info */ + CS_FreeRegInfo (S); + + /* Return the number of changes made */ + return Changes; +} + + + /*****************************************************************************/ /* Remove unused loads and stores */ /*****************************************************************************/ @@ -726,17 +1007,17 @@ unsigned OptUnusedLoads (CodeSeg* S) /* Check which sort of load or transfer it is */ unsigned R; switch (E->OPC) { - case OP65_DEA: - case OP65_INA: - case OP65_LDA: + case OP65_DEA: + case OP65_INA: + case OP65_LDA: case OP65_TXA: case OP65_TYA: R = REG_A; break; - case OP65_DEX: - case OP65_INX: - case OP65_LDX: + case OP65_DEX: + case OP65_INX: + case OP65_LDX: case OP65_TAX: R = REG_X; break; - case OP65_DEY: - case OP65_INY: + case OP65_DEY: + case OP65_INY: case OP65_LDY: case OP65_TAY: R = REG_Y; break; default: goto NextEntry; /* OOPS */ @@ -746,11 +1027,11 @@ unsigned OptUnusedLoads (CodeSeg* S) if ((GetRegInfo (S, I+1, R) & R) == 0) { /* Register value is not used, remove the load */ - CS_DelEntry (S, I); + CS_DelEntry (S, I); - /* Remember, we had changes. Account the deleted entry in I. */ - ++Changes; - --I; + /* Remember, we had changes. Account the deleted entry in I. */ + ++Changes; + --I; } } @@ -798,6 +1079,8 @@ unsigned OptUnusedStores (CodeSeg* S) /* Remember, we had changes */ ++Changes; + /* Continue with next insn */ + continue; } } @@ -867,12 +1150,12 @@ unsigned OptDupLoads (CodeSeg* S) break; case OP65_STA: - /* If we store into a known zero page location, and this + /* If we store into a known zero page location, and this * location does already contain the value to be stored, * remove the store. */ if (RegValIsKnown (In->RegA) && /* Value of A is known */ - E->AM == AM65_ZP && /* Store into zp */ + E->AM == AM65_ZP && /* Store into zp */ In->RegA == ZPRegVal (E->Chg, In)) { /* Value identical */ Delete = 1; @@ -900,7 +1183,7 @@ unsigned OptDupLoads (CodeSeg* S) In->RegX == In->RegA && E->AM != AM65_ABSY && E->AM != AM65_ZPY) { - /* Use the A register instead */ + /* Use the A register instead */ CE_ReplaceOPC (E, OP65_STA); } break; @@ -920,12 +1203,12 @@ unsigned OptDupLoads (CodeSeg* S) * that in the A register, replace the store by a STA. The * optimizer will then remove the load instruction for Y * later. If replacement by A is not possible try a - * replacement by X, but check for invalid addressing modes + * replacement by X, but check for invalid addressing modes * in this case. */ } else if (RegValIsKnown (In->RegY)) { if (In->RegY == In->RegA) { - CE_ReplaceOPC (E, OP65_STA); + CE_ReplaceOPC (E, OP65_STA); } else if (In->RegY == In->RegX && E->AM != AM65_ABSX && E->AM != AM65_ZPX) { @@ -953,7 +1236,7 @@ unsigned OptDupLoads (CodeSeg* S) !CE_UseLoadFlags (N)) { /* Value is identical and not followed by a branch */ Delete = 1; - } + } break; case OP65_TAY: @@ -973,39 +1256,39 @@ unsigned OptDupLoads (CodeSeg* S) !CE_UseLoadFlags (N)) { /* Value is identical and not followed by a branch */ Delete = 1; - } - break; + } + break; - case OP65_TYA: + case OP65_TYA: if (RegValIsKnown (In->RegY) && - In->RegY == In->RegA && - (N = CS_GetNextEntry (S, I)) != 0 && + In->RegY == In->RegA && + (N = CS_GetNextEntry (S, I)) != 0 && !CE_UseLoadFlags (N)) { - /* Value is identical and not followed by a branch */ - Delete = 1; - } - break; + /* Value is identical and not followed by a branch */ + Delete = 1; + } + break; - default: - break; + default: + break; - } + } - /* Delete the entry if requested */ - if (Delete) { + /* Delete the entry if requested */ + if (Delete) { - /* Register value is not used, remove the load */ - CS_DelEntry (S, I); + /* Register value is not used, remove the load */ + CS_DelEntry (S, I); - /* Remember, we had changes */ - ++Changes; + /* Remember, we had changes */ + ++Changes; - } else { + } else { - /* Next entry */ - ++I; + /* Next entry */ + ++I; - } + } } @@ -1027,10 +1310,10 @@ unsigned OptStoreLoad (CodeSeg* S) unsigned I = 0; while (I < CS_GetEntryCount (S)) { - CodeEntry* N; - CodeEntry* X; + CodeEntry* N; + CodeEntry* X; - /* Get next entry */ + /* Get next entry */ CodeEntry* E = CS_GetEntry (S, I); /* Check if it is a store instruction followed by a load from the @@ -1105,7 +1388,7 @@ unsigned OptTransfers1 (CodeSeg* S) if (I == 0) { /* No preceeding entry */ goto NextEntry; - } + } P = CS_GetEntry (S, I-1); if ((P->Info & OF_SETF) == 0) { /* Does not set the flags */ @@ -1210,12 +1493,355 @@ 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 UsedRegs = REG_NONE; /* Track used registers */ + 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 { + Initialize, + Search, + FoundXfer, + FoundStore + } State = Initialize; + + /* 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 Initialize: + /* Clear the list of used registers */ + UsedRegs = REG_NONE; + /* FALLTHROUGH */ + + case Search: + 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 = Initialize; + + /* 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 = Initialize; + } + + /* 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 = Initialize; + + /* Does this insn have a label? */ + } else if (CE_HasLabel (E)) { + + /* Too complex to handle - bail out */ + I = Xfer; + State = Initialize; + + } else { + /* Track used registers */ + UsedRegs |= E->Use; + } + 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) && + (StoreEntry->AM != AM65_ZP || + (StoreEntry->Chg & UsedRegs) == 0) && + !MemAccess (S, Xfer+1, Store-1, StoreEntry)) { + + /* 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 after the xfer insn */ + CS_InsertEntry (S, X, Xfer+1); + + /* Remove the xfer instead */ + CS_DelEntry (S, Xfer); + + /* 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 = Initialize; + break; + + } + + /* Next entry */ + ++I; + } + + /* Return the number of changes made */ + return Changes; +} + + + +unsigned OptTransfers4 (CodeSeg* S) +/* Replace a load of a register followed by a transfer insn of the same register + * by a load of the second register if possible. + */ +{ + unsigned Changes = 0; + unsigned Load = 0; /* Index of load insn */ + unsigned Xfer = 0; /* Index of transfer insn */ + CodeEntry* LoadEntry = 0; /* Pointer to load insn */ + CodeEntry* XferEntry = 0; /* Pointer to xfer insn */ + + enum { + Search, + FoundLoad, + FoundXfer + } State = Search; + + /* Walk over the entries. Look for a load instruction that is followed by + * a load later. + */ + unsigned I = 0; + while (I < CS_GetEntryCount (S)) { + + /* Get next entry */ + CodeEntry* E = CS_GetEntry (S, I); + + switch (State) { + + case Search: + if (E->Info & OF_LOAD) { + /* Found start of sequence */ + Load = I; + LoadEntry = E; + State = FoundLoad; + } + break; + + case FoundLoad: + /* 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 = Load; + State = Search; + + /* Does this insn use the target register of the load? */ + } else if ((E->Use & LoadEntry->Chg) != 0) { + + /* It it's a xfer instruction, and the block is a basic + * block, proceed. Otherwise restart + */ + if ((E->Info & OF_XFR) != 0 && + CS_IsBasicBlock (S, Load, I)) { + Xfer = I; + XferEntry = E; + State = FoundXfer; + } else { + I = Load; + State = Search; + } + + /* Does this insn change the target register of the load? */ + } else if (E->Chg & LoadEntry->Chg) { + + /* We *may* add code here to remove the load, but I'm + * currently not sure about the consequences, so I won't + * do that and bail out instead. + */ + I = Load; + State = Search; + } + break; + + case FoundXfer: + /* We are at the instruction behind the xfer. If the register + * isn't used later, and we have an address mode match, we can + * replace the transfer by a load and remove the initial load. + */ + if ((GetRegInfo (S, I, LoadEntry->Chg) & LoadEntry->Chg) == 0 && + (LoadEntry->AM == AM65_ABS || + LoadEntry->AM == AM65_ZP || + LoadEntry->AM == AM65_IMM) && + !MemAccess (S, Load+1, Xfer-1, LoadEntry)) { + + /* Generate the replacement load insn */ + CodeEntry* X = 0; + switch (XferEntry->OPC) { + + case OP65_TXA: + case OP65_TYA: + X = NewCodeEntry (OP65_LDA, + LoadEntry->AM, + LoadEntry->Arg, + 0, + LoadEntry->LI); + break; + + case OP65_TAX: + X = NewCodeEntry (OP65_LDX, + LoadEntry->AM, + LoadEntry->Arg, + 0, + LoadEntry->LI); + break; + + case OP65_TAY: + X = NewCodeEntry (OP65_LDY, + LoadEntry->AM, + LoadEntry->Arg, + 0, + LoadEntry->LI); + break; + + default: + break; + } + + /* If we have a replacement load, change the code */ + if (X) { + /* Insert after the xfer insn */ + CS_InsertEntry (S, X, Xfer+1); + + /* Remove the xfer instead */ + CS_DelEntry (S, Xfer); + + /* Remove the initial load */ + CS_DelEntry (S, Load); + + /* 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 = Search; + 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 */ { unsigned Changes = 0; unsigned Push = 0; /* Index of push insn */ unsigned Pop = 0; /* Index of pop insn */ + unsigned ChgA = 0; /* Flag for A changed */ enum { Searching, FoundPush, @@ -1234,6 +1860,8 @@ unsigned OptPushPop (CodeSeg* S) unsigned I = 0; while (I < CS_GetEntryCount (S)) { + CodeEntry* X; + /* Get next entry */ CodeEntry* E = CS_GetEntry (S, I); @@ -1243,6 +1871,7 @@ unsigned OptPushPop (CodeSeg* S) if (E->OPC == OP65_PHA) { /* Found start of sequence */ Push = I; + ChgA = 0; State = FoundPush; } break; @@ -1251,29 +1880,67 @@ unsigned OptPushPop (CodeSeg* S) if (E->OPC == OP65_PHA) { /* Inner push/pop, restart */ Push = I; + ChgA = 0; } else if (E->OPC == OP65_PLA) { /* Found a matching pop */ Pop = I; - State = FoundPop; + /* Check that the block between Push and Pop is a basic + * block (one entry, one exit). Otherwise ignore it. + */ + if (CS_IsBasicBlock (S, Push, Pop)) { + State = FoundPop; + } else { + /* Go into searching mode again */ + State = Searching; + } + } else if (E->Chg & REG_A) { + ChgA = 1; } break; case FoundPop: - /* Next insn, just check if it is no conditional branch and - * that A is not used later. Check also that the range we have - * found now is a basic block, which means that the PHA is the - * only entrance and the PLA the only exit. + /* We're at the instruction after the PLA. + * Check for the following conditions: + * - If this instruction is a store of A, and A is not used + * later, we may replace the PHA by the store and remove + * pla if several other conditions are met. + * - If this instruction is not a conditional branch, and A + * is either unused later, or not changed by the code + * between push and pop, we may remove PHA and PLA. */ - if ((E->Info & OF_CBRA) == 0 && - !RegAUsed (S, I) && - CS_IsBasicBlock (S, Push, Pop)) { + if (E->OPC == OP65_STA && + !RegAUsed (S, I+1) && + !MemAccess (S, Push+1, Pop-1, E)) { + + /* Insert a STA after the PHA */ + X = NewCodeEntry (E->OPC, E->AM, E->Arg, E->JumpTo, E->LI); + CS_InsertEntry (S, X, Push+1); + + /* Remove the PHA instead */ + CS_DelEntry (S, Push); + + /* 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; + + } else if ((E->Info & OF_CBRA) == 0 && + (!RegAUsed (S, I) || !ChgA)) { + /* 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; + } /* Go into search mode again */ State = Searching; @@ -1309,11 +1976,13 @@ unsigned OptPrecalc (CodeSeg* S) /* Get next entry */ CodeEntry* E = CS_GetEntry (S, I); - /* Get a pointer to the output registers of the insn */ + /* Get pointers to the input and output registers of the insn */ const RegContents* Out = &E->RI->Out; + const RegContents* In = &E->RI->In; - /* Argument for LDA and flag */ + /* Argument for LDn and flag */ const char* Arg = 0; + opc_t OPC = OP65_LDA; /* Handle the different instructions */ switch (E->OPC) { @@ -1327,37 +1996,57 @@ unsigned OptPrecalc (CodeSeg* S) case OP65_LDX: if (E->AM != AM65_IMM && RegValIsKnown (Out->RegX)) { - /* Result of load is known */ + /* Result of load is known but register is X */ Arg = MakeHexArg (Out->RegX); + OPC = OP65_LDX; } break; case OP65_LDY: if (E->AM != AM65_IMM && RegValIsKnown (Out->RegY)) { - /* Result of load is known */ + /* Result of load is known but register is Y */ Arg = MakeHexArg (Out->RegY); + OPC = OP65_LDY; } break; - case OP65_ADC: - case OP65_ASL: case OP65_EOR: - case OP65_LSR: - case OP65_SBC: if (RegValIsKnown (Out->RegA)) { /* Accu op zp with known contents */ Arg = MakeHexArg (Out->RegA); } break; + case OP65_ADC: + case OP65_SBC: + /* If this is an operation with an immediate operand of zero, + * and the register is zero, the operation won't give us any + * results we don't already have (including the flags), so + * remove it. Something like this is generated as a result of + * a compare where parts of the values are known to be zero. + */ + if (In->RegA == 0 && CE_IsKnownImm (E, 0x00)) { + /* 0-0 or 0+0 -> remove */ + CS_DelEntry (S, I); + ++Changes; + } + break; + case OP65_AND: if (CE_IsKnownImm (E, 0xFF)) { /* AND with 0xFF, remove */ CS_DelEntry (S, I); ++Changes; + } else if (CE_IsKnownImm (E, 0x00)) { + /* AND with 0x00, replace by lda #$00 */ + Arg = MakeHexArg (0x00); } else if (RegValIsKnown (Out->RegA)) { /* Accu AND zp with known contents */ Arg = MakeHexArg (Out->RegA); + } else if (In->RegA == 0xFF) { + /* AND but A contains 0xFF - replace by lda */ + CE_ReplaceOPC (E, OP65_LDA); + ++Changes; } break; @@ -1366,9 +2055,16 @@ unsigned OptPrecalc (CodeSeg* S) /* ORA with zero, remove */ CS_DelEntry (S, I); ++Changes; + } else if (CE_IsKnownImm (E, 0xFF)) { + /* ORA with 0xFF, replace by lda #$ff */ + Arg = MakeHexArg (0xFF); } else if (RegValIsKnown (Out->RegA)) { /* Accu AND zp with known contents */ Arg = MakeHexArg (Out->RegA); + } else if (In->RegA == 0) { + /* ORA but A contains 0x00 - replace by lda */ + CE_ReplaceOPC (E, OP65_LDA); + ++Changes; } break; @@ -1379,7 +2075,7 @@ unsigned OptPrecalc (CodeSeg* S) /* Check if we have to replace the insn by LDA */ if (Arg) { - CodeEntry* X = NewCodeEntry (OP65_LDA, AM65_IMM, Arg, 0, E->LI); + CodeEntry* X = NewCodeEntry (OPC, AM65_IMM, Arg, 0, E->LI); CS_InsertEntry (S, X, I+1); CS_DelEntry (S, I); ++Changes; @@ -1465,3 +2161,117 @@ unsigned OptBranchDist (CodeSeg* S) +/*****************************************************************************/ +/* Optimize indirect loads */ +/*****************************************************************************/ + + + +unsigned OptIndLoads1 (CodeSeg* S) +/* Change + * + * lda (zp),y + * + * into + * + * lda (zp,x) + * + * provided that x and y are both zero. + */ +{ + unsigned Changes = 0; + unsigned I; + + /* Generate register info for this step */ + CS_GenRegInfo (S); + + /* Walk over the entries */ + I = 0; + while (I < CS_GetEntryCount (S)) { + + /* Get next entry */ + CodeEntry* E = CS_GetEntry (S, I); + + /* Check if it's what we're looking for */ + if (E->OPC == OP65_LDA && + E->AM == AM65_ZP_INDY && + E->RI->In.RegY == 0 && + E->RI->In.RegX == 0) { + + /* Replace by the same insn with other addressing mode */ + CodeEntry* X = NewCodeEntry (E->OPC, AM65_ZPX_IND, E->Arg, 0, E->LI); + CS_InsertEntry (S, X, I+1); + + /* Remove the old insn */ + CS_DelEntry (S, I); + ++Changes; + } + + /* Next entry */ + ++I; + + } + + /* Free register info */ + CS_FreeRegInfo (S); + + /* Return the number of changes made */ + return Changes; +} + + + +unsigned OptIndLoads2 (CodeSeg* S) +/* Change + * + * lda (zp,x) + * + * into + * + * lda (zp),y + * + * provided that x and y are both zero. + */ +{ + unsigned Changes = 0; + unsigned I; + + /* Generate register info for this step */ + CS_GenRegInfo (S); + + /* Walk over the entries */ + I = 0; + while (I < CS_GetEntryCount (S)) { + + /* Get next entry */ + CodeEntry* E = CS_GetEntry (S, I); + + /* Check if it's what we're looking for */ + if (E->OPC == OP65_LDA && + E->AM == AM65_ZPX_IND && + E->RI->In.RegY == 0 && + E->RI->In.RegX == 0) { + + /* Replace by the same insn with other addressing mode */ + CodeEntry* X = NewCodeEntry (E->OPC, AM65_ZP_INDY, E->Arg, 0, E->LI); + CS_InsertEntry (S, X, I+1); + + /* Remove the old insn */ + CS_DelEntry (S, I); + ++Changes; + } + + /* Next entry */ + ++I; + + } + + /* Free register info */ + CS_FreeRegInfo (S); + + /* Return the number of changes made */ + return Changes; +} + + +