/*****************************************************************************/ /* */ /* coptstop.c */ /* */ /* Optimize operations that take operands via the stack */ /* */ /* */ /* */ /* (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 */ /* warranty. In no event will the authors be held liable for any damages */ /* arising from the use of this software. */ /* */ /* Permission is granted to anyone to use this software for any purpose, */ /* including commercial applications, and to alter it and redistribute it */ /* freely, subject to the following restrictions: */ /* */ /* 1. The origin of this software must not be misrepresented; you must not */ /* claim that you wrote the original software. If you use this software */ /* in a product, an acknowledgment in the product documentation would be */ /* appreciated but is not required. */ /* 2. Altered source versions must be plainly marked as such, and must not */ /* be misrepresented as being the original software. */ /* 3. This notice may not be removed or altered from any source */ /* distribution. */ /* */ /*****************************************************************************/ #include /* common */ #include "chartype.h" /* cc65 */ #include "codeent.h" #include "codeinfo.h" #include "coptstop.h" /*****************************************************************************/ /* Load tracking data */ /*****************************************************************************/ /* LoadRegInfo flags set by DirectOp */ #define LI_NONE 0x00 #define LI_DIRECT 0x01 /* Direct op may be used */ #define LI_RELOAD_Y 0x02 /* Reload index register Y */ #define LI_REMOVE 0x04 /* Load may be removed */ /* Structure that tells us how to load the lhs values */ typedef struct LoadRegInfo LoadRegInfo; struct LoadRegInfo { int LoadIndex; /* Index of load insn, -1 if invalid */ CodeEntry* LoadEntry; /* The actual entry, 0 if invalid */ unsigned char Flags; /* Tells us how to load */ unsigned char Offs; /* Stack offset if data is on stack */ }; /* Now combined for both registers */ typedef struct LoadInfo LoadInfo; struct LoadInfo { LoadRegInfo A; /* Info for A register */ LoadRegInfo X; /* Info for X register */ LoadRegInfo Y; /* Info for Y register */ }; /*****************************************************************************/ /* Data */ /*****************************************************************************/ /* Flags for the functions */ typedef enum { OP_NONE = 0x00, /* Nothing special */ OP_A_KNOWN = 0x01, /* Value of A must be known */ OP_X_ZERO = 0x02, /* X must be zero */ OP_LHS_LOAD = 0x04, /* Must have load insns for LHS */ OP_LHS_LOAD_DIRECT = 0x0C, /* Must have direct load insn for LHS */ OP_RHS_LOAD = 0x10, /* Must have load insns for RHS */ OP_RHS_LOAD_DIRECT = 0x30, /* Must have direct load insn for RHS */ } OP_FLAGS; /* Structure forward decl */ typedef struct StackOpData StackOpData; /* Structure that describes an optimizer subfunction for a specific op */ typedef unsigned (*OptFunc) (StackOpData* D); typedef struct OptFuncDesc OptFuncDesc; struct OptFuncDesc { const char* Name; /* Name of the replaced runtime function */ OptFunc Func; /* Function pointer */ unsigned UnusedRegs; /* Regs that must not be used later */ OP_FLAGS Flags; /* Flags */ }; /* Structure that holds the needed data */ struct StackOpData { CodeSeg* Code; /* Pointer to code segment */ unsigned Flags; /* Flags to remember things */ /* Pointer to optimizer subfunction description */ const OptFuncDesc* OptFunc; /* ZP register usage inside the sequence */ unsigned UsedRegs; /* Register load information for lhs and rhs */ LoadInfo Lhs; LoadInfo Rhs; /* Several indices of insns in the code segment */ int PushIndex; /* Index of call to pushax in codeseg */ int OpIndex; /* Index of actual operation */ /* Pointers to insns in the code segment */ CodeEntry* PrevEntry; /* Entry before the call to pushax */ CodeEntry* PushEntry; /* Pointer to entry with call to pushax */ CodeEntry* OpEntry; /* Pointer to entry with op */ CodeEntry* NextEntry; /* Entry after the op */ const char* ZPLo; /* Lo byte of zero page loc to use */ const char* ZPHi; /* Hi byte of zero page loc to use */ unsigned IP; /* Insertion point used by some routines */ }; /*****************************************************************************/ /* Load tracking code */ /*****************************************************************************/ static void ClearLoadRegInfo (LoadRegInfo* RI) /* Clear a LoadRegInfo struct */ { RI->LoadIndex = -1; } static void FinalizeLoadRegInfo (LoadRegInfo* RI, CodeSeg* S) /* Prepare a LoadRegInfo struct for use */ { /* Get the entry */ if (RI->LoadIndex >= 0) { RI->LoadEntry = CS_GetEntry (S, RI->LoadIndex); } else { RI->LoadEntry = 0; } RI->Flags = LI_NONE; } static void ClearLoadInfo (LoadInfo* LI) /* Clear a LoadInfo struct */ { ClearLoadRegInfo (&LI->A); ClearLoadRegInfo (&LI->X); ClearLoadRegInfo (&LI->Y); } static void AdjustLoadRegInfo (LoadRegInfo* RI, int DelIndex, int Change) /* Adjust a load register info struct after deleting or inserting an entry * with a given index */ { CHECK (abs (Change) == 1); if (Change < 0) { /* Deletion */ if (DelIndex < RI->LoadIndex) { --RI->LoadIndex; } else if (DelIndex == RI->LoadIndex) { /* Has been removed */ RI->LoadIndex = -1; RI->LoadEntry = 0; } } else { /* Insertion */ if (DelIndex <= RI->LoadIndex) { ++RI->LoadIndex; } } } static void FinalizeLoadInfo (LoadInfo* LI, CodeSeg* S) /* Prepare a LoadInfo struct for use */ { /* Get the entries */ FinalizeLoadRegInfo (&LI->A, S); FinalizeLoadRegInfo (&LI->X, S); FinalizeLoadRegInfo (&LI->Y, S); } static void AdjustLoadInfo (LoadInfo* LI, int DelIndex, int Change) /* Adjust a load info struct after deleting entry with a given index */ { AdjustLoadRegInfo (&LI->A, DelIndex, Change); AdjustLoadRegInfo (&LI->X, DelIndex, Change); AdjustLoadRegInfo (&LI->Y, DelIndex, Change); } static void TrackLoads (LoadInfo* LI, CodeEntry* E, int I) /* Track loads for a code entry */ { if (E->Info & OF_LOAD) { if (E->Chg & REG_A) { LI->A.LoadIndex = I; } if (E->Chg & REG_X) { LI->X.LoadIndex = I; } if (E->Chg & REG_Y) { LI->Y.LoadIndex = I; } } else if (E->Info & OF_XFR) { switch (E->OPC) { case OP65_TAX: LI->X.LoadIndex = LI->A.LoadIndex; break; case OP65_TAY: LI->Y.LoadIndex = LI->A.LoadIndex; break; case OP65_TXA: LI->A.LoadIndex = LI->X.LoadIndex; break; case OP65_TYA: LI->A.LoadIndex = LI->Y.LoadIndex; break; default: break; } } else if (CE_IsCallTo (E, "ldaxysp")) { /* Both registers set, Y changed */ LI->A.LoadIndex = I; LI->X.LoadIndex = I; LI->Y.LoadIndex = -1; } else { if (E->Chg & REG_A) { LI->A.LoadIndex = -1; } if (E->Chg & REG_X) { LI->X.LoadIndex = -1; } if (E->Chg & REG_Y) { LI->Y.LoadIndex = -1; } } } /*****************************************************************************/ /* Helpers */ /*****************************************************************************/ static void AdjustStackOffset (StackOpData* D, unsigned Offs) /* Adjust the offset for all stack accesses in the range PushIndex to OpIndex. * OpIndex is adjusted according to the insertions. */ { /* Walk over all entries */ int I = D->PushIndex + 1; while (I < D->OpIndex) { CodeEntry* E = CS_GetEntry (D->Code, I); int NeedCorrection = 0; if ((E->Use & REG_SP) != 0) { /* Check for some things that should not happen */ CHECK (E->AM == AM65_ZP_INDY || E->RI->In.RegY >= (short) Offs); CHECK (strcmp (E->Arg, "sp") == 0); /* We need to correct this one */ NeedCorrection = 1; } else if (CE_IsCallTo (E, "ldaxysp")) { /* We need to correct this one */ NeedCorrection = 1; } if (NeedCorrection) { /* Get the code entry before this one. If it's a LDY, adjust the * value. */ CodeEntry* P = CS_GetPrevEntry (D->Code, I); if (P && P->OPC == OP65_LDY && CE_IsConstImm (P)) { /* The Y load is just before the stack access, adjust it */ CE_SetNumArg (P, P->Num - Offs); } else { /* Insert a new load instruction before the stack access */ const char* Arg = MakeHexArg (E->RI->In.RegY - Offs); CodeEntry* X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, E->LI); CS_InsertEntry (D->Code, X, I++); /* One more inserted entries */ ++D->OpIndex; } /* If we need the value of Y later, be sure to reload it */ if (RegYUsed (D->Code, I+1)) { const char* Arg = MakeHexArg (E->RI->In.RegY); CodeEntry* X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, E->LI); CS_InsertEntry (D->Code, X, I+1); /* One more inserted entries */ ++D->OpIndex; /* Skip this instruction in the next round */ ++I; } } /* Next entry */ ++I; } } static void InsertEntry (StackOpData* D, CodeEntry* E, int Index) /* Insert a new entry. Depending on Index, D->PushIndex and D->OpIndex will * be adjusted by this function. */ { /* Insert the entry into the code segment */ CS_InsertEntry (D->Code, E, Index); /* Adjust register loads if necessary */ AdjustLoadInfo (&D->Lhs, Index, 1); AdjustLoadInfo (&D->Rhs, Index, 1); /* Adjust the indices if necessary */ if (D->PushEntry && Index <= D->PushIndex) { ++D->PushIndex; } if (D->OpEntry && Index <= D->OpIndex) { ++D->OpIndex; } } static void DelEntry (StackOpData* D, int Index) /* Delete an entry. Depending on Index, D->PushIndex and D->OpIndex will be * adjusted by this function, and PushEntry/OpEntry may get invalidated. */ { /* Delete the entry from the code segment */ CS_DelEntry (D->Code, Index); /* Adjust register loads if necessary */ AdjustLoadInfo (&D->Lhs, Index, -1); AdjustLoadInfo (&D->Rhs, Index, -1); /* Adjust the other indices if necessary */ if (Index < D->PushIndex) { --D->PushIndex; } else if (Index == D->PushIndex) { D->PushEntry = 0; } if (Index < D->OpIndex) { --D->OpIndex; } else if (Index == D->OpIndex) { D->OpEntry = 0; } } static void CheckOneDirectOp (LoadRegInfo* LI, unsigned char Offs) /* Check if the given entry is a lda instruction with an addressing mode * that allows us to replace it by another operation (like ora). If so, we may * use this location for the or and must not save the value in the zero * page location. */ { /* Get the load entry */ CodeEntry* E = LI->LoadEntry; if (E == 0) { /* No load insn */ return; } /* Check the load entry */ if (E) { /* Must check the call first since addressing mode is ABS, so second * "if" will catch otherwise. */ if (CE_IsCallTo (E, "ldaxysp")) { /* Same as single loads from stack. Since we must distinguish * between A and X here, the necessary offset is passed to the * function as a parameter. */ LI->Offs = (unsigned char) E->RI->In.RegY - Offs; LI->Flags |= (LI_DIRECT | LI_RELOAD_Y); } else if (E->AM == AM65_IMM || E->AM == AM65_ZP || E->AM == AM65_ABS) { /* These insns are all ok and replaceable */ LI->Flags |= LI_DIRECT; } else if (E->AM == AM65_ZP_INDY && RegValIsKnown (E->RI->In.RegY) && strcmp (E->Arg, "sp") == 0) { /* A load from the stack with known offset is also ok, but in this * case we must reload the index register later. Please note that * a load indirect via other zero page locations is not ok, since * these locations may change between the push and the actual * operation. */ LI->Offs = (unsigned char) E->RI->In.RegY; LI->Flags |= (LI_DIRECT | LI_RELOAD_Y); } } } static void CheckDirectOp (StackOpData* D) /* Check if the given entry is a lda instruction with an addressing mode * that allows us to replace it by another operation (like ora). If so, we may * use this location for the or and must not save the value in the zero * page location. */ { /* Check flags for all load instructions */ CheckOneDirectOp (&D->Lhs.A, 1); CheckOneDirectOp (&D->Lhs.X, 0); CheckOneDirectOp (&D->Rhs.A, 1); CheckOneDirectOp (&D->Rhs.X, 0); } static void ReplacePushByStore (StackOpData* D) /* Replace the call to the push subroutine by a store into the zero page * location (actually, the push is not replaced, because we need it for * later, but the name is still ok since the push will get removed at the * end of each routine). */ { CodeEntry* X; /* Store the value into the zeropage instead of pushing it. Check high * byte first so that the store is later in A/X order. */ if ((D->Lhs.X.Flags & LI_DIRECT) == 0) { X = NewCodeEntry (OP65_STX, AM65_ZP, D->ZPHi, 0, D->PushEntry->LI); InsertEntry (D, X, D->PushIndex+1); } if ((D->Lhs.A.Flags & LI_DIRECT) == 0) { X = NewCodeEntry (OP65_STA, AM65_ZP, D->ZPLo, 0, D->PushEntry->LI); InsertEntry (D, X, D->PushIndex+1); } } static void AddOpLow (StackOpData* D, opc_t OPC) /* Add an op for the low byte of an operator. This function honours the * OP_DIRECT and OP_RELOAD_Y flags and generates the necessary instructions. * All code is inserted at the current insertion point. */ { CodeEntry* X; if ((D->Lhs.A.Flags & LI_DIRECT) != 0) { /* Op with a variable location. If the location is on the stack, we * need to reload the Y register. */ if ((D->Lhs.A.Flags & LI_RELOAD_Y) == 0) { /* opc ... */ CodeEntry* LoadA = D->Lhs.A.LoadEntry; X = NewCodeEntry (OPC, LoadA->AM, LoadA->Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* ldy #offs */ const char* Arg = MakeHexArg (D->Lhs.A.Offs); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* opc (sp),y */ X = NewCodeEntry (OPC, AM65_ZP_INDY, "sp", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* In both cases, we can remove the load */ D->Lhs.A.Flags |= LI_REMOVE; } else { /* Op with temp storage */ X = NewCodeEntry (OPC, AM65_ZP, D->ZPLo, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } } static void AddOpHigh (StackOpData* D, opc_t OPC) /* Add an op for the high byte of an operator. Special cases (constant values * or similar) have to be checked separately, the function covers only the * generic case. Code is inserted at the insertion point. */ { CodeEntry* X; /* pha */ X = NewCodeEntry (OP65_PHA, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* txa */ X = NewCodeEntry (OP65_TXA, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); if ((D->Lhs.X.Flags & LI_DIRECT) != 0) { if ((D->Lhs.X.Flags & LI_RELOAD_Y) == 0) { /* opc xxx */ CodeEntry* LoadX = D->Lhs.X.LoadEntry; X = NewCodeEntry (OPC, LoadX->AM, LoadX->Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* ldy #const */ const char* Arg = MakeHexArg (D->Lhs.X.Offs); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* opc (sp),y */ X = NewCodeEntry (OPC, AM65_ZP_INDY, "sp", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* In both cases, we can remove the load */ D->Lhs.X.Flags |= LI_REMOVE; } else { /* opc zphi */ X = NewCodeEntry (OPC, AM65_ZP, D->ZPHi, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* tax */ X = NewCodeEntry (OP65_TAX, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* pla */ X = NewCodeEntry (OP65_PLA, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } static void RemoveRegLoads (StackOpData* D, LoadInfo* LI) /* Remove register load insns */ { /* Both registers may be loaded with one insn, but DelEntry will in this * case clear the other one. */ if (LI->A.LoadIndex >= 0 && (LI->A.Flags & LI_REMOVE)) { DelEntry (D, LI->A.LoadIndex); } if (LI->X.LoadIndex >= 0 && (LI->X.Flags & LI_REMOVE)) { DelEntry (D, LI->X.LoadIndex); } } static void RemoveRemainders (StackOpData* D) /* Remove the code that is unnecessary after translation of the sequence */ { /* Remove the register loads for lhs and rhs */ RemoveRegLoads (D, &D->Lhs); RemoveRegLoads (D, &D->Rhs); /* Remove the push and the operator routine */ DelEntry (D, D->OpIndex); DelEntry (D, D->PushIndex); } static int IsRegVar (StackOpData* D) /* If the value pushed is that of a zeropage variable, replace ZPLo and ZPHi * in the given StackOpData struct by the variable and return true. Otherwise * leave D untouched and return false. */ { CodeEntry* LoadA = D->Lhs.A.LoadEntry; CodeEntry* LoadX = D->Lhs.X.LoadEntry; unsigned Len; /* Must have both load insns */ if (LoadA == 0 || LoadX == 0) { return 0; } /* Must be loads from zp */ if (LoadA->AM != AM65_ZP || LoadX->AM != AM65_ZP) { return 0; } /* Must be the same zp loc with high byte in X */ Len = strlen (LoadA->Arg); if (strncmp (LoadA->Arg, LoadX->Arg, Len) != 0 || strcmp (LoadX->Arg + Len, "+1") != 0) { return 0; } /* Use the zero page location directly */ D->ZPLo = LoadA->Arg; D->ZPHi = LoadX->Arg; return 1; } /*****************************************************************************/ /* Actual optimization functions */ /*****************************************************************************/ static unsigned Opt___bzero (StackOpData* D) /* Optimize the __bzero sequence if possible */ { CodeEntry* X; const char* Arg; CodeLabel* L; /* Check if we're using a register variable */ if (!IsRegVar (D)) { /* Store the value into the zeropage instead of pushing it */ ReplacePushByStore (D); } /* If the return value of __bzero is used, we have to add code to reload * a/x from the pointer variable. */ if (RegAXUsed (D->Code, D->OpIndex+1)) { X = NewCodeEntry (OP65_LDA, AM65_ZP, D->ZPLo, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+1); X = NewCodeEntry (OP65_LDX, AM65_ZP, D->ZPHi, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+2); } /* X is always zero, A contains the size of the data area to zero. * Note: A may be zero, in which case the operation is null op. */ if (D->OpEntry->RI->In.RegA != 0) { /* lda #$00 */ X = NewCodeEntry (OP65_LDA, AM65_IMM, "$00", 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+1); /* The value of A is known */ if (D->OpEntry->RI->In.RegA <= 0x81) { /* Loop using the sign bit */ /* ldy #count-1 */ Arg = MakeHexArg (D->OpEntry->RI->In.RegA - 1); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+2); /* L: sta (zp),y */ X = NewCodeEntry (OP65_STA, AM65_ZP_INDY, D->ZPLo, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+3); L = CS_GenLabel (D->Code, X); /* dey */ X = NewCodeEntry (OP65_DEY, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+4); /* bpl L */ X = NewCodeEntry (OP65_BPL, AM65_BRA, L->Name, L, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+5); } else { /* Loop using an explicit compare */ /* ldy #$00 */ X = NewCodeEntry (OP65_LDY, AM65_IMM, "$00", 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+2); /* L: sta (zp),y */ X = NewCodeEntry (OP65_STA, AM65_ZP_INDY, D->ZPLo, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+3); L = CS_GenLabel (D->Code, X); /* iny */ X = NewCodeEntry (OP65_INY, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+4); /* cpy #count */ Arg = MakeHexArg (D->OpEntry->RI->In.RegA); X = NewCodeEntry (OP65_CPY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+5); /* bne L */ X = NewCodeEntry (OP65_BNE, AM65_BRA, L->Name, L, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+6); } } /* Remove the push and the call to the __bzero function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } static unsigned Opt_staspidx (StackOpData* D) /* Optimize the staspidx sequence if possible */ { CodeEntry* X; /* Check if we're using a register variable */ if (!IsRegVar (D)) { /* Store the value into the zeropage instead of pushing it */ ReplacePushByStore (D); } /* Replace the store subroutine call by a direct op */ X = NewCodeEntry (OP65_STA, AM65_ZP_INDY, D->ZPLo, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+1); /* Remove the push and the call to the staspidx function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } static unsigned Opt_staxspidx (StackOpData* D) /* Optimize the staxspidx sequence if possible */ { CodeEntry* X; /* Check if we're using a register variable */ if (!IsRegVar (D)) { /* Store the value into the zeropage instead of pushing it */ ReplacePushByStore (D); } /* Inline the store */ /* sta (zp),y */ X = NewCodeEntry (OP65_STA, AM65_ZP_INDY, D->ZPLo, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+1); if (RegValIsKnown (D->OpEntry->RI->In.RegY)) { /* Value of Y is known */ const char* Arg = MakeHexArg (D->OpEntry->RI->In.RegY + 1); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); } else { X = NewCodeEntry (OP65_INY, AM65_IMP, 0, 0, D->OpEntry->LI); } InsertEntry (D, X, D->OpIndex+2); if (RegValIsKnown (D->OpEntry->RI->In.RegX)) { /* Value of X is known */ const char* Arg = MakeHexArg (D->OpEntry->RI->In.RegX); X = NewCodeEntry (OP65_LDA, AM65_IMM, Arg, 0, D->OpEntry->LI); } else { /* Value unknown */ X = NewCodeEntry (OP65_TXA, AM65_IMP, 0, 0, D->OpEntry->LI); } InsertEntry (D, X, D->OpIndex+3); /* sta (zp),y */ X = NewCodeEntry (OP65_STA, AM65_ZP_INDY, D->ZPLo, 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+4); /* If we remove staxspidx, we must restore the Y register to what the * function would return. */ X = NewCodeEntry (OP65_LDY, AM65_IMM, "$00", 0, D->OpEntry->LI); InsertEntry (D, X, D->OpIndex+5); /* Remove the push and the call to the staxspidx function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } static unsigned Opt_tosaddax (StackOpData* D) /* Optimize the tosaddax sequence if possible */ { CodeEntry* X; CodeEntry* N; /* We need the entry behind the add */ CHECK (D->NextEntry != 0); /* Check if the X register is known and zero when the add is done, and * if the add is followed by * * ldy #$00 * jsr ldauidx ; or ldaidx * * If this is true, the addition does actually add an offset to a pointer * before it is dereferenced. Since both subroutines take an offset in Y, * we can pass the offset (instead of #$00) and remove the addition * alltogether. */ if (D->OpEntry->RI->In.RegX == 0 && D->NextEntry->OPC == OP65_LDY && CE_IsKnownImm (D->NextEntry, 0) && !CE_HasLabel (D->NextEntry) && (N = CS_GetNextEntry (D->Code, D->OpIndex + 1)) != 0 && (CE_IsCallTo (N, "ldauidx") || CE_IsCallTo (N, "ldaidx"))) { int Signed = (strcmp (N->Arg, "ldaidx") == 0); /* Store the value into the zeropage instead of pushing it */ ReplacePushByStore (D); /* Replace the ldy by a tay. Be sure to create the new entry before * deleting the ldy, since we will reference the line info from this * insn. */ X = NewCodeEntry (OP65_TAY, AM65_IMP, 0, 0, D->NextEntry->LI); DelEntry (D, D->OpIndex + 1); InsertEntry (D, X, D->OpIndex + 1); /* Replace the call to ldaidx/ldauidx. Since X is already zero, and * the ptr is in the zero page location, we just need to load from * the pointer, and fix X in case of ldaidx. */ X = NewCodeEntry (OP65_LDA, AM65_ZP_INDY, D->ZPLo, 0, N->LI); DelEntry (D, D->OpIndex + 2); InsertEntry (D, X, D->OpIndex + 2); if (Signed) { CodeLabel* L; /* Add sign extension - N is unused now */ N = CS_GetNextEntry (D->Code, D->OpIndex + 2); CHECK (N != 0); L = CS_GenLabel (D->Code, N); X = NewCodeEntry (OP65_BPL, AM65_BRA, L->Name, L, X->LI); InsertEntry (D, X, D->OpIndex + 3); X = NewCodeEntry (OP65_DEX, AM65_IMP, 0, 0, X->LI); InsertEntry (D, X, D->OpIndex + 4); } } else { /* Store the value into the zeropage instead of pushing it */ ReplacePushByStore (D); /* Inline the add */ D->IP = D->OpIndex+1; /* clc */ X = NewCodeEntry (OP65_CLC, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* Low byte */ AddOpLow (D, OP65_ADC); /* High byte */ if (D->PushEntry->RI->In.RegX == 0) { /* The high byte is the value in X plus the carry */ CodeLabel* L = CS_GenLabel (D->Code, D->NextEntry); X = NewCodeEntry (OP65_BCC, AM65_BRA, L->Name, L, D->OpEntry->LI); InsertEntry (D, X, D->IP++); X = NewCodeEntry (OP65_INX, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else if (D->OpEntry->RI->In.RegX == 0) { /* The high byte is that of the first operand plus carry */ CodeLabel* L; if (RegValIsKnown (D->PushEntry->RI->In.RegX)) { /* Value of first op high byte is known */ const char* Arg = MakeHexArg (D->PushEntry->RI->In.RegX); X = NewCodeEntry (OP65_LDX, AM65_IMM, Arg, 0, D->OpEntry->LI); } else { /* Value of first op high byte is unknown */ X = NewCodeEntry (OP65_LDX, AM65_ZP, D->ZPHi, 0, D->OpEntry->LI); } InsertEntry (D, X, D->IP++); /* bcc label */ L = CS_GenLabel (D->Code, D->NextEntry); X = NewCodeEntry (OP65_BCC, AM65_BRA, L->Name, L, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* inx */ X = NewCodeEntry (OP65_INX, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* High byte is unknown */ AddOpHigh (D, OP65_ADC); } } /* Remove the push and the call to the tosaddax function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } static unsigned Opt_tosandax (StackOpData* D) /* Optimize the tosandax sequence if possible */ { CodeEntry* X; /* Store the value into the zeropage instead of pushing it */ ReplacePushByStore (D); /* Inline the and, low byte */ D->IP = D->OpIndex + 1; AddOpLow (D, OP65_AND); /* High byte */ if (D->PushEntry->RI->In.RegX == 0 || D->OpEntry->RI->In.RegX == 0) { /* The high byte is zero */ X = NewCodeEntry (OP65_LDX, AM65_IMM, "$00", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* High byte is unknown */ AddOpHigh (D, OP65_AND); } /* Remove the push and the call to the tosandax function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } static unsigned Opt_tosgeax (StackOpData* D) /* Optimize the tosgeax sequence if possible. */ { CodeEntry* X; CodeLabel* L; /* Inline the sbc */ D->IP = D->OpIndex+1; /* Must be true because of OP_RHS_LOAD */ CHECK ((D->Rhs.A.Flags & LI_DIRECT) != 0); /* If the location is on the stack, we need to reload the Y register. */ if ((D->Rhs.A.Flags & LI_RELOAD_Y) == 0) { /* cmp ... */ CodeEntry* LoadA = D->Rhs.A.LoadEntry; X = NewCodeEntry (OP65_CMP, LoadA->AM, LoadA->Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* ldy #offs */ const char* Arg = MakeHexArg (D->Rhs.A.Offs); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* cmp (sp),y */ X = NewCodeEntry (OP65_CMP, AM65_ZP_INDY, "sp", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* In both cases, we can remove the load */ D->Rhs.A.Flags |= LI_REMOVE; /* txa */ X = NewCodeEntry (OP65_TXA, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* Must be true because of OP_RHS_LOAD */ CHECK ((D->Rhs.X.Flags & LI_DIRECT) != 0); /* If the location is on the stack, we need to reload the Y register. */ if ((D->Rhs.X.Flags & LI_RELOAD_Y) == 0) { /* sbc ... */ CodeEntry* LoadX = D->Rhs.X.LoadEntry; X = NewCodeEntry (OP65_SBC, LoadX->AM, LoadX->Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* ldy #offs */ const char* Arg = MakeHexArg (D->Rhs.X.Offs); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* sbc (sp),y */ X = NewCodeEntry (OP65_SBC, AM65_ZP_INDY, "sp", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* In both cases, we can remove the load */ D->Rhs.X.Flags |= LI_REMOVE; /* eor #$80 */ X = NewCodeEntry (OP65_EOR, AM65_IMM, "$80", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* asl a */ X = NewCodeEntry (OP65_ASL, AM65_ACC, "a", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); L = CS_GenLabel (D->Code, X); /* Insert a bvs L before the eor insn */ X = NewCodeEntry (OP65_BVS, AM65_BRA, L->Name, L, D->OpEntry->LI); InsertEntry (D, X, D->IP - 2); ++D->IP; /* lda #$00 */ X = NewCodeEntry (OP65_LDA, AM65_IMM, "$00", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* ldx #$00 */ X = NewCodeEntry (OP65_LDX, AM65_IMM, "$00", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* rol a */ X = NewCodeEntry (OP65_ROL, AM65_ACC, "a", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* Remove the push and the call to the tosgeax function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } static unsigned Opt_tosltax (StackOpData* D) /* Optimize the tosltax sequence if possible. */ { CodeEntry* X; CodeLabel* L; /* Inline the sbc */ D->IP = D->OpIndex+1; /* Must be true because of OP_RHS_LOAD */ CHECK ((D->Rhs.A.Flags & LI_DIRECT) != 0); /* If the location is on the stack, we need to reload the Y register. */ if ((D->Rhs.A.Flags & LI_RELOAD_Y) == 0) { /* cmp ... */ CodeEntry* LoadA = D->Rhs.A.LoadEntry; X = NewCodeEntry (OP65_CMP, LoadA->AM, LoadA->Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* ldy #offs */ const char* Arg = MakeHexArg (D->Rhs.A.Offs); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* cmp (sp),y */ X = NewCodeEntry (OP65_CMP, AM65_ZP_INDY, "sp", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* In both cases, we can remove the load */ D->Rhs.A.Flags |= LI_REMOVE; /* txa */ X = NewCodeEntry (OP65_TXA, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* Must be true because of OP_RHS_LOAD */ CHECK ((D->Rhs.X.Flags & LI_DIRECT) != 0); /* If the location is on the stack, we need to reload the Y register. */ if ((D->Rhs.X.Flags & LI_RELOAD_Y) == 0) { /* sbc ... */ CodeEntry* LoadX = D->Rhs.X.LoadEntry; X = NewCodeEntry (OP65_SBC, LoadX->AM, LoadX->Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* ldy #offs */ const char* Arg = MakeHexArg (D->Rhs.X.Offs); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* sbc (sp),y */ X = NewCodeEntry (OP65_SBC, AM65_ZP_INDY, "sp", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* In both cases, we can remove the load */ D->Rhs.X.Flags |= LI_REMOVE; /* eor #$80 */ X = NewCodeEntry (OP65_EOR, AM65_IMM, "$80", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* asl a */ X = NewCodeEntry (OP65_ASL, AM65_ACC, "a", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); L = CS_GenLabel (D->Code, X); /* Insert a bvc L before the eor insn */ X = NewCodeEntry (OP65_BVC, AM65_BRA, L->Name, L, D->OpEntry->LI); InsertEntry (D, X, D->IP - 2); ++D->IP; /* lda #$00 */ X = NewCodeEntry (OP65_LDA, AM65_IMM, "$00", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* ldx #$00 */ X = NewCodeEntry (OP65_LDX, AM65_IMM, "$00", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* rol a */ X = NewCodeEntry (OP65_ROL, AM65_ACC, "a", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* Remove the push and the call to the tosltax function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } static unsigned Opt_tosorax (StackOpData* D) /* Optimize the tosorax sequence if possible */ { CodeEntry* X; /* Store the value into the zeropage instead of pushing it */ ReplacePushByStore (D); /* Inline the or, low byte */ D->IP = D->OpIndex + 1; AddOpLow (D, OP65_ORA); /* High byte */ if (RegValIsKnown (D->PushEntry->RI->In.RegX) && RegValIsKnown (D->OpEntry->RI->In.RegX)) { /* Both values known, precalculate the result */ unsigned char Result = D->PushEntry->RI->In.RegX | D->OpEntry->RI->In.RegX; const char* Arg = MakeHexArg (Result); X = NewCodeEntry (OP65_LDX, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else if (D->PushEntry->RI->In.RegX != 0) { /* High byte is unknown */ AddOpHigh (D, OP65_ORA); } /* Remove the push and the call to the tosorax function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } static unsigned Opt_tossubax (StackOpData* D) /* Optimize the tossubax sequence if possible. Note: subtraction is not * commutative! */ { CodeEntry* X; /* Inline the sbc */ D->IP = D->OpIndex+1; /* sec */ X = NewCodeEntry (OP65_SEC, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* Must be true because of OP_RHS_LOAD */ CHECK ((D->Rhs.A.Flags & LI_DIRECT) != 0); /* If the location is on the stack, we need to reload the Y register. */ if ((D->Rhs.A.Flags & LI_RELOAD_Y) == 0) { /* sbc ... */ CodeEntry* LoadA = D->Rhs.A.LoadEntry; X = NewCodeEntry (OP65_SBC, LoadA->AM, LoadA->Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* ldy #offs */ const char* Arg = MakeHexArg (D->Rhs.A.Offs); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* sbc (sp),y */ X = NewCodeEntry (OP65_SBC, AM65_ZP_INDY, "sp", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* In both cases, we can remove the load */ D->Rhs.A.Flags |= LI_REMOVE; /* pha */ X = NewCodeEntry (OP65_PHA, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* txa */ X = NewCodeEntry (OP65_TXA, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* Must be true because of OP_RHS_LOAD */ CHECK ((D->Rhs.X.Flags & LI_DIRECT) != 0); /* If the location is on the stack, we need to reload the Y register. */ if ((D->Rhs.X.Flags & LI_RELOAD_Y) == 0) { /* sbc ... */ CodeEntry* LoadX = D->Rhs.X.LoadEntry; X = NewCodeEntry (OP65_SBC, LoadX->AM, LoadX->Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* ldy #offs */ const char* Arg = MakeHexArg (D->Rhs.X.Offs); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* sbc (sp),y */ X = NewCodeEntry (OP65_SBC, AM65_ZP_INDY, "sp", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* In both cases, we can remove the load */ D->Rhs.X.Flags |= LI_REMOVE; /* tax */ X = NewCodeEntry (OP65_TAX, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* pla */ X = NewCodeEntry (OP65_PLA, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* Remove the push and the call to the tossubax function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } static unsigned Opt_tosugeax (StackOpData* D) /* Optimize the tosugeax sequence if possible. */ { CodeEntry* X; /* Inline the sbc */ D->IP = D->OpIndex+1; /* Must be true because of OP_RHS_LOAD */ CHECK ((D->Rhs.A.Flags & LI_DIRECT) != 0); /* If the location is on the stack, we need to reload the Y register. */ if ((D->Rhs.A.Flags & LI_RELOAD_Y) == 0) { /* cmp ... */ CodeEntry* LoadA = D->Rhs.A.LoadEntry; X = NewCodeEntry (OP65_CMP, LoadA->AM, LoadA->Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* ldy #offs */ const char* Arg = MakeHexArg (D->Rhs.A.Offs); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* cmp (sp),y */ X = NewCodeEntry (OP65_CMP, AM65_ZP_INDY, "sp", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* In both cases, we can remove the load */ D->Rhs.A.Flags |= LI_REMOVE; /* txa */ X = NewCodeEntry (OP65_TXA, AM65_IMP, 0, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* Must be true because of OP_RHS_LOAD */ CHECK ((D->Rhs.X.Flags & LI_DIRECT) != 0); /* If the location is on the stack, we need to reload the Y register. */ if ((D->Rhs.X.Flags & LI_RELOAD_Y) == 0) { /* sbc ... */ CodeEntry* LoadX = D->Rhs.X.LoadEntry; X = NewCodeEntry (OP65_SBC, LoadX->AM, LoadX->Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else { /* ldy #offs */ const char* Arg = MakeHexArg (D->Rhs.X.Offs); X = NewCodeEntry (OP65_LDY, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* sbc (sp),y */ X = NewCodeEntry (OP65_SBC, AM65_ZP_INDY, "sp", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } /* In both cases, we can remove the load */ D->Rhs.X.Flags |= LI_REMOVE; /* lda #$00 */ X = NewCodeEntry (OP65_LDA, AM65_IMM, "$00", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* ldx #$00 */ X = NewCodeEntry (OP65_LDX, AM65_IMM, "$00", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* rol a */ X = NewCodeEntry (OP65_ROL, AM65_ACC, "a", 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); /* Remove the push and the call to the tosugeax function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } static unsigned Opt_tosxorax (StackOpData* D) /* Optimize the tosxorax sequence if possible */ { CodeEntry* X; /* Store the value into the zeropage instead of pushing it */ ReplacePushByStore (D); /* Inline the xor, low byte */ D->IP = D->OpIndex + 1; AddOpLow (D, OP65_EOR); /* High byte */ if (RegValIsKnown (D->PushEntry->RI->In.RegX) && RegValIsKnown (D->OpEntry->RI->In.RegX)) { /* Both values known, precalculate the result */ const char* Arg = MakeHexArg (D->PushEntry->RI->In.RegX ^ D->OpEntry->RI->In.RegX); X = NewCodeEntry (OP65_LDX, AM65_IMM, Arg, 0, D->OpEntry->LI); InsertEntry (D, X, D->IP++); } else if (D->PushEntry->RI->In.RegX != 0) { /* High byte is unknown */ AddOpHigh (D, OP65_EOR); } /* Remove the push and the call to the tosandax function */ RemoveRemainders (D); /* We changed the sequence */ return 1; } /*****************************************************************************/ /* Code */ /*****************************************************************************/ static const OptFuncDesc FuncTable[] = { { "__bzero", Opt___bzero, REG_NONE, OP_X_ZERO | OP_A_KNOWN }, { "staspidx", Opt_staspidx, REG_NONE, OP_NONE }, { "staxspidx", Opt_staxspidx, REG_AX, OP_NONE }, { "tosaddax", Opt_tosaddax, REG_NONE, OP_NONE }, { "tosandax", Opt_tosandax, REG_NONE, OP_NONE }, { "tosgeax", Opt_tosgeax, REG_NONE, OP_RHS_LOAD_DIRECT }, { "tosltax", Opt_tosltax, REG_NONE, OP_RHS_LOAD_DIRECT }, { "tosorax", Opt_tosorax, REG_NONE, OP_NONE }, { "tossubax", Opt_tossubax, REG_NONE, OP_RHS_LOAD_DIRECT }, { "tosugeax", Opt_tosugeax, REG_NONE, OP_RHS_LOAD_DIRECT }, { "tosxorax", Opt_tosxorax, REG_NONE, OP_NONE }, }; #define FUNC_COUNT (sizeof(FuncTable) / sizeof(FuncTable[0])) static int CmpFunc (const void* Key, const void* Func) /* Compare function for bsearch */ { return strcmp (Key, ((const OptFuncDesc*) Func)->Name); } static const OptFuncDesc* FindFunc (const char* Name) /* Find the function with the given name. Return a pointer to the table entry * or NULL if the function was not found. */ { return bsearch (Name, FuncTable, FUNC_COUNT, sizeof(OptFuncDesc), CmpFunc); } static int CmpHarmless (const void* Key, const void* Entry) /* Compare function for bsearch */ { return strcmp (Key, *(const char**)Entry); } static int HarmlessCall (const char* Name) /* Check if this is a call to a harmless subroutine that will not interrupt * the pushax/op sequence when encountered. */ { static const char* Tab[] = { "aslax1", "aslax2", "asrax1", "asrax2", "bnegax", "ldaxidx", "ldaxysp", "negax", "shlax1", "shlax2", "shrax1", "shrax2", }; void* R = bsearch (Name, Tab, sizeof (Tab) / sizeof (Tab[0]), sizeof (Tab[0]), CmpHarmless); return (R != 0); } static void ResetStackOpData (StackOpData* Data) /* Reset the given data structure */ { Data->OptFunc = 0; Data->UsedRegs = REG_NONE; ClearLoadInfo (&Data->Lhs); ClearLoadInfo (&Data->Rhs); Data->PushIndex = -1; Data->OpIndex = -1; } static int PreCondOk (StackOpData* D) /* Check if the preconditions for a call to the optimizer subfunction are * satisfied. As a side effect, this function will also choose the zero page * register to use. */ { /* Check the flags */ unsigned UnusedRegs = D->OptFunc->UnusedRegs; if (UnusedRegs != REG_NONE && (GetRegInfo (D->Code, D->OpIndex+1, UnusedRegs) & UnusedRegs) != 0) { /* Cannot optimize */ return 0; } if ((D->OptFunc->Flags & OP_A_KNOWN) != 0 && RegValIsUnknown (D->OpEntry->RI->In.RegA)) { /* Cannot optimize */ return 0; } if ((D->OptFunc->Flags & OP_X_ZERO) != 0 && D->OpEntry->RI->In.RegX != 0) { /* Cannot optimize */ return 0; } if ((D->OptFunc->Flags & OP_LHS_LOAD) != 0) { if (D->Lhs.A.LoadIndex < 0 || D->Lhs.X.LoadIndex < 0) { /* Cannot optimize */ return 0; } else if ((D->OptFunc->Flags & OP_LHS_LOAD_DIRECT) != 0) { if ((D->Lhs.A.Flags & D->Lhs.X.Flags & LI_DIRECT) == 0) { /* Cannot optimize */ return 0; } } } if ((D->OptFunc->Flags & OP_RHS_LOAD) != 0) { if (D->Rhs.A.LoadIndex < 0 || D->Rhs.X.LoadIndex < 0) { /* Cannot optimize */ return 0; } else if ((D->OptFunc->Flags & OP_RHS_LOAD_DIRECT) != 0) { if ((D->Rhs.A.Flags & D->Rhs.X.Flags & LI_DIRECT) == 0) { /* Cannot optimize */ return 0; } } } /* Determine the zero page locations to use */ if ((D->UsedRegs & REG_PTR1) == REG_NONE) { D->ZPLo = "ptr1"; D->ZPHi = "ptr1+1"; } else if ((D->UsedRegs & REG_SREG) == REG_NONE) { D->ZPLo = "sreg"; D->ZPHi = "sreg+1"; } else if ((D->UsedRegs & REG_PTR2) == REG_NONE) { D->ZPLo = "ptr2"; D->ZPHi = "ptr2+1"; } else { /* No registers available */ return 0; } /* Determine if we have a basic block */ return CS_IsBasicBlock (D->Code, D->PushIndex, D->OpIndex); } /*****************************************************************************/ /* Code */ /*****************************************************************************/ unsigned OptStackOps (CodeSeg* S) /* Optimize operations that take operands via the stack */ { unsigned Changes = 0; /* Number of changes in one run */ StackOpData Data; unsigned I; enum { Initialize, Search, FoundPush, FoundOp } State = Initialize; /* Generate register info */ CS_GenRegInfo (S); /* Remember the code segment in the info struct */ Data.Code = S; /* Look for a call to pushax followed by a call to some other function * that takes it's first argument on the stack, and the second argument * in the primary register. * It depends on the code between the two if we can handle/transform the * sequence, so check this code for the following list of things: * * - the range must be a basic block (one entry, one exit) * - there may not be accesses to local variables with unknown * offsets (because we have to adjust these offsets). * - no subroutine calls * - no jump labels * * Since we need a zero page register later, do also check the * intermediate code for zero page use. */ I = 0; while (I < CS_GetEntryCount (S)) { /* Get the next entry */ CodeEntry* E = CS_GetEntry (S, I); /* Actions depend on state */ switch (State) { case Initialize: ResetStackOpData (&Data); State = Search; /* FALLTHROUGH */ case Search: /* While searching, track register load insns, so we can tell * what is in a register once pushax is encountered. */ if (CE_IsCallTo (E, "pushax")) { Data.PushIndex = I; State = FoundPush; } else { /* Track load insns */ TrackLoads (&Data.Lhs, E, I); } break; case FoundPush: /* We' found a pushax before. Search for a stack op that may * follow and in the meantime, track zeropage usage and check * for code that will disable us from translating the sequence. */ if (E->OPC == OP65_JSR) { /* Subroutine call: Check if this is one of the functions, * we're going to replace. */ Data.OptFunc = FindFunc (E->Arg); if (Data.OptFunc) { /* Remember the op index and go on */ Data.OpIndex = I; Data.OpEntry = E; State = FoundOp; break; } else if (!HarmlessCall (E->Arg)) { /* A call to an unkown subroutine: We need to start * over after the last pushax. Note: This will also * happen if we encounter a call to pushax! */ I = Data.PushIndex; State = Initialize; break; } else { /* Track register usage */ Data.UsedRegs |= (E->Use | E->Chg); TrackLoads (&Data.Rhs, E, I); } } else if (E->Info & OF_STORE && (E->Chg & REG_ZP) == 0) { /* Too dangerous - there may be a change of a variable * within the sequence. */ I = Data.PushIndex; State = Initialize; break; } else if ((E->Use & REG_SP) != 0 && (E->AM != AM65_ZP_INDY || RegValIsUnknown (E->RI->In.RegY) || E->RI->In.RegY < 2)) { /* If we are using the stack, and we don't have "indirect Y" * addressing mode, or the value of Y is unknown, or less * than two, we cannot cope with this piece of code. Having * an unknown value of Y means that we cannot correct the * stack offset, while having an offset less than two means * that the code works with the value on stack which is to * be removed. */ I = Data.PushIndex; State = Initialize; break; } else { /* Other stuff: Track register usage */ Data.UsedRegs |= (E->Use | E->Chg); TrackLoads (&Data.Rhs, E, I); } break; case FoundOp: /* Track zero page location usage beyond this point */ Data.UsedRegs |= GetRegInfo (S, I, REG_SREG | REG_PTR1 | REG_PTR2); /* Finalize the load info */ FinalizeLoadInfo (&Data.Lhs, S); FinalizeLoadInfo (&Data.Rhs, S); /* Set flags for direct operations */ CheckDirectOp (&Data); /* If the Lhs loads do load from zeropage, we have to include * them into UsedRegs registers used. The Rhs loads have already * been tracked. */ if (Data.Lhs.A.LoadEntry && Data.Lhs.A.LoadEntry->AM == AM65_ZP) { Data.UsedRegs |= Data.Lhs.A.LoadEntry->Use; } if (Data.Lhs.X.LoadEntry && Data.Lhs.X.LoadEntry->AM == AM65_ZP) { Data.UsedRegs |= Data.Lhs.X.LoadEntry->Use; } /* Check the preconditions. If they aren't ok, reset the insn * pointer to the pushax and start over. We will loose part of * load tracking but at least a/x has probably lost between * pushax and here and will be tracked again when restarting. */ if (!PreCondOk (&Data)) { I = Data.PushIndex; State = Initialize; break; } /* Adjust stack offsets to account for the upcoming removal */ AdjustStackOffset (&Data, 2); /* Regenerate register info, since AdjustStackOffset changed * the code */ CS_GenRegInfo (S); /* Prepare the remainder of the data structure. */ Data.PrevEntry = CS_GetPrevEntry (S, Data.PushIndex); Data.PushEntry = CS_GetEntry (S, Data.PushIndex); Data.OpEntry = CS_GetEntry (S, Data.OpIndex); Data.NextEntry = CS_GetNextEntry (S, Data.OpIndex); /* Call the optimizer function */ Changes += Data.OptFunc->Func (&Data); /* Regenerate register info */ CS_GenRegInfo (S); /* Done */ State = Initialize; break; } /* Next entry */ ++I; } /* Free the register info */ CS_FreeRegInfo (S); /* Return the number of changes made */ return Changes; }