mirror of
https://github.com/cc65/cc65.git
synced 2024-11-19 06:31:31 +00:00
Trace register usage, remove duplicate loads
git-svn-id: svn://svn.cc65.org/cc65/trunk@793 b7a2c559-68d2-44c3-8de9-860c34a00d81
This commit is contained in:
cuz
parent
38f076a59e
commit
f98db88f36
@ -1296,6 +1296,7 @@ static OptFunc OptFuncs [] = {
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{ OptCmp5, "OptCmp5", 0 },
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/* Remove unused loads */
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{ OptUnusedLoads, "OptUnusedLoads", 0 },
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{ OptDuplicateLoads, "OptDuplicateLoads", 0 },
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/* Optimize branch distance */
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{ OptBranchDist, "OptBranchDist", 0 },
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};
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@ -44,6 +44,32 @@
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/*****************************************************************************/
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/* Macros */
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/*****************************************************************************/
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/* Macro to increment and decrement register contents if they're valid */
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#define INC(reg,val) if ((reg) >= 0) (reg) = ((reg) + val) & 0xFF
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#define DEC(reg,val) if ((reg) >= 0) (reg) = ((reg) - val) & 0xFF
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/*****************************************************************************/
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/* Helpers */
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/*****************************************************************************/
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static int IsKnownImm (const CodeEntry* E)
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/* Return true if the argument of E is a known immediate value */
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{
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return (E->AM == AM65_IMM && (E->Flags & CEF_NUMARG) != 0);
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}
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/*****************************************************************************/
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/* Replace jumps to RTS by RTS */
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/*****************************************************************************/
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@ -606,20 +632,20 @@ unsigned OptUnusedLoads (CodeSeg* S)
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/* Check which sort of load or transfer it is */
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unsigned R;
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switch (E->OPC) {
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case OP65_TXA:
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case OP65_TYA:
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case OP65_LDA: R = REG_A; break;
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case OP65_TAX:
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case OP65_TXA:
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case OP65_TYA:
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case OP65_LDA: R = REG_A; break;
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case OP65_TAX:
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case OP65_LDX: R = REG_X; break;
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case OP65_TAY:
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case OP65_LDY: R = REG_Y; break;
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default: goto NextEntry; /* OOPS */
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case OP65_TAY:
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case OP65_LDY: R = REG_Y; break;
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default: goto NextEntry; /* OOPS */
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}
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/* Get register usage and check if the register value is used later */
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if ((GetRegInfo (S, I+1) & R) == 0) {
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/* Register value is not used, remove the load */
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/* Register value is not used, remove the load */
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CS_DelEntry (S, I);
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/* Remember, we had changes */
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@ -629,8 +655,400 @@ unsigned OptUnusedLoads (CodeSeg* S)
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}
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NextEntry:
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/* Next entry */
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++I;
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/* Next entry */
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++I;
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}
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/* Return the number of changes made */
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return Changes;
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}
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unsigned OptDuplicateLoads (CodeSeg* S)
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/* Remove loads of registers where the value loaded is already in the register. */
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{
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unsigned Changes = 0;
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/* Remember the last load instructions for all registers */
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int RegA = -1;
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int RegX = -1;
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int RegY = -1;
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/* Walk over the entries */
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unsigned I = 0;
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while (I < CS_GetEntryCount (S)) {
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unsigned char Use, Chg;
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/* Get next entry */
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CodeEntry* E = CS_GetEntry (S, I);
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/* Assume we won't delete the entry */
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int Delete = 0;
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/* If this entry has a label attached, remove all knownledge about the
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* register contents. This may be improved but for now it's ok.
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*/
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if (CE_HasLabel (E)) {
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RegA = RegX = RegY = -1;
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}
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/* Handle the different instructions */
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switch (E->OPC) {
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case OP65_ADC:
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/* We don't know the value of the carry, so the result is
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* always unknown.
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*/
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RegA = -1;
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break;
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case OP65_AND:
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if (RegA >= 0) {
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if (IsKnownImm (E)) {
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RegA &= (int) E->Num;
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} else {
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RegA = -1;
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}
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}
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break;
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case OP65_ASL:
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if (RegA >= 0) {
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RegA = (RegA << 1) & 0xFF;
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}
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break;
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case OP65_BCC:
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break;
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case OP65_BCS:
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break;
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case OP65_BEQ:
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break;
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case OP65_BIT:
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break;
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case OP65_BMI:
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break;
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case OP65_BNE:
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break;
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case OP65_BPL:
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break;
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case OP65_BRA:
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break;
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case OP65_BRK:
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break;
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case OP65_BVC:
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break;
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case OP65_BVS:
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break;
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case OP65_CLC:
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break;
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case OP65_CLD:
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break;
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case OP65_CLI:
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break;
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case OP65_CLV:
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break;
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case OP65_CMP:
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break;
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case OP65_CPX:
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break;
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case OP65_CPY:
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break;
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case OP65_DEA:
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DEC (RegA, 1);
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break;
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case OP65_DEC:
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break;
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case OP65_DEX:
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DEC (RegX, 1);
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break;
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case OP65_DEY:
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DEC (RegY, 1);
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break;
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case OP65_EOR:
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if (RegA >= 0) {
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if (IsKnownImm (E)) {
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RegA ^= (int) E->Num;
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} else {
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RegA = -1;
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}
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}
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break;
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case OP65_INA:
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INC (RegA, 1);
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break;
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case OP65_INC:
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break;
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case OP65_INX:
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INC (RegX, 1);
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break;
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case OP65_INY:
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INC (RegY, 1);
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break;
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case OP65_JCC:
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break;
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case OP65_JCS:
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break;
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case OP65_JEQ:
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break;
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case OP65_JMI:
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break;
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case OP65_JMP:
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break;
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case OP65_JNE:
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break;
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case OP65_JPL:
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break;
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case OP65_JSR:
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/* Get the code info for the function */
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GetFuncInfo (E->Arg, &Use, &Chg);
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if (Chg & REG_A) {
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RegA = -1;
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}
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if (Chg & REG_X) {
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RegX = -1;
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}
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if (Chg & REG_Y) {
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RegY = -1;
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}
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break;
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case OP65_JVC:
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break;
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case OP65_JVS:
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break;
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case OP65_LDA:
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if (IsKnownImm (E)) {
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CodeEntry* N = CS_GetNextEntry (S, I);
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if (RegA >= 0 && RegA == E->Num && N && (N->Info & OF_FBRA) == 0) {
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Delete = 1;
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} else {
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RegA = (unsigned char) E->Num;
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}
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} else {
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/* A is now unknown */
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RegA = -1;
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}
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break;
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case OP65_LDX:
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if (IsKnownImm (E)) {
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CodeEntry* N = CS_GetNextEntry (S, I);
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if (RegX >= 0 && RegX == E->Num && N && (N->Info & OF_FBRA) == 0) {
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Delete = 1;
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} else {
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RegX = (unsigned char) E->Num;
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}
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} else {
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/* X is now unknown */
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RegX = -1;
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}
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break;
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case OP65_LDY:
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if (IsKnownImm (E)) {
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CodeEntry* N = CS_GetNextEntry (S, I);
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if (RegY >= 0 && RegY == E->Num && N && (N->Info & OF_FBRA) == 0) {
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Delete = 1;
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} else {
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RegY = (unsigned char) E->Num;
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}
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} else {
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/* Y is now unknown */
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RegY = -1;
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}
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break;
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case OP65_LSR:
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if (RegA >= 0) {
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RegA = (RegA >> 1) & 0xFF;
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}
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break;
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case OP65_NOP:
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break;
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case OP65_ORA:
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if (RegA >= 0) {
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if (IsKnownImm (E)) {
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RegA |= (unsigned char) E->Num;
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} else {
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/* A is now unknown */
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RegA = -1;
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}
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}
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break;
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case OP65_PHA:
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break;
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case OP65_PHP:
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break;
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case OP65_PHX:
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break;
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case OP65_PHY:
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break;
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case OP65_PLA:
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RegA = -1;
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break;
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case OP65_PLP:
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break;
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case OP65_PLX:
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RegX = -1;
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break;
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case OP65_PLY:
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RegY = -1;
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break;
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case OP65_ROL:
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RegA = -1;
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break;
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case OP65_ROR:
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RegA = -1;
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break;
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case OP65_RTI:
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break;
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case OP65_RTS:
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break;
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case OP65_SBC:
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RegA = -1;
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break;
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case OP65_SEC:
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break;
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case OP65_SED:
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break;
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case OP65_SEI:
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break;
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case OP65_STA:
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break;
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case OP65_STX:
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/* If the value in the X register is known and the same as
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* that in the A register, replace the store by a STA. The
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* optimizer will then remove the load instruction for X
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* later. STX does support the zeropage,y addressing mode,
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* so be sure to check for that.
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*/
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if (RegX >= 0 && RegX == RegA &&
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E->AM != AM65_ABSY && E->AM != AM65_ZPY) {
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/* Use the A register instead */
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CE_ReplaceOPC (E, OP65_STA);
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}
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break;
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case OP65_STY:
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/* If the value in the Y register is known and the same as
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* that in the A register, replace the store by a STA. The
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* optimizer will then remove the load instruction for Y
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* later.
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*/
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if (RegY >= 0 && RegY == RegA) {
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CE_ReplaceOPC (E, OP65_STA);
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}
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break;
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case OP65_TAX:
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RegX = RegA;
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break;
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case OP65_TAY:
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RegY = RegA;
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break;
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case OP65_TRB:
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break;
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case OP65_TSB:
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break;
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case OP65_TSX:
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RegX = -1;
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break;
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case OP65_TXA:
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RegA = RegX;
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break;
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case OP65_TXS:
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break;
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case OP65_TYA:
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RegA = RegY;
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break;
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default:
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break;
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}
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/* Delete the entry if requested */
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if (Delete) {
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/* Register value is not used, remove the load */
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CS_DelEntry (S, I);
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/* Remember, we had changes */
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++Changes;
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} else {
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/* Next entry */
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++I;
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}
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}
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@ -678,7 +1096,7 @@ unsigned OptBranchDist (CodeSeg* S)
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unsigned J = I;
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while (J < TI) {
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CodeEntry* N = CS_GetEntry (S, J++);
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Distance += N->Size;
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Distance += N->Size;
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}
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} else {
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/* Backward branch */
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@ -51,7 +51,7 @@
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unsigned OptRTSJumps (CodeSeg* S);
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/* Replace jumps to RTS by RTS */
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unsigned OptDeadJumps (CodeSeg* S);
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unsigned OptDeadJumps (CodeSeg* S);
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/* Remove dead jumps (jumps to the next instruction) */
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unsigned OptDeadCode (CodeSeg* S);
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@ -89,6 +89,9 @@ unsigned OptCondBranches (CodeSeg* S);
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unsigned OptUnusedLoads (CodeSeg* S);
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/* Remove loads of registers where the value loaded is not used later. */
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unsigned OptDuplicateLoads (CodeSeg* S);
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/* Remove loads of registers where the value loaded is already in the register. */
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unsigned OptBranchDist (CodeSeg* S);
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/* Change branches for the distance needed. */
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@ -169,6 +169,7 @@ typedef enum {
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AM65_IMM, /* immidiate */
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AM65_ZP, /* zeropage */
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AM65_ZPX, /* zeropage,X */
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AM65_ZPY, /* zeropage,Y */
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AM65_ABS, /* absolute */
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AM65_ABSX, /* absolute,X */
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AM65_ABSY, /* absolute,Y */
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Reference in New Issue
Block a user