#include "pcode.h"
#include "pcoderegs.h"
#include "pcodeflow.h"
+#include "main.h"
extern void dbg_dumpregusage(void);
extern pCode * findPrevInstruction(pCode *pci);
extern int pCodeSearchCondition(pCode *pc, unsigned int cond, int contIfSkip);
char *pCode2str(char *str, int size, pCode *pc);
void SAFE_snprintf(char **str, size_t *size, const char *format, ...);
+//static int sameRegs (const regs *reg1, const regs *reg2);
+
int total_registers_saved=0;
int register_optimization=1;
{
pCode *pc=NULL;
- pCode *pcprev=NULL;
regs *reg;
addSetIfnotP(& (PCFL(pcfl)->registers), reg);
- if((PCC_REGISTER | PCC_LITERAL) & PCI(pc)->inCond)
+ if(PCC_REGISTER & PCI(pc)->inCond)
addSetIfnotP(& (reg->reglives.usedpFlows), pcfl);
if(PCC_REGISTER & PCI(pc)->outCond)
}
- pcprev = pc;
pc = findNextInstruction(pc->next);
}
*-----------------------------------------------------------------*/
static void Remove1pcode(pCode *pc, regs *reg, int debug_code)
{
-
+
pCode *pcn=NULL;
if(!reg || !pc)
return 0;
}
+#if 0
+static int regIsLocal (regs *reg)
+{
+ if (!reg) return 1;
+ /* temporaries are local */
+ if (reg->type == REG_TMP) return 1;
+ /* registers named r0x... are local */
+ if (reg->name && !strncmp(reg->name,"r0x", 3))
+ {
+ //fprintf (stderr, "reg %s is not marked REG_TMP...\n", reg->name);
+ return 1;
+ }
+
+ return 0;
+}
+#endif
+
/*-----------------------------------------------------------------*
* void pCodeOptime2pCodes(pCode *pc1, pCode *pc2)
*
regs *reg1, *reg2;
int t = total_registers_saved;
+
+ if (!isPCI(pc1) || !isPCI(pc2)) return 0;
+ if (PCI(pc1)->pcflow != PCI(pc2)->pcflow) return 0;
if(pc2->seq < pc1->seq) {
pct1 = pc2;
pc2 = pc1;
pc1 = pct1;
}
+
+ /* disable this optimization for now -- it's buggy */
+ if(pic14_options.disable_df) return 0;
//fprintf(stderr,"pCodeOptime2pCodes\n");
//pc1->print(stderr,pc1);
//pc2->print(stderr,pc2);
-
+
if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_MOVFW) ){
pCode *newpc;
int regUsed = 0;
if(pct2 && PCI(pct2)->op == POC_MOVWF) {
wSaved = wUsed = 1; /* Maybe able to replace with clrf pc2->next->reg. */
} else {
- wUsed = pCodeSearchCondition(pct2,PCC_W,1) > 0;
+ wUsed = pCodeSearchCondition(pct2,PCC_W,1) != -1;
}
regUsed = regUsedinRange(pct2,0,reg);
- if ((regUsed&&wUsed) || (pCodeSearchCondition(pct2,PCC_Z,0) > 1)) {
+ if ((regUsed&&wUsed) || (pCodeSearchCondition(pct2,PCC_Z,0) != -1)) {
/* Do not optimise as exisiting code is required. */
} else {
/* Can optimise. */
pct2 = findNextInstruction(pc2->next);
- if(pCodeSearchCondition(pct2, PCC_Z,0) > 0) {
+ /* We must ensure that is destroyed before being read---IORLW must be performed unless this is proven. */
+ if(pCodeSearchCondition(pct2, PCC_Z,0) != -1) {
pct2 = newpCode(POC_IORLW, newpCodeOpLit(0));
pct2->seq = pc2->seq;
PCI(pct2)->pcflow = PCFL(pcfl_used);
if (reg2 && !regIsSpecial (reg2, 1) && !regUsedinRange(pc1,pc2,reg2)) {
pCode *pct3 = findNextInstruction(pct2->next);
/* Check following instructions are not relying on the use of W or the Z flag condiction */
- if ((pCodeSearchCondition(pct3,PCC_Z,0) < 1) || (pCodeSearchCondition(pct3,PCC_W,0) < 1)) {
+ /* XXX: We must ensure that this value is destroyed before use---otherwise it might be used in
+ * subsequent flows (checking for < 1 is insufficient). */
+ if ((pCodeSearchCondition(pct3,PCC_Z,0) == -1) && (pCodeSearchCondition(pct3,PCC_W,0) == -1)) {
DFPRINTF((stderr, " optimising MOVF reg ... MOVF reg,W MOVWF reg2 to MOVWF reg2 ...\n"));
pct2->seq = pc1->seq;
unlinkpCode(pct2);
}
}
+#if 0
+
+/* The following routines implement pCode optimizations based on
+ * dataflow analysis. The effects should be similar to those
+ * of pCodeOptime2pCodes() but more powerful.
+ *
+ * Unfortunately, the current approach (comparing operands by
+ * their associated registers) is seriously flawed:
+ * Some pCodeOps do not provide access to their repsective regs
+ * (PO_DIRs are created from arbitrary strings, immediates need
+ * to take offset and index into account, ...)
+ *
+ * This has to be rewritten based on pCodeOps instead of regs...
+ */
+
+/* ------------------------------------------------------------------
+ Returns TRUE iff reg1 and reg2 are the same registers.
+ ------------------------------------------------------------------ */
+
+static int sameRegs (const regs *reg1, const regs *reg2)
+{
+ if (reg1 == reg2) return 1;
+ if (!reg1 || !reg2) return 0;
+ assert (reg1->name && reg2->name);
+
+ /* Compare names, as rIdx is not unique... */
+ if (!strcmp(reg1->name, reg2->name)) return 1;
+
+ /* Name mismatch -- not the same register. */
+ return 0;
+}
+
+/* ------------------------------------------------------------------
+ Returns 1 if the register is live at pc (read in this flow),
+ returns -1 if the register is NOT live at pc (assigned a new value
+ prior to readingi the old value in this flow) or
+ return 0 if the register is not mentioned.
+ ------------------------------------------------------------------ */
+
+static int checkRegInFlow (regs **reg, int *cond, pCode *pc)
+{
+ const int verbose = 0;
+ /* find next PCI at or after pc */
+ while (pc && isPCFL(pc)) pc = pc->next;
+
+ assert (reg && cond);
+
+ /* remove pseudo flags from cond */
+ *cond &= ~(PCC_REGISTER | PCC_EXAMINE_PCOP);
+
+ if (verbose && pc)
+ {
+ fprintf (stderr, "Checking for reg %s, cond %x on pc ", *reg ? (*reg)->name : "<none>", *cond); pc->print (stderr, pc);
+ }
+
+ while (pc && !isPCFL(pc))
+ {
+ if (verbose)
+ {
+ fprintf (stderr, " now checking for reg %s, cond %x on pc ", *reg ? (*reg)->name : "<none>", *cond);
+ pc->print (stderr, pc);
+ }
+ if (isPCI(pc))
+ {
+ pCode *pcprev;
+ regs *op = NULL;
+ int prevIsSkip = 0;
+
+ pcprev = findPrevInstruction (pc);
+ if (pcprev && isPCI_SKIP(pcprev))
+ prevIsSkip = 1;
+
+ if ((PCI(pc)->inCond | PCI(pc)->outCond) & PCC_REGISTER)
+ {
+ op = getRegFromInstruction (pc);
+
+ /* pCodeOpRegBits do not provide register information... */
+ //if (!op) { __asm__("int3"); pc->print (stderr, pc); }
+ //assert (op);
+ if (!op)
+ {
+ if (reg)
+ return 1; /* assume `reg' is alive */
+ }
+
+ /* SPECIAL CASE: jump to unknown destination -- assume everything alive */
+ if (op->type == PO_PCL)
+ {
+ return 1;
+ }
+ } // if
+
+ if (PCI(pc)->inCond & PCC_REGISTER)
+ {
+ /* `op' is live (possibly read) */
+ if (*reg && sameRegs (op, *reg))
+ {
+ if (verbose)
+ {
+ fprintf (stderr, "reg is read in pc ");
+ pc->print (stderr, pc);
+ }
+ return 1;
+ }
+ }
+
+ /* handle additional implicit operands */
+ switch (PCI(pc)->op)
+ {
+ case POC_CALL: /* read arguments from WREG, clobbers WREG */
+ if (*cond & PCC_W)
+ {
+ if (verbose)
+ {
+ fprintf (stderr, "conditions are read at pc ");
+ pc->print (stderr, pc);
+ }
+ return 1;
+ }
+ *cond &= ~PCC_W;
+ break;
+ case POC_RETURN: /* returns WREG to caller */
+ //fprintf (stderr, "reached RETURN, reg %s, cond %x\n", *reg ? (*reg)->name : "<none>", *cond);
+ if (*cond & PCC_W)
+ {
+ if (verbose)
+ {
+ fprintf (stderr, "conditions are read at pc ");
+ pc->print (stderr, pc);
+ }
+ return 1;
+ }
+ /* afterwards, no condition is alive */
+ *cond = 0;
+ /* afterwards, all local registers are dead */
+ if (*reg && regIsLocal (*reg)) *reg = NULL;
+ break;
+ case POC_RETLW:
+ case POC_RETFIE: /* this does not erturn WREG to the "caller", thus its rather a RETLW */
+ /* this discards WREG */
+ *cond &= ~PCC_W;
+ /* afterwards, no condition is alive */
+ *cond = 0;
+ /* afterwards, all local registers are dead */
+ if (*reg && regIsLocal (*reg)) *reg = NULL;
+ break;
+ default:
+ /* no implicit arguments */
+ break;
+ }
+
+ if (PCI(pc)->inCond & (*cond))
+ {
+ /* a condition is read */
+ if (verbose)
+ {
+ fprintf (stderr, "conditions are read at pc ");
+ pc->print (stderr, pc);
+ }
+ return 1;
+ }
+
+ /* remove outConds from `cond' */
+ (*cond) &= ~(PCI(pc)->outCond);
+
+ if (PCI(pc)->outCond & PCC_REGISTER)
+ {
+ /* `op' is (possibly) discarded */
+ if (*reg && !prevIsSkip && sameRegs (op, *reg))
+ {
+ if (verbose)
+ {
+ fprintf (stderr, "reg is assigned (cont'd) at pc ");
+ pc->print (stderr, pc);
+ }
+ *reg = NULL;
+ }
+ }
+
+ /* have all interesting conditions/registers been discarded? */
+ if (!(*reg) && !(*cond))
+ {
+ if (verbose)
+ {
+ fprintf (stderr, "reg and conditions are discarded after ");
+ pc->print (stderr, pc);
+ }
+ return -1;
+ }
+ } // if
+
+ pc = pc->next;
+ } // while
+
+ /* no use of (or only conditional writes to) `reg' found in flow */
+ if (verbose)
+ {
+ fprintf (stderr, "analysis inconclusive: reg %s, cond %x remains\n", *reg ? "remains" : "is void", *cond);
+ }
+ return 0;
+}
+
+/* ------------------------------------------------------------------
+ This will return 1 only if
+ - reg is NULL or of type REG_TMP
+ - reg is NULL or its value is discarded after pc
+ - cond is 0 or all conditions are overwritten before being used
+ ------------------------------------------------------------------ */
+
+typedef struct {
+ pCode *pc;
+ regs *reg;
+ int cond;
+} df_state_t;
+
+df_state_t *df_free_states = NULL;
+
+static df_state_t *
+df_newState (regs *reg, int cond, pCode *pc)
+{
+ df_state_t *state;
+
+ if (df_free_states) {
+ state = df_free_states;
+ df_free_states = (df_state_t *)df_free_states->pc;
+ } else {
+ state = Safe_calloc(1, sizeof(df_state_t));
+ }
+ state->pc = pc;
+ state->reg = reg;
+ state->cond = cond;
+ return state;
+}
+
+static int
+df_containsState (set *set, df_state_t *state)
+{
+ /* scan set for presence of `state' */
+ df_state_t *curr;
+ for (curr = setFirstItem (set); curr; curr = setNextItem (set))
+ {
+ if ((curr->pc == state->pc)
+ && (curr->reg == state->reg)
+ && (curr->cond == state->cond))
+ {
+ /* `state' found */
+ return 1;
+ }
+ }
+ return 0;
+}
+
+static void
+df_releaseState (df_state_t *state)
+{
+ state->pc = (pCode *)df_free_states;
+ df_free_states = (df_state_t *)state;
+ state->reg = NULL;
+ state->cond = 0;
+}
+
+static void
+df_removeStates ()
+{
+ df_state_t *next;
+ while (df_free_states)
+ {
+ next = (df_state_t *)df_free_states->pc;
+ Safe_free(df_free_states);
+ df_free_states = next;
+ } // while
+}
+
+int regIsDead (regs *reg, int cond, pCode *pc)
+{
+ set *seenStates = NULL;
+ set *todo = NULL;
+ pCode *curr;
+ df_state_t *state;
+ int result = 1;
+
+ /* sanity checks */
+ if (reg && !regIsLocal (reg)) return 0;
+
+ pc = findNextInstruction (pc->next);
+
+ addSet (&todo, df_newState(reg, cond, pc));
+
+ while ((result == 1) && (state = getSet (&todo)))
+ {
+ int res;
+
+ if (df_containsState (seenStates, state)) continue;
+ addSet (&seenStates, state);
+
+ curr = state->pc;
+ reg = state->reg;
+ cond = state->cond;
+
+ //fprintf (stderr, "Checking for reg %s/cond %x at pc ", reg ? reg->name : "<none>", cond);
+ //curr->print (stderr, curr);
+
+ res = checkRegInFlow (®, &cond, curr);
+ switch (res)
+ {
+ case 1: /* `reg' or `cond' is read---not dead */
+ result = 0;
+ break;
+ case -1: /* `reg' and `cond' are discarded in this flow---need to check other open flows */
+ break;
+ default: /* `reg' is not read and (possibly) not assigned---check successor flows */
+ if (curr)
+ {
+ pCodeFlow *pcfl = PCI(curr)->pcflow;
+ pCodeFlowLink *link;
+ pCode *first;
+ assert (pcfl);
+
+ for (link = setFirstItem(pcfl->to); link; link = setNextItem (pcfl->to))
+ {
+ /* add the first pCodeInstruction in the new flow to `todo' */
+ first = findNextInstruction (&link->pcflow->pc);
+ if (first) addSet (&todo, df_newState (reg, cond, first));
+ } // for
+ }
+ break;
+ } // switch
+ } // while
+
+ /* clean up */
+ while (NULL != (state = getSet (&todo))) { df_releaseState (state); }
+ while (NULL != (state = getSet (&seenStates))) { df_releaseState (state); }
+
+ /* if result remained 1, `reg' is not even possibly read and thus dead */
+ return result;
+}
+
+
+
+/* ------------------------------------------------------------------
+ Safely remove a pCode.
+ This needs to check that the previous instruction was no SKIP
+ (otherwise the SKIP instruction would have to be removed as well,
+ which may not be done for SFRs (side-effects on read possible)).
+ ------------------------------------------------------------------ */
+
+extern void unBuildFlow (pBlock *pb);
+extern void RegsUnMapLiveRanges ();
+extern void BuildFlow (pBlock *pb);
+extern void LinkFlow (pBlock *pb);
+extern void BuildFlowTree (pBlock *pb);
+extern void pCodeRegMapLiveRanges (pBlock *pb);
+extern pFile *the_pFile;
+
+static int pCodeRemove (pCode *pc, const char *comment)
+{
+ pCode *pcprev, *pcnext;
+ unsigned int result = 0;
+
+ /* Sanity checks. */
+ if (!pc) return 0;
+ if (!isPCI(pc)) return 0;
+
+ pcprev = findPrevInstruction (pc->prev);
+ if (pcprev && isPCI_SKIP(pcprev))
+ {
+ /* bail out until we know how to fix the Flow... */
+ //return 0;
+
+ /* we also need to remove the preceeding SKIP instruction(s) */
+ result = pCodeRemove (pcprev, "=DF= removing preceeding SKIP as well");
+ if (!result)
+ {
+ /* previous instruction could not be removed -- this cannot be removed as well */
+ return result;
+ }
+ /* FIXME: We now have to update the flow! */
+ } // if
+
+ /* do not remove pCodes with SFRs as operands (even reading them might cause side effects) */
+ {
+ regs *reg;
+ reg = getRegFromInstruction (pc);
+ /* accesses to the STATUS register aer always safe, but others... */
+ if (reg && reg->type == REG_SFR && reg->pc_type != PO_STATUS) return result;
+ }
+
+ /* MUST SUCEED FROM NOW ON (or ervert the changes done since NOW ;-)) */
+
+ /* fix flow */
+ if (PCI(pc)->pcflow && PCI(pc)->pcflow->end == pc)
+ {
+ pCode *pcprev;
+ pcprev = findPrevInstruction (pc->prev);
+ if (PCI(pcprev)->pcflow == PCI(pc)->pcflow)
+ {
+ PCI(pc)->pcflow->end = pcprev;
+ } else {
+ pBlock *pb = pc->pb;
+ RegsUnMapLiveRanges();
+ unBuildFlow(pb);
+ BuildFlow(pb);
+ LinkFlow(pb);
+ BuildFlowTree(pb);
+ for (pb = the_pFile->pbHead; pb; pb = pb->next)
+ {
+ pCodeRegMapLiveRanges(pb);
+ }
+ }
+ }
+
+ /* attach labels to next instruction */
+ pcnext = findNextInstruction (pc->next);
+ if (pcnext)
+ {
+ PCI(pcnext)->label = pBranchAppend (PCI(pcnext)->label, PCI(pc)->label);
+ if (!PCI(pcnext)->cline) PCI(pcnext)->cline = PCI(pc)->cline;
+ }
+ else
+ {
+ fprintf (stderr, "Cannot move a label...\n");
+ exit(-1);
+ }
+
+ if (comment)
+ {
+ char buffer[512];
+ int size = 512;
+ char *pbuff = &buffer[0];
+
+ SAFE_snprintf (&pbuff, &size, "; %s:%u(%s): %s", __FILE__, __LINE__, __FUNCTION__, comment);
+ pCodeInsertAfter(pc->prev, newpCodeCharP (&buffer[0]));
+ } // if
+
+ if (1)
+ {
+ /* replace removed pCode with out-commented version of itself */
+ char buffer[512];
+ int size = 512;
+ char *pbuff = &buffer[0];
+
+ SAFE_snprintf (&pbuff, &size, "; %s:%u(%s): ", __FILE__, __LINE__, __FUNCTION__);
+ pCode2str (pbuff, size, pc);
+ pCodeInsertAfter(pc->prev, newpCodeCharP (&buffer[0]));
+ }
+
+ pc->destruct (pc);
+ return result+1;
+}
+
+/* ------------------------------------------------------------------
+ Find and remove dead pCodes.
+ ------------------------------------------------------------------ */
+
+static int removeIfDeadPCI (pCode *pc)
+{
+ pCode *pcnext = NULL;
+ pCode *curr;
+ unsigned int outCond;
+ unsigned int result = 0;
+ regs *dst;
+
+ if (!pc) return 0;
+ dst = NULL;
+
+ /* skip non-PCIs */
+ pcnext = findNextInstruction (pc->next);
+ if (!isPCI(pc)) return 0;
+
+ switch (PCI(pc)->op)
+ {
+ case POC_ADDLW:
+ case POC_ADDWF:
+ case POC_ADDFW:
+ case POC_ANDLW:
+ case POC_ANDWF:
+ case POC_ANDFW:
+ case POC_BCF:
+ case POC_BSF:
+ //case POC_BTFSC:
+ //case POC_BTFSS:
+ //case POC_CALL:
+ case POC_COMF:
+ case POC_COMFW:
+ case POC_CLRF:
+ case POC_CLRW:
+ //case POC_CLRWDT:
+ case POC_DECF:
+ case POC_DECFW:
+ //case POC_DECFSZ:
+ //case POC_DECFSZW:
+ //case POC_GOTO:
+ case POC_INCF:
+ case POC_INCFW:
+ //case POC_INCFSZ:
+ //case POC_INCFSZW:
+ case POC_IORLW:
+ case POC_IORWF:
+ case POC_IORFW:
+ case POC_MOVF:
+ case POC_MOVFW:
+ case POC_MOVLW:
+ case POC_MOVWF:
+ case POC_NOP:
+ //case POC_RETLW:
+ //case POC_RETURN:
+ //case POC_RETFIE:
+ case POC_RLF:
+ case POC_RLFW:
+ case POC_RRF:
+ case POC_RRFW:
+ case POC_SUBLW:
+ case POC_SUBWF:
+ case POC_SUBFW:
+ case POC_SWAPF:
+ case POC_SWAPFW:
+ //case POC_TRIS:
+ case POC_XORLW:
+ case POC_XORWF:
+ case POC_XORFW:
+ //case POC_BANKSEL:
+ //case POC_PAGESEL:
+ break;
+
+ default:
+ /* do not remove unknown PCIs */
+ return 0;
+ } // switch
+
+ /* redundant checks---those instructions may never be removed */
+ if (isPCI_BRANCH(pc)) return 0;
+ if (isPCI_SKIP(pc)) return 0;
+
+ outCond = PCI(pc)->outCond;
+ curr = pcnext;
+
+ /* unknown operands assigned to, then ignore */
+ if ((outCond & (PCC_REGISTER | PCC_C | PCC_Z | PCC_DC | PCC_W)) != outCond)
+ return 0;
+
+ if (outCond & PCC_REGISTER)
+ {
+ dst = getRegFromInstruction (pc);
+ if (!dst) return 0;
+
+ /* special reg? */
+ if (!regIsLocal (dst)) return 0;
+ if (regIsSpecial (dst,0)) return 0;
+ }
+
+ //fprintf (stderr, "--> checking for liveness pc "); pc->print (stderr, pc);
+ if (regIsDead (dst, outCond, pc))
+ {
+ /* no result from pc has been used -- pc is `dead' */
+ //fprintf (stderr, "--> reg %s and cond %x assumed unused\n", dst ? dst->name : "<none>", outCond);
+ //fprintf (stderr, "--> removing dead pc "); pc->print (stderr, pc);
+ result = pCodeRemove (pc, "=DF= removed dead pCode");
+ }
+
+ return result;
+}
+
+/* ------------------------------------------------------------------
+ This routine is intended to safely replace one pCodeInstruction
+ with a different pCodeInstruction.
+ If desired, the replaced pCode will be left in (commented out) for
+ debugging.
+ Further, an optional comment can be inserted to indicate the
+ reason for the possible removal of the pCode.
+ ------------------------------------------------------------------ */
+
+static void replace_PCI (pCodeInstruction *pc, pCodeInstruction *newpc, char *comment)
+{
+ newpc->from = pBranchAppend (newpc->from, pc->from);
+ newpc->to = pBranchAppend (newpc->to, pc->to);
+ newpc->label = pBranchAppend (newpc->label, pc->label);
+ //newpc->pcflow = pc->pcflow; // updated in pCodeInsertAfter, ->pb is as well
+ newpc->cline = pc->cline;
+
+ newpc->pc.seq = pc->pc.seq;
+
+ pCodeInsertAfter (&pc->pc, &newpc->pc);
+
+ /* FIXME: replacing pc will break the liverange maps (usedpCodes, ...) */
+
+ if (comment)
+ {
+ pCodeInsertAfter (&pc->pc, newpCodeCharP (comment));
+ } // if
+
+ if (1)
+ {
+ /* replace pc with commented out version of itself */
+ char buffer[1024], buffer2[1024];
+ char *pbuff = &buffer[0];
+ int size=1024;
+ pCode2str (&buffer2[0],1024,&pc->pc);
+ SAFE_snprintf (&pbuff,&size,"%s:%u(%s): removed pCode was %s\t", __FILE__, __LINE__, __FUNCTION__, &buffer2[0]);
+ pCodeInsertAfter (&pc->pc, newpCodeCharP (&buffer[0]));
+ } // if
+
+ pc->pc.destruct (&pc->pc);
+}
+
+/* ------------------------------------------------------------------
+ Find the first (unique) assignment to `reg' (prior to pc).
+ ------------------------------------------------------------------ */
+
+pCode *findAssignmentToReg (regs *reg, pCode *pc)
+{
+ pCode *curr;
+
+ assert (pc && isPCI(pc) && reg);
+
+ curr = findPrevInstruction (pc->prev);
+
+ while (curr && PCI(curr)->pcflow == PCI(pc)->pcflow)
+ {
+ if (PCI(curr)->outCond & PCC_REGISTER)
+ {
+ regs *op = getRegFromInstruction (curr);
+ if (op && (sameRegs(op,reg)))
+ return curr;
+ } // if
+ curr = findPrevInstruction (curr->prev);
+ } // while
+
+ /* no assignment to reg found */
+ return NULL;
+}
+
+/* ------------------------------------------------------------------
+ Find a register that holds the same value as `reg' (an alias).
+ ------------------------------------------------------------------ */
+
+regs *findRegisterAlias (regs *reg, pCode *pc)
+{
+ pCode *curr;
+
+ if(!reg) return NULL;
+
+ if (regIsSpecial (reg, 0)) return NULL;
+
+ curr = findAssignmentToReg (reg, pc);
+
+ /* no assignment found --> no alias found */
+ if (!curr) return NULL;
+
+ switch (PCI(curr)->op)
+ {
+ case POC_MOVWF:
+ /* find previous assignment to WREG */
+ while (curr && !(PCI(curr)->outCond & PCC_W))
+ curr = findPrevInstruction (curr->prev);
+ if (curr && PCI(curr)->op == POC_MOVFW)
+ {
+ regs *op = getRegFromInstruction (curr);
+ /* alias must not be changed since assignment... */
+ if (PCI(curr)->pcop)
+ {
+ switch (PCI(curr)->pcop->type)
+ {
+ case PO_GPR_REGISTER:
+ case PO_GPR_TEMP:
+ /* these operands are ok */
+ break;
+ default:
+ /* not a plain register operand */
+ return NULL;
+ break;
+ }
+ }
+ if (!op || regIsSpecial (op, 0) || !regIsUnchangedSince (op, pc, curr)) return NULL;
+ //fprintf (stderr, "found register alias for %s: %s\n", reg->name, op && op->name ? op->name : "<no name>");
+ return op;
+ } else {
+ /* unknown source to WREG -- unknown register alias */
+ return NULL;
+ }
+ break;
+
+ default:
+ /* unhandled instruction -- assume unknown source, no alias */
+ return NULL;
+ }
+
+ /* no alias found */
+ return NULL;
+}
+
+/* ------------------------------------------------------------------
+ Analyze a single pCodeInstruction's dataflow relations and replace
+ it with a better variant if possible.
+ ------------------------------------------------------------------ */
+
+void analyzeAndReplacePCI (pCodeInstruction *pci)
+{
+ regs *op_reg, *alias_reg;
+
+ assert (pci);
+
+ if (!isPCI(pci)) return;
+
+ switch (pci->op)
+ {
+ case POC_MOVFW:
+ case POC_ADDFW:
+ case POC_ANDFW:
+ case POC_IORFW:
+ case POC_XORFW:
+ /* try to find a different source register */
+ op_reg = getRegFromInstruction (&pci->pc);
+ if (pci->op == POC_MOVFW) /* touches Z */
+ {
+ pCode *assignment = findAssignmentToReg (op_reg, &pci->pc);
+ if (assignment && isPCI(assignment) && (PCI(assignment)->op == POC_CLRF))
+ {
+ replace_PCI (pci, PCI(newpCode(POC_MOVLW, newpCodeOpLit(0))), "replaced with CLRF");
+ return;
+ }
+ }
+
+ alias_reg = findRegisterAlias (op_reg, &pci->pc);
+ if (alias_reg)
+ {
+ replace_PCI (pci, PCI(newpCode(pci->op, newpCodeOpRegFromStr (alias_reg->name))), "=DF= replaced with move from register alias");
+ }
+ break;
+
+ default:
+ /* do not optimize */
+ break;
+ } // switch
+}
+
+extern pFile *the_pFile;
+
+/* ------------------------------------------------------------------
+ Find and remove dead pCodes.
+ ------------------------------------------------------------------ */
+
+static int removeDeadPCIs (void)
+{
+ pBlock *pb;
+ unsigned int removed = 0;
+
+ if (!the_pFile) return removed;
+
+ do {
+ removed = 0;
+
+ /* iterate over all pBlocks */
+ for (pb = the_pFile->pbHead; pb; pb = pb->next)
+ {
+ pCode *pc, *pcnext = NULL;
+
+ /* iterate over all pCodes */
+ for (pc = findNextInstruction (pb->pcHead); pc; pc = pcnext)
+ {
+ pcnext = findNextInstruction (pc->next);
+ removed += removeIfDeadPCI (pc);
+ } // while
+ } // for pb
+
+ fprintf (stderr, "[removed %u dead pCodes]\n", removed);
+ } while (removed);
+
+ return 0;
+}
+
+/* ------------------------------------------------------------------
+ This routine tries to optimize the dataflow by...
+ (1)
+
+ This routine leaves in dead pCodes (assignments whose results are
+ not used) -- these should be removed in a following sweep phase.
+ ------------------------------------------------------------------ */
+
+void optimizeDataflow (void)
+{
+ pBlock *pb;
+
+ if (!the_pFile) return;
+
+ //fprintf (stderr, "%s:%u(%s): Starting optimization...\n", __FILE__, __LINE__, __FUNCTION__);
+
+ /* iterate over all pBlocks */
+ for (pb = the_pFile->pbHead; pb; pb = pb->next)
+ {
+ pCode *pc, *pcnext = NULL;
+
+ /* iterate over all pCodes */
+ for (pc = findNextInstruction (pb->pcHead); pc; pc = pcnext)
+ {
+ pcnext = findNextInstruction (pc->next);
+ analyzeAndReplacePCI (PCI(pc));
+ } // while
+ } // for pb
+
+ while (removeDeadPCIs ()) { /* remove dead codes in multiple passes */};
+ df_removeStates ();
+}
+
+#endif
+
/*-----------------------------------------------------------------*
* void pCodeRegOptimeRegUsage(pBlock *pb)
*-----------------------------------------------------------------*/
int passes;
int saved = 0;
int t = total_registers_saved;
-
+
+#if 0
+ /* This is currently broken (need rewrite to correctly
+ * hamdle arbitrary pCodeOps instead of registers only). */
+ if (!pic14_options.disable_df)
+ optimizeDataflow ();
+#endif
+
if(!register_optimization)
return;
#define OPT_PASSES 4
projects / fw / sdcc / blobdiff