Patch from Jim Hawkridge that prevents stack registers from being optimized away.
[fw/sdcc] / src / pic / pcoderegs.c
index 82c585cbc0087ed2ad070364defa69f538706d2e..633e8df50fde076d9c402afc99e5171818bb7499 100644 (file)
 #include "pcodeflow.h"
 
 extern void pCodeInsertAfter(pCode *pc1, pCode *pc2);
+extern void pCodeInsertBefore(pCode *pc1, pCode *pc2);
 extern void dbg_dumpregusage(void);
 extern pCode * findPrevInstruction(pCode *pci);
 extern pBranch * pBranchAppend(pBranch *h, pBranch *n);
 void unlinkpCode(pCode *pc);
-
+extern int pCodeSearchCondition(pCode *pc, unsigned int cond);
+char *pCode2str(char *str, int size, pCode *pc);
+void SAFE_snprintf(char **str, size_t *size, const  char  *format, ...);
 int total_registers_saved=0;
+int register_optimization=1;
 
 /*-----------------------------------------------------------------*
  * void AddRegToFlow(regs *reg, pCodeFlow *pcfl)
@@ -231,18 +235,16 @@ void pCodeRegMapLiveRanges(pBlock *pb)
 /*-----------------------------------------------------------------*
  *
  *-----------------------------------------------------------------*/
-static void Remove1pcode(pCode *pc, regs *reg)
+static void Remove1pcode(pCode *pc, regs *reg, int debug_code)
 {
+
   pCode *pcn=NULL;
 
   if(!reg || !pc)
     return;
 
   deleteSetItem (&(reg->reglives.usedpCodes),pc);
-/*
-  fprintf(stderr,"removing instruction:\n");
-  pc->print(stderr,pc);
-*/
+
   if(PCI(pc)->label) {
     pcn = findNextInstruction(pc->next);
 
@@ -264,6 +266,25 @@ static void Remove1pcode(pCode *pc, regs *reg)
     }
   }
 
+
+  if(1){
+    /*
+      Debug stuff. Comment out the instruction we're about to delete.
+    */
+
+    char buff1[256];
+    size_t size = 256;
+
+    char *pbuff,**ppbuff;
+    pbuff = buff1;
+    ppbuff = &pbuff;
+
+    SAFE_snprintf(ppbuff,&size, ";%d", debug_code);
+    pCode2str(*ppbuff, size, pc);
+    pCodeInsertBefore(pc, newpCodeCharP(buff1));
+    //fprintf(stderr,"removing instruction:\n%s\n",buff1);
+  }
+
   pc->destruct(pc);
 
 }
@@ -296,7 +317,7 @@ void  RemoveRegsFromSet(set *regset)
 
        pc = setFirstItem(reg->reglives.usedpCodes);
 
-       if(reg->type == REG_SFR) {
+       if(reg->type == REG_SFR || reg->type == REG_STK) {
          //fprintf(stderr, "not removing SFR reg %s even though used only once\n",reg->name);
          continue;
        }
@@ -324,7 +345,7 @@ void  RemoveRegsFromSet(set *regset)
            fprintf(stderr,"reg %s, type =%d\n",r->name, r->type);
          }
          //fprintf(stderr," removing reg %s because it is used only once\n",reg->name);
-         Remove1pcode(pc, reg);
+         Remove1pcode(pc, reg, 1);
          /*
            unlinkpCode(pc);
            deleteSetItem (&(reg->reglives.usedpCodes),pc);
@@ -346,8 +367,7 @@ void RemoveUnusedRegisters(void)
 {
   /* First, get rid of registers that are used only one time */
 
-
-  RemoveRegsFromSet(dynInternalRegs);
+  //RemoveRegsFromSet(dynInternalRegs);
   RemoveRegsFromSet(dynAllocRegs);
   RemoveRegsFromSet(dynStackRegs);
   /*
@@ -365,14 +385,16 @@ void RemoveUnusedRegisters(void)
  *-----------------------------------------------------------------*/
 static void Remove2pcodes(pCode *pcflow, pCode *pc1, pCode *pc2, regs *reg, int can_free)
 {
+  static int debug_code=99;
   if(!reg)
     return;
 
+  //fprintf(stderr,"%s\n",__FUNCTION__);
   if(pc1)
-    Remove1pcode(pc1, reg);
+    Remove1pcode(pc1, reg, debug_code++);
 
   if(pc2) {
-    Remove1pcode(pc2, reg);
+    Remove1pcode(pc2, reg, debug_code++);
     deleteSetItem (&(PCFL(pcflow)->registers), reg);
 
     if(can_free) {
@@ -420,18 +442,23 @@ int regUsedinRange(pCode *pc1, pCode *pc2, regs *reg)
  * 
  *
  *-----------------------------------------------------------------*/
-void pCodeOptime2pCodes(pCode *pc1, pCode *pc2, pCode *pcfl_used, regs *reg, int can_free)
+int pCodeOptime2pCodes(pCode *pc1, pCode *pc2, pCode *pcfl_used, regs *reg, int can_free, int optimize_level)
 {
   pCode *pct1, *pct2;
   regs  *reg1, *reg2;
 
+  int t = total_registers_saved;
+
   if(pc2->seq < pc1->seq) {
     pct1 = pc2;
     pc2 = pc1;
     pc1 = pct1;
   }
-
-
+/*
+  fprintf(stderr,"pCodeOptime2pCodes\n");
+  pc1->print(stderr,pc1);
+  pc2->print(stderr,pc2);
+*/
   if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_MOVFW) ){
 
     /*
@@ -446,9 +473,8 @@ void pCodeOptime2pCodes(pCode *pc1, pCode *pc2, pCode *pcfl_used, regs *reg, int
     */
 
     pCode *newpc;
-    //fprintf(stderr, "   CLRF/MOVFW. instruction after MOVFW is:\n");
+    fprintf(stderr, "   CLRF/MOVFW. instruction after MOVFW is:\n");
     pct1 = findNextInstruction(pc2->next);
-    //t->print(stderr,t);
 
     if(PCI(pct1)->op == POC_MOVWF) {
       newpc = newpCode(POC_CLRF, PCI(pct1)->pcop);
@@ -465,8 +491,16 @@ void pCodeOptime2pCodes(pCode *pc1, pCode *pc2, pCode *pcfl_used, regs *reg, int
     total_registers_saved++;  // debugging stats.
 
   } else if((PCI(pc1)->op == POC_CLRF) && (PCI(pc2)->op == POC_IORFW) ){
-    //fprintf(stderr, "   CLRF/IORFW.\n");
+    fprintf(stderr, "   CLRF/IORFW.\n");
+
+    pct2 = findNextInstruction(pc2->next);
 
+    if(pCodeSearchCondition(pct2, PCC_Z) > 0) {
+      pct2 = newpCode(POC_IORLW, newpCodeOpLit(0));
+      pct2->seq = pc2->seq;
+      PCI(pct2)->pcflow = PCFL(pcfl_used);
+      pCodeInsertAfter(pc1,pct2);
+    }
     Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
     total_registers_saved++;  // debugging stats.
 
@@ -475,18 +509,49 @@ void pCodeOptime2pCodes(pCode *pc1, pCode *pc2, pCode *pcfl_used, regs *reg, int
     pct2 = findNextInstruction(pc2->next);
 
     if(PCI(pc2)->op == POC_MOVFW) {
-      //fprintf(stderr, "   MOVWF/MOVFW. instruction after MOVFW is:\n");
-      //pct2->print(stderr,pct2);
+      /*
+       fprintf(stderr, "   MOVWF/MOVFW. instruction after MOVFW is:\n");
+       pct2->print(stderr,pct2);
+      */
 
       if(PCI(pct2)->op == POC_MOVWF) {
+       /*
+         Change:
+
+           movwf   reg
+
+           stuff...
+
+           movf    reg,w
+            movwf   reg2
+
+         To:
+
+           
+       */
        reg2 = getRegFromInstruction(pct2);
+       //if(reg2 && !regUsedinRange(pc1,pc2,reg2) && (reg2->type != REG_SFR)) {
        if(reg2 && !regUsedinRange(pc1,pc2,reg2)) {
-         pct2->seq = pc1->seq;
-         unlinkpCode(pct2);
-         pCodeInsertAfter(pc1,pct2);
-         Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
-         total_registers_saved++;  // debugging stats.
-         return;
+
+         if(pCodeSearchCondition(pct2, PCC_Z) < 1) {
+           pCode *pct3 = findNextInstruction(pct2->next);
+           fprintf(stderr,"ABCD\n");
+           pct2->seq = pc1->seq;
+           unlinkpCode(pct2);
+           pCodeInsertAfter(findPrevInstruction(pc1->prev),pct2);
+
+#define usesW(x)       ((x) && (isPCI(x)) && ( (PCI(x)->inCond & PCC_W) != 0))
+
+           if(usesW(pct3))
+             ; // Remove2pcodes(pcfl_used, pc1, NULL, reg, can_free);
+           else
+             Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
+
+           total_registers_saved++;  // debugging stats.
+           return 1;
+           } else {
+             //fprintf(stderr,"didn't optimize because Z bit is used\n");
+           }
        }
 /*
        fprintf(stderr, " couldn't optimize\n");
@@ -499,44 +564,89 @@ void pCodeOptime2pCodes(pCode *pc1, pCode *pc2, pCode *pcfl_used, regs *reg, int
     }
 
     pct1 = findPrevInstruction(pc1->prev);
-    if(pct1 && 
-       (PCI(pct1)->pcflow == PCI(pc1)->pcflow) && 
-       (PCI(pct1)->op == POC_MOVFW)) {
+    if(pct1 && (PCI(pct1)->pcflow == PCI(pc1)->pcflow)) {
 
-      reg1 = getRegFromInstruction(pct1);
-      if(reg1 && !regUsedinRange(pc1,pc2,reg1)) {
-       //fprintf(stderr, "   MOVF/MOVFW. \n");
-       /*
-         movf   reg1,w
-         movwf  reg
+      if ( (PCI(pct1)->op == POC_MOVFW) &&
+          (PCI(pc2)->op == POC_MOVFW)) {
 
-         stuff...
-         opcode reg,w
-       */
-       pct2 = newpCode(PCI(pc2)->op, PCI(pct1)->pcop);
-       pCodeInsertAfter(pc2, pct2);
-       PCI(pct2)->pcflow = PCFL(pcfl_used);
-       pct2->seq = pc2->seq;
+       reg1 = getRegFromInstruction(pct1);
+       if(reg1 && !regUsedinRange(pc1,pc2,reg1)) {
+         /*
+           fprintf(stderr, "   MOVF/MOVFW. \n");
+           fprintf(stderr, "     ...optimizing\n");
+         */
 
-       Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
-       Remove2pcodes(pcfl_used, pct1, NULL, reg1, 0);
-       total_registers_saved++;  // debugging stats.
+         /*
+           Change:
+
+           movf   reg1,w
+           movwf  reg
+
+           stuff...
+           movf   reg,w
+
+           To:
+
+           stuff...
+
+           movf   reg1,w
+
+           Or, if we're not deleting the register then the "To" is:
+
+           stuff...
 
+           movf   reg1,w
+           movwf  reg
+
+
+         */
+         pct2 = newpCode(PCI(pc2)->op, PCI(pct1)->pcop);
+         pCodeInsertAfter(pc2, pct2);
+         PCI(pct2)->pcflow = PCFL(pcfl_used);
+         pct2->seq = pc2->seq;
+
+         if(can_free) {
+           Remove2pcodes(pcfl_used, pc1, pc2, reg, can_free);
+         } else {
+           /* If we're not freeing the register then that means (probably)
+            * the register is needed somewhere else.*/
+           unlinkpCode(pc1);
+           pCodeInsertAfter(pct2, pc1);
+
+           Remove2pcodes(pcfl_used, pc2, NULL, reg, can_free);
+         }
+
+         Remove2pcodes(pcfl_used, pct1, NULL, reg1, 0);
+         total_registers_saved++;  // debugging stats.
+
+       }
+      } else if ( (PCI(pct1)->op == POC_MOVWF) &&
+          (PCI(pc2)->op == POC_MOVFW)) {
+       //fprintf(stderr,"movwf MOVWF/MOVFW\n");
+       if(optimize_level > 1 && can_free) {
+         pct2 = newpCode(POC_MOVFW, PCI(pc1)->pcop);
+         pCodeInsertAfter(pc2, pct2);
+         Remove2pcodes(pcfl_used, pc1, pc2, reg, 1);
+         total_registers_saved++;  // debugging stats.
+       }
       }
-    }
 
 
+    }
+
   }
 
+  return (total_registers_saved != t);
 }
 
 /*-----------------------------------------------------------------*
  * void pCodeRegOptimeRegUsage(pBlock *pb) 
  *-----------------------------------------------------------------*/
-void OptimizeRegUsage(set *fregs)
+void OptimizeRegUsage(set *fregs, int optimize_multi_uses, int optimize_level)
 {
   regs *reg;
   int used;
+  pCode *pc1=NULL, *pc2=NULL;
 
 
   while(fregs) {
@@ -550,7 +660,7 @@ void OptimizeRegUsage(set *fregs)
     reg = fregs->item;
     fregs = fregs->next;
 
-    if(reg->type == REG_SFR) {
+    if(reg->type == REG_SFR || reg->type == REG_STK) {
       //fprintf(stderr,"skipping SFR: %s\n",reg->name);
       continue;
     }
@@ -566,7 +676,6 @@ void OptimizeRegUsage(set *fregs)
        * instructions are examined. If possible, they're optimized out.
        */
 
-      pCode *pc1, *pc2;
 /*
       fprintf (stderr, "OptimizeRegUsage: %s  addr=0x%03x rIdx=0x%03x type=%d used=%d\n",
               reg->name,
@@ -588,7 +697,7 @@ void OptimizeRegUsage(set *fregs)
 
          //fprintf(stderr, "  and used in same flow\n");
 
-         pCodeOptime2pCodes(pc1, pc2, pcfl_used, reg, 1);
+         pCodeOptime2pCodes(pc1, pc2, pcfl_used, reg, 1,optimize_level);
 
        } else {
          // fprintf(stderr, "  and used in different flows\n");
@@ -599,10 +708,10 @@ void OptimizeRegUsage(set *fregs)
 
        /*
          register has been used twice without ever being assigned */
-       //fprintf(stderr,"WARNING %s: reg %s used without being assigned\n",__FUNCTION__,reg->name);
+       fprintf(stderr,"WARNING %s: reg %s used without being assigned\n",__FUNCTION__,reg->name);
 
       } else {
-       //fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
+       fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
        Remove2pcodes(pcfl_assigned, pc1, pc2, reg, 1);
        total_registers_saved++;  // debugging stats.
       }
@@ -613,13 +722,13 @@ void OptimizeRegUsage(set *fregs)
       if(used && !pcfl_used && pcfl_assigned) {
        pCode *pc;
 
-       //fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
+       fprintf(stderr,"WARNING %s: reg %s assigned without being used\n",__FUNCTION__,reg->name);
 
        pc = setFirstItem(reg->reglives.usedpCodes);
        while(pc) {
 
          pcfl_assigned = PCODE(PCI(pc)->pcflow);
-         Remove1pcode(pc, reg);
+         Remove1pcode(pc, reg,2);
 
          deleteSetItem (&(PCFL(pcfl_assigned)->registers), reg);
          /*
@@ -634,10 +743,43 @@ void OptimizeRegUsage(set *fregs)
        reg->wasUsed = 0;
 
        total_registers_saved++;  // debugging stats.
-      } else if(used > 2) {
+      } else if( (used > 2) && optimize_multi_uses) {
+
+       set *rset1=NULL;
+       set *rset2=NULL;
+       int searching=1;
+
+       pCodeFlow *pcfl1=NULL, *pcfl2=NULL;
 
        /* examine the number of times this register is used */
 
+
+       rset1 = reg->reglives.usedpCodes;
+       while(rset1 && searching) {
+
+         pc1 = rset1->item;
+         rset2 = rset1->next;
+
+         if(pc1 && isPCI(pc1) &&  ( (pcfl1 = PCI(pc1)->pcflow) != NULL) ) {
+
+           //while(rset2 && searching) {
+           if(rset2) {
+
+             pc2 = rset2->item;
+             if(pc2 && isPCI(pc2)  &&  ( (pcfl2 = PCI(pc2)->pcflow) != NULL) )  {
+               if(pcfl2 == pcfl1) {
+
+                 if(pCodeOptime2pCodes(pc1, pc2, pcfl_used, reg, 0,optimize_level))
+                   searching = 0;
+               }
+             }
+
+             //rset2 = rset2->next;
+             
+           }
+         }
+         rset1 = rset1->next;
+       }
       }
     }
 
@@ -647,26 +789,33 @@ void OptimizeRegUsage(set *fregs)
 /*-----------------------------------------------------------------*
  * void pCodeRegOptimeRegUsage(pBlock *pb) 
  *-----------------------------------------------------------------*/
-void pCodeRegOptimizeRegUsage(void)
+void pCodeRegOptimizeRegUsage(int level)
 {
 
-  int passes = 4;
+  int passes;
   int saved = 0;
   int t = total_registers_saved;
 
+  if(!register_optimization)
+    return;
+#define OPT_PASSES 4
+  passes = OPT_PASSES;
+
   do {
     saved = total_registers_saved;
 
     /* Identify registers used in one flow sequence */
-    OptimizeRegUsage(dynAllocRegs);
-    OptimizeRegUsage(dynStackRegs);
-    OptimizeRegUsage(dynDirectRegs);
+    OptimizeRegUsage(dynAllocRegs,level, (OPT_PASSES-passes));
+    OptimizeRegUsage(dynStackRegs,level, (OPT_PASSES-passes));
+    OptimizeRegUsage(dynDirectRegs,0, (OPT_PASSES-passes));
 
     if(total_registers_saved != saved)
-      fprintf(stderr, " *** Saved %d registers, total saved %d ***\n", total_registers_saved-saved,total_registers_saved);
-
+      fprintf(stderr, " *** pass %d, Saved %d registers, total saved %d ***\n", 
+             (1+OPT_PASSES-passes),total_registers_saved-saved,total_registers_saved);
+      
+    passes--;
 
-  } while( passes-- && (total_registers_saved != saved));
+  } while( passes && ((total_registers_saved != saved) || (passes==OPT_PASSES-1)) );
 
   if(total_registers_saved == t) 
     fprintf(stderr, "No registers saved on this pass\n");