+ if (!port->peep.getRegsRead || !port->peep.getRegsWritten)
+ return;
+
+ /* If this was an interrupt handler using bank 0 that called another */
+ /* function, then all registers must be saved; nothing to optimized. */
+ if (IFFUNC_ISISR (sym->type) && IFFUNC_HASFCALL(sym->type)
+ && !FUNC_REGBANK(sym->type))
+ return;
+
+ /* There are no push/pops to optimize if not callee-saves or ISR */
+ if (!(FUNC_CALLEESAVES (sym->type) || FUNC_ISISR (sym->type)))
+ return;
+
+ /* If there were stack parameters, we cannot optimize without also */
+ /* fixing all of the stack offsets; this is too dificult to consider. */
+ if (FUNC_HASSTACKPARM(sym->type))
+ return;
+
+ /* Compute the registers actually used */
+ regsUsed = newBitVect (mcs51_nRegs);
+ regsUsedPrologue = newBitVect (mcs51_nRegs);
+ while (lnp)
+ {
+ if (lnp->ic && lnp->ic->op == FUNCTION)
+ regsUsedPrologue = bitVectUnion (regsUsedPrologue, port->peep.getRegsWritten(lnp));
+ else
+ regsUsed = bitVectUnion (regsUsed, port->peep.getRegsWritten(lnp));
+
+ if (lnp->ic && lnp->ic->op == FUNCTION && lnp->prev
+ && lnp->prev->ic && lnp->prev->ic->op == ENDFUNCTION)
+ break;
+ if (!lnp->prev)
+ break;
+ lnp = lnp->prev;
+ }
+
+ if (bitVectBitValue (regsUsedPrologue, CND_IDX)
+ && !bitVectBitValue (regsUsed, CND_IDX))
+ {
+ regsUsed = bitVectUnion (regsUsed, regsUsedPrologue);
+ if (IFFUNC_ISISR (sym->type) && !FUNC_REGBANK(sym->type)
+ && !sym->stack)
+ bitVectUnSetBit (regsUsed, CND_IDX);
+ }
+ else
+ regsUsed = bitVectUnion (regsUsed, regsUsedPrologue);
+
+ /* If this was an interrupt handler that called another function */
+ /* function, then assume A, B, DPH, & DPL may be modified by it. */
+ if (IFFUNC_ISISR (sym->type) && IFFUNC_HASFCALL(sym->type))
+ {
+ regsUsed = bitVectSetBit (regsUsed, DPL_IDX);
+ regsUsed = bitVectSetBit (regsUsed, DPH_IDX);
+ regsUsed = bitVectSetBit (regsUsed, B_IDX);
+ regsUsed = bitVectSetBit (regsUsed, A_IDX);
+ regsUsed = bitVectSetBit (regsUsed, CND_IDX);
+ }
+
+ /* Remove the unneeded push/pops */
+ regsUnneeded = newBitVect (mcs51_nRegs);
+ while (lnp)
+ {
+ if (lnp->ic && (lnp->ic->op == FUNCTION || lnp->ic->op == ENDFUNCTION))
+ {
+ if (!strncmp(lnp->line, "push", 4))
+ {
+ idx = bitVectFirstBit (port->peep.getRegsRead(lnp));
+ if (idx>=0 && !bitVectBitValue (regsUsed, idx))
+ {
+ connectLine (lnp->prev, lnp->next);
+ regsUnneeded = bitVectSetBit (regsUnneeded, idx);
+ }
+ }
+ if (!strncmp(lnp->line, "pop", 3) || !strncmp(lnp->line, "mov", 3))
+ {
+ idx = bitVectFirstBit (port->peep.getRegsWritten(lnp));
+ if (idx>=0 && !bitVectBitValue (regsUsed, idx))
+ {
+ connectLine (lnp->prev, lnp->next);
+ regsUnneeded = bitVectSetBit (regsUnneeded, idx);
+ }
+ }
+ }
+ lnp = lnp->next;
+ }
+
+ for (idx = 0; idx < regsUnneeded->size; idx++)
+ if (bitVectBitValue (regsUnneeded, idx))
+ emitcode ("", ";\teliminated unneeded push/pop %s", mcs51_regWithIdx (idx)->dname);
+
+ freeBitVect (regsUnneeded);
+ freeBitVect (regsUsed);
+ freeBitVect (regsUsedPrologue);