types.c

#include "defs.h"
#include "data.h"
#include "decl.h"

// Types and type handling
// Copyright (c) 2019 Warren Toomey, GPL3

// Given two primitive types,
// return true if they are compatible,
// false otherwise. Also return either
// zero or an A_WIDEN operation if one
// has to be widened to match the other.
// If onlyright is true, only widen left to right.
int type_compatible(int *left, int *right, int onlyright) {
  int leftsize, rightsize;

  // Same types, they are compatible
  if (*left == *right) {
    *left = *right = 0;
    return (1);
  }
  // Get the sizes for each type
  leftsize = genprimsize(*left);
  rightsize = genprimsize(*right);

  // Types with zero size are not
  // not compatible with anything
  if ((leftsize == 0) || (rightsize == 0))
    return (0);

  // Widen types as required
  if (leftsize < rightsize) {
    *left = A_WIDEN;
    *right = 0;
    return (1);
  }
  if (rightsize < leftsize) {
    if (onlyright)
      return (0);
    *left = 0;
    *right = A_WIDEN;
    return (1);
  }
  // Anything remaining is the same size
  // and thus compatible
  *left = *right = 0;
  return (1);
}

// Given a primitive type, return
// the type which is a pointer to it
int pointer_to(int type) {
  int newtype;
  switch (type) {
    case P_VOID:
      newtype = P_VOIDPTR;
      break;
    case P_CHAR:
      newtype = P_CHARPTR;
      break;
    case P_INT:
      newtype = P_INTPTR;
      break;
    case P_LONG:
      newtype = P_LONGPTR;
      break;
    default:
      fatald("Unrecognised in pointer_to: type", type);
  }
  return (newtype);
}

// Given a primitive pointer type, return
// the type which it points to
int value_at(int type) {
  int newtype;
  switch (type) {
    case P_VOIDPTR:
      newtype = P_VOID;
      break;
    case P_CHARPTR:
      newtype = P_CHAR;
      break;
    case P_INTPTR:
      newtype = P_INT;
      break;
    case P_LONGPTR:
      newtype = P_LONG;
      break;
    default:
      fatald("Unrecognised in value_at: type", type);
  }
  return (newtype);
}