SimplifyLibCalls.cpp

          if (!isa<PointerType>(FTy->getReturnType()))
            continue;
          setDoesNotThrow(F);
          setDoesNotAlias(F, 0);
        }
      case 'h':
        if ((NameLen == 5 && !strcmp(NameStr, "htonl")) ||
            (NameLen == 5 && !strcmp(NameStr, "htons"))) {
          setDoesNotThrow(F);
          setDoesNotAccessMemory(F);
        }
        break;
      case 'n':
        if ((NameLen == 5 && !strcmp(NameStr, "ntohl")) ||
            (NameLen == 5 && !strcmp(NameStr, "ntohs"))) {
          setDoesNotThrow(F);
          setDoesNotAccessMemory(F);
        }
      case '_':
        if ((NameLen == 8 && !strcmp(NameStr, "__strdup")) ||
            (NameLen == 9 && !strcmp(NameStr, "__strndup"))) {
          if (FTy->getNumParams() < 1 ||
              !isa<PointerType>(FTy->getReturnType()) ||
              !isa<PointerType>(FTy->getParamType(0)))
            continue;
          setDoesNotThrow(F);
          setDoesNotAlias(F, 0);
          setDoesNotCapture(F, 1);
        } else if (NameLen == 10 && !strcmp(NameStr, "__strtok_r")) {
          if (FTy->getNumParams() != 3 ||
              !isa<PointerType>(FTy->getParamType(1)))
            continue;
          setDoesNotThrow(F);
          setDoesNotCapture(F, 2);
        } else if (NameLen == 8 && !strcmp(NameStr, "_IO_getc")) {
          if (FTy->getNumParams() != 1 ||
              !isa<PointerType>(FTy->getParamType(0)))
            continue;
          setDoesNotThrow(F);
          setDoesNotCapture(F, 1);
        } else if (NameLen == 8 && !strcmp(NameStr, "_IO_putc")) {
          if (FTy->getNumParams() != 2 ||
              !isa<PointerType>(FTy->getParamType(1)))
            continue;
          setDoesNotThrow(F);
          setDoesNotCapture(F, 2);
        }
      case 1:
        if (NameLen == 15 && !strcmp(NameStr, "\1__isoc99_scanf")) {
          if (FTy->getNumParams() < 1 ||
              !isa<PointerType>(FTy->getParamType(0)))
            continue;
          setDoesNotThrow(F);
          setDoesNotCapture(F, 1);
        } else if (NameLen == 16 && !strcmp(NameStr, "\1__isoc99_sscanf")) {
          if (FTy->getNumParams() < 1 ||
              !isa<PointerType>(FTy->getParamType(0)))
            continue;
          setDoesNotThrow(F);
          setDoesNotCapture(F, 1);
          setDoesNotCapture(F, 2);
        }
        break;
    }
  }
  return Modified;
}

// TODO:
//   Additional cases that we need to add to this file:
//
// cbrt:
//   * cbrt(expN(X))  -> expN(x/3)
//   * cbrt(sqrt(x))  -> pow(x,1/6)
//   * cbrt(sqrt(x))  -> pow(x,1/9)
//
// cos, cosf, cosl:
//   * cos(-x)  -> cos(x)
//
// exp, expf, expl:
//   * exp(log(x))  -> x
//
// log, logf, logl:
//   * log(exp(x))   -> x
//   * log(x**y)     -> y*log(x)
//   * log(exp(y))   -> y*log(e)
//   * log(exp2(y))  -> y*log(2)
//   * log(exp10(y)) -> y*log(10)
//   * log(sqrt(x))  -> 0.5*log(x)
//   * log(pow(x,y)) -> y*log(x)
//
// lround, lroundf, lroundl:
//   * lround(cnst) -> cnst'
//
// memcmp:
//   * memcmp(x,y,l)   -> cnst
//      (if all arguments are constant and strlen(x) <= l and strlen(y) <= l)
//
// pow, powf, powl:
//   * pow(exp(x),y)  -> exp(x*y)
//   * pow(sqrt(x),y) -> pow(x,y*0.5)
//   * pow(pow(x,y),z)-> pow(x,y*z)
//
// puts:
//   * puts("") -> putchar("\n")
//
// round, roundf, roundl:
//   * round(cnst) -> cnst'
//
// signbit:
//   * signbit(cnst) -> cnst'
//   * signbit(nncst) -> 0 (if pstv is a non-negative constant)
//
// sqrt, sqrtf, sqrtl:
//   * sqrt(expN(x))  -> expN(x*0.5)
//   * sqrt(Nroot(x)) -> pow(x,1/(2*N))
//   * sqrt(pow(x,y)) -> pow(|x|,y*0.5)
//
// stpcpy:
//   * stpcpy(str, "literal") ->
//           llvm.memcpy(str,"literal",strlen("literal")+1,1)
// strrchr:
//   * strrchr(s,c) -> reverse_offset_of_in(c,s)
//      (if c is a constant integer and s is a constant string)
//   * strrchr(s1,0) -> strchr(s1,0)
//
// strncat:
//   * strncat(x,y,0) -> x
//   * strncat(x,y,0) -> x (if strlen(y) = 0)
//   * strncat(x,y,l) -> strcat(x,y) (if y and l are constants an l > strlen(y))
//
// strncpy:
//   * strncpy(d,s,0) -> d
//   * strncpy(d,s,l) -> memcpy(d,s,l,1)
//      (if s and l are constants)
//
// strpbrk:
//   * strpbrk(s,a) -> offset_in_for(s,a)
//      (if s and a are both constant strings)
//   * strpbrk(s,"") -> 0
//   * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
//
// strspn, strcspn:
//   * strspn(s,a)   -> const_int (if both args are constant)
//   * strspn("",a)  -> 0
//   * strspn(s,"")  -> 0
//   * strcspn(s,a)  -> const_int (if both args are constant)
//   * strcspn("",a) -> 0
//   * strcspn(s,"") -> strlen(a)
//
// strstr:
//   * strstr(x,x)  -> x
//   * strstr(s1,s2) -> offset_of_s2_in(s1)
//       (if s1 and s2 are constant strings)
//
// tan, tanf, tanl:
//   * tan(atan(x)) -> x
//
// trunc, truncf, truncl:
//   * trunc(cnst) -> cnst'
//
//