[PATCH] D45736: [SimplifyLibcalls] Replace locked IO with unlocked IO

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 added a comment.

In https://reviews.llvm.org/D45736#1070347, @efriedma wrote:

> > So maybe somehow check if module has only static functions (+main)?
>
> You might be able to get this to work, but there are a lot of weird edge cases, and it wouldn't be very useful in practice; most programs have more than one source code file.
>
> The practical approach would be to use something like llvm::PointerMayBeCaptured to prove no other thread knows the value of the FILE*.


Code:
static void test(void) {

  FILE *f = fopen("file", "w");
  char s[10];
  fwrite(s, 10, 10, f);

}

int main(void) {

  capt_test();

}

static bool isInSingleThread(CallInst *CI, IRBuilder<> &B) {

  for (unsigned i = 0; i < CI->getNumOperands(); ++i) {
    Value *Op = CI->getOperand(i);
    if (Op->getType()->isPointerTy() && !isa<GlobalValue>(Op)) {
      errs() << "pty is " << i << " and "
             << PointerMayBeCaptured(Op, false, false) << "\n";
      if (PointerMayBeCaptured(Op, false, false))
        return false;
    }
  }
  
  return true;

}

I got that that pointers may be captured. Did I use it wrongly?


Repository:
  rL LLVM

https://reviews.llvm.org/D45736