[llvm] r189495 - PR16995: DebugInfo: Don't overwrite existing member lists when adding template arguments

[Eric Christopher]

On Wed, Aug 28, 2013 at 10:28 AM, David Blaikie <dblaikie at gmail.com> wrote:
> Author: dblaikie
> Date: Wed Aug 28 12:28:16 2013
> New Revision: 189495
>
> URL: http://llvm.org/viewvc/llvm-project?rev=189495&view=rev
> Log:
> PR16995: DebugInfo: Don't overwrite existing member lists when adding template arguments
>
> With the added debug assertions this fix is covered by existing Clang
> tests. (& found some other issues, also fixed)
>

This actually seems to be checking that we don't have a NULL array
being passed in and the debug checks are that we have a
super/identical set of elements when we're going to replace?

I do wish we could have a test that fails when the code isn't there.

> -  N->replaceOperandWith(10, Elements);
> +  if (Elements) {
> +#ifndef NDEBUG
> +    // Check that we're not dropping any elements on the floor here

Silly nit: Needs a '.'

> +    if (const MDNode *El = cast_or_null<MDNode>(N->getOperand(10))) {
> +      for (unsigned i = 0; i != El->getNumOperands(); ++i) {
> +        if (i == 0 && isa<ConstantInt>(El->getOperand(i)))
> +          continue;
> +        const MDNode *E = cast<MDNode>(El->getOperand(i));
> +        bool found = false;
> +        for (unsigned j = 0; !found && j != Elements.getNumElements(); ++j) {
> +          found = E == Elements.getElement(j);
> +        }
> +        assert(found && "Losing a member during member list replacement");
> +      }
> +    }
> +#endif
> +    N->replaceOperandWith(10, Elements);
> +  }
>    if (TParams)
>      N->replaceOperandWith(13, TParams);

Any reason we don't want the same check here? I haven't gone through
the path we're taking to get here from the bug to check.

Also, comments :)

-eric