Hi Rafael,
Do you think we could rely for this case on post commit review?
Cheers,
Vassil
On 04/24/2014 08:52 PM, Rafael Espíndola wrote:
ping 3
On 24 March 2014 00:01, Rafael Espíndola <[email protected]> wrote:
ping 2
On 17 March 2014 06:59, Vassil Vassilev <[email protected]> wrote:
ping...
On 03/11/2014 01:05 PM, Rafael Espíndola wrote:
I am not sure I understand the intended semantics of the UnnamedAddr
argument to GetOrCreateLLVMGlobal. Is it “this use does not care about the
specific address”? Because, if so, the (existing) logic is completely
backwards: we need to be *clearing* the flag on the global if the argument
is ever *false*. And that seems like the most reasonable semantics,
frankly.
Also, the idea in the existing code that all runtime variables are
unnamed_addr seems bogus to me. __dso_handle is a specific example of a
variable whose address value *is* semantically important. This sort of
thing would be important if there were any plausible transformations at all
that involve unnamed_addr on external variable declarations.
Also, the assertion is wrong: if something introduces a “runtime"
declaration (e.g. by just declaring and using a global variable with the
right name) before CodeGen emits its first intrinsic use of it, the
declaration will not be marked unnamed_addr.
So, basically, right now, this entire code path is useless and wrong. Is
there a plan to apply it in situations where it wouldn’t be useless, i.e. to
non-runtime user declarations?
So, on how the patch is organized:
* The structure the patch uses is that when the variable is first
created, its unnamed_addr is set to the value of the argument.
* We then check that no user expect that a variable is unnamed_addr
when in fact it isn't. I tried to make the check more strict by
asserting that Entry->getUnnamedAddr() == UnnamedAddr, but that fails
deep down in some objc cases that create runtime variables and access
them as regular ones.
But to the more important point: Should we be adding unnamed_addr in
the first place? I am not sure. Back in
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20110110/037796.html
Chris asked if we should. I could not find the entire discussion (the
patch that ended up being committed is simpler) and I am still not
sure exactly when CreateRuntimeVariable should be used.
An alternative patch that simply never sets it in
CreateRuntimeVariable is attached.
Cheers,
Rafael
_______________________________________________
cfe-commits mailing list
[email protected]
http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
