hoy added inline comments.
================
Comment at: llvm/include/llvm/IR/Intrinsics.td:1309
+// Intrinsic to obtain the address of a thread_local variable.
+def int_threadlocal : Intrinsic<[llvm_ptr_ty], [llvm_ptr_ty]>;
+
----------------
lxfind wrote:
> hoy wrote:
> > lxfind wrote:
> > > hoy wrote:
> > > > hoy wrote:
> > > > > With the intrinsic, can TLS variable reference in the same coroutine
> > > > > or regular routine be DCE-ed anymore?
> > > > Sorry, I meant CSE-ed.
> > > Since the intrinsics does not have readnone attribute, it won't be CSE-ed
> > > before CoroSplit.
> > > However after CoroSplit, it will be lowered back to the direct reference
> > > of the TLS, and will be CSE-ed by latter passes.
> > > I can add a test function to demonstrate that too.
> > Sounds good. Can you please point out what optimization passes CSE-ed tls
> > reference without this implementation? I'm wondering if those optimizations
> > can be postponed to after CoroSplit.
> To clarify, it wasn't just CSE that would merge the references of the same
> TLS.
> For instance, without this patch, a reference to "tls_variable" will just be
> "@tls_variable". For code like this:
>
> @tls_variable = internal thread_local global i32 0, align 4
>
> define i32* @foo(){
> ret i32* @tls_variable
> }
>
> define void @bar() {
> %tls1 = call i32* @foo()
> ..coro.suspend..
> %tls2 = call i32* @foo()
> %cond = icmp eq i32* %tls1, %tls2
> }
>
> When foo() is inlined into bar(), all uses of %tls1 will be replaced with
> @tls_variable.
Thanks for the explanation. I have a dumb question. Why isn't corosplit placed
at the very beginning of the pipeline?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D92661/new/
https://reviews.llvm.org/D92661
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