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[llvm][documentation] Fix coroutines documentation #66420

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Merged
merged 2 commits into from
Sep 18, 2023
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[llvm][documentation] Fix coroutines documentation #66420

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71c5d85
[llvm][documentation] Fix coroutines documentation
Sep 12, 2023
8f4de77
Merge branch 'main' into coroutines_doc_fix
ChuanqiXu9 Sep 18, 2023
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16 changes: 11 additions & 5 deletions llvm/docs/Coroutines.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -385,7 +385,7 @@ Outlined resume part of the coroutine will reside in function `f.resume`:
entry:
%inc.spill.addr = getelementptr %f.frame, ptr %frame.ptr.resume, i64 0, i32 2
%inc.spill = load i32, ptr %inc.spill.addr, align 4
%inc = add i32 %n.val, 1
%inc = add i32 %inc.spill, 1
store i32 %inc, ptr %inc.spill.addr, align 4
tail call void @print(i32 %inc)
ret void
Expand Down Expand Up @@ -494,8 +494,13 @@ as the code in the previous section):
i8 1, label %cleanup]

In this case, the coroutine frame would include a suspend index that will
indicate at which suspend point the coroutine needs to resume. The resume
function will use an index to jump to an appropriate basic block and will look
indicate at which suspend point the coroutine needs to resume.

.. code-block:: llvm

%f.frame = type { ptr, ptr, i32, i32 }

The resume function will use an index to jump to an appropriate basic block and will look
as follows:

.. code-block:: llvm
Expand All @@ -507,10 +512,11 @@ as follows:
%switch = icmp eq i8 %index, 0
%n.addr = getelementptr inbounds %f.Frame, ptr %FramePtr, i64 0, i32 3
%n = load i32, ptr %n.addr, align 4

br i1 %switch, label %loop.resume, label %loop

loop.resume:
%sub = xor i32 %n, -1
%sub = sub nsw i32 0, %n
call void @print(i32 %sub)
br label %suspend
loop:
Expand Down Expand Up @@ -586,7 +592,7 @@ correct resume point):
%save2 = call token @llvm.coro.save(ptr %hdl)
call void @async_op2(ptr %hdl)
%suspend2 = call i1 @llvm.coro.suspend(token %save2, i1 false)
switch i8 %suspend1, label %suspend [i8 0, label %resume2
switch i8 %suspend2, label %suspend [i8 0, label %resume2
i8 1, label %cleanup]

.. _coroutine promise:
Expand Down