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2d33745172
Summary:
The purpose of coro.end intrinsic is to allow frontends to mark the cleanup and
other code that is only relevant during the initial invocation of the coroutine
and should not be present in resume and destroy parts.
In landing pads coro.end is replaced with an appropriate instruction to unwind to
caller. The handling of coro.end differs depending on whether the target is
using landingpad or WinEH exception model.
For landingpad based exception model, it is expected that frontend uses the
`coro.end`_ intrinsic as follows:
```
ehcleanup:
%InResumePart = call i1 @llvm.coro.end(i8* null, i1 true)
br i1 %InResumePart, label %eh.resume, label %cleanup.cont
cleanup.cont:
; rest of the cleanup
eh.resume:
%exn = load i8*, i8** %exn.slot, align 8
%sel = load i32, i32* %ehselector.slot, align 4
%lpad.val = insertvalue { i8*, i32 } undef, i8* %exn, 0
%lpad.val29 = insertvalue { i8*, i32 } %lpad.val, i32 %sel, 1
resume { i8*, i32 } %lpad.val29
```
The `CoroSpit` pass replaces `coro.end` with ``True`` in the resume functions,
thus leading to immediate unwind to the caller, whereas in start function it
is replaced with ``False``, thus allowing to proceed to the rest of the cleanup
code that is only needed during initial invocation of the coroutine.
For Windows Exception handling model, a frontend should attach a funclet bundle
referring to an enclosing cleanuppad as follows:
```
ehcleanup:
%tok = cleanuppad within none []
%unused = call i1 @llvm.coro.end(i8* null, i1 true) [ "funclet"(token %tok) ]
cleanupret from %tok unwind label %RestOfTheCleanup
```
The `CoroSplit` pass, if the funclet bundle is present, will insert
``cleanupret from %tok unwind to caller`` before
the `coro.end`_ intrinsic and will remove the rest of the block.
Reviewers: majnemer
Reviewed By: majnemer
Subscribers: llvm-commits, mehdi_amini
Differential Revision: https://reviews.llvm.org/D25543
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297223 91177308-0d34-0410-b5e6-96231b3b80d8
60 lines
1.6 KiB
LLVM
60 lines
1.6 KiB
LLVM
; First example from Doc/Coroutines.rst (two block loop)
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; RUN: opt < %s -enable-coroutines -O2 -S | FileCheck %s
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define i8* @f(i32 %n) {
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entry:
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%id = call token @llvm.coro.id(i32 0, i8* null, i8* null, i8* null)
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%size = call i32 @llvm.coro.size.i32()
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%alloc = call i8* @malloc(i32 %size)
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%hdl = call i8* @llvm.coro.begin(token %id, i8* %alloc)
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br label %loop
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loop:
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%n.val = phi i32 [ %n, %entry ], [ %inc, %resume ]
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call void @print(i32 %n.val)
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%0 = call i8 @llvm.coro.suspend(token none, i1 false)
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switch i8 %0, label %suspend [i8 0, label %resume
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i8 1, label %cleanup]
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resume:
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%inc = add i32 %n.val, 1
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br label %loop
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cleanup:
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%mem = call i8* @llvm.coro.free(token %id, i8* %hdl)
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call void @free(i8* %mem)
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br label %suspend
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suspend:
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call i1 @llvm.coro.end(i8* %hdl, i1 0)
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ret i8* %hdl
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}
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; CHECK-LABEL: @main(
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define i32 @main() {
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entry:
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%hdl = call i8* @f(i32 4)
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call void @llvm.coro.resume(i8* %hdl)
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call void @llvm.coro.resume(i8* %hdl)
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call void @llvm.coro.destroy(i8* %hdl)
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ret i32 0
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; CHECK: entry:
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; CHECK: call void @print(i32 4)
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; CHECK: call void @print(i32 5)
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; CHECK: call void @print(i32 6)
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; CHECK: ret i32 0
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}
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declare token @llvm.coro.id(i32, i8*, i8*, i8*)
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declare i8* @llvm.coro.alloc(token)
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declare i8* @llvm.coro.free(token, i8*)
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declare i32 @llvm.coro.size.i32()
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declare i8 @llvm.coro.suspend(token, i1)
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declare void @llvm.coro.resume(i8*)
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declare void @llvm.coro.destroy(i8*)
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declare i8* @llvm.coro.begin(token, i8*)
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declare i1 @llvm.coro.end(i8*, i1)
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declare noalias i8* @malloc(i32)
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declare void @print(i32)
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declare void @free(i8*)
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