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Gor Nishanov 026990c96b [Coroutines] Part11: Add final suspend handling.
Summary:
A frontend may designate a particular suspend to be final, by setting the second argument of the coro.suspend intrinsic to true. Such a suspend point has two properties:

* it is possible to check whether a suspended coroutine is at the final suspend point via coro.done intrinsic;
* a resumption of a coroutine stopped at the final suspend point leads to undefined behavior. The only possible action for a coroutine at a final suspend point is destroying it via coro.destroy intrinsic.

This patch adds final suspend handling logic to CoroEarly and CoroSplit passes.
Now, the final suspend point example from docs\Coroutines.rst compiles and produces expected result (see test/Transform/Coroutines/ex5.ll).

Reviewers: majnemer

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D24068

llvm-svn: 280646
2016-09-05 04:44:30 +00:00

74 lines
2.1 KiB
LLVM

; Fifth example from Doc/Coroutines.rst (final suspend)
; RUN: opt < %s -O2 -enable-coroutines -S | FileCheck %s
define i8* @f(i32 %n) {
entry:
%id = call token @llvm.coro.id(i32 0, i8* null, i8* null, i8* null)
%size = call i32 @llvm.coro.size.i32()
%alloc = call i8* @malloc(i32 %size)
%hdl = call noalias i8* @llvm.coro.begin(token %id, i8* %alloc)
br label %while.cond
while.cond:
%n.val = phi i32 [ %n, %entry ], [ %dec, %while.body ]
%cmp = icmp sgt i32 %n.val, 0
br i1 %cmp, label %while.body, label %while.end
while.body:
%dec = add nsw i32 %n.val, -1
call void @print(i32 %n.val) #4
%s = call i8 @llvm.coro.suspend(token none, i1 false)
switch i8 %s, label %suspend [i8 0, label %while.cond
i8 1, label %cleanup]
while.end:
%s.final = call i8 @llvm.coro.suspend(token none, i1 true)
switch i8 %s.final, label %suspend [i8 0, label %trap
i8 1, label %cleanup]
trap:
call void @llvm.trap()
unreachable
cleanup:
%mem = call i8* @llvm.coro.free(token %id, i8* %hdl)
call void @free(i8* %mem)
br label %suspend
suspend:
call void @llvm.coro.end(i8* %hdl, i1 false)
ret i8* %hdl
}
declare noalias i8* @malloc(i32)
declare void @print(i32)
declare void @llvm.trap()
declare void @free(i8* nocapture)
declare token @llvm.coro.id( i32, i8*, i8*, i8*)
declare i32 @llvm.coro.size.i32()
declare i8* @llvm.coro.begin(token, i8*)
declare token @llvm.coro.save(i8*)
declare i8 @llvm.coro.suspend(token, i1)
declare i8* @llvm.coro.free(token, i8*)
declare void @llvm.coro.end(i8*, i1)
; CHECK-LABEL: @main
define i32 @main() {
entry:
%hdl = call i8* @f(i32 4)
br label %while
while:
call void @llvm.coro.resume(i8* %hdl)
%done = call i1 @llvm.coro.done(i8* %hdl)
br i1 %done, label %end, label %while
end:
call void @llvm.coro.destroy(i8* %hdl)
ret i32 0
; CHECK: call void @print(i32 4)
; CHECK: call void @print(i32 3)
; CHECK: call void @print(i32 2)
; CHECK: call void @print(i32 1)
; CHECK: ret i32 0
}
declare i1 @llvm.coro.done(i8*)
declare void @llvm.coro.resume(i8*)
declare void @llvm.coro.destroy(i8*)