[coro async] Disable lifetime.start sinking for ABI::Async and ABI::Retcon

It does not handle loops correctly i.e it moves the lifetime.start
intrinsic into a loop rendering the stack object as not alive for part
of the loop.

```
  entry:
    %obj = alloca i8
    lifetime.start(%obj)

    br loop

  loop:
    coro.suspend()
    escape(%obj)
    cond_br %cond, label %exit, label loop

    br loop

  exit:
    lifetime.end(%obj

```

After sinking:

```
  entry:
    %obj = alloca i8
    br loop

  loop:
    coro.suspend()
    lifetime.start(%obj)
    escape(%obj)
    cond_br %cond, label %exit, label loop

    br loop

  exit:
    lifetime.end(%obj

```

rdar://83411917

Differential Revision: https://reviews.llvm.org/D110953

diff --git a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
index ea0b65a..ee4d99d 100644 (file)
--- a/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroFrame.cpp
@@ -2670,7 +2670,10 @@ void coro::buildCoroutineFrame(Function &F, Shape &Shape) {
     }
   }
 
-  sinkLifetimeStartMarkers(F, Shape, Checker);
+  if (Shape.ABI != coro::ABI::Async && Shape.ABI != coro::ABI::Retcon &&
+      Shape.ABI != coro::ABI::RetconOnce)
+    sinkLifetimeStartMarkers(F, Shape, Checker);
+
   if (Shape.ABI != coro::ABI::Async || !Shape.CoroSuspends.empty())
     collectFrameAllocas(F, Shape, Checker, FrameData.Allocas);
   LLVM_DEBUG(dumpAllocas(FrameData.Allocas));

diff --git a/llvm/test/Transforms/Coroutines/coro-async-addr-lifetime-start-bug.ll b/llvm/test/Transforms/Coroutines/coro-async-addr-lifetime-start-bug.ll
new file mode 100644 (file)
index 0000000..bcfaaa6
--- /dev/null
+++ b/llvm/test/Transforms/Coroutines/coro-async-addr-lifetime-start-bug.ll
@@ -0,0 +1,115 @@
+; RUN: opt < %s -enable-coroutines -passes='default<O0>' -S | FileCheck --check-prefixes=CHECK %s
+; RUN: opt < %s -enable-coroutines -O0 -S | FileCheck --check-prefixes=CHECK %s
+
+target datalayout = "p:64:64:64"
+
+%async.task = type { i64 }
+%async.actor = type { i64 }
+%async.fp = type <{ i32, i32 }>
+
+%async.ctxt = type { i8*, void (i8*, %async.task*, %async.actor*)* }
+
+; The async callee.
+@my_other_async_function_fp = external global <{ i32, i32 }>
+declare void @my_other_async_function(i8* %async.ctxt)
+
+@my_async_function_fp = constant <{ i32, i32 }>
+  <{ i32 trunc ( ; Relative pointer to async function
+       i64 sub (
+         i64 ptrtoint (void (i8*)* @my_async_function to i64),
+         i64 ptrtoint (i32* getelementptr inbounds (<{ i32, i32 }>, <{ i32, i32 }>* @my_async_function_fp, i32 0, i32 1) to i64)
+       )
+     to i32),
+     i32 128    ; Initial async context size without space for frame
+}>
+
+define swiftcc void @my_other_async_function_fp.apply(i8* %fnPtr, i8* %async.ctxt) {
+  %callee = bitcast i8* %fnPtr to void(i8*)*
+  tail call swiftcc void %callee(i8* %async.ctxt)
+  ret void
+}
+
+declare void @escape(i64*)
+declare void @store_resume(i8*)
+declare i1 @exitLoop()
+define i8* @resume_context_projection(i8* %ctxt) {
+entry:
+  %resume_ctxt_addr = bitcast i8* %ctxt to i8**
+  %resume_ctxt = load i8*, i8** %resume_ctxt_addr, align 8
+  ret i8* %resume_ctxt
+}
+
+define swiftcc void @my_async_function(i8* swiftasync %async.ctxt) {
+entry:
+  %escaped_addr = alloca i64
+
+  %id = call token @llvm.coro.id.async(i32 128, i32 16, i32 0,
+          i8* bitcast (<{i32, i32}>* @my_async_function_fp to i8*))
+  %hdl = call i8* @llvm.coro.begin(token %id, i8* null)
+  %ltb = bitcast i64* %escaped_addr to i8*
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %ltb)
+  br label %callblock
+
+
+callblock:
+
+  %callee_context = call i8* @context_alloc()
+
+  %resume.func_ptr = call i8* @llvm.coro.async.resume()
+  call void @store_resume(i8* %resume.func_ptr)
+  %resume_proj_fun = bitcast i8*(i8*)* @resume_context_projection to i8*
+  %callee = bitcast void(i8*)* @asyncSuspend to i8*
+  %res = call {i8*, i8*, i8*} (i32, i8*, i8*, ...) @llvm.coro.suspend.async(i32 0,
+                                                  i8* %resume.func_ptr,
+                                                  i8* %resume_proj_fun,
+                                                  void (i8*, i8*)* @my_other_async_function_fp.apply,
+                                                  i8* %callee, i8* %callee_context)
+  call void @escape(i64* %escaped_addr)
+  %exitCond = call i1 @exitLoop()
+
+;; We used to move the lifetime.start intrinsic here =>
+;; This exposes two bugs:
+;  1.) The code should use the basic block start not end as insertion point
+;  More problematically:
+;  2.) The code marks the stack object as not alive for part of the loop.
+
+  br i1 %exitCond, label %loop_exit, label %loop
+  %res2 = call {i8*, i8*, i8*} (i32, i8*, i8*, ...) @llvm.coro.suspend.async(i32 0,
+                                                  i8* %resume.func_ptr,
+                                                  i8* %resume_proj_fun,
+                                                  void (i8*, i8*)* @my_other_async_function_fp.apply,
+                                                  i8* %callee, i8* %callee_context)
+ 
+  %exitCond2 = call i1 @exitLoop()
+  br i1 %exitCond2, label %loop_exit, label %loop
+
+loop:
+  br label %callblock
+
+loop_exit:
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %ltb)
+  call i1 (i8*, i1, ...) @llvm.coro.end.async(i8* %hdl, i1 false)
+  unreachable
+}
+
+; CHECK: define {{.*}} void @my_async_function.resume.0(
+; CHECK-NOT:  call void @llvm.lifetime.start.p0i8(i64 4, i8* %3)
+; CHECK:  br i1 %exitCond, label %loop_exit, label %loop
+; CHECK: lifetime.end
+; CHECK: }
+
+declare { i8*, i8*, i8*, i8* } @llvm.coro.suspend.async.sl_p0i8p0i8p0i8p0i8s(i32, i8*, i8*, ...)
+declare i8* @llvm.coro.prepare.async(i8*)
+declare token @llvm.coro.id.async(i32, i32, i32, i8*)
+declare i8* @llvm.coro.begin(token, i8*)
+declare i1 @llvm.coro.end.async(i8*, i1, ...)
+declare i1 @llvm.coro.end(i8*, i1)
+declare {i8*, i8*, i8*} @llvm.coro.suspend.async(i32, i8*, i8*, ...)
+declare i8* @context_alloc()
+declare void @llvm.coro.async.context.dealloc(i8*)
+declare swiftcc void @asyncSuspend(i8*)
+declare i8* @llvm.coro.async.resume()
+declare void @llvm.coro.async.size.replace(i8*, i8*)
+declare void @llvm.lifetime.start.p0i8(i64 immarg, i8* nocapture) #0
+declare void @llvm.lifetime.end.p0i8(i64 immarg, i8* nocapture) #0
+attributes #0 = { argmemonly nofree nosync nounwind willreturn }