From 1b6aec8e2562e494431b968bad0884e978bc4e2b Mon Sep 17 00:00:00 2001
From: Gor Nishanov <GorNishanov@gmail.com>
Date: Sat, 8 Oct 2016 00:22:50 +0000
Subject: [coroutines] Store an address of destroy OR cleanup part in the
 coroutine frame.

Summary:
If heap allocation of a coroutine is elided, we need to make sure that we will update an address stored in the coroutine frame from f.destroy to f.cleanup.
Before this change, CoroSplit synthesized these stores after coro.begin:

```
    store void (%f.Frame*)* @f.resume, void (%f.Frame*)** %resume.addr
    store void (%f.Frame*)* @f.destroy, void (%f.Frame*)** %destroy.addr

```

In those cases where we did heap elision, but were not able to devirtualize all indirect calls, destroy call will attempt to "free" the coroutine frame stored on the stack. Oops.

Now we use select to put an appropriate coroutine subfunction in the destroy slot. As bellow:

```
    store void (%f.Frame*)* @f.resume, void (%f.Frame*)** %resume.addr
    %0 = select i1 %need.alloc, void (%f.Frame*)* @f.destroy, void (%f.Frame*)* @f.cleanup
    store void (%f.Frame*)* %0, void (%f.Frame*)** %destroy.addr
```

Reviewers: majnemer

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D25377

llvm-svn: 283625
---
 llvm/test/Transforms/Coroutines/coro-split-00.ll | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

(limited to 'llvm/test/Transforms/Coroutines')

diff --git a/llvm/test/Transforms/Coroutines/coro-split-00.ll b/llvm/test/Transforms/Coroutines/coro-split-00.ll
index 7f933e03989..12aec27b2fe 100644
--- a/llvm/test/Transforms/Coroutines/coro-split-00.ll
+++ b/llvm/test/Transforms/Coroutines/coro-split-00.ll
@@ -4,9 +4,17 @@
 define i8* @f() "coroutine.presplit"="1" {
 entry:
   %id = call token @llvm.coro.id(i32 0, i8* null, i8* null, i8* null)
+  %need.alloc = call i1 @llvm.coro.alloc(token %id)
+  br i1 %need.alloc, label %dyn.alloc, label %begin
+
+dyn.alloc:  
   %size = call i32 @llvm.coro.size.i32()
   %alloc = call i8* @malloc(i32 %size)
-  %hdl = call i8* @llvm.coro.begin(token %id, i8* %alloc)
+  br label %begin
+
+begin:
+  %phi = phi i8* [ null, %entry ], [ %alloc, %dyn.alloc ]
+  %hdl = call i8* @llvm.coro.begin(token %id, i8* %phi)
   call void @print(i32 0)
   %0 = call i8 @llvm.coro.suspend(token none, i1 false)
   switch i8 %0, label %suspend [i8 0, label %resume 
@@ -26,6 +34,10 @@ suspend:
 
 ; CHECK-LABEL: @f(
 ; CHECK: call i8* @malloc
+; CHECK: @llvm.coro.begin(token %id, i8* %phi)
+; CHECK: store void (%f.Frame*)* @f.resume, void (%f.Frame*)** %resume.addr
+; CHECK: %[[SEL:.+]] = select i1 %need.alloc, void (%f.Frame*)* @f.destroy, void (%f.Frame*)* @f.cleanup
+; CHECK: store void (%f.Frame*)* %[[SEL]], void (%f.Frame*)** %destroy.addr
 ; CHECK: call void @print(i32 0)
 ; CHECK-NOT: call void @print(i32 1)
 ; CHECK-NOT: call void @free(
@@ -45,6 +57,12 @@ suspend:
 ; CHECK: call void @free(
 ; CHECK: ret void
 
+; CHECK-LABEL: @f.cleanup(
+; CHECK-NOT: call i8* @malloc
+; CHECK-NOT: call void @print(
+; CHECK-NOT: call void @free(
+; CHECK: ret void
+
 declare i8* @llvm.coro.free(token, i8*)
 declare i32 @llvm.coro.size.i32()
 declare i8  @llvm.coro.suspend(token, i1)
@@ -52,7 +70,7 @@ declare void @llvm.coro.resume(i8*)
 declare void @llvm.coro.destroy(i8*)
 
 declare token @llvm.coro.id(i32, i8*, i8*, i8*)
-declare i8* @llvm.coro.alloc(token)
+declare i1 @llvm.coro.alloc(token)
 declare i8* @llvm.coro.begin(token, i8*)
 declare void @llvm.coro.end(i8*, i1) 
 
-- 
cgit v1.2.3