[coroutines][PR40979] Ignore unreachable uses across suspend points

Summary:
Depends on https://reviews.llvm.org/D59069.

https://bugs.llvm.org/show_bug.cgi?id=40979 describes a bug in which the
-coro-split pass would assert that a use was across a suspend point from
a definition. Normally this would mean that a value would "spill" across
a suspend point and thus need to be stored in the coroutine frame. However,
in this case the use was unreachable, and so it would not be necessary
to store the definition on the frame.

To prevent the assert, simply remove unreachable basic blocks from a
coroutine function before computing spills. This avoids the assert
reported in PR40979.

Reviewers: GorNishanov, tks2103

Reviewed By: GorNishanov

Subscribers: EricWF, jdoerfert, llvm-commits, lewissbaker

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59068

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@355852 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Coroutines/CoroSplit.cpp b/lib/Transforms/Coroutines/CoroSplit.cpp
index f7d3072ccbcb496ddc39735bc7e125732a20ba5a..a8de9fe3feb6807630dd626367ada91a92fbc8ed 100644 (file)
--- a/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -777,6 +777,8 @@ static void relocateInstructionBefore(CoroBeginInst *CoroBegin, Function &F) {
 }
 
 static void splitCoroutine(Function &F, CallGraph &CG, CallGraphSCC &SCC) {
+  EliminateUnreachableBlocks(F);
+
   coro::Shape Shape(F);
   if (!Shape.CoroBegin)
     return;

diff --git a/test/Transforms/Coroutines/coro-frame-unreachable.ll b/test/Transforms/Coroutines/coro-frame-unreachable.ll
new file mode 100644 (file)
index 0000000..9d6bae6
--- /dev/null
+++ b/test/Transforms/Coroutines/coro-frame-unreachable.ll
@@ -0,0 +1,50 @@
+; Check that coro-split doesn't choke on intrinsics in unreachable blocks
+; RUN: opt < %s -coro-split -S
+
+define i8* @f(i1 %arg) "coroutine.presplit"="1" personality i32 0 {
+entry:
+  %arg.addr = alloca i1
+  store i1 %arg, i1* %arg.addr
+  %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 i8* @llvm.coro.begin(token %id, i8* %alloc)
+  br label %cont
+
+cont:
+  %0 = call i8 @llvm.coro.suspend(token none, i1 false)
+  switch i8 %0, label %suspend [i8 0, label %resume
+                                i8 1, label %cleanup]
+resume:
+  br label %cleanup
+
+cleanup:
+  %mem = call i8* @llvm.coro.free(token %id, i8* %hdl)
+  call void @free(i8* %mem)
+  br label %suspend
+
+suspend:
+  call i1 @llvm.coro.end(i8* %hdl, i1 0)
+  ret i8* %hdl
+
+no.predecessors:
+  %argval = load i1, i1* %arg.addr
+  call void @print(i1 %argval)
+  br label %suspend
+
+}
+
+declare i8* @llvm.coro.free(token, i8*)
+declare i32 @llvm.coro.size.i32()
+declare i8  @llvm.coro.suspend(token, i1)
+declare void @llvm.coro.resume(i8*)
+declare void @llvm.coro.destroy(i8*)
+
+declare token @llvm.coro.id(i32, i8*, i8*, i8*)
+declare i1 @llvm.coro.alloc(token)
+declare i8* @llvm.coro.begin(token, i8*)
+declare i1 @llvm.coro.end(i8*, i1)
+
+declare noalias i8* @malloc(i32)
+declare void @print(i1)
+declare void @free(i8*)