[llvm] 9bdf04c - [Coroutines] Prevent infinite loop in simplifyTerminatorLeadingToRet

[Chuanqi Xu via llvm-commits]

Author: Chuanqi Xu
Date: 2023-07-03T10:40:38+08:00
New Revision: 9bdf04c8f9d40d0aa4cbaf011b1877d88dc6dbc6

URL: https://github.com/llvm/llvm-project/commit/9bdf04c8f9d40d0aa4cbaf011b1877d88dc6dbc6
DIFF: https://github.com/llvm/llvm-project/commit/9bdf04c8f9d40d0aa4cbaf011b1877d88dc6dbc6.diff

LOG: [Coroutines] Prevent infinite loop in simplifyTerminatorLeadingToRet

Close https://github.com/llvm/llvm-project/issues/63639

This comes from the oversight the refactoring that we missed a `return
false;` in the loop.

Added: 
    llvm/test/Transforms/Coroutines/coro-split-musttail13.ll

Modified: 
    llvm/lib/Transforms/Coroutines/CoroSplit.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
index 82ba35be5e4de6..07b879ff417437 100644
--- a/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
+++ b/llvm/lib/Transforms/Coroutines/CoroSplit.cpp
@@ -1352,6 +1352,8 @@ static bool simplifyTerminatorLeadingToRet(Instruction *InitialInst) {
       I = GetFirstValidInstruction(BB->getFirstNonPHIOrDbgOrLifetime());
       continue;
     }
+
+    return false;
   }
 
   return false;

diff  --git a/llvm/test/Transforms/Coroutines/coro-split-musttail13.ll b/llvm/test/Transforms/Coroutines/coro-split-musttail13.ll
new file mode 100644
index 00000000000000..29823cee57a08d
--- /dev/null
+++ b/llvm/test/Transforms/Coroutines/coro-split-musttail13.ll
@@ -0,0 +1,74 @@
+; Tests that coro-split won't fall in infinite loop when simplify the terminators leading to ret.
+; RUN: opt < %s -passes='cgscc(coro-split),simplifycfg,early-cse' -S | FileCheck %s
+
+declare void @fakeresume1(ptr)
+declare void @may_throw(ptr)
+declare void @print()
+
+define void @f(i1 %cond) #0 personality i32 3 {
+entry:
+  %id = call token @llvm.coro.id(i32 0, ptr null, ptr null, ptr null)
+  %alloc = call ptr @malloc(i64 16) #3
+  %vFrame = call noalias nonnull ptr @llvm.coro.begin(token %id, ptr %alloc)
+
+  %save = call token @llvm.coro.save(ptr null)
+
+  %init_suspend = call i8 @llvm.coro.suspend(token %save, i1 false)
+  switch i8 %init_suspend, label %coro.end [
+    i8 0, label %await.ready
+    i8 1, label %coro.end
+  ]
+await.ready:
+  call fastcc void @fakeresume1(ptr align 8 null)
+  invoke void @may_throw(ptr null)
+    to label %ready unwind label %lpad
+
+ready:
+  %save2 = call token @llvm.coro.save(ptr null)
+  %suspend = call i8 @llvm.coro.suspend(token %save2, i1 true)
+  %switch = icmp ult i8 %suspend, 2
+  br i1 %switch, label %cleanup, label %coro.end
+
+cleanup:
+  %free.handle = call ptr @llvm.coro.free(token %id, ptr %vFrame)
+  %.not = icmp eq ptr %free.handle, null
+  br i1 %.not, label %coro.end, label %coro.free
+
+lpad:
+  %lpval = landingpad { ptr, i32 }
+     cleanup
+
+  %need.resume = call i1 @llvm.coro.end(ptr null, i1 true)
+  resume { ptr, i32 } %lpval
+
+coro.free:
+  call void @delete(ptr nonnull %free.handle) #2
+  br label %coro.end
+
+coro.end:
+  call i1 @llvm.coro.end(ptr null, i1 false)
+  ret void
+}
+
+; CHECK-LABEL: @f.resume(
+; CHECK-NOT:          musttail call fastcc void @fakeresume1(
+; CHECK:     }
+
+
+declare token @llvm.coro.id(i32, ptr readnone, ptr nocapture readonly, ptr) #1
+declare i1 @llvm.coro.alloc(token) #2
+declare i64 @llvm.coro.size.i64() #3
+declare ptr @llvm.coro.begin(token, ptr writeonly) #2
+declare token @llvm.coro.save(ptr) #2
+declare ptr @llvm.coro.frame() #3
+declare i8 @llvm.coro.suspend(token, i1) #2
+declare ptr @llvm.coro.free(token, ptr nocapture readonly) #1
+declare i1 @llvm.coro.end(ptr, i1) #2
+declare ptr @llvm.coro.subfn.addr(ptr nocapture readonly, i8) #1
+declare ptr @malloc(i64)
+declare void @delete(ptr nonnull) #2
+
+attributes #0 = { presplitcoroutine }
+attributes #1 = { argmemonly nounwind readonly }
+attributes #2 = { nounwind }
+attributes #3 = { nounwind readnone }