[InlineFunction] Fix logic to update PHI nodes in an exceptional block

when inlining tasks at an invoke instruction.  Addresses issue llvm#73.

llvm/lib/Transforms/Utils/InlineFunction.cpp

@@ -653,9 +653,11 @@ static void HandleInlinedTasksHelper(
     // Promote any calls in the block to invokes.
     if (BasicBlock *NewBB = HandleCallsInBlockInlinedThroughInvoke(
             BB, UnwindEdge)) {
-      // Update any PHI nodes in the exceptional block to indicate that there
-      // is now a new entry in them.
-      Invoke.addIncomingPHIValuesFor(NewBB);
+      // If this is the topmost invocation of HandleInlinedTasksHelper, update
+      // any PHI nodes in the exceptional block to indicate that there is now a
+      // new entry in them.
+      if (nullptr == ParentWorklist)
+        Invoke.addIncomingPHIValuesFor(NewBB);
       BlocksToProcess.insert(
           cast<InvokeInst>(NewBB->getTerminator())->getNormalDest());
     }
@@ -692,7 +694,7 @@ static void HandleInlinedTasksHelper(
       continue;
     }
 
-    // Process a detach instruction specially.  In particular, process th
+    // Process a detach instruction specially.  In particular, process the
     // spawned task recursively.
     if (DetachInst *DI = dyn_cast<DetachInst>(BB->getTerminator())) {
       if (!DI->hasUnwindDest()) {
@@ -709,8 +711,13 @@ static void HandleInlinedTasksHelper(
         // If the new unwind edge is not used, remove it.
         if (pred_empty(SubTaskUnwindEdge))
           SubTaskUnwindEdge->eraseFromParent();
-        else
+        else {
           DetachesToReplace.push_back(DI);
+          // Update PHI nodes in the exceptional block to indicate that
+          // SubTaskUnwindEdge is a new entry in them.  This should only have an
+          // effect for the topmost call to HandleInlinedTasksHelper.
+          Invoke.addIncomingPHIValuesFor(SubTaskUnwindEdge);
+        }
 
       } else if (Visited.insert(DI->getUnwindDest()).second) {
         // If the detach-unwind isn't dead, add it to the worklist.
@@ -740,6 +747,11 @@ static void HandleInlinedTasksHelper(
   // Replace detaches that now require unwind destinations.
   while (!DetachesToReplace.empty()) {
     DetachInst *DI = DetachesToReplace.pop_back_val();
+    // If this is the topmost invocation of HandleInlinedTasksHelper, update any
+    // PHI nodes in the exceptional block to indicate that there is now a new
+    // entry in them.
+    if (nullptr == ParentWorklist)
+      Invoke.addIncomingPHIValuesFor(DI->getParent());
     ReplaceInstWithInst(DI, DetachInst::Create(
                             DI->getDetached(), DI->getContinue(), UnwindEdge,
                             DI->getSyncRegion()));

llvm/test/Transforms/Tapir/inline-task-update-phi.ll

@@ -0,0 +1,94 @@
+; RUN: opt < %s -inline -S -o - | FileCheck %s
+; RUN: opt < %s -passes='inline' -S -o - | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+$_ZN5outerC2ERKS_ = comdat any
+
+$_ZNSt5arrayI5outerLm2EED2Ev = comdat any
+
+define dso_local void @main() local_unnamed_addr #0 personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
+entry:
+  invoke void @_ZN5outerC2ERKS_()
+          to label %invoke.cont unwind label %lpad
+
+invoke.cont:                                      ; preds = %entry
+  invoke void @_ZN5outerC2ERKS_()
+          to label %invoke.cont1 unwind label %lpad
+
+invoke.cont1:                                     ; preds = %invoke.cont
+  ret void
+
+lpad:                                             ; preds = %entry, %invoke.cont
+  %arrayinit.endOfInit.0.idx = phi i64 [ 1, %invoke.cont ], [ 0, %entry ]
+  %0 = landingpad { i8*, i32 }
+          cleanup
+  resume { i8*, i32 } %0
+}
+
+; CHECK: define {{.*}}void @main()
+; CHECK: entry:
+; CHECK: detach within %{{.*}}, label %[[PFOR_BODY_1:.+]], label %{{.*}} unwind label %lpad
+
+; CHECK: [[PFOR_BODY_1]]:
+; CHECK-NEXT: invoke void @_Znwm()
+; CHECK-NEXT: to label %{{.*}} unwind label %[[LPAD1:.+]]
+
+; CHECK: [[LPAD1]]:
+; CHECK: invoke void @llvm.detached.rethrow.sl_p0i8i32s(token %{{.*}},
+; CHECK-NEXT: to label %{{.*}} unwind label %lpad
+
+; CHECK: invoke.cont:
+; CHECK: detach within %{{.*}}, label %[[PFOR_BODY_2:.+]], label %{{.*}} unwind label %lpad
+
+; CHECK: [[PFOR_BODY_2]]:
+; CHECK-NEXT: invoke void @_Znwm()
+; CHECK-NEXT: to label %{{.*}} unwind label %[[LPAD2:.+]]
+
+; CHECK: [[LPAD2]]:
+; CHECK: invoke void @llvm.detached.rethrow.sl_p0i8i32s(token %{{.*}},
+; CHECK-NEXT: to label %{{.*}} unwind label %lpad
+
+; CHECK: lpad:
+; CHECK-NEXT: %arrayinit.endOfInit.0.idx = phi i64 [ 0, %[[LPAD1]] ], [ 0, %entry ], [ 1, %[[LPAD2]] ], [ 1, %invoke.cont ]
+
+define dso_local void @_ZN5outerC2ERKS_() unnamed_addr #1 comdat align 2 personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
+entry:
+  %syncreg = call token @llvm.syncregion.start()
+  br label %pfor.cond
+
+pfor.cond:                                        ; preds = %entry
+  detach within %syncreg, label %pfor.body.entry, label %pfor.inc
+
+pfor.body.entry:                                  ; preds = %pfor.cond
+  br label %pfor.body
+
+pfor.body:                                        ; preds = %pfor.body.entry
+  call void @_Znwm() #3
+  unreachable
+
+pfor.inc:                                         ; preds = %pfor.cond
+  unreachable
+}
+
+declare dso_local i32 @__gxx_personality_v0(...)
+
+define dso_local void @_ZNSt5arrayI5outerLm2EED2Ev() unnamed_addr #1 comdat align 2 {
+entry:
+  ret void
+}
+
+; Function Attrs: argmemonly nounwind willreturn
+declare token @llvm.syncregion.start() #2
+
+declare dso_local void @_Znwm() local_unnamed_addr #1
+
+attributes #0 = { "target-cpu"="x86-64" }
+attributes #1 = { "use-soft-float"="false" }
+attributes #2 = { argmemonly nounwind willreturn }
+attributes #3 = { builtin }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 12.0.0 (git@github.com:OpenCilk/opencilk-project.git 973aa8d610bafa8c98286f78c034ce1c27c26eec)"}