[PATCH] D15835: [SplitLandingPadPredecessors] Create a PHINode for the original landingpad only if it has some uses

[Chen Li via llvm-commits]

chenli updated the summary for this revision.
chenli removed a subscriber: sanjoy.
chenli updated this revision to Diff 44092.
chenli added a comment.

Update patch w.r.t Philip's comments.


http://reviews.llvm.org/D15835

Files:
  lib/Transforms/Utils/BasicBlockUtils.cpp
  test/Transforms/RewriteStatepointsForGC/two-invokes-one-landingpad.ll

Index: test/Transforms/RewriteStatepointsForGC/two-invokes-one-landingpad.ll
===================================================================
--- /dev/null
+++ test/Transforms/RewriteStatepointsForGC/two-invokes-one-landingpad.ll
@@ -0,0 +1,33 @@
+; RUN: opt %s -rewrite-statepoints-for-gc -rs4gc-use-deopt-bundles -S | FileCheck %s
+
+declare void @some_call(i64 addrspace(1)*)
+
+declare i32 @"dummy_personality_function"()
+
+define i64 addrspace(1)* @test(i64 addrspace(1)* %obj, i64 addrspace(1)* %obj1)
+  gc "statepoint-example"
+  personality i32 ()* @"dummy_personality_function" {
+entry:
+  invoke void @some_call(i64 addrspace(1)* %obj) [ "deopt"() ]
+          to label %second_invoke unwind label %exceptional_return
+
+second_invoke:                                    ; preds = %entry
+  invoke void @some_call(i64 addrspace(1)* %obj) [ "deopt"() ]
+          to label %normal_return unwind label %exceptional_return
+
+normal_return:                                    ; preds = %second_invoke
+  ret i64 addrspace(1)* %obj
+
+; CHECK: exceptional_return1:
+; CHECK-NEXT: %lpad2 = landingpad token
+
+; CHECK: exceptional_return.split-lp:
+; CHECK-NEXT: %lpad.split-lp = landingpad token
+
+; CHECK: exceptional_return:
+; CHECK-NOT: phi token
+
+exceptional_return:                               ; preds = %second_invoke, %entry
+  %lpad = landingpad token cleanup
+  ret i64 addrspace(1)* %obj1
+}
Index: lib/Transforms/Utils/BasicBlockUtils.cpp
===================================================================
--- lib/Transforms/Utils/BasicBlockUtils.cpp
+++ lib/Transforms/Utils/BasicBlockUtils.cpp
@@ -626,11 +626,17 @@
     Clone2->setName(Twine("lpad") + Suffix2);
     NewBB2->getInstList().insert(NewBB2->getFirstInsertionPt(), Clone2);
 
-    // Create a PHI node for the two cloned landingpad instructions.
-    PHINode *PN = PHINode::Create(LPad->getType(), 2, "lpad.phi", LPad);
-    PN->addIncoming(Clone1, NewBB1);
-    PN->addIncoming(Clone2, NewBB2);
-    LPad->replaceAllUsesWith(PN);
+    // Create a PHI node for the two cloned landingpad instructions only
+    // if the original landingpad instruction has some uses.
+    if (!LPad->use_empty()) {
+      assert(!LPad->getType()->isTokenTy() &&
+             "Split cannot be applied if LPad is token type. Otherwise an "
+             "invalid PHINode of token type would be created.");
+      PHINode *PN = PHINode::Create(LPad->getType(), 2, "lpad.phi", LPad);
+      PN->addIncoming(Clone1, NewBB1);
+      PN->addIncoming(Clone2, NewBB2);
+      LPad->replaceAllUsesWith(PN);
+    }
     LPad->eraseFromParent();
   } else {
     // There is no second clone. Just replace the landing pad with the first


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