[llvm] r345966 - Allow null-valued function operands in getCalledFunction()

[David Stenberg via llvm-commits]

Author: dstenb
Date: Fri Nov  2 04:46:24 2018
New Revision: 345966

URL: http://llvm.org/viewvc/llvm-project?rev=345966&view=rev
Log:
Allow null-valued function operands in getCalledFunction()

Summary:
Change the dynamic cast in CallBase::getCalledFunction() to allow
null-valued function operands.

This patch fixes a crash that occurred when a funtion operand of a
call instruction was dropped, and later on a metadata-carrying
instruction was printed out. When allocating the metadata slot numbers,
getCalledFunction() would be invoked on the call with the dropped
operand, resulting in a failed non-null assertion in isa<>.

This fixes PR38924, in which a printout in DBCE crashed due to this.

This aligns getCalledFunction() with getCalledValue(), as the latter
allows the operand to be null.

Reviewers: vsk, dexonsmith, hfinkel

Reviewed By: dexonsmith

Subscribers: hfinkel, llvm-commits

Differential Revision: https://reviews.llvm.org/D52537

Modified:
    llvm/trunk/include/llvm/IR/Instructions.h
    llvm/trunk/unittests/IR/MetadataTest.cpp

Modified: llvm/trunk/include/llvm/IR/Instructions.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/Instructions.h?rev=345966&r1=345965&r2=345966&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/Instructions.h (original)
+++ llvm/trunk/include/llvm/IR/Instructions.h Fri Nov  2 04:46:24 2018
@@ -1523,7 +1523,7 @@ public:
   /// indirect function invocation.
   ///
   Function *getCalledFunction() const {
-    return dyn_cast<Function>(Op<-InstTy::ArgOffset>());
+    return dyn_cast_or_null<Function>(Op<-InstTy::ArgOffset>());
   }
 
   /// Determine whether this call has the given attribute.

Modified: llvm/trunk/unittests/IR/MetadataTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/IR/MetadataTest.cpp?rev=345966&r1=345965&r2=345966&view=diff
==============================================================================
--- llvm/trunk/unittests/IR/MetadataTest.cpp (original)
+++ llvm/trunk/unittests/IR/MetadataTest.cpp Fri Nov  2 04:46:24 2018
@@ -402,6 +402,27 @@ TEST_F(MDNodeTest, PrintFromMetadataAsVa
   EXPECT_PRINTER_EQ("metadata !0", MAV0->printAsOperand(OS, true, MST));
   EXPECT_PRINTER_EQ("metadata !1", MAV1->printAsOperand(OS, true, MST));
 }
+
+TEST_F(MDNodeTest, PrintWithDroppedCallOperand) {
+  Module M("test", Context);
+
+  auto *FTy = FunctionType::get(Type::getVoidTy(Context), false);
+  auto *F0 = Function::Create(FTy, GlobalValue::ExternalLinkage, "F0", &M);
+  auto *F1 = Function::Create(FTy, GlobalValue::ExternalLinkage, "F1", &M);
+  auto *BB0 = BasicBlock::Create(Context, "entry", F0);
+
+  CallInst *CI0 = CallInst::Create(F1, "", BB0);
+  CI0->dropAllReferences();
+
+  auto *R0 = ReturnInst::Create(Context, BB0);
+  auto *N0 = MDNode::getDistinct(Context, None);
+  R0->setMetadata("md", N0);
+
+  // Printing the metadata node would previously result in a failed assertion
+  // due to the call instruction's dropped function operand.
+  ModuleSlotTracker MST(&M);
+  EXPECT_PRINTER_EQ("!0 = distinct !{}", N0->print(OS, MST));
+}
 #undef EXPECT_PRINTER_EQ
 
 TEST_F(MDNodeTest, NullOperand) {