Fix LLVMSetMetadata and LLVMAddNamedMetadataOperand for single value MDNodes

Summary:
MetadataAsValue uses a canonical format that strips the MDNode if it
contains only a single constant value. This triggers an assertion when
trying to cast the value to a MDNode.

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7165

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227319 91177308-0d34-0410-b5e6-96231b3b80d8

lib/IR/Core.cpp

@@ -563,9 +563,23 @@ LLVMValueRef LLVMGetMetadata(LLVMValueRef Inst, unsigned KindID) {
   return nullptr;
 }
 
-void LLVMSetMetadata(LLVMValueRef Inst, unsigned KindID, LLVMValueRef MD) {
-  MDNode *N =
-      MD ? cast<MDNode>(unwrap<MetadataAsValue>(MD)->getMetadata()) : nullptr;
+// MetadataAsValue uses a canonical format which strips the actual MDNode for
+// MDNode with just a single constant value, storing just a ConstantAsMetadata
+// This undoes this canonicalization, reconstructing the MDNode.
+static MDNode *extractMDNode(MetadataAsValue *MAV) {
+  Metadata *MD = MAV->getMetadata();
+  assert((isa<MDNode>(MD) || isa<ConstantAsMetadata>(MD)) &&
+      "Expected a metadata node or a canonicalized constant");
+
+  if (MDNode *N = dyn_cast<MDNode>(MD))
+    return N;
+
+  return MDNode::get(MAV->getContext(), MD);
+}
+
+void LLVMSetMetadata(LLVMValueRef Inst, unsigned KindID, LLVMValueRef Val) {
+  MDNode *N = Val ? extractMDNode(unwrap<MetadataAsValue>(Val)) : nullptr;
+
   unwrap<Instruction>(Inst)->setMetadata(KindID, N);
 }
 
@@ -795,7 +809,7 @@ void LLVMAddNamedMetadataOperand(LLVMModuleRef M, const char* name,
     return;
   if (!Val)
     return;
-  N->addOperand(cast<MDNode>(unwrap<MetadataAsValue>(Val)->getMetadata()));
+  N->addOperand(extractMDNode(unwrap<MetadataAsValue>(Val)));
 }
 
 /*--.. Operations on scalar constants ......................................--*/

test/Bindings/llvm-c/add_named_metadata_operand.ll

@@ -0,0 +1,2 @@
+; RUN: llvm-c-test --add-named-metadata-operand < /dev/null
+; This used to trigger an assertion

test/Bindings/llvm-c/set_metadata.ll

@@ -0,0 +1,2 @@
+; RUN: llvm-c-test --set-metadata < /dev/null
+; This used to trigger an assertion

tools/llvm-c-test/CMakeLists.txt

@@ -41,6 +41,7 @@ add_llvm_tool(llvm-c-test
   include-all.c
   main.c
   module.c
+  metadata.c
   object.c
   targets.c
   )

tools/llvm-c-test/llvm-c-test.h

@@ -27,6 +27,10 @@ int calc(void);
 // disassemble.c
 int disassemble(void);
 
+// metadata.c
+int add_named_metadata_operand(void);
+int set_metadata(void);
+
 // object.c
 int object_list_sections(void);
 int object_list_symbols(void);

tools/llvm-c-test/main.c

@@ -65,6 +65,10 @@ int main(int argc, char **argv) {
     return disassemble();
   } else if (argc == 2 && !strcmp(argv[1], "--calc")) {
     return calc();
+  } else if (argc == 2 && !strcmp(argv[1], "--add-named-metadata-operand")) {
+    return add_named_metadata_operand();
+  } else if (argc == 2 && !strcmp(argv[1], "--set-metadata")) {
+    return set_metadata();
   } else {
     print_usage();
   }

tools/llvm-c-test/metadata.c

@@ -0,0 +1,39 @@
+/*===-- object.c - tool for testing libLLVM and llvm-c API ----------------===*\
+|*                                                                            *|
+|*                     The LLVM Compiler Infrastructure                       *|
+|*                                                                            *|
+|* This file is distributed under the University of Illinois Open Source      *|
+|* License. See LICENSE.TXT for details.                                      *|
+|*                                                                            *|
+|*===----------------------------------------------------------------------===*|
+|*                                                                            *|
+|* This file implements the --add-named-metadata-operand and --set-metadata   *|
+|* commands in llvm-c-test.                                                   *|
+|*                                                                            *|
+\*===----------------------------------------------------------------------===*/
+
+#include "llvm-c-test.h"
+#include "llvm-c/Core.h"
+
+int add_named_metadata_operand(void) {
+  LLVMModuleRef m = LLVMModuleCreateWithName("Mod");
+  LLVMValueRef values[] = { LLVMConstInt(LLVMInt32Type(), 0, 0) };
+
+  // This used to trigger an assertion
+  LLVMAddNamedMetadataOperand(m, "name", LLVMMDNode(values, 1));
+
+  return 0;
+}
+
+int set_metadata(void) {
+  LLVMBuilderRef b = LLVMCreateBuilder();
+  LLVMValueRef values[] = { LLVMConstInt(LLVMInt32Type(), 0, 0) };
+
+  // This used to trigger an assertion
+  LLVMSetMetadata(
+      LLVMBuildRetVoid(b),
+      LLVMGetMDKindID("kind", 4),
+      LLVMMDNode(values, 1));
+
+  return 0;
+}