Fix a regression on the disassembling C API.

The fix is easy. Unfortunately, we had 0 tests, so adding one was somewhat
complicated.

Thanks to Kevin Enderby for the report.

llvm-svn: 221899

2 files changed, 65 insertions, 0 deletions

diff --git a/llvm/unittests/MC/CMakeLists.txt b/llvm/unittests/MC/CMakeLists.txt
index 95a3fff2b52..c82bcde0b24 100644
--- a/llvm/unittests/MC/CMakeLists.txt
+++ b/llvm/unittests/MC/CMakeLists.txt
@@ -1,9 +1,12 @@
 set(LLVM_LINK_COMPONENTS
+  ${LLVM_TARGETS_TO_BUILD}
   MC
+  MCDisassembler
   Support
   )
 
 add_llvm_unittest(MCTests
+  Disassembler.cpp
   StringTableBuilderTest.cpp
   YAMLTest.cpp
   )
diff --git a/llvm/unittests/MC/Disassembler.cpp b/llvm/unittests/MC/Disassembler.cpp
new file mode 100644
index 00000000000..e432b15bb48
--- /dev/null
+++ b/llvm/unittests/MC/Disassembler.cpp
@@ -0,0 +1,62 @@
+//===- llvm/unittest/Object/Disassembler.cpp ------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm-c/Disassembler.h"
+#include "llvm/Support/TargetSelect.h"
+#include "gtest/gtest.h"
+
+using namespace llvm;
+
+static const char *symbolLookupCallback(void *DisInfo, uint64_t ReferenceValue,
+                                        uint64_t *ReferenceType,
+                                        uint64_t ReferencePC,
+                                        const char **ReferenceName) {
+  *ReferenceType = LLVMDisassembler_ReferenceType_InOut_None;
+  return nullptr;
+}
+
+TEST(Disassembler, Test1) {
+  llvm::InitializeAllTargetInfos();
+  llvm::InitializeAllTargetMCs();
+  llvm::InitializeAllDisassemblers();
+
+  uint8_t Bytes[] = {0x90, 0x90, 0xeb, 0xfd};
+  uint8_t *BytesP = Bytes;
+  const char OutStringSize = 100;
+  char OutString[OutStringSize];
+  LLVMDisasmContextRef DCR = LLVMCreateDisasm("x86_64-pc-linux", nullptr, 0,
+                                              nullptr, symbolLookupCallback);
+  if (!DCR)
+    return;
+
+  size_t InstSize;
+  unsigned NumBytes = sizeof(Bytes);
+  unsigned PC = 0;
+
+  InstSize = LLVMDisasmInstruction(DCR, BytesP, NumBytes, PC, OutString,
+                                   OutStringSize);
+  EXPECT_EQ(InstSize, 1U);
+  EXPECT_EQ(StringRef(OutString), "\tnop");
+  PC += InstSize;
+  BytesP += InstSize;
+  NumBytes -= InstSize;
+
+  InstSize = LLVMDisasmInstruction(DCR, BytesP, NumBytes, PC, OutString,
+                                   OutStringSize);
+  EXPECT_EQ(InstSize, 1U);
+  EXPECT_EQ(StringRef(OutString), "\tnop");
+  PC += InstSize;
+  BytesP += InstSize;
+  NumBytes -= InstSize;
+
+  InstSize = LLVMDisasmInstruction(DCR, BytesP, NumBytes, PC, OutString,
+                                   OutStringSize);
+  EXPECT_EQ(InstSize, 2U);
+  EXPECT_EQ(StringRef(OutString), "\tjmp\t0x1");
+}