AsmParser: Add a function to parse a standalone constant value.

This commit extends the interface provided by the AsmParser library by adding a
function that allows the user to parse a standalone contant value.

This change is useful for MIR serialization, as it will allow the MIR Parser to
parse the constant values in a machine constant pool.

Reviewers: Duncan P. N. Exon Smith

Differential Revision: http://reviews.llvm.org/D10280

llvm-svn: 242579

include/llvm/AsmParser/Parser.h

@@ -18,6 +18,7 @@
 
 namespace llvm {
 
+class Constant;
 class LLVMContext;
 class Module;
 struct SlotMapping;
@@ -79,6 +80,14 @@ std::unique_ptr<Module> parseAssembly(MemoryBufferRef F, SMDiagnostic &Err,
 bool parseAssemblyInto(MemoryBufferRef F, Module &M, SMDiagnostic &Err,
                        SlotMapping *Slots = nullptr);
 
+/// Parse a type and a constant value in the given string.
+///
+/// The constant value can be any LLVM constant, including a constant
+/// expression.
+///
+/// \return null on error.
+Constant *parseConstantValue(StringRef Asm, SMDiagnostic &Err, const Module &M);
+
 } // End llvm namespace
 
 #endif

lib/AsmParser/LLParser.cpp

@@ -48,6 +48,17 @@ bool LLParser::Run() {
          ValidateEndOfModule();
 }
 
+bool LLParser::parseStandaloneConstantValue(Constant *&C) {
+  Lex.Lex();
+
+  Type *Ty = nullptr;
+  if (ParseType(Ty) || parseConstantValue(Ty, C))
+    return true;
+  if (Lex.getKind() != lltok::Eof)
+    return Error(Lex.getLoc(), "expected end of string");
+  return false;
+}
+
 /// ValidateEndOfModule - Do final validity and sanity checks at the end of the
 /// module.
 bool LLParser::ValidateEndOfModule() {
@@ -4065,6 +4076,30 @@ bool LLParser::ConvertValIDToValue(Type *Ty, ValID &ID, Value *&V,
   llvm_unreachable("Invalid ValID");
 }
 
+bool LLParser::parseConstantValue(Type *Ty, Constant *&C) {
+  C = nullptr;
+  ValID ID;
+  auto Loc = Lex.getLoc();
+  if (ParseValID(ID, /*PFS=*/nullptr))
+    return true;
+  switch (ID.Kind) {
+  case ValID::t_APSInt:
+  case ValID::t_APFloat:
+  case ValID::t_Constant:
+  case ValID::t_ConstantStruct:
+  case ValID::t_PackedConstantStruct: {
+    Value *V;
+    if (ConvertValIDToValue(Ty, ID, V, /*PFS=*/nullptr))
+      return true;
+    assert(isa<Constant>(V) && "Expected a constant value");
+    C = cast<Constant>(V);
+    return false;
+  }
+  default:
+    return Error(Loc, "expected a constant value");
+  }
+}
+
 bool LLParser::ParseValue(Type *Ty, Value *&V, PerFunctionState *PFS) {
   V = nullptr;
   ValID ID;

lib/AsmParser/LLParser.h

@@ -143,6 +143,8 @@ namespace llvm {
           Slots(Slots), BlockAddressPFS(nullptr) {}
     bool Run();
 
+    bool parseStandaloneConstantValue(Constant *&C);
+
     LLVMContext &getContext() { return Context; }
 
   private:
@@ -343,6 +345,7 @@ namespace llvm {
     bool ConvertValIDToValue(Type *Ty, ValID &ID, Value *&V,
                              PerFunctionState *PFS);
 
+    bool parseConstantValue(Type *Ty, Constant *&C);
     bool ParseValue(Type *Ty, Value *&V, PerFunctionState *PFS);
     bool ParseValue(Type *Ty, Value *&V, PerFunctionState &PFS) {
       return ParseValue(Ty, V, &PFS);

lib/AsmParser/Parser.cpp

@@ -66,3 +66,15 @@ std::unique_ptr<Module> llvm::parseAssemblyString(StringRef AsmString,
   MemoryBufferRef F(AsmString, "<string>");
   return parseAssembly(F, Err, Context, Slots);
 }
+
+Constant *llvm::parseConstantValue(StringRef Asm, SMDiagnostic &Err,
+                                   const Module &M) {
+  SourceMgr SM;
+  std::unique_ptr<MemoryBuffer> Buf = MemoryBuffer::getMemBuffer(Asm);
+  SM.AddNewSourceBuffer(std::move(Buf), SMLoc());
+  Constant *C;
+  if (LLParser(Asm, SM, Err, const_cast<Module *>(&M))
+          .parseStandaloneConstantValue(C))
+    return nullptr;
+  return C;
+}

unittests/AsmParser/AsmParserTest.cpp

@@ -10,6 +10,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/AsmParser/Parser.h"
 #include "llvm/AsmParser/SlotMapping.h"
+#include "llvm/IR/Constants.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Support/SourceMgr.h"
@@ -64,4 +65,51 @@ TEST(AsmParserTest, SlotMappingTest) {
   EXPECT_EQ(Mapping.MetadataNodes.count(1), 0u);
 }
 
+TEST(AsmParserTest, TypeAndConstantValueParsing) {
+  LLVMContext &Ctx = getGlobalContext();
+  SMDiagnostic Error;
+  StringRef Source = "define void @test() {\n  entry:\n  ret void\n}";
+  auto Mod = parseAssemblyString(Source, Error, Ctx);
+  ASSERT_TRUE(Mod != nullptr);
+  auto &M = *Mod;
+
+  const Value *V;
+  V = parseConstantValue("double 3.5", Error, M);
+  ASSERT_TRUE(V);
+  EXPECT_TRUE(V->getType()->isDoubleTy());
+  ASSERT_TRUE(isa<ConstantFP>(V));
+  EXPECT_TRUE(cast<ConstantFP>(V)->isExactlyValue(3.5));
+
+  V = parseConstantValue("i32 42", Error, M);
+  ASSERT_TRUE(V);
+  EXPECT_TRUE(V->getType()->isIntegerTy());
+  ASSERT_TRUE(isa<ConstantInt>(V));
+  EXPECT_TRUE(cast<ConstantInt>(V)->equalsInt(42));
+
+  V = parseConstantValue("<4 x i32> <i32 0, i32 1, i32 2, i32 3>", Error, M);
+  ASSERT_TRUE(V);
+  EXPECT_TRUE(V->getType()->isVectorTy());
+  ASSERT_TRUE(isa<ConstantDataVector>(V));
+
+  V = parseConstantValue("i32 add (i32 1, i32 2)", Error, M);
+  ASSERT_TRUE(V);
+  ASSERT_TRUE(isa<ConstantInt>(V));
+
+  V = parseConstantValue("i8* blockaddress(@test, %entry)", Error, M);
+  ASSERT_TRUE(V);
+  ASSERT_TRUE(isa<BlockAddress>(V));
+
+  EXPECT_FALSE(parseConstantValue("duble 3.25", Error, M));
+  EXPECT_EQ(Error.getMessage(), "expected type");
+
+  EXPECT_FALSE(parseConstantValue("i32 3.25", Error, M));
+  EXPECT_EQ(Error.getMessage(), "floating point constant invalid for type");
+
+  EXPECT_FALSE(parseConstantValue("i32* @foo", Error, M));
+  EXPECT_EQ(Error.getMessage(), "expected a constant value");
+
+  EXPECT_FALSE(parseConstantValue("i32 3, ", Error, M));
+  EXPECT_EQ(Error.getMessage(), "expected end of string");
+}
+
 } // end anonymous namespace