review: add constraint on magnitude of signed integer

Author: inbelic

clang/lib/Parse/ParseHLSLRootSignature.cpp

@@ -878,7 +878,7 @@ std::optional<uint32_t> RootSignatureParser::handleUIntLiteral() {
   assert(Literal.isIntegerLiteral() &&
          "NumSpelling can only consist of digits");
 
-  llvm::APSInt Val = llvm::APSInt(32, false);
+  llvm::APSInt Val = llvm::APSInt(32, /*IsUnsigned=*/true);
   if (Literal.GetIntegerValue(Val)) {
     // Report that the value has overflowed
     PP.getDiagnostics().Report(CurToken.TokLoc,
@@ -901,8 +901,12 @@ std::optional<int32_t> RootSignatureParser::handleIntLiteral(bool Negated) {
   assert(Literal.isIntegerLiteral() &&
          "NumSpelling can only consist of digits");
 
-  llvm::APSInt Val = llvm::APSInt(32, true);
-  if (Literal.GetIntegerValue(Val)) {
+  llvm::APSInt Val = llvm::APSInt(32, /*IsUnsigned=*/true);
+  // GetIntegerValue will overwrite Val from the parsed Literal and return
+  // true if it overflows as a 32-bit unsigned int. Then check that it also
+  // doesn't overflow as a signed 32-bit int.
+  int64_t MaxMagnitude = -static_cast<int64_t>(std::numeric_limits<int32_t>::min());
+  if (Literal.GetIntegerValue(Val) || MaxMagnitude < Val.getExtValue()) {
     // Report that the value has overflowed
     PP.getDiagnostics().Report(CurToken.TokLoc,
                                diag::err_hlsl_number_literal_overflow)

clang/unittests/Parse/ParseHLSLRootSignatureTest.cpp

@@ -774,6 +774,28 @@ TEST_F(ParseHLSLRootSignatureTest, InvalidLexOverflowedNumberTest) {
   ASSERT_TRUE(Consumer->isSatisfied());
 }
 
+TEST_F(ParseHLSLRootSignatureTest, InvalidParseOverflowedNegativeNumberTest) {
+  // This test will check that parsing fails due to a unsigned integer having
+  // too large of a magnitude to be interpreted as its negative
+  const llvm::StringLiteral Source = R"cc(
+    StaticSampler(s0, mipLODBias = -4294967295)
+  )cc";
+
+  TrivialModuleLoader ModLoader;
+  auto PP = createPP(Source, ModLoader);
+  auto TokLoc = SourceLocation();
+
+  hlsl::RootSignatureLexer Lexer(Source, TokLoc);
+  SmallVector<RootElement> Elements;
+  hlsl::RootSignatureParser Parser(Elements, Lexer, *PP);
+
+  // Test correct diagnostic produced
+  Consumer->setExpected(diag::err_hlsl_number_literal_overflow);
+  ASSERT_TRUE(Parser.parse());
+
+  ASSERT_TRUE(Consumer->isSatisfied());
+}
+
 TEST_F(ParseHLSLRootSignatureTest, InvalidLexOverflowedFloatTest) {
   // This test will check that the lexing fails due to a float overflow
   const llvm::StringLiteral Source = R"cc(