Disassembler tool indents to 15 by default

The assigned-to result Id appears to the left of the 15th column.

Add --no-indent option.

The API form of the disassembler does not indent by default.

include/libspirv/libspirv.h

@@ -243,6 +243,7 @@ typedef enum spv_binary_to_text_options_t {
   SPV_BINARY_TO_TEXT_OPTION_NONE = SPV_BIT(0),
   SPV_BINARY_TO_TEXT_OPTION_PRINT = SPV_BIT(1),
   SPV_BINARY_TO_TEXT_OPTION_COLOR = SPV_BIT(2),
+  SPV_BINARY_TO_TEXT_OPTION_INDENT = SPV_BIT(3),
   SPV_FORCE_32_BIT_ENUM(spv_binary_to_text_options_t)
 } spv_binary_to_text_options_t;
 

source/disassemble.cpp

@@ -46,6 +46,8 @@ namespace {
 // A Disassembler instance converts a SPIR-V binary to its assembly
 // representation.
 class Disassembler {
+  enum { kStandardIndent = 15 };
+
  public:
   Disassembler(const libspirv::AssemblyGrammar& grammar, uint32_t const* words,
                size_t num_words, uint32_t options)
@@ -55,6 +57,9 @@ class Disassembler {
         print_(spvIsInBitfield(SPV_BINARY_TO_TEXT_OPTION_PRINT, options)),
         color_(print_ &&
                spvIsInBitfield(SPV_BINARY_TO_TEXT_OPTION_COLOR, options)),
+        indent_(spvIsInBitfield(SPV_BINARY_TO_TEXT_OPTION_INDENT, options)
+                    ? kStandardIndent
+                    : 0),
         text_(),
         out_(print_ ? out_stream() : out_stream(text_)),
         stream_(out_.get()) {}
@@ -113,6 +118,7 @@ class Disassembler {
   const libspirv::AssemblyGrammar& grammar_;
   const bool print_;  // Should we also print to the standard output stream?
   const bool color_;  // Should we print in colour?
+  const int indent_;  // How much to indent. 0 means don't indent
   spv_endianness_t endian_;  // The detected endianness of the binary.
   std::stringstream text_;   // Captures the text, if not printing.
   out_stream out_;  // The Output stream.  Either to text_ or standard output.
@@ -135,12 +141,31 @@ spv_result_t Disassembler::HandleHeader(spv_endianness_t endian,
   return SPV_SUCCESS;
 }
 
+// Returns the number of digits in n.
+int NumDigits(uint32_t n) {
+  if (n < 10) return 0;
+  if (n < 100) return 1;
+  if (n < 1000) return 2;
+  if (n < 10000) return 3;
+  if (n < 100000) return 4;
+  if (n < 1000000) return 5;
+  if (n < 10000000) return 6;
+  if (n < 100000000) return 7;
+  if (n < 1000000000) return 8;
+  return 9;
+}
+
 spv_result_t Disassembler::HandleInstruction(
     const spv_parsed_instruction_t& inst) {
   if (inst.result_id) {
     SetBlue();
-    stream_ << "%" << inst.result_id << " = ";
+    // Indent if needed, but account for the 4 characters in "%" and " = "
+    if (indent_) stream_ << std::setw(indent_ - 4 - NumDigits(inst.result_id));
+    stream_ << "%" << inst.result_id;
     ResetColor();
+    stream_ << " = ";
+  } else {
+    stream_ << std::string(indent_, ' ');
   }
 
   stream_ << "Op" << spvOpcodeString(inst.opcode);

test/BinaryToText.cpp

@@ -364,4 +364,28 @@ TEST_F(OperandTypeTest, OptionalTypedLiteralNumber) {
   EXPECT_EQ(input, EncodeAndDecodeSuccessfully(input));
 }
 
+using IndentTest = spvtest::TextToBinaryTest;
+
+TEST_F(IndentTest, Sample) {
+  const std::string input = R"(
+OpCapability Shader
+OpMemoryModel Logical GLSL450
+%1 = OpTypeInt 32 0
+%2 = OpTypeStruct %1 %3 %4 %5 %6 %7 %8 %9 %10 ; force IDs into double digits
+%11 = OpConstant %1 42
+OpStore %2 %3 Aligned|Volatile 4 ; bogus, but not indented
+)";
+  const std::string expected =
+      R"(               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+          %1 = OpTypeInt 32 0
+          %2 = OpTypeStruct %1 %3 %4 %5 %6 %7 %8 %9 %10
+         %11 = OpConstant %1 42
+               OpStore %2 %3 Volatile|Aligned 4
+)";
+  EXPECT_THAT(
+      EncodeAndDecodeSuccessfully(input, SPV_BINARY_TO_TEXT_OPTION_INDENT),
+      expected);
+}
+
 }  // anonymous namespace

test/TestFixture.h

@@ -84,9 +84,16 @@ class TextToBinaryTestBase : public T {
     return diagnostic->error;
   }
 
-  // Encodes SPIR-V text into binary and then decodes the binary. Returns the
-  // decoded text.
+  // Encodes SPIR-V text into binary and then decodes the binary using
+  // default options. Returns the decoded text.
   std::string EncodeAndDecodeSuccessfully(const std::string& text) {
+    return EncodeAndDecodeSuccessfully(text, SPV_BINARY_TO_TEXT_OPTION_NONE);
+  }
+
+  // Encodes SPIR-V text into binary and then decodes the binary using
+  // given options. Returns the decoded text.
+  std::string EncodeAndDecodeSuccessfully(const std::string& text,
+                                          uint32_t disassemble_options) {
     DestroyBinary();
     spv_result_t error =
         spvTextToBinary(text.c_str(), text.size(), &binary, &diagnostic);
@@ -99,8 +106,7 @@ class TextToBinaryTestBase : public T {
 
     spv_text decoded_text;
     error = spvBinaryToText(binary->code, binary->wordCount,
-                            SPV_BINARY_TO_TEXT_OPTION_NONE, &decoded_text,
-                            &diagnostic);
+                            disassemble_options, &decoded_text, &diagnostic);
     if (error) {
       spvDiagnosticPrint(diagnostic);
       spvDiagnosticDestroy(diagnostic);

tools/dis/dis.cpp

@@ -46,6 +46,8 @@ Options:
 
   --no-color      Don't print in color.
                   The default when output goes to a file.
+
+  --no-indent     Don't indent instructions.
 )",
       argv0, argv0);
 }
@@ -63,6 +65,7 @@ int main(int argc, char** argv) {
 #ifdef SPIRV_COLOR_TERMINAL
   allow_color = true;
 #endif
+  bool allow_indent = true;
 
   for (int argi = 1; argi < argc; ++argi) {
     if ('-' == argv[argi][0]) {
@@ -81,6 +84,7 @@ int main(int argc, char** argv) {
         case '-': {
           // Long options
           if (0 == strcmp(argv[argi], "--no-color")) allow_color = false;
+          if (0 == strcmp(argv[argi], "--no-indent")) allow_indent = false;
           if (0 == strcmp(argv[argi], "--help")) {
             print_usage(argv[0]);
             return 0;
@@ -102,6 +106,9 @@ int main(int argc, char** argv) {
 
   uint32_t options = SPV_BINARY_TO_TEXT_OPTION_NONE;
 
+  if (allow_indent)
+    options |= SPV_BINARY_TO_TEXT_OPTION_INDENT;
+
   if (!outFile) {
     // Print to standard output.
     options |= SPV_BINARY_TO_TEXT_OPTION_PRINT;