The version header word has 3 byte-size components.

Bits 24-31: 0
Bits 16-23: SPIR-V major number (1)
Bits  8-15: SPIR-V minor number (0)
Bits   0-7: SPIR-V minor number (2)

The assembler will construct the word appropriately,
and the disassemble will print it in major.minor.revision form.

include/libspirv/libspirv.h

@@ -38,6 +38,14 @@ extern "C" {
 #include <stddef.h>
 #include <stdint.h>
 
+// Versions
+// This library is based on SPIR-V 1.0 Rev2
+// TODO(dneto): Use the values from the SPIR-V header, when it's updated for
+// SPIR-V 1.0 public release.
+#define SPV_SPIRV_VERSION_MAJOR 1
+#define SPV_SPIRV_VERSION_MINOR 0
+#define SPV_SPIRV_VERSION_REVISION 2
+
 // Helpers
 
 #define spvIsInBitfield(value, bitfield) (value == (value & bitfield))

source/disassemble.cpp

@@ -135,7 +135,9 @@ spv_result_t Disassembler::HandleHeader(spv_endianness_t endian,
   const char* generator_tool =
       spvGeneratorStr(SPV_GENERATOR_TOOL_PART(generator));
   stream_ << "; SPIR-V\n"
-          << "; Version: " << version << "\n"
+          << "; Version: " << SPV_SPIRV_VERSION_MAJOR_PART(version) << "."
+          << SPV_SPIRV_VERSION_MINOR_PART(version) << "."
+          << SPV_SPIRV_VERSION_REVISION_PART(version) << "\n"
           << "; Generator: " << generator_tool;
   // For unknown tools, print the numeric tool value.
   if (0 == strcmp("Unknown", generator_tool)) {

source/spirv_constant.h

@@ -29,6 +29,20 @@
 
 #include "libspirv/libspirv.h"
 
+// Version number macros.
+
+// Evaluates to a well-formed version header word, given valid
+// SPIR-V version major, minor, and revision numbers.
+#define SPV_SPIRV_VERSION_WORD(MAJOR, MINOR, REVISION)                  \
+  ((uint32_t(uint8_t(MAJOR)) << 16) | (uint32_t(uint8_t(MINOR)) << 8) | \
+   uint8_t(REVISION))
+// Returns the major version extracted from a version header word.
+#define SPV_SPIRV_VERSION_MAJOR_PART(WORD) ((uint32_t(WORD) >> 16) & 0xff)
+// Returns the minor version extracted from a version header word.
+#define SPV_SPIRV_VERSION_MINOR_PART(WORD) ((uint32_t(WORD) >> 8) & 0xff)
+// Returns the revision number extracted from a version header word.
+#define SPV_SPIRV_VERSION_REVISION_PART(WORD) (uint32_t(WORD) & 0xff)
+
 // Header indices
 
 #define SPV_INDEX_MAGIC_NUMBER 0u

source/text.cpp

@@ -667,7 +667,9 @@ SetHeader(uint32_t* words, const uint32_t bound) {
   if (!words) return SPV_ERROR_INVALID_BINARY;
 
   words[SPV_INDEX_MAGIC_NUMBER] = SpvMagicNumber;
-  words[SPV_INDEX_VERSION_NUMBER] = SpvVersion;
+  words[SPV_INDEX_VERSION_NUMBER] =
+      SPV_SPIRV_VERSION_WORD(SPV_SPIRV_VERSION_MAJOR, SPV_SPIRV_VERSION_MINOR,
+                             SPV_SPIRV_VERSION_REVISION);
   words[SPV_INDEX_GENERATOR_NUMBER] =
       SPV_GENERATOR_WORD(SPV_GENERATOR_KHRONOS_ASSEMBLER, kAssemblerVersion);
   words[SPV_INDEX_BOUND] = bound;

test/BinaryToText.cpp

@@ -395,6 +395,25 @@ OpStore %2 %3 Aligned|Volatile 4 ; bogus, but not indented
       expected);
 }
 
+// Test version string.
+TEST_F(TextToBinaryTest, VersionString) {
+  auto words = CompileSuccessfully("");
+  spv_text decoded_text = nullptr;
+  spv_diagnostic diagnostic = nullptr;
+  EXPECT_THAT(spvBinaryToText(context, words.data(), words.size(),
+                              SPV_BINARY_TO_TEXT_OPTION_NONE, &decoded_text,
+                              &diagnostic),
+              Eq(SPV_SUCCESS));
+  EXPECT_EQ(nullptr, diagnostic);
+
+  EXPECT_EQ(1, SPV_SPIRV_VERSION_MAJOR);
+  EXPECT_EQ(0, SPV_SPIRV_VERSION_MINOR);
+  EXPECT_EQ(2, SPV_SPIRV_VERSION_REVISION);
+  EXPECT_THAT(decoded_text->str, HasSubstr("Version: 1.0.2\n"))
+      << EncodeAndDecodeSuccessfully("");
+  spvTextDestroy(decoded_text);
+}
+
 // Test generator string.
 
 // A test case for the generator string.  This allows us to

test/ExtInstGLSLstd450.cpp

@@ -66,7 +66,7 @@ OpFunctionEnd
 )";
   const std::string spirv_header =
       R"(; SPIR-V
-; Version: 100
+; Version: 1.0.2
 ; Generator: Khronos SPIR-V Tools Assembler; 0
 ; Bound: 9
 ; Schema: 0)";