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shaderc: Remove unused uniforms from SPIRV shader.

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This commit is contained in:
Branimir Karadžić 2018-04-13 17:12:43 -07:00
parent 9ee64bce99
commit ec3241a869
1 changed files with 48 additions and 2 deletions
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50
tools/shaderc/shaderc_spirv.cpp
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@ -533,7 +533,7 @@ namespace bgfx { namespace spirv
// fprintf(stderr, "%s\n", _message);
// }
static bool compile(const Options& _options, uint32_t _version, const std::string& _code, bx::WriterI* _writer)
static bool compile(const Options& _options, uint32_t _version, const std::string& _code, bx::WriterI* _writer, bool _firstPass)
{
BX_UNUSED(_version);
@ -627,6 +627,52 @@ namespace bgfx { namespace spirv
uint16_t size = 0;
program->buildReflection();
if (_firstPass)
{
const size_t strLength = bx::strLen("uniform");
// first time through, we just find unused uniforms and get rid of them
std::string output;
bx::Error err;
LineReader reader(_code.c_str() );
while (err.isOk() )
{
char str[4096];
int32_t len = bx::read(&reader, str, BX_COUNTOF(str), &err);
if (err.isOk() )
{
std::string strLine(str, len);
for (int32_t ii = 0, num = program->getNumLiveUniformVariables(); ii < num; ++ii)
{
size_t index = strLine.find("uniform ");
if (index == std::string::npos)
{
continue;
}
// matching lines like: uniform u_name;
// we want to replace "uniform" with "static" so that it's no longer
// included in the uniform blob that the application must upload
// we can't just remove them, because unused functions might still reference
// them and cause a compile error when they're gone
if (!!bx::findIdentifierMatch(strLine.c_str(), program->getUniformName(ii) ) )
{
break;
}
strLine = strLine.replace(index, strLength, "static");
}
output += strLine;
}
}
// recompile with the unused uniforms converted to statics
return compile(_options, _version, output.c_str(), _writer, false);
}
{
uint16_t count = (uint16_t)program->getNumLiveUniformVariables();
bx::write(_writer, count);
@ -723,7 +769,7 @@ namespace bgfx { namespace spirv
bool compileSPIRVShader(const Options& _options, uint32_t _version, const std::string& _code, bx::WriterI* _writer)
{
return spirv::compile(_options, _version, _code, _writer);
return spirv::compile(_options, _version, _code, _writer, true);
}
} // namespace bgfx