mvkConvertSPIRVToMSL failing

[wtholliday]

Related to #1448, I replaced the following code:

- (NSString*) toMSL:(NSString*) text {
    
    mvk::GLSLToSPIRVConverter toSpirv;
    toSpirv.setGLSL(std::string(text.UTF8String));
    if(!toSpirv.convert(kMVKGLSLConversionShaderStageFragment, true, true)) {
        printf("failed to convert to SPIRV: %s\n", toSpirv.getResultLog().c_str());
        return nil;
    }

    mvk::SPIRVToMSLConverter toMSL;
    toMSL.setSPIRV(toSpirv.getSPIRV());
    mvk::SPIRVToMSLConversionConfiguration ctx;
    if(!toMSL.convert(ctx)) {
        printf("failed to convert to MSL: %s\n", toMSL.getResultLog().c_str());
        return nil;
    }

    return [NSString stringWithUTF8String:toMSL.getMSL().c_str()];
    
}

with:

- (NSString*) toMSL:(NSString*) text {

    uint32_t* spvCode = NULL;
    size_t spvLength = 0;
    char* resultLog = NULL;
    if(!mvkConvertGLSLToSPIRV(text.UTF8String, kMVKGLSLConversionShaderStageFragment, &spvCode, &spvLength, &resultLog, true, true)) {
        printf("failed to convert to SPIRV: %s\n", resultLog);
        free(spvCode);
        return nil;
    }

    free(resultLog);

    char* msl = NULL;
    if(!mvkConvertSPIRVToMSL(spvCode, spvLength, &msl, &resultLog, true, true)) {
        printf("failed to convert to MSL: %s\n", resultLog);
        free(spvCode);
        free(msl);
        return nil;
    }

    auto result = [NSString stringWithUTF8String:msl];
    free(msl);
    free(spvCode);
    return result;
    
}

Now I get:

MSL conversion error: SPIR-V instructions cannot consume 0 words. Invalid SPIR-V file.

Is there anything obvious I'm doing wrong here?

(I did this so I could use a separate SPIRV-Cross to introspect on the SPIRV).

[wtholliday]

Looks like mvkConvertSPIRVToMSL takes a length in words, whereas mvkConvertGLSLToSPIRV returns a length in bytes.

Had to do:
mvkConvertSPIRVToMSL(spvCode, spvLength/sizeof(uint32_t), &msl, &resultLog, true, true)

MoltenVK should be consistent, I would think.