Code generation is incorrect with impure functions due to optimization pass

[ArielG-NV]

The first call to simplifyIR (after lowerLValueCast in linkAndOptimizeIR) simplifies functions which are impure and have side effects in the body (and not the arguments). It is likely all simplifyIR calls exhibit this behavior.

edit:
This issue is due to incorrect checking in isPureFunctionalCall

example case:

//TEST(compute, vulkan):COMPARE_COMPUTE(filecheck-buffer=BUF):-vk -compute -entry computeMain -allow-glsl
//TEST(compute, vulkan):COMPARE_COMPUTE(filecheck-buffer=BUF):-vk -compute -entry computeMain -allow-glsl -emit-spirv-directly
#version 430
precision highp float;
precision highp int;

//TEST_INPUT:ubuffer(data=[0], stride=4):out,name=outputBuffer
buffer MyBlockName2
{
    uint data[1];
} outputBuffer;

layout(local_size_x = 4) in;

void sideEffectInit(int val)
{
    outputBuffer.data[0] = val;
}
void computeMain()
{
    outputBuffer.data[0] = 1000;
    sideEffectInit(4);
    // BUF: 4
}

this compiles computeMain currently into:

void computeMain()
{
    outputBuffer.data[0] = 1000;
}

computeMain should instead compile effectively into:

void computeMain()
{
    outputBuffer.data[0] = 1000;
    sideEffectInit(4);
}

[csyonghe]

isPureFunctionCall looks for the IRReadNoneDecoration on the callee, which is propagated during propagateFuncProperties.

propagateFuncProperties does check for the body of the function for any side effects.

In this case I suspect the root cause is that the stores into a GLSL storage buffer isn't counted as having global side effect for some reason. Need to debug into propagateFuncPropertiesImpl to see why it decides the function has no side effect.