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Disable optimizations in debug when compiling shaders #2976

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13 changes: 9 additions & 4 deletions sources/engine/Stride.Shaders.Compiler/Direct3D/ShaderCompiler.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,10 +8,7 @@
using SharpDX.D3DCompiler;
using Stride.Core.Diagnostics;
using Stride.Core.Storage;
using Stride.Rendering;
using Stride.Graphics;
using ConstantBufferType = Stride.Shaders.ConstantBufferType;
using ShaderBytecode = Stride.Shaders.ShaderBytecode;
using ShaderVariableType = SharpDX.D3DCompiler.ShaderVariableType;

namespace Stride.Shaders.Compiler.Direct3D
Expand All @@ -23,13 +20,21 @@ public ShaderBytecodeResult Compile(string shaderSource, string entryPoint, Shad
var isDebug = effectParameters.Debug;
var optimLevel = effectParameters.OptimizationLevel;
var profile = effectParameters.Profile;

var shaderModel = ShaderStageToString(stage) + "_" + ShaderProfileFromGraphicsProfile(profile);

var shaderFlags = ShaderFlags.None;
if (isDebug)
{
shaderFlags = ShaderFlags.Debug;

// Disable optimizations when debugging, except for Graphics Profiles 9.3 and below
// where optimizations are required to have valid shaders (otherwise compilation fails
// indicating too many instruction slots used)
if (profile >= GraphicsProfile.Level_10_0)
{
shaderFlags |= ShaderFlags.SkipOptimization;
}
}
switch (optimLevel)
{
Expand Down
28 changes: 19 additions & 9 deletions sources/engine/Stride.Shaders.Compiler/OpenGL/ShaderCompiler.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,10 +2,8 @@
// Distributed under the MIT license. See the LICENSE.md file in the project root for more information.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using Stride.Core;
using Stride.Core.Extensions;
Expand All @@ -14,9 +12,7 @@
using Stride.Graphics;
using Stride.Core.Shaders.Ast;
using Stride.Core.Shaders.Ast.Glsl;
using Stride.Core.Shaders.Ast.Hlsl;
using Stride.Core.Shaders.Convertor;
using Stride.Core.Shaders.Writer.Hlsl;
using ConstantBuffer = Stride.Core.Shaders.Ast.Hlsl.ConstantBuffer;
using StorageQualifier = Stride.Core.Shaders.Ast.StorageQualifier;

Expand Down Expand Up @@ -80,7 +76,7 @@ public ShaderBytecodeResult Compile(string shaderSource, string entryPoint, Shad
return shaderBytecodeResult;

if (effectParameters.Platform == GraphicsPlatform.OpenGLES) // TODO: Add check to run on android only. The current version breaks OpenGL ES on windows.
{
{
//TODO: Remove this ugly hack!
if (shaderSource.Contains($"Texture2D StrideInternal_TextureExt0") && shader.Contains("uniform sampler2D"))
{
Expand Down Expand Up @@ -111,6 +107,20 @@ public ShaderBytecodeResult Compile(string shaderSource, string entryPoint, Shad
var inputFileName = Path.ChangeExtension(Path.GetTempFileName(), inputFileExtension);
var outputFileName = Path.ChangeExtension(inputFileName, ".spv");

var args = $"-V"; // Generate SPIR-V binary

// Add debug info if needed
if (effectParameters.Debug)
{
args += " -g"; // Generate debug information
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@Kryptos-FR Kryptos-FR Nov 18, 2025 •
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String concatenation creates garbage that needs to be cleaned up by the GC. Let's try to avoid that.

It can be achieved in multiple ways: either with a StringBuilder or with string interpolation (which the compiler can optimize).

For instance (pseudo code):

bool isDebug = ...;

var str = $"{isDebug ? "-D" : ""} some literal {filename}";

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@Ethereal77 Ethereal77 Nov 19, 2025

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I did write it with string concatenation because the function already allocates a lot (to start, two Dictionarys at the top, the ShaderBytecodeResult, the ShaderBytecode, BinarySerializationWriter, MemoryStream, and even calls Encoding.ASCII.GetBytes() several times) 😢.

Also, I tried interpolation, but I think it obfuscates the logic a bit:

string args = $"-V {                  // Generate SPIR-V binary
    (effectParameters.Debug
        ? effectParameters.Profile < GraphicsProfile.Level_10_0
            ? "-g"                    // Generate debug information
            : "-g -Od"                // Generate debug and disable optimizations (only for level 10.0+)
        : "")
    } -o {outputFileName} {inputFileName}";

This is the version with StringBuilder:

var argsBuilder = new StringBuilder();

argsBuilder.Append("-V");  // Generate SPIR-V binary

if (effectParameters.Debug)
{
    argsBuilder.Append(" -g");  // Generate debug information

    if (effectParameters.Profile >= GraphicsProfile.Level_10_0)
    {
        argsBuilder.Append(" -Od"); // Disable optimizations
    }
}
argsBuilder.Append($" -o {outputFileName} {inputFileName}");
string args = argsBuilder.ToString();

What do you think? Obviously, interpolation just allocates once (the final string), but reads worse, while StringBuilder allocates twice (hopefully, not counting internal buffers), and reads better.


if (effectParameters.Profile >= GraphicsProfile.Level_10_0)
{
args += " -Od"; // Disable optimizations
}
}
args += $" -o {outputFileName} {inputFileName}";

// Write shader source to disk
File.WriteAllBytes(inputFileName, Encoding.ASCII.GetBytes(shader));

Expand All @@ -131,7 +141,7 @@ public ShaderBytecodeResult Compile(string shaderSource, string entryPoint, Shad
default:
throw new PlatformNotSupportedException();
}
ShellHelper.RunProcessAndRedirectToLogger(filename, $"-V -o {outputFileName} {inputFileName}", null, shaderBytecodeResult);
ShellHelper.RunProcessAndRedirectToLogger(filename, args, workingDirectory: null, shaderBytecodeResult);

if (!File.Exists(outputFileName))
{
Expand Down Expand Up @@ -163,13 +173,13 @@ public ShaderBytecodeResult Compile(string shaderSource, string entryPoint, Shad
// store string on OpenGL platforms
rawData = Encoding.UTF8.GetBytes(shader);
}

var bytecodeId = ObjectId.FromBytes(rawData);
var bytecode = new ShaderBytecode(bytecodeId, rawData);
bytecode.Stage = stage;

shaderBytecodeResult.Bytecode = bytecode;

return shaderBytecodeResult;
}

Expand Down Expand Up @@ -262,7 +272,7 @@ private string Compile(string shaderSource, string entryPoint, ShaderStage stage
MarkResourceBindingAsUsed(reflection, resourceBindingIndex, stage);
}
}

foreach (var variable in glslShader.Declarations.OfType<Variable>().Where(x => (x.Qualifiers.Contains(StorageQualifier.Uniform))))
{
// Check if we have a variable that starts or ends with this name (in case of samplers)
Expand Down
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