From 9eadd12e33d65b8c9101ddef1d77d1c9a07e07bf Mon Sep 17 00:00:00 2001
From: Jamie Nicol <jnicol@mozilla.com>
Date: Thu, 30 Apr 2026 09:43:22 +0100
Subject: [PATCH] Revert "Translator: Do not validate uniform packing"

This reverts commit ad96e4bb5071aa32dc4b5782ae710b3989f04664.

Co-authored-by: Erich Gubler <erichdongubler@gmail.com>
---
 include/GLSLANG/ShaderLang.h         |  6 +++++
 src/compiler/translator/Compiler.cpp | 37 ++++++++++++++++++++++++++++
 src/libANGLE/Shader.cpp              |  1 +
 3 files changed, 44 insertions(+)

diff --git a/include/GLSLANG/ShaderLang.h b/include/GLSLANG/ShaderLang.h
index 135daac147..351b5745ac 100644
--- a/include/GLSLANG/ShaderLang.h
+++ b/include/GLSLANG/ShaderLang.h
@@ -208,6 +208,12 @@ struct ShCompileOptions
     // Whether SPV_EXT_demote_to_helper_invocation can be used.
     uint64_t useDemoteToHelperInvocation : 1;
 
+    // Enforce the GLSL 1.017 Appendix A section 7 packing restrictions.  This flag only enforces
+    // (and can only enforce) the packing restrictions for uniform variables in both vertex and
+    // fragment shaders. ShCheckVariablesWithinPackingLimits() lets embedders enforce the packing
+    // restrictions for varying variables during program link time.
+    uint64_t enforcePackingRestrictions : 1;
+
     // This flag ensures all indirect (expression-based) array indexing is clamped to the bounds of
     // the array. This ensures, for example, that you cannot read off the end of a uniform, whether
     // an array vec234, or mat234 type.
diff --git a/src/compiler/translator/Compiler.cpp b/src/compiler/translator/Compiler.cpp
index ebf0bd49c6..052eaa22bb 100644
--- a/src/compiler/translator/Compiler.cpp
+++ b/src/compiler/translator/Compiler.cpp
@@ -26,6 +26,7 @@
 #include "compiler/translator/OutputTree.h"
 #include "compiler/translator/ParseContext.h"
 #include "compiler/translator/SizeClipCullDistance.h"
+#include "compiler/translator/VariablePacker.h"
 #include "compiler/translator/ir/src/compile.h"
 #include "compiler/translator/tree_ops/ClampFragDepth.h"
 #include "compiler/translator/tree_ops/ClampIndirectIndices.h"
@@ -356,6 +357,26 @@ size_t GetGlobalMaxTokenSize(ShShaderSpec spec)
     }
 }
 
+int GetMaxUniformVectorsForShaderType(GLenum shaderType, const ShBuiltInResources &resources)
+{
+    switch (shaderType)
+    {
+        case GL_VERTEX_SHADER:
+            return resources.MaxVertexUniformVectors;
+        case GL_FRAGMENT_SHADER:
+            return resources.MaxFragmentUniformVectors;
+
+        // TODO (jiawei.shao@intel.com): check if we need finer-grained component counting
+        case GL_COMPUTE_SHADER:
+            return resources.MaxComputeUniformComponents / 4;
+        case GL_GEOMETRY_SHADER_EXT:
+            return resources.MaxGeometryUniformComponents / 4;
+        default:
+            UNREACHABLE();
+            return -1;
+    }
+}
+
 namespace
 {
 class [[nodiscard]] TScopedSymbolTableLevel
@@ -1130,6 +1151,22 @@ bool TCompiler::checkAndSimplifyAST(TIntermBlock *root,
             }
         }
 
+        if (compileOptions.enforcePackingRestrictions)
+        {
+            int maxUniformVectors = GetMaxUniformVectorsForShaderType(mShaderType, mResources);
+            if (mShaderType == GL_VERTEX_SHADER && compileOptions.emulateClipOrigin)
+            {
+                --maxUniformVectors;
+            }
+            // Returns true if, after applying the packing rules in the GLSL ES 1.00.17 spec
+            // Appendix A, section 7, the shader does not use too many uniforms.
+            if (!CheckVariablesInPackingLimits(maxUniformVectors, mUniforms))
+            {
+                mDiagnostics.globalError("too many uniforms");
+                return false;
+            }
+        }
+
         if (compileOptions.scalarizeVecAndMatConstructorArgs)
         {
             if (!ScalarizeVecAndMatConstructorArgs(this, root, &mSymbolTable))
diff --git a/src/libANGLE/Shader.cpp b/src/libANGLE/Shader.cpp
index 81559a11c3..e7d680289a 100644
--- a/src/libANGLE/Shader.cpp
+++ b/src/libANGLE/Shader.cpp
@@ -639,6 +639,7 @@ void Shader::compile(const Context *context, angle::JobResultExpectancy resultEx
         options.initGLPosition             = true;
         options.limitCallStackDepth        = true;
         options.limitExpressionComplexity  = true;
+        options.enforcePackingRestrictions = true;
         options.initSharedVariables        = true;
         options.rejectWebglShadersWithLargeVariables    = true;
         options.rejectWebglShadersWithUndefinedBehavior = true;
-- 
2.54.0