Bug 1910306 - [angle] Cherry-pick zero-initialization of unwritten GLSL out params. a=dmeehan

Original Revision: https://phabricator.services.mozilla.com/D218019

Differential Revision: https://phabricator.services.mozilla.com/D218213

gfx/angle/checkout/out/gen/angle/angle_commit.h

@@ -1,5 +1,5 @@
-#define ANGLE_COMMIT_HASH "791816843657"
+#define ANGLE_COMMIT_HASH "419cd2c3213b"
 #define ANGLE_COMMIT_HASH_SIZE 12
-#define ANGLE_COMMIT_DATE "2024-06-06 10:35:11 -0700"
+#define ANGLE_COMMIT_DATE "2024-07-29 14:40:59 -0700"
-#define ANGLE_COMMIT_POSITION 19738
+#define ANGLE_COMMIT_POSITION 19739
 #define ANGLE_HAS_BINARY_LOADING

gfx/angle/checkout/src/compiler/translator/tree_ops/InitializeVariables.cpp

@@ -309,6 +309,37 @@ class InitializeLocalsTraverser : public TIntermTraverser
         return false;
     }
 
+    bool visitFunctionDefinition(Visit visit, TIntermFunctionDefinition *node) override
+    {
+        // Initialize output function arguments as well, the parameter passed in at call time may be
+        // clobbered if the function doesn't fully write to the argument.
+
+        TIntermSequence initCode;
+
+        const TFunction *function = node->getFunction();
+        for (size_t paramIndex = 0; paramIndex < function->getParamCount(); ++paramIndex)
+        {
+            const TVariable *paramVariable = function->getParam(paramIndex);
+            const TType &paramType         = paramVariable->getType();
+
+            if (paramType.getQualifier() != EvqParamOut)
+            {
+                continue;
+            }
+
+            CreateInitCode(new TIntermSymbol(paramVariable), mCanUseLoopsToInitialize,
+                           mHighPrecisionSupported, &initCode, mSymbolTable);
+        }
+
+        if (!initCode.empty())
+        {
+            TIntermSequence *body = node->getBody()->getSequence();
+            body->insert(body->begin(), initCode.begin(), initCode.end());
+        }
+
+        return true;
+    }
+
   private:
     int mShaderVersion;
     bool mCanUseLoopsToInitialize;

gfx/angle/cherry_picks.txt

@@ -1,3 +1,20 @@
+commit 419cd2c3213b594f8e2488bf48034fed20ace81d
+Author: Shahbaz Youssefi <syoussefi@chromium.org>
+Date:   Mon Mar 27 13:05:36 2023 -0400
+
+    Translator: Initialize out arguments too for WebGL
+    
+    Local variables were initialized for WebGL, but not `out` arguments.
+    However, `out` arguments completely overwrite the passed-in variable at
+    call site, so they should also be zeroed out.
+    
+    Bug: chromium:1425685
+    Change-Id: Ib2f61a962eea74c4933aafa4d5ad377189cec578
+    Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4375137
+    Reviewed-by: Geoff Lang <geofflang@chromium.org>
+    Reviewed-by: Kenneth Russell <kbr@chromium.org>
+    Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
+
 commit 7918168436578718b234bfd56da152e34a85af1d
 Author: Kelsey Gilbert <kelsey.gilbert@mozilla.com>
 Date:   Tue Jun 4 15:37:29 2024 -0700