From a9dc249f6b25acc6c9c767d55e2eb53a6c841073 Mon Sep 17 00:00:00 2001
From: Tzarial <zork@google.com>
Date: Mon, 22 Jun 2026 14:58:38 +0000
Subject: [PATCH] Fix robust resource init bypass for packed depth/stencil

Clearing only one aspect of a packed depth-stencil attachment was
acting as a partial clear of the underlying resource. The per-resource
init-state flag is shared between the depth and stencil bindings, so
marking one aspect Initialized incorrectly suppresses robust-init
of the other aspect. This patch ensures that if only one aspect is
cleared and the other aspect needs init, we fall back to full init.

Bug: b/513048462
Test: RobustResourceInitTestES3.DepthClearBypassStencilInit
Change-Id: Ic1e6a351e9e59045b9b088c59077d3b729ddd987
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/8003418
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Tzarial <zork@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
---
diff --git a/src/libANGLE/Framebuffer.cpp b/src/libANGLE/Framebuffer.cpp
index 482f284..42db090 100644
--- a/src/libANGLE/Framebuffer.cpp
+++ b/src/libANGLE/Framebuffer.cpp
@@ -1671,6 +1671,27 @@
         return angle::Result::Continue;
     }
 
+    // Clearing only one aspect of a packed depth-stencil attachment is a partial
+    // clear of the underlying resource. While the framebuffer tracks depth and
+    // stencil initialization needs separately in mState.mResourceNeedsInit, the
+    // underlying resource (texture level or renderbuffer) has a single shared
+    // InitState. Marking one aspect as Initialized updates the shared resource state,
+    // which would incorrectly suppress robust-init of the other aspect.
+    if (depth && !stencil && mState.mDepthAttachment.isAttached() &&
+        mState.mDepthAttachment.getStencilSize() > 0 &&
+        mState.mResourceNeedsInit[DIRTY_BIT_DEPTH_ATTACHMENT])
+    {
+        *needsInitOut = true;
+        return angle::Result::Continue;
+    }
+    if (stencil && !depth && mState.mStencilAttachment.isAttached() &&
+        mState.mStencilAttachment.getDepthSize() > 0 &&
+        mState.mResourceNeedsInit[DIRTY_BIT_STENCIL_ATTACHMENT])
+    {
+        *needsInitOut = true;
+        return angle::Result::Continue;
+    }
+
     // Scissors can affect clearing.
     if (glState.isScissorTestEnabled())
     {
diff --git a/src/tests/gl_tests/RobustResourceInitTest.cpp b/src/tests/gl_tests/RobustResourceInitTest.cpp
index c1924d6..058d729 100644
--- a/src/tests/gl_tests/RobustResourceInitTest.cpp
+++ b/src/tests/gl_tests/RobustResourceInitTest.cpp
@@ -4156,6 +4156,124 @@
     EXPECT_GL_NO_ERROR();
 }
 
+// Tests that partial clear of a packed depth-stencil attachment doesn't
+// incorrectly bypass robust initialization for the other aspect.
+TEST_P(RobustResourceInitTestES3, DepthClearWithStencilInit)
+{
+    ANGLE_SKIP_TEST_IF(!hasGLExtension());
+
+    constexpr int kSize = 16;
+
+    // Create a new FBO with a packed depth-stencil texture.
+    GLTexture dsTex;
+    glBindTexture(GL_TEXTURE_2D, dsTex);
+    glTexStorage2D(GL_TEXTURE_2D, 1, GL_DEPTH24_STENCIL8, kSize, kSize);
+
+    GLTexture colorTex;
+    glBindTexture(GL_TEXTURE_2D, colorTex);
+    glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA8, kSize, kSize);
+
+    GLFramebuffer fbo;
+    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorTex, 0);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, dsTex, 0);
+    EXPECT_GL_FRAMEBUFFER_COMPLETE(GL_FRAMEBUFFER);
+
+    // Clear only depth. This should leave the stencil aspect in MayNeedInit state,
+    // which shouldn't be overridden to Initialized.
+    glClear(GL_DEPTH_BUFFER_BIT);
+
+    // Then bind the stencil attachment here so that we can verify it was initialized:
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_TEXTURE_2D, dsTex, 0);
+
+    // Verify stencil is initialized to 0. We can do this by using the stencil side channel.
+    // robust-init mandates 0.
+    glEnable(GL_STENCIL_TEST);
+    glStencilFunc(GL_EQUAL, 0x00, 0xFF);
+    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
+
+    ANGLE_GL_PROGRAM(drawRed, essl1_shaders::vs::Simple(), essl1_shaders::fs::Red());
+    drawQuad(drawRed, essl1_shaders::PositionAttrib(), 0.95f, 1.0f, true);
+
+    // Read the color buffer to verify that stencil test passed for all pixels.
+    EXPECT_PIXEL_RECT_EQ(0, 0, kSize, kSize, GLColor::red);
+    EXPECT_GL_NO_ERROR();
+}
+
+// Tests that partial clear of a packed depth-stencil attachment (stencil-only) doesn't
+// incorrectly bypass robust initialization for the depth aspect.
+TEST_P(RobustResourceInitTestES3, StencilClearWithDepthInit)
+{
+    ANGLE_SKIP_TEST_IF(!hasGLExtension());
+
+    constexpr int kSize = 16;
+
+    // Create a new FBO with a packed depth-stencil texture.
+    GLTexture dsTex;
+    glBindTexture(GL_TEXTURE_2D, dsTex);
+    glTexStorage2D(GL_TEXTURE_2D, 1, GL_DEPTH24_STENCIL8, kSize, kSize);
+
+    GLTexture colorTex;
+    glBindTexture(GL_TEXTURE_2D, colorTex);
+    glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA8, kSize, kSize);
+
+    GLFramebuffer fbo;
+    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorTex, 0);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_TEXTURE_2D, dsTex, 0);
+    EXPECT_GL_FRAMEBUFFER_COMPLETE(GL_FRAMEBUFFER);
+
+    // Clear only stencil. This should leave the depth aspect in MayNeedInit state,
+    // which shouldn't be overridden to Initialized.
+    glClear(GL_STENCIL_BUFFER_BIT);
+
+    // Unbind the depth-stencil texture from the FBO so we can sample it as a texture.
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_TEXTURE_2D, 0, 0);
+
+    // Bind the texture to texture unit 0 and set filters.
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_2D, dsTex);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+    // Verify depth == 1.0 via shader sampling
+    constexpr char kVS[] = R"(#version 300 es
+in vec4 aPosition;
+void main()
+{
+    gl_Position = aPosition;
+})";
+
+    constexpr char kFS[] = R"(#version 300 es
+precision highp float;
+uniform highp sampler2D uDepthTex;
+out vec4 outColor;
+void main()
+{
+    float depth = texture(uDepthTex, vec2(0.5, 0.5)).r;
+    if (abs(depth - 1.0) < 0.001)
+    {
+        outColor = vec4(0.0, 1.0, 0.0, 1.0); // green
+    }
+    else
+    {
+        outColor = vec4(1.0, 0.0, 0.0, 1.0); // red
+    }
+})";
+
+    ANGLE_GL_PROGRAM(depthSampleProg, kVS, kFS);
+    glUseProgram(depthSampleProg);
+    GLint texLoc = glGetUniformLocation(depthSampleProg, "uDepthTex");
+    ASSERT_NE(texLoc, -1);
+    glUniform1i(texLoc, 0);
+
+    drawQuad(depthSampleProg, "aPosition", 0.0f);
+
+    // Read the color buffer to verify that depth was successfully initialized to 1.0f.
+    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
+    EXPECT_GL_NO_ERROR();
+}
+
 ANGLE_INSTANTIATE_TEST_ES2_AND_ES3_AND(
     RobustResourceInitTest,
     ES3_METAL().enable(Feature::EmulateDontCareLoadWithRandomClear),

diff --git a/src/tests/gl_tests/RobustResourceInitTest.cpp b/src/tests/gl_tests/RobustResourceInitTest.cpp
index c1924d6..058d729 100644
--- a/src/tests/gl_tests/RobustResourceInitTest.cpp
+++ b/src/tests/gl_tests/RobustResourceInitTest.cpp
@@ -4156,6 +4156,124 @@
     EXPECT_GL_NO_ERROR();
 }
 
+// Tests that partial clear of a packed depth-stencil attachment doesn't
+// incorrectly bypass robust initialization for the other aspect.
+TEST_P(RobustResourceInitTestES3, DepthClearWithStencilInit)
+{
+    ANGLE_SKIP_TEST_IF(!hasGLExtension());
+
+    constexpr int kSize = 16;
+
+    // Create a new FBO with a packed depth-stencil texture.
+    GLTexture dsTex;
+    glBindTexture(GL_TEXTURE_2D, dsTex);
+    glTexStorage2D(GL_TEXTURE_2D, 1, GL_DEPTH24_STENCIL8, kSize, kSize);
+
+    GLTexture colorTex;
+    glBindTexture(GL_TEXTURE_2D, colorTex);
+    glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA8, kSize, kSize);
+
+    GLFramebuffer fbo;
+    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorTex, 0);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, dsTex, 0);
+    EXPECT_GL_FRAMEBUFFER_COMPLETE(GL_FRAMEBUFFER);
+
+    // Clear only depth. This should leave the stencil aspect in MayNeedInit state,
+    // which shouldn't be overridden to Initialized.
+    glClear(GL_DEPTH_BUFFER_BIT);
+
+    // Then bind the stencil attachment here so that we can verify it was initialized:
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_TEXTURE_2D, dsTex, 0);
+
+    // Verify stencil is initialized to 0. We can do this by using the stencil side channel.
+    // robust-init mandates 0.
+    glEnable(GL_STENCIL_TEST);
+    glStencilFunc(GL_EQUAL, 0x00, 0xFF);
+    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
+
+    ANGLE_GL_PROGRAM(drawRed, essl1_shaders::vs::Simple(), essl1_shaders::fs::Red());
+    drawQuad(drawRed, essl1_shaders::PositionAttrib(), 0.95f, 1.0f, true);
+
+    // Read the color buffer to verify that stencil test passed for all pixels.
+    EXPECT_PIXEL_RECT_EQ(0, 0, kSize, kSize, GLColor::red);
+    EXPECT_GL_NO_ERROR();
+}
+
+// Tests that partial clear of a packed depth-stencil attachment (stencil-only) doesn't
+// incorrectly bypass robust initialization for the depth aspect.
+TEST_P(RobustResourceInitTestES3, StencilClearWithDepthInit)
+{
+    ANGLE_SKIP_TEST_IF(!hasGLExtension());
+
+    constexpr int kSize = 16;
+
+    // Create a new FBO with a packed depth-stencil texture.
+    GLTexture dsTex;
+    glBindTexture(GL_TEXTURE_2D, dsTex);
+    glTexStorage2D(GL_TEXTURE_2D, 1, GL_DEPTH24_STENCIL8, kSize, kSize);
+
+    GLTexture colorTex;
+    glBindTexture(GL_TEXTURE_2D, colorTex);
+    glTexStorage2D(GL_TEXTURE_2D, 1, GL_RGBA8, kSize, kSize);
+
+    GLFramebuffer fbo;
+    glBindFramebuffer(GL_FRAMEBUFFER, fbo);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, colorTex, 0);
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_TEXTURE_2D, dsTex, 0);
+    EXPECT_GL_FRAMEBUFFER_COMPLETE(GL_FRAMEBUFFER);
+
+    // Clear only stencil. This should leave the depth aspect in MayNeedInit state,
+    // which shouldn't be overridden to Initialized.
+    glClear(GL_STENCIL_BUFFER_BIT);
+
+    // Unbind the depth-stencil texture from the FBO so we can sample it as a texture.
+    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_TEXTURE_2D, 0, 0);
+
+    // Bind the texture to texture unit 0 and set filters.
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_2D, dsTex);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+    // Verify depth == 1.0 via shader sampling
+    constexpr char kVS[] = R"(#version 300 es
+in vec4 aPosition;
+void main()
+{
+    gl_Position = aPosition;
+})";
+
+    constexpr char kFS[] = R"(#version 300 es
+precision highp float;
+uniform highp sampler2D uDepthTex;
+out vec4 outColor;
+void main()
+{
+    float depth = texture(uDepthTex, vec2(0.5, 0.5)).r;
+    if (abs(depth - 1.0) < 0.001)
+    {
+        outColor = vec4(0.0, 1.0, 0.0, 1.0); // green
+    }
+    else
+    {
+        outColor = vec4(1.0, 0.0, 0.0, 1.0); // red
+    }
+})";
+
+    ANGLE_GL_PROGRAM(depthSampleProg, kVS, kFS);
+    glUseProgram(depthSampleProg);
+    GLint texLoc = glGetUniformLocation(depthSampleProg, "uDepthTex");
+    ASSERT_NE(texLoc, -1);
+    glUniform1i(texLoc, 0);
+
+    drawQuad(depthSampleProg, "aPosition", 0.0f);
+
+    // Read the color buffer to verify that depth was successfully initialized to 1.0f.
+    EXPECT_PIXEL_COLOR_EQ(0, 0, GLColor::green);
+    EXPECT_GL_NO_ERROR();
+}
+
 ANGLE_INSTANTIATE_TEST_ES2_AND_ES3_AND(
     RobustResourceInitTest,
     ES3_METAL().enable(Feature::EmulateDontCareLoadWithRandomClear),