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Commit 1e4f8b02 by Shahbaz Youssefi Committed by Commit Bot
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Vulkan: Generate gl_Position.z correction in SPIR-V

Instead of having the translator output code to transform gl_Position.z to Vulkan clip space in the vertex stage, this change makes the SPIR-V transformer perform this operation on the last geometry stage. An alternative solution would be to generate this transformation in the translator in every geometry stage, each controlled by a separate specialization constant. This change avoids unnecessary modifications to earlier stages. Additionally, the transformer is already modifying gl_Position.xy for pre-rotation, so the addition of a small transformation of gl_Position.z in the same spot is rather trivial. Bug: angleproject:5479 Change-Id: Id971179ba47b206204bfdaf3b2b295ef97dd5117 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2598585 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: 's avatarCharlie Lao <cclao@google.com> Reviewed-by: 's avatarJamie Madill <jmadill@chromium.org>
parent d2e76b73
Showing with 128 additions and 58 deletions
src/compiler/translator/TranslatorVulkan.cpp
......@@ -267,46 +267,6 @@ ANGLE_NO_DISCARD bool ReplaceGLDepthRangeWithDriverUniform(TCompiler *compiler,
return ReplaceVariableWithTyped(compiler, root, depthRangeVar, angleEmulatedDepthRangeRef);
}
// This operation performs the viewport depth translation needed by Vulkan. In GL the viewport
// transformation is slightly different - see the GL 2.0 spec section "2.12.1 Controlling the
// Viewport". In Vulkan the corresponding spec section is currently "23.4. Coordinate
// Transformations".
// The equations reduce to an expression:
//
// z_vk = 0.5 * (w_gl + z_gl)
//
// where z_vk is the depth output of a Vulkan vertex shader and z_gl is the same for GL.
ANGLE_NO_DISCARD bool AppendVertexShaderDepthCorrectionToMain(TCompiler *compiler,
TIntermBlock *root,
TSymbolTable *symbolTable)
{
// Create a symbol reference to "gl_Position"
const TVariable *position = BuiltInVariable::gl_Position();
TIntermSymbol *positionRef = new TIntermSymbol(position);
// Create a swizzle to "gl_Position.z"
TVector<int> swizzleOffsetZ = {2};
TIntermSwizzle *positionZ = new TIntermSwizzle(positionRef, swizzleOffsetZ);
// Create a constant "0.5"
TIntermConstantUnion *oneHalf = CreateFloatNode(0.5f);
// Create a swizzle to "gl_Position.w"
TVector<int> swizzleOffsetW = {3};
TIntermSwizzle *positionW = new TIntermSwizzle(positionRef->deepCopy(), swizzleOffsetW);
// Create the expression "(gl_Position.z + gl_Position.w) * 0.5".
TIntermBinary *zPlusW = new TIntermBinary(EOpAdd, positionZ, positionW);
TIntermBinary *halfZPlusW = new TIntermBinary(EOpMul, zPlusW, oneHalf);
// Create the assignment "gl_Position.z = (gl_Position.z + gl_Position.w) * 0.5"
TIntermTyped *positionZLHS = positionZ->deepCopy();
TIntermBinary *assignment = new TIntermBinary(TOperator::EOpAssign, positionZLHS, halfZPlusW);
// Append the assignment as a statement at the end of the shader.
return RunAtTheEndOfShader(compiler, root, assignment, symbolTable);
}
ANGLE_NO_DISCARD bool AppendTransformFeedbackOutputToMain(TCompiler *compiler,
TIntermBlock *root,
TSymbolTable *symbolTable)
......@@ -1082,10 +1042,18 @@ bool TranslatorVulkan::translateImpl(TIntermBlock *root,
{
return false;
}
if (!AppendVertexShaderDepthCorrectionToMain(this, root, &getSymbolTable()))
// Work around a bug in SwiftShader where missing gl_Position causes an assertion error.
// This code appends gl_Position = gl_Position; to the end of the shader.
// b/176161380
TIntermSymbol *position = new TIntermSymbol(BuiltInVariable::gl_Position());
TIntermBinary *assignment =
new TIntermBinary(TOperator::EOpAssign, position, position->deepCopy());
if (!RunAtTheEndOfShader(this, root, assignment, &getSymbolTable()))
{
return false;
}
break;
}
......
src/libANGLE/renderer/glslang_wrapper_utils.cpp
......@@ -1187,6 +1187,8 @@ class SpirvTransformerBase : angle::NonCopyable
const angle::FixedVector<uint32_t, 4> &constituents);
void writeCompositeExtract(uint32_t id, uint32_t typeId, uint32_t compositeId, uint32_t field);
void writeConstant(uint32_t id, uint32_t typeId, uint32_t value);
void writeFAdd(uint32_t id, uint32_t typeId, uint32_t operand1, uint32_t operand2);
void writeFMul(uint32_t id, uint32_t typeId, uint32_t operand1, uint32_t operand2);
void writeFNegate(uint32_t id, uint32_t typeId, uint32_t operand);
void writeLoad(uint32_t id, uint32_t typeId, uint32_t pointerId);
void writeMemberDecorate(uint32_t typeId, uint32_t member, uint32_t decoration, uint32_t value);
......@@ -1394,6 +1396,56 @@ void SpirvTransformerBase::writeConstant(uint32_t id, uint32_t typeId, uint32_t
copyInstruction(constant.data(), kConstantInstructionLength);
}
void SpirvTransformerBase::writeFAdd(uint32_t id,
uint32_t typeId,
uint32_t operand1,
uint32_t operand2)
{
// SPIR-V 1.0 Section 3.32 Instructions, OpFAdd
constexpr size_t kTypeIdIndex = 1;
constexpr size_t kIdIndex = 2;
constexpr size_t kOperand1Index = 3;
constexpr size_t kOperand2Index = 4;
constexpr size_t kFAddInstructionLength = 5;
std::array<uint32_t, kFAddInstructionLength> fAdd = {};
// Fill the fields.
SetSpirvInstructionOp(fAdd.data(), spv::OpFAdd);
SetSpirvInstructionLength(fAdd.data(), kFAddInstructionLength);
fAdd[kTypeIdIndex] = typeId;
fAdd[kIdIndex] = id;
fAdd[kOperand1Index] = operand1;
fAdd[kOperand2Index] = operand2;
copyInstruction(fAdd.data(), kFAddInstructionLength);
}
void SpirvTransformerBase::writeFMul(uint32_t id,
uint32_t typeId,
uint32_t operand1,
uint32_t operand2)
{
// SPIR-V 1.0 Section 3.32 Instructions, OpFMul
constexpr size_t kTypeIdIndex = 1;
constexpr size_t kIdIndex = 2;
constexpr size_t kOperand1Index = 3;
constexpr size_t kOperand2Index = 4;
constexpr size_t kFMulInstructionLength = 5;
std::array<uint32_t, kFMulInstructionLength> fMul = {};
// Fill the fields.
SetSpirvInstructionOp(fMul.data(), spv::OpFMul);
SetSpirvInstructionLength(fMul.data(), kFMulInstructionLength);
fMul[kTypeIdIndex] = typeId;
fMul[kIdIndex] = id;
fMul[kOperand1Index] = operand1;
fMul[kOperand2Index] = operand2;
copyInstruction(fMul.data(), kFMulInstructionLength);
}
void SpirvTransformerBase::writeFNegate(uint32_t id, uint32_t typeId, uint32_t operand)
{
// SPIR-V 1.0 Section 3.32 Instructions, OpFNegate
......@@ -1665,6 +1717,7 @@ class SpirvTransformer final : public SpirvTransformerBase
void writeInputPreamble();
void writeOutputPrologue();
void preRotateXY(uint32_t xId, uint32_t yId, uint32_t *rotatedXIdOut, uint32_t *rotatedYIdOut);
void transformZToVulkanClipSpace(uint32_t zId, uint32_t wId, uint32_t *correctedZIdOut);
// Special flags:
GlslangSpirvOptions mOptions;
......@@ -1723,6 +1776,7 @@ class SpirvTransformer final : public SpirvTransformerBase
// - mVec4OutTypePointerId: id of OpTypePointer Output %mVec4ID
// - mIntId: id of OpTypeInt 32 1
// - mInt0Id: id of OpConstant %mIntID 0
// - mFloatHalfId: id of OpConstant %mFloatId 0.5f
// - mOutputPerVertexTypePointerId: id of OpTypePointer Output %mOutputPerVertex.typeId
// - mOutputPerVertexId: id of OpVariable %mOutputPerVertexTypePointerId Output
//
......@@ -1731,6 +1785,7 @@ class SpirvTransformer final : public SpirvTransformerBase
uint32_t mVec4OutTypePointerId = 0;
uint32_t mIntId = 0;
uint32_t mInt0Id = 0;
uint32_t mFloatHalfId = 0;
uint32_t mOutputPerVertexTypePointerId = 0;
uint32_t mOutputPerVertexId = 0;
};
......@@ -1954,8 +2009,9 @@ void SpirvTransformer::transformInstruction()
// present in the original shader need to be done here.
void SpirvTransformer::writePendingDeclarations()
{
// Currently, only pre-rotation requires declarations that may not necessarily be in the shader.
if (IsRotationIdentity(mOptions.preRotation))
// Pre-rotation and transformation of depth to Vulkan clip space require declarations that may
// not necessarily be in the shader.
if (IsRotationIdentity(mOptions.preRotation) && !mOptions.transformPositionToVulkanClipSpace)
{
return;
}
......@@ -1987,6 +2043,12 @@ void SpirvTransformer::writePendingDeclarations()
ASSERT(mInt0Id == 0);
mInt0Id = getNewId();
writeConstant(mInt0Id, mIntId, 0);
constexpr uint32_t kFloatHalfAsUint = 0x3F00'0000;
ASSERT(mFloatHalfId == 0);
mFloatHalfId = getNewId();
writeConstant(mFloatHalfId, mFloatId, kFloatHalfAsUint);
}
// Called by transformInstruction to insert necessary instructions for casting varyings.
......@@ -2054,13 +2116,22 @@ void SpirvTransformer::writeOutputPrologue()
}
}
// Transform gl_Position to account for prerotation if necessary.
if (mOutputPerVertexId == 0 || IsRotationIdentity(mOptions.preRotation))
// Transform gl_Position to account for prerotation and Vulkan clip space if necessary.
if (mOutputPerVertexId == 0 ||
(IsRotationIdentity(mOptions.preRotation) && !mOptions.transformPositionToVulkanClipSpace))
{
return;
}
// Generate the following SPIR-V for prerotation:
// In GL the viewport transformation is slightly different - see the GL 2.0 spec section "2.12.1
// Controlling the Viewport". In Vulkan the corresponding spec section is currently "23.4.
// Coordinate Transformations". The following transformation needs to be done:
//
// z_vk = 0.5 * (w_gl + z_gl)
//
// where z_vk is the depth output of a Vulkan geometry-stage shader and z_gl is the same for GL.
// Generate the following SPIR-V for prerotation and depth transformation:
//
// // Create an access chain to output gl_PerVertex.gl_Position, which is always at index 0.
// %PositionPointer = OpAccessChain %mVec4OutTypePointerId %mOutputPerVertexId %mInt0Id
......@@ -2072,12 +2143,18 @@ void SpirvTransformer::writeOutputPrologue()
// %y = OpCompositeExtract %mFloatId %Position 1
// %z = OpCompositeExtract %mFloatId %Position 2
// %w = OpCompositeExtract %mFloatId %Position 3
//
// // Transform %x and %y based on pre-rotation. This could include swapping the two ids
// // (in the transformer, no need to generate SPIR-V instructions for that), and/or
// // negating either component. To negate a component, the following instruction is used:
// (optional:) %negated = OpFNegate %mFloatId %component
// // Create the rotated gl_Position from the rotated x and y components.
// %RotatedPosition = OpCompositeConstruct %mVec4Id %rotatedX %rotatedY %z %w
//
// // Transform %z if necessary, based on the above formula.
// %zPlusW = OpFAdd %mFloatId %z %w
// %correctedZ = OpFMul %mFloatId %zPlusW %mFloatHalfId
//
// // Create the rotated gl_Position from the rotated x and y and corrected z components.
// %RotatedPosition = OpCompositeConstruct %mVec4Id %rotatedX %rotatedY %correctedZ %w
// // Store the results back in gl_Position
// OpStore %PositionPointer %RotatedPosition
//
......@@ -2100,7 +2177,11 @@ void SpirvTransformer::writeOutputPrologue()
uint32_t rotatedYId = 0;
preRotateXY(xId, yId, &rotatedXId, &rotatedYId);
writeCompositeConstruct(rotatedPositionId, mVec4Id, {rotatedXId, rotatedYId, zId, wId});
uint32_t correctedZId = 0;
transformZToVulkanClipSpace(zId, wId, &correctedZId);
writeCompositeConstruct(rotatedPositionId, mVec4Id,
{rotatedXId, rotatedYId, correctedZId, wId});
writeStore(positionPointerId, rotatedPositionId);
}
......@@ -2148,6 +2229,26 @@ void SpirvTransformer::preRotateXY(uint32_t xId,
}
}
void SpirvTransformer::transformZToVulkanClipSpace(uint32_t zId,
uint32_t wId,
uint32_t *correctedZIdOut)
{
if (!mOptions.transformPositionToVulkanClipSpace)
{
*correctedZIdOut = zId;
return;
}
const uint32_t zPlusWId = getNewId();
*correctedZIdOut = getNewId();
// %zPlusW = OpFAdd %mFloatId %z %w
writeFAdd(zPlusWId, mFloatId, zId, wId);
// %correctedZ = OpFMul %mFloatId %zPlusW %mFloatHalfId
writeFMul(*correctedZIdOut, mFloatId, zPlusWId, mFloatHalfId);
}
void SpirvTransformer::visitDecorate(const uint32_t *instruction)
{
// SPIR-V 1.0 Section 3.32 Instructions, OpDecorate
......
src/libANGLE/renderer/glslang_wrapper_utils.h
......@@ -58,6 +58,7 @@ struct GlslangSpirvOptions
{
gl::ShaderType shaderType = gl::ShaderType::InvalidEnum;
SurfaceRotation preRotation = SurfaceRotation::Identity;
bool transformPositionToVulkanClipSpace = false;
bool removeEarlyFragmentTestsOptimization = false;
bool removeDebugInfo = false;
bool isTransformFeedbackStage = false;
......
src/libANGLE/renderer/metal/mtl_glslang_utils.mm
......@@ -458,8 +458,9 @@ angle::Result GlslangGetShaderSpirvCode(ErrorHandler *context,
for (const gl::ShaderType shaderType : linkedShaderStages)
{
GlslangSpirvOptions options;
options.shaderType = shaderType;
options.isTransformFeedbackStage = shaderType == gl::ShaderType::Vertex;
options.shaderType = shaderType;
options.transformPositionToVulkanClipSpace = true;
options.isTransformFeedbackStage = shaderType == gl::ShaderType::Vertex;
angle::Result status = GlslangTransformSpirvCode(
[context](GlslangError error) { return HandleError(context, error); }, options,
......
src/libANGLE/renderer/vulkan/ProgramExecutableVk.cpp
......@@ -33,10 +33,11 @@ bool ValidateTransformedSpirV(ContextVk *contextVk,
for (gl::ShaderType shaderType : linkedShaderStages)
{
GlslangSpirvOptions options;
options.shaderType = shaderType;
options.preRotation = SurfaceRotation::FlippedRotated90Degrees;
options.removeDebugInfo = true;
options.isTransformFeedbackStage = shaderType == lastPreFragmentStage;
options.shaderType = shaderType;
options.preRotation = SurfaceRotation::FlippedRotated90Degrees;
options.transformPositionToVulkanClipSpace = true;
options.removeDebugInfo = true;
options.isTransformFeedbackStage = shaderType == lastPreFragmentStage;
SpirvBlob transformed;
if (GlslangWrapperVk::TransformSpirV(contextVk, options, variableInfoMap,
......@@ -140,6 +141,7 @@ angle::Result ProgramInfo::initProgram(ContextVk *contextVk,
if (isLastPreFragmentStage)
{
options.preRotation = static_cast<SurfaceRotation>(optionBits.surfaceRotation);
options.transformPositionToVulkanClipSpace = true;
}
ANGLE_TRY(GlslangWrapperVk::TransformSpirV(contextVk, options, variableInfoMap,
......
src/tests/gl_tests/GeometryShaderTest.cpp
......@@ -1412,9 +1412,6 @@ TEST_P(GeometryShaderTest, DepthViewportTransform)
{
ANGLE_SKIP_TEST_IF(!IsGLExtensionEnabled("GL_EXT_geometry_shader"));
// http://anglebug.com/5479
ANGLE_SKIP_TEST_IF(IsVulkan());
constexpr char kVS[] = R"(#version 310 es
void main()
{
......
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