Skip texel address sample offset if zero

src/Pipeline/SpirvShader.cpp

@@ -2481,11 +2481,11 @@ SpirvShader::Operand::Operand(const SpirvShader *shader, const EmitState *state,
 {}
 
 SpirvShader::Operand::Operand(const EmitState *state, const Object &object)
-    : constant(object.constantValue.data())
+    : constant(object.kind == SpirvShader::Object::Kind::Constant ? object.constantValue.data() : nullptr)
     , intermediate(object.kind == SpirvShader::Object::Kind::Intermediate ? &state->getIntermediate(object.id()) : nullptr)
     , componentCount(intermediate ? intermediate->componentCount : object.constantValue.size())
 {
-	ASSERT(intermediate || (object.kind == SpirvShader::Object::Kind::Constant));
+	ASSERT(intermediate || constant);
 }
 
 SpirvShader::Operand::Operand(const Intermediate &value)
@@ -2495,6 +2495,24 @@ SpirvShader::Operand::Operand(const Intermediate &value)
 {
 }
 
+bool SpirvShader::Operand::isConstantZero() const
+{
+	if(!constant)
+	{
+		return false;
+	}
+
+	for(uint32_t i = 0; i < componentCount; i++)
+	{
+		if(constant[i] != 0)
+		{
+			return false;
+		}
+	}
+
+	return true;
+}
+
 SpirvRoutine::SpirvRoutine(vk::PipelineLayout const *pipelineLayout)
     : pipelineLayout(pipelineLayout)
 {

src/Pipeline/SpirvShader.hpp

@@ -1069,6 +1069,8 @@ private:
 			return SIMD::UInt(constant[i]);
 		}
 
+		bool isConstantZero() const;
+
 	private:
 		RR_PRINT_ONLY(friend struct rr::PrintValue::Ty<Operand>;)
 

src/Pipeline/SpirvShaderImage.cpp

@@ -558,8 +558,11 @@ SIMD::Pointer SpirvShader::GetTexelAddress(EmitState const *state, Pointer<Byte>
 	if(sampleId.value())
 	{
 		Operand sample(this, state, sampleId);
-		n = sample.Int(0);
-		ptrOffset += n * samplePitch;
+		if(!sample.isConstantZero())
+		{
+			n = sample.Int(0);
+			ptrOffset += n * samplePitch;
+		}
 	}
 
 	// If the out-of-bounds behavior is set to nullify, then each coordinate must be tested individually.
@@ -584,8 +587,12 @@ SIMD::Pointer SpirvShader::GetTexelAddress(EmitState const *state, Pointer<Byte>
 
 		if(sampleId.value())
 		{
-			SIMD::UInt sampleCount = *Pointer<UInt>(descriptor + OFFSET(vk::StorageImageDescriptor, sampleCount));
-			oobMask |= As<SIMD::Int>(CmpNLT(As<SIMD::UInt>(n), sampleCount));
+			Operand sample(this, state, sampleId);
+			if(!sample.isConstantZero())
+			{
+				SIMD::UInt sampleCount = *Pointer<UInt>(descriptor + OFFSET(vk::StorageImageDescriptor, sampleCount));
+				oobMask |= As<SIMD::Int>(CmpNLT(As<SIMD::UInt>(n), sampleCount));
+			}
 		}
 
 		constexpr int32_t OOB_OFFSET = 0x7FFFFFFF - 16;  // SIMD pointer offsets are signed 32-bit, so this is the largest offset (for 16-byte texels).