[spirv] Error on implicit-lod sampling in non-fragment shaders (#3128)

* [spirv] Error on implicit-lod sampling in non-fragment shaders

* formatting

tools/clang/lib/SPIRV/SpirvEmitter.cpp

@@ -4178,7 +4178,8 @@ SpirvInstruction *SpirvEmitter::createImageSample(
 
   // Implicit-lod instructions are only allowed in pixel shader.
   if (!spvContext.isPS() && !isExplicit)
-    needsLegalization = true;
+    emitError("sampling with implicit lod is only allowed in fragment shaders",
+              loc);
 
   auto *retVal = spvBuilder.createImageSample(
       texelType, imageType, image, sampler, coordinate, compareVal, bias, lod,

tools/clang/test/CodeGenSPIRV/texture.sample-invalid-implicit-lod.hlsl

@@ -0,0 +1,40 @@
+// Run: %dxc -T vs_6_0 -E main
+
+SamplerState gSampler : register(s5);
+
+// Note: The front end forbids sampling from non-floating-point texture formats.
+
+Texture1D   <float4> t1 : register(t1);
+Texture2D   <float4> t2 : register(t2);
+Texture3D   <float4> t3 : register(t3);
+TextureCube <float4> t4 : register(t4);
+
+float4 main(int2 offset: A) : SV_Position {
+// CHECK: sampling with implicit lod is only allowed in fragment shaders
+    float4 val1 = t1.Sample(gSampler, 0.5);
+
+// CHECK: sampling with implicit lod is only allowed in fragment shaders
+    float4 val2 = t2.Sample(gSampler, float2(0.5, 0.25), offset);
+
+// CHECK: sampling with implicit lod is only allowed in fragment shaders
+    float4 val3 = t3.Sample(gSampler, float3(0.5, 0.25, 0.3), 3);
+
+// CHECK: sampling with implicit lod is only allowed in fragment shaders
+    float4 val4 = t4.Sample(gSampler, float3(0.5, 0.25, 0.3));
+
+    float clamp;
+// CHECK: sampling with implicit lod is only allowed in fragment shaders
+    float4 val5 = t2.Sample(gSampler, float2(0.5, 0.25), offset, clamp);
+
+// CHECK: sampling with implicit lod is only allowed in fragment shaders
+    float4 val6 = t4.Sample(gSampler, float3(0.5, 0.25, 0.3), /*clamp*/ 2.0f);
+
+    uint status;
+// CHECK: sampling with implicit lod is only allowed in fragment shaders
+    float4 val7 = t2.Sample(gSampler, float2(0.5, 0.25), offset, clamp, status);
+
+// CHECK: sampling with implicit lod is only allowed in fragment shaders
+    float4 val8 = t4.Sample(gSampler, float3(0.5, 0.25, 0.3), /*clamp*/ 2.0f, status);
+
+    return float4(0.0, 0.0, 0.0, 1.0);
+}

tools/clang/unittests/SPIRV/CodeGenSpirvTest.cpp

@@ -918,6 +918,9 @@ TEST_F(FileTest, TextureSampleCmpLevelZero) {
 TEST_F(FileTest, TextureArraySampleCmpLevelZero) {
   runFileTest("texture.array.sample-cmp-level-zero.hlsl");
 }
+TEST_F(FileTest, TextureSampleInvalidImplicitLod) {
+  runFileTest("texture.sample-invalid-implicit-lod.hlsl", Expect::Failure);
+}
 
 // For structured buffer methods
 TEST_F(FileTest, StructuredBufferLoad) {