opt: Add support for OpExtInst to capability trim pass (#5836)

The grammar does track required capabilities for extended instruction
set operations, so we just need to look them up.

source/opt/trim_capabilities_pass.cpp

@@ -27,6 +27,7 @@
 
 #include "source/enum_set.h"
 #include "source/enum_string_mapping.h"
+#include "source/ext_inst.h"
 #include "source/opt/ir_context.h"
 #include "source/opt/reflect.h"
 #include "source/spirv_target_env.h"
@@ -49,6 +50,9 @@ constexpr uint32_t kOpTypeImageSampledIndex = kOpTypeImageMSIndex + 1;
 constexpr uint32_t kOpTypeImageFormatIndex = kOpTypeImageSampledIndex + 1;
 constexpr uint32_t kOpImageReadImageIndex = 0;
 constexpr uint32_t kOpImageSparseReadImageIndex = 0;
+constexpr uint32_t kOpExtInstSetInIndex = 0;
+constexpr uint32_t kOpExtInstInstructionInIndex = 1;
+constexpr uint32_t kOpExtInstImportNameInIndex = 0;
 
 // DFS visit of the type defined by `instruction`.
 // If `condition` is true, children of the current node are visited.
@@ -514,6 +518,35 @@ void TrimCapabilitiesPass::addInstructionRequirementsForOperand(
   }
 }
 
+void TrimCapabilitiesPass::addInstructionRequirementsForExtInst(
+    Instruction* instruction, CapabilitySet* capabilities) const {
+  assert(instruction->opcode() == spv::Op::OpExtInst &&
+         "addInstructionRequirementsForExtInst must be passed an OpExtInst "
+         "instruction");
+
+  const auto* def_use_mgr = context()->get_def_use_mgr();
+
+  const Instruction* extInstImport = def_use_mgr->GetDef(
+      instruction->GetSingleWordInOperand(kOpExtInstSetInIndex));
+  uint32_t extInstruction =
+      instruction->GetSingleWordInOperand(kOpExtInstInstructionInIndex);
+
+  const Operand& extInstSet =
+      extInstImport->GetInOperand(kOpExtInstImportNameInIndex);
+
+  spv_ext_inst_type_t instructionSet =
+      spvExtInstImportTypeGet(extInstSet.AsString().c_str());
+
+  spv_ext_inst_desc desc = {};
+  auto result =
+      context()->grammar().lookupExtInst(instructionSet, extInstruction, &desc);
+  if (result != SPV_SUCCESS) {
+    return;
+  }
+
+  addSupportedCapabilitiesToSet(desc, capabilities);
+}
+
 void TrimCapabilitiesPass::addInstructionRequirements(
     Instruction* instruction, CapabilitySet* capabilities,
     ExtensionSet* extensions) const {
@@ -523,8 +556,12 @@ void TrimCapabilitiesPass::addInstructionRequirements(
     return;
   }
 
-  addInstructionRequirementsForOpcode(instruction->opcode(), capabilities,
+  if (instruction->opcode() == spv::Op::OpExtInst) {
-                                      extensions);
+    addInstructionRequirementsForExtInst(instruction, capabilities);
+  } else {
+    addInstructionRequirementsForOpcode(instruction->opcode(), capabilities,
+                                        extensions);
+  }
 
   // Second case: one of the opcode operand is gated by a capability.
   const uint32_t operandCount = instruction->NumOperands();

source/opt/trim_capabilities_pass.h

@@ -90,6 +90,7 @@ class TrimCapabilitiesPass : public Pass {
       spv::Capability::ImageMSArray,
       spv::Capability::Int16,
       spv::Capability::Int64,
+      spv::Capability::InterpolationFunction,
       spv::Capability::Linkage,
       spv::Capability::MinLod,
       spv::Capability::PhysicalStorageBufferAddresses,
@@ -160,6 +161,9 @@ class TrimCapabilitiesPass : public Pass {
                                             CapabilitySet* capabilities,
                                             ExtensionSet* extensions) const;
 
+  void addInstructionRequirementsForExtInst(Instruction* instruction,
+                                            CapabilitySet* capabilities) const;
+
   // Given an `instruction`, determines the capabilities it requires, and output
   // them in `capabilities`. The returned capabilities form a subset of
   // kSupportedCapabilities.

test/opt/trim_capabilities_pass_test.cpp

@@ -3149,6 +3149,69 @@ TEST_P(TrimCapabilitiesPassTestSubgroupClustered_Unsigned,
   EXPECT_EQ(std::get<1>(result), Pass::Status::SuccessWithChange);
 }
 
+TEST_F(TrimCapabilitiesPassTest, InterpolationFunction_RemovedIfNotUsed) {
+  const std::string kTest = R"(
+               OpCapability Shader
+               OpCapability InterpolationFunction
+; CHECK-NOT:   OpCapability InterpolationFunction
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Fragment %main "main" %out_var_SV_Target
+               OpExecutionMode %main OriginUpperLeft
+               OpSource HLSL 660
+               OpName %out_var_SV_Target "out.var.SV_Target"
+               OpName %main "main"
+               OpDecorate %out_var_SV_Target Location 0
+      %float = OpTypeFloat 32
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+       %void = OpTypeVoid
+          %7 = OpTypeFunction %void
+%out_var_SV_Target = OpVariable %_ptr_Output_v4float Output
+       %main = OpFunction %void None %7
+          %8 = OpLabel
+               OpReturn
+               OpFunctionEnd
+  )";
+  const auto result =
+      SinglePassRunAndMatch<TrimCapabilitiesPass>(kTest, /* skip_nop= */ false);
+  EXPECT_EQ(std::get<1>(result), Pass::Status::SuccessWithChange);
+}
+
+TEST_F(TrimCapabilitiesPassTest,
+       InterpolationFunction_RemainsWithInterpolateAtCentroid) {
+  const std::string kTest = R"(
+               OpCapability Shader
+               OpCapability InterpolationFunction
+; CHECK:       OpCapability InterpolationFunction
+     %std450 = OpExtInstImport "GLSL.std.450"
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Fragment %main "main" %out_var_SV_Target %gl_PointCoord
+               OpExecutionMode %main OriginUpperLeft
+               OpSource HLSL 660
+               OpName %out_var_SV_Target "out.var.SV_Target"
+               OpName %main "main"
+               OpDecorate %out_var_SV_Target Location 0
+               OpDecorate %gl_PointCoord BuiltIn PointCoord
+      %float = OpTypeFloat 32
+    %v2float = OpTypeVector %float 2
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+%_ptr_Input_v2float = OpTypePointer Input %v2float
+       %void = OpTypeVoid
+          %7 = OpTypeFunction %void
+%out_var_SV_Target = OpVariable %_ptr_Output_v4float Output
+%gl_PointCoord = OpVariable %_ptr_Input_v2float Input
+       %main = OpFunction %void None %7
+          %8 = OpLabel
+          %9 = OpExtInst %v4float %std450 InterpolateAtCentroid %gl_PointCoord
+               OpReturn
+               OpFunctionEnd
+  )";
+  const auto result =
+      SinglePassRunAndMatch<TrimCapabilitiesPass>(kTest, /* skip_nop= */ false);
+  EXPECT_EQ(std::get<1>(result), Pass::Status::SuccessWithoutChange);
+}
+
 INSTANTIATE_TEST_SUITE_P(
     TrimCapabilitiesPassTestSubgroupClustered_Unsigned_I,
     TrimCapabilitiesPassTestSubgroupClustered_Unsigned,