spirv-reader: remove builtin-inputs special cases

Remove special case handling of pointers and values related
to builtins SampleId, VertexIndex, and InstanceIndex.
These map to private variables with store type matching the
type stated in the SPIR-V code. There is no need to generate
special case code for user-written functions accessing those variables.

Therefore:
- Remove SkipReason enums associated with those builtin inputs
- Remove newly unreachable code.

Bug: tint:508
Change-Id: I22ea86d49e14f171a92863d9f02145606ad37683
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/55321
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: James Price <jrprice@google.com>
Commit-Queue: James Price <jrprice@google.com>
Auto-Submit: David Neto <dneto@google.com>

src/reader/spirv/function.cc

@@ -2309,20 +2309,6 @@ TypedExpression FunctionEmitter::MakeExpression(uint32_t id) {
       Fail() << "unhandled use of a pointer to the PointSize builtin, with ID: "
              << id;
       return {};
-    case SkipReason::kSampleIdBuiltinPointer:
-      Fail() << "unhandled use of a pointer to the SampleId builtin, with ID: "
-             << id;
-      return {};
-    case SkipReason::kVertexIndexBuiltinPointer:
-      Fail()
-          << "unhandled use of a pointer to the VertexIndex builtin, with ID: "
-          << id;
-      return {};
-    case SkipReason::kInstanceIndexBuiltinPointer:
-      Fail() << "unhandled use of a pointer to the InstanceIndex builtin, with "
-                "ID: "
-             << id;
-      return {};
     case SkipReason::kSampleMaskInBuiltinPointer:
       Fail()
           << "unhandled use of a pointer to the SampleMask builtin, with ID: "
@@ -3423,22 +3409,6 @@ bool FunctionEmitter::EmitStatement(const spvtools::opt::Instruction& inst) {
           GetDefInfo(inst.result_id())->skip =
               SkipReason::kPointSizeBuiltinValue;
           return true;
-        case SkipReason::kSampleIdBuiltinPointer:
-        case SkipReason::kVertexIndexBuiltinPointer:
-        case SkipReason::kInstanceIndexBuiltinPointer: {
-          auto name = NameForSpecialInputBuiltin(skip_reason);
-          if (name.empty()) {
-            return Fail() << "internal error: unhandled special input builtin "
-                             "variable: "
-                          << inst.PrettyPrint();
-          }
-          ast::Expression* id_expr = create<ast::IdentifierExpression>(
-              Source{}, builder_.Symbols().Register(name));
-
-          auto* loaded_type = parser_impl_.ConvertType(inst.type_id());
-          auto expr = TypedExpression{loaded_type, id_expr};
-          return EmitConstDefinition(inst, expr);
-        }
         case SkipReason::kSampleMaskInBuiltinPointer: {
           auto name = namer_.Name(sample_mask_in_id);
           ast::Expression* id_expr = create<ast::IdentifierExpression>(
@@ -3573,28 +3543,6 @@ bool FunctionEmitter::EmitStatement(const spvtools::opt::Instruction& inst) {
                 << inst.PrettyPrint();
 }
 
-std::string FunctionEmitter::NameForSpecialInputBuiltin(
-    SkipReason skip_reason) {
-  SpvBuiltIn spv_builtin = SpvBuiltIn(0);
-  switch (skip_reason) {
-    case SkipReason::kSampleIdBuiltinPointer:
-      spv_builtin = SpvBuiltInSampleId;
-      break;
-    case SkipReason::kVertexIndexBuiltinPointer:
-      spv_builtin = SpvBuiltInVertexIndex;
-      break;
-    case SkipReason::kInstanceIndexBuiltinPointer:
-      spv_builtin = SpvBuiltInInstanceIndex;
-      break;
-    default:
-      // Invalid. Issue the error in the caller.
-      return "";
-  }
-  // The SPIR-V variable is i32, but WGSL requires u32.
-  auto var_id = parser_impl_.IdForSpecialBuiltIn(spv_builtin);
-  return namer_.Name(var_id);
-}
-
 TypedExpression FunctionEmitter::MakeOperand(
     const spvtools::opt::Instruction& inst,
     uint32_t operand_index) {
@@ -4279,15 +4227,6 @@ bool FunctionEmitter::RegisterSpecialBuiltInVariables() {
       case SpvBuiltInPointSize:
         def->skip = SkipReason::kPointSizeBuiltinPointer;
         break;
-      case SpvBuiltInSampleId:
-        def->skip = SkipReason::kSampleIdBuiltinPointer;
-        break;
-      case SpvBuiltInVertexIndex:
-        def->skip = SkipReason::kVertexIndexBuiltinPointer;
-        break;
-      case SpvBuiltInInstanceIndex:
-        def->skip = SkipReason::kInstanceIndexBuiltinPointer;
-        break;
       case SpvBuiltInSampleMask: {
         // Distinguish between input and output variable.
         const auto storage_class =
@@ -4301,6 +4240,9 @@ bool FunctionEmitter::RegisterSpecialBuiltInVariables() {
         }
         break;
       }
+      case SpvBuiltInSampleId:
+      case SpvBuiltInInstanceIndex:
+      case SpvBuiltInVertexIndex:
       case SpvBuiltInLocalInvocationIndex:
       case SpvBuiltInLocalInvocationId:
       case SpvBuiltInGlobalInvocationId:

src/reader/spirv/function.h

@@ -214,19 +214,6 @@ enum class SkipReason {
   /// supported by WebGPU.
   kPointSizeBuiltinValue,
 
-  /// `kSampleIdBuiltinPointer`: the value is a pointer to the SampleId builtin
-  /// variable.  Don't generate its address.
-  kSampleIdBuiltinPointer,
-
-  /// `kVertexIndexBuiltinPointer`: the value is a pointer to the VertexIndex
-  /// builtin variable.  Don't generate its address.
-  kVertexIndexBuiltinPointer,
-
-  /// `kInstanceIndexBuiltinPointer`: the value is a pointer to the
-  /// InstanceIndex
-  /// builtin variable.  Don't generate its address.
-  kInstanceIndexBuiltinPointer,
-
   /// `kSampleMaskInBuiltinPointer`: the value is a pointer to the SampleMaskIn
   /// builtin input variable.  Don't generate its address.
   kSampleMaskInBuiltinPointer,
@@ -339,15 +326,6 @@ inline std::ostream& operator<<(std::ostream& o, const DefInfo& di) {
     case SkipReason::kPointSizeBuiltinValue:
       o << " skip:pointsize_value";
       break;
-    case SkipReason::kSampleIdBuiltinPointer:
-      o << " skip:sampleid_pointer";
-      break;
-    case SkipReason::kVertexIndexBuiltinPointer:
-      o << " skip:vertexindex_pointer";
-      break;
-    case SkipReason::kInstanceIndexBuiltinPointer:
-      o << " skip:instanceindex_pointer";
-      break;
     case SkipReason::kSampleMaskInBuiltinPointer:
       o << " skip:samplemaskin_pointer";
       break;
@@ -795,13 +773,6 @@ class FunctionEmitter {
     return SkipReason::kDontSkip;
   }
 
-  /// Returns the WGSL variable name for an input builtin variable whose
-  /// translation is managed via the SkipReason mechanism.
-  /// @param skip_reason the skip reason for the special variable
-  /// @returns the variable name for a special builtin variable
-  /// that is handled via the "skip" mechanism.
-  std::string NameForSpecialInputBuiltin(SkipReason skip_reason);
-
   /// Returns the most deeply nested structured construct which encloses the
   /// WGSL scopes of names declared in both block positions. Each position must
   /// be a valid index into the function block order array.

src/reader/spirv/parser_impl_module_var_test.cc

@@ -2443,18 +2443,31 @@ TEST_F(SpvModuleScopeVarParserTest, SampleId_I32_Load_CopyObject) {
   ASSERT_TRUE(p->BuildAndParseInternalModule()) << p->error() << assembly;
   EXPECT_TRUE(p->error().empty());
   const auto module_str = p->program().to_str();
-
+  const std::string expected =
-  // Correct declaration
+      R"(Module{
-  EXPECT_THAT(module_str, HasSubstr(R"(
   Variable{
     x_1
     private
     undefined
     __i32
-  })")) <<module_str;
+  }
-
+  Function main_1 -> __void
-  // Correct creation of value
+  ()
-  EXPECT_THAT(module_str, HasSubstr(R"(
+  {
+    VariableDeclStatement{
+      VariableConst{
+        x_11
+        none
+        undefined
+        __ptr_none__i32
+        {
+          UnaryOp[not set]{
+            address-of
+            Identifier[not set]{x_1}
+          }
+        }
+      }
+    }
     VariableDeclStatement{
       VariableConst{
         x_2
@@ -2462,14 +2475,15 @@ TEST_F(SpvModuleScopeVarParserTest, SampleId_I32_Load_CopyObject) {
         undefined
         __i32
         {
-          Identifier[not set]{x_1}
+          UnaryOp[not set]{
+            indirection
+            Identifier[not set]{x_11}
+          }
         }
       }
-    })"))
+    }
-      << module_str;
+    Return{}
-
+  }
-  // Correct parameter on entry point
-  EXPECT_THAT(module_str, HasSubstr(R"(
   Function main -> __void
   StageDecoration{fragment}
   (
@@ -2489,8 +2503,15 @@ TEST_F(SpvModuleScopeVarParserTest, SampleId_I32_Load_CopyObject) {
       Bitcast[not set]<__i32>{
         Identifier[not set]{x_1_param}
       }
-    })"))
+    }
-      << module_str;
+    Call[not set]{
+      Identifier[not set]{main_1}
+      (
+      )
+    }
+  }
+}
+)";
 }
 
 TEST_F(SpvModuleScopeVarParserTest, SampleId_I32_Load_AccessChain) {
@@ -2668,6 +2689,20 @@ TEST_F(SpvModuleScopeVarParserTest, SampleId_U32_Load_CopyObject) {
   Function main_1 -> __void
   ()
   {
+    VariableDeclStatement{
+      VariableConst{
+        x_11
+        none
+        undefined
+        __ptr_none__u32
+        {
+          UnaryOp[not set]{
+            address-of
+            Identifier[not set]{x_1}
+          }
+        }
+      }
+    }
     VariableDeclStatement{
       VariableConst{
         x_2
@@ -2675,7 +2710,10 @@ TEST_F(SpvModuleScopeVarParserTest, SampleId_U32_Load_CopyObject) {
         undefined
         __u32
         {
-          Identifier[not set]{x_1}
+          UnaryOp[not set]{
+            indirection
+            Identifier[not set]{x_11}
+          }
         }
       }
     }
@@ -2944,18 +2982,16 @@ TEST_F(SpvModuleScopeVarParserTest, SampleMask_In_U32_CopyObject) {
   ASSERT_TRUE(p->BuildAndParseInternalModule()) << p->error() << assembly;
   EXPECT_TRUE(p->error().empty());
   const auto module_str = p->program().to_str();
-
+  const std::string expected = R"(Module{
-  // Correct declaration
-  EXPECT_THAT(module_str, HasSubstr(R"(
   Variable{
     x_1
     private
     undefined
     __array__u32_1
-  })")) <<module_str;
+  }
-
+  Function main_1 -> __void
-  // Correct creation of value
+  ()
-  EXPECT_THAT(module_str, HasSubstr(R"(
+  {
     VariableDeclStatement{
       VariableConst{
         x_4
@@ -2969,10 +3005,9 @@ TEST_F(SpvModuleScopeVarParserTest, SampleMask_In_U32_CopyObject) {
           }
         }
       }
-    })"));
+    }
-
+    Return{}
-  // Correct parameter on entry point
+  }
-  EXPECT_THAT(module_str, HasSubstr(R"(
   Function main -> __void
   StageDecoration{fragment}
   (
@@ -2993,8 +3028,16 @@ TEST_F(SpvModuleScopeVarParserTest, SampleMask_In_U32_CopyObject) {
         ScalarConstructor[not set]{0}
       }
       Identifier[not set]{x_1_param}
-    })"))
+    }
-      << module_str;
+    Call[not set]{
+      Identifier[not set]{main_1}
+      (
+      )
+    }
+  }
+}
+)";
+  EXPECT_EQ(module_str, expected) << module_str;
 }
 
 TEST_F(SpvModuleScopeVarParserTest, SampleMask_In_U32_AccessChain) {
@@ -3955,6 +3998,20 @@ TEST_F(SpvModuleScopeVarParserTest, VertexIndex_I32_Load_CopyObject) {
   Function main_1 -> __void
   ()
   {
+    VariableDeclStatement{
+      VariableConst{
+        x_11
+        none
+        undefined
+        __ptr_none__i32
+        {
+          UnaryOp[not set]{
+            address-of
+            Identifier[not set]{x_1}
+          }
+        }
+      }
+    }
     VariableDeclStatement{
       VariableConst{
         x_2
@@ -3962,7 +4019,10 @@ TEST_F(SpvModuleScopeVarParserTest, VertexIndex_I32_Load_CopyObject) {
         undefined
         __i32
         {
-          Identifier[not set]{x_1}
+          UnaryOp[not set]{
+            indirection
+            Identifier[not set]{x_11}
+          }
         }
       }
     }
@@ -4066,34 +4126,6 @@ TEST_F(SpvModuleScopeVarParserTest, VertexIndex_I32_Load_AccessChain) {
   EXPECT_EQ(module_str, expected);
 }
 
-TEST_F(SpvModuleScopeVarParserTest, VertexIndex_I32_FunctParam) {
-  // TODO(dneto): Passing by pointer-to-input is not allowed.
-  // Remove this test.
-  const std::string assembly = VertexIndexPreamble("%int") + R"(
-    %helper_ty = OpTypeFunction %int %ptr_ty
-    %helper = OpFunction %int None %helper_ty
-    %param = OpFunctionParameter %ptr_ty
-    %helper_entry = OpLabel
-    %3 = OpLoad %int %param
-    OpReturnValue %3
-    OpFunctionEnd
-
-    %main = OpFunction %void None %voidfn
-    %entry = OpLabel
-    %result = OpFunctionCall %int %helper %1
-    OpReturn
-    OpFunctionEnd
- )";
-  auto p = parser(test::Assemble(assembly));
-  // TODO(dneto): We can handle this if we make a shadow variable and mutate
-  // the parameter type.
-  ASSERT_FALSE(p->BuildAndParseInternalModule());
-  EXPECT_THAT(
-      p->error(),
-      HasSubstr(
-          "unhandled use of a pointer to the VertexIndex builtin, with ID: 1"));
-}
-
 TEST_F(SpvModuleScopeVarParserTest, VertexIndex_U32_Load_Direct) {
   const std::string assembly = VertexIndexPreamble("%uint") + R"(
     %main = OpFunction %void None %voidfn
@@ -4181,6 +4213,20 @@ TEST_F(SpvModuleScopeVarParserTest, VertexIndex_U32_Load_CopyObject) {
   Function main_1 -> __void
   ()
   {
+    VariableDeclStatement{
+      VariableConst{
+        x_11
+        none
+        undefined
+        __ptr_none__u32
+        {
+          UnaryOp[not set]{
+            address-of
+            Identifier[not set]{x_1}
+          }
+        }
+      }
+    }
     VariableDeclStatement{
       VariableConst{
         x_2
@@ -4188,7 +4234,10 @@ TEST_F(SpvModuleScopeVarParserTest, VertexIndex_U32_Load_CopyObject) {
         undefined
         __u32
         {
-          Identifier[not set]{x_1}
+          UnaryOp[not set]{
+            indirection
+            Identifier[not set]{x_11}
+          }
         }
       }
     }
@@ -4421,6 +4470,20 @@ TEST_F(SpvModuleScopeVarParserTest, InstanceIndex_I32_Load_CopyObject) {
   Function main_1 -> __void
   ()
   {
+    VariableDeclStatement{
+      VariableConst{
+        x_11
+        none
+        undefined
+        __ptr_none__i32
+        {
+          UnaryOp[not set]{
+            address-of
+            Identifier[not set]{x_1}
+          }
+        }
+      }
+    }
     VariableDeclStatement{
       VariableConst{
         x_2
@@ -4428,7 +4491,10 @@ TEST_F(SpvModuleScopeVarParserTest, InstanceIndex_I32_Load_CopyObject) {
         undefined
         __i32
         {
-          Identifier[not set]{x_1}
+          UnaryOp[not set]{
+            indirection
+            Identifier[not set]{x_11}
+          }
         }
       }
     }
@@ -4643,6 +4709,20 @@ TEST_F(SpvModuleScopeVarParserTest, InstanceIndex_U32_Load_CopyObject) {
   Function main_1 -> __void
   ()
   {
+    VariableDeclStatement{
+      VariableConst{
+        x_11
+        none
+        undefined
+        __ptr_none__u32
+        {
+          UnaryOp[not set]{
+            address-of
+            Identifier[not set]{x_1}
+          }
+        }
+      }
+    }
     VariableDeclStatement{
       VariableConst{
         x_2
@@ -4650,7 +4730,10 @@ TEST_F(SpvModuleScopeVarParserTest, InstanceIndex_U32_Load_CopyObject) {
         undefined
         __u32
         {
-          Identifier[not set]{x_1}
+          UnaryOp[not set]{
+            indirection
+            Identifier[not set]{x_11}
+          }
         }
       }
     }