tint: fix const eval short-circuiting with mixed runtime and constant expressions

For logical binary expressions that can be short-circuited, if the rhs
tree contained a mix of constant and runtime expressions, we would
erroneously mark the node as runtime, although some of its children were
resolved as kNotEvaluated. This would then fail during backend
generation.

This is a fork of 115820, addressing review comments, as amaiorano is OOO this week.

Bug: chromium:1403752
Bug: tint:1581
Change-Id: I18682c7fe1db092d280390881ff86b3c0db23e9b
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/116020
Commit-Queue: Ben Clayton <bclayton@google.com>
Reviewed-by: James Price <jrprice@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Auto-Submit: Ben Clayton <bclayton@google.com>

src/tint/ir/builder_impl_test.cc

@@ -1697,7 +1697,7 @@ TEST_F(IR_BuilderImplTest, EmitExpression_Binary_ShiftRight) {
 }
 
 TEST_F(IR_BuilderImplTest, EmitExpression_Binary_Compound) {
-    auto* expr = LogicalOr(LessThan(1_u, Add(Shr(3_u, 4_u), 9_u)),
+    auto* expr = LogicalAnd(LessThan(1_u, Add(Shr(3_u, 4_u), 9_u)),
                             GreaterThan(2.5_f, Div(6.7_f, Mul(2.3_f, 5.5_f))));
     WrapInFunction(expr);
 
@@ -1714,7 +1714,7 @@ TEST_F(IR_BuilderImplTest, EmitExpression_Binary_Compound) {
 %4 (f32) = 2.3 * 5.5
 %5 (f32) = 6.7 / %4 (f32)
 %6 (bool) = 2.5 > %5 (f32)
-%7 (bool) = %3 (bool) || %6 (bool)
+%7 (bool) = %3 (bool) && %6 (bool)
 )");
 }
 

src/tint/resolver/const_eval_binary_op_test.cc

@@ -2208,6 +2208,32 @@ TEST_F(ResolverConstEvalTest, ShortCircuit_Or_Error_Swizzle) {
     EXPECT_EQ(r()->error(), "12:34 error: invalid vector swizzle member");
 }
 
+////////////////////////////////////////////////
+// Short-Circuit Mixed Constant and Runtime
+////////////////////////////////////////////////
+
+TEST_F(ResolverConstEvalTest, ShortCircuit_And_MixedConstantAndRuntime) {
+    // var j : i32;
+    // let result = false && j < (0 - 8);
+    auto* j = Decl(Var("j", ty.i32()));
+    auto* binary = LogicalAnd(Expr(false), LessThan("j", Sub(0_a, 8_a)));
+    auto* result = Let("result", binary);
+    WrapInFunction(j, result);
+    EXPECT_TRUE(r()->Resolve()) << r()->error();
+    ValidateAnd(Sem(), binary);
+}
+
+TEST_F(ResolverConstEvalTest, ShortCircuit_Or_MixedConstantAndRuntime) {
+    // var j : i32;
+    // let result = true || j < (0 - 8);
+    auto* j = Decl(Var("j", ty.i32()));
+    auto* binary = LogicalOr(Expr(true), LessThan("j", Sub(0_a, 8_a)));
+    auto* result = Let("result", binary);
+    WrapInFunction(j, result);
+    EXPECT_TRUE(r()->Resolve()) << r()->error();
+    ValidateOr(Sem(), binary);
+}
+
 ////////////////////////////////////////////////
 // Short-Circuit Nested
 ////////////////////////////////////////////////

src/tint/resolver/intrinsic_table.cc

@@ -356,7 +356,7 @@ const type::AbstractFloat* build_fa(MatchState& state) {
 }
 
 bool match_fa(MatchState& state, const type::Type* ty) {
-    return (state.earliest_eval_stage == sem::EvaluationStage::kConstant) &&
+    return (state.earliest_eval_stage <= sem::EvaluationStage::kConstant) &&
            ty->IsAnyOf<Any, type::AbstractNumeric>();
 }
 
@@ -365,7 +365,7 @@ const type::AbstractInt* build_ia(MatchState& state) {
 }
 
 bool match_ia(MatchState& state, const type::Type* ty) {
-    return (state.earliest_eval_stage == sem::EvaluationStage::kConstant) &&
+    return (state.earliest_eval_stage <= sem::EvaluationStage::kConstant) &&
            ty->IsAnyOf<Any, type::AbstractInt>();
 }
 

src/tint/resolver/resolver.cc

@@ -2620,13 +2620,18 @@ sem::Expression* Resolver::Literal(const ast::LiteralExpression* literal) {
     }
 
     const constant::Value* val = nullptr;
+    auto stage = sem::EvaluationStage::kConstant;
+    if (skip_const_eval_.Contains(literal)) {
+        stage = sem::EvaluationStage::kNotEvaluated;
+    }
+    if (stage == sem::EvaluationStage::kConstant) {
         if (auto r = const_eval_.Literal(ty, literal)) {
             val = r.Get();
         } else {
             return nullptr;
         }
-    return builder_->create<sem::Expression>(literal, ty, sem::EvaluationStage::kConstant,
+    }
-                                             current_statement_, std::move(val),
+    return builder_->create<sem::Expression>(literal, ty, stage, current_statement_, std::move(val),
                                              /* has_side_effects */ false);
 }
 
@@ -2899,15 +2904,21 @@ sem::Expression* Resolver::Binary(const ast::BinaryExpression* expr) {
     }
 
     const constant::Value* value = nullptr;
-    if (stage == sem::EvaluationStage::kConstant) {
-        if (op.const_eval_fn) {
     if (skip_const_eval_.Contains(expr)) {
+        // This expression is short-circuited by an ancestor expression.
+        // Do not const-eval.
         stage = sem::EvaluationStage::kNotEvaluated;
-            } else if (skip_const_eval_.Contains(expr->rhs)) {
+    } else if (lhs->Stage() == sem::EvaluationStage::kConstant &&
-                // Only the rhs should be short-circuited, use the lhs value
+               rhs->Stage() == sem::EvaluationStage::kNotEvaluated) {
+        // Short-circuiting binary expression. Use the LHS value and stage.
         value = lhs->ConstantValue();
-            } else {
+        stage = sem::EvaluationStage::kConstant;
-                auto const_args = utils::Vector{lhs->ConstantValue(), rhs->ConstantValue()};
+    } else if (stage == sem::EvaluationStage::kConstant) {
+        // Both LHS and RHS have expressions that are constant evaluation stage.
+        if (op.const_eval_fn) {  // Do we have a @const operator?
+            // Yes. Perform any required abstract argument values implicit conversions to the
+            // overload parameter types, and const-eval.
+            utils::Vector const_args{lhs->ConstantValue(), rhs->ConstantValue()};
             // Implicit conversion (e.g. AInt -> AFloat)
             if (!Convert(const_args[0], op.lhs, lhs->Declaration()->source)) {
                 return nullptr;
@@ -2920,8 +2931,9 @@ sem::Expression* Resolver::Binary(const ast::BinaryExpression* expr) {
             } else {
                 return nullptr;
             }
-            }
         } else {
+            // The arguments have constant values, but the operator cannot be const-evaluated. This
+            // can only be evaluated at runtime.
             stage = sem::EvaluationStage::kRuntime;
         }
     }

src/tint/sem/expression.cc

@@ -39,6 +39,9 @@ Expression::Expression(const ast::Expression* declaration,
       has_side_effects_(has_side_effects) {
     TINT_ASSERT(Semantic, type_);
     TINT_ASSERT(Semantic, (constant != nullptr) == (stage == EvaluationStage::kConstant));
+    if (constant != nullptr) {
+        TINT_ASSERT(Semantic, type_ == constant->Type());
+    }
 }
 
 Expression::~Expression() = default;

test/tint/bug/chromium/1403752.wgsl

@@ -0,0 +1 @@
+fn d(){var j:i32;for(;0<0&&j<0-8;){}}

test/tint/bug/chromium/1403752.wgsl.expected.dxc.hlsl

@@ -0,0 +1,12 @@
+[numthreads(1, 1, 1)]
+void unused_entry_point() {
+  return;
+}
+
+void d() {
+  int j = 0;
+  {
+    for(; false; ) {
+    }
+  }
+}

test/tint/bug/chromium/1403752.wgsl.expected.fxc.hlsl

@@ -0,0 +1,12 @@
+[numthreads(1, 1, 1)]
+void unused_entry_point() {
+  return;
+}
+
+void d() {
+  int j = 0;
+  {
+    for(; false; ) {
+    }
+  }
+}

test/tint/bug/chromium/1403752.wgsl.expected.glsl

@@ -0,0 +1,14 @@
+#version 310 es
+
+layout(local_size_x = 1, local_size_y = 1, local_size_z = 1) in;
+void unused_entry_point() {
+  return;
+}
+void d() {
+  int j = 0;
+  {
+    for(; false; ) {
+    }
+  }
+}
+

test/tint/bug/chromium/1403752.wgsl.expected.msl

@@ -0,0 +1,9 @@
+#include <metal_stdlib>
+
+using namespace metal;
+void d() {
+  int j = 0;
+  for(; false; ) {
+  }
+}
+

test/tint/bug/chromium/1403752.wgsl.expected.spvasm

@@ -0,0 +1,42 @@
+; SPIR-V
+; Version: 1.3
+; Generator: Google Tint Compiler; 0
+; Bound: 19
+; Schema: 0
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint GLCompute %unused_entry_point "unused_entry_point"
+               OpExecutionMode %unused_entry_point LocalSize 1 1 1
+               OpName %unused_entry_point "unused_entry_point"
+               OpName %d "d"
+               OpName %j "j"
+       %void = OpTypeVoid
+          %1 = OpTypeFunction %void
+        %int = OpTypeInt 32 1
+%_ptr_Function_int = OpTypePointer Function %int
+         %10 = OpConstantNull %int
+       %bool = OpTypeBool
+       %true = OpConstantTrue %bool
+%unused_entry_point = OpFunction %void None %1
+          %4 = OpLabel
+               OpReturn
+               OpFunctionEnd
+          %d = OpFunction %void None %1
+          %6 = OpLabel
+          %j = OpVariable %_ptr_Function_int Function %10
+               OpBranch %11
+         %11 = OpLabel
+               OpLoopMerge %12 %13 None
+               OpBranch %14
+         %14 = OpLabel
+               OpSelectionMerge %17 None
+               OpBranchConditional %true %18 %17
+         %18 = OpLabel
+               OpBranch %12
+         %17 = OpLabel
+               OpBranch %13
+         %13 = OpLabel
+               OpBranch %11
+         %12 = OpLabel
+               OpReturn
+               OpFunctionEnd

test/tint/bug/chromium/1403752.wgsl.expected.wgsl

@@ -0,0 +1,5 @@
+fn d() {
+  var j : i32;
+  for(; ((0 < 0) && (j < (0 - 8))); ) {
+  }
+}