[wasm] Introduce the TrapIf and TrapUnless operators to generate trap code.

src/compiler/x64/instruction-selector-x64.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <algorithm>
 
 #include "src/base/adapters.h"
+#include "src/compiler/compiler-source-position-table.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Adds X64-specific methods for generating operands.
 class X64OperandGenerator final : public OperandGenerator {
@@ skipping 1662 matching lines @@
   opcode = cont->Encode(opcode);
   inputs[input_count++] = right;
 
   if (cont->IsBranch()) {
     inputs[input_count++] = g.Label(cont->true_block());
     inputs[input_count++] = g.Label(cont->false_block());
     selector->Emit(opcode, 0, nullptr, input_count, inputs);
   } else if (cont->IsDeoptimize()) {
     selector->EmitDeoptimize(opcode, 0, nullptr, input_count, inputs,
                              cont->reason(), cont->frame_state());
-  } else {
-    DCHECK(cont->IsSet());
+  } else if (cont->IsSet()) {
     InstructionOperand output = g.DefineAsRegister(cont->result());
     selector->Emit(opcode, 1, &output, input_count, inputs);
+  } else {
+    DCHECK(cont->IsTrap());
+    inputs[input_count++] = g.UseImmediate(cont->trap_id());
+    Instruction* instr =
+        selector->Emit(opcode, 0, nullptr, input_count, inputs);
+    selector->SetSourcePosition(instr, *cont->source_position());

[Jarin, 2016/12/15 09:06:30]

It is strange that the general source position mechanism from
InstructionSelector::VisitBlock does not kick in. Any idea why? Or are the other
cases here broken, too?

[ahaas, 2016/12/15 11:35:18]

The problem with source positions is that source positions are only collected
for call nodes. I changed the code in instruction-selector.cc now so that also
source positions are collected for TrapIf and TrapUnless nodes. Thereby I can
remove all the source position handling here in the platform-specific
instruction selector.

   }
 }
 
 // Shared routine for multiple compare operations.
 void VisitCompare(InstructionSelector* selector, InstructionCode opcode,
                   InstructionOperand left, InstructionOperand right,
                   FlagsContinuation* cont) {
   X64OperandGenerator g(selector);
   opcode = cont->Encode(opcode);
   if (cont->IsBranch()) {
     selector->Emit(opcode, g.NoOutput(), left, right,
                    g.Label(cont->true_block()), g.Label(cont->false_block()));
   } else if (cont->IsDeoptimize()) {
     selector->EmitDeoptimize(opcode, g.NoOutput(), left, right, cont->reason(),
                              cont->frame_state());
+  } else if (cont->IsSet()) {
+    selector->Emit(opcode, g.DefineAsRegister(cont->result()), left, right);
   } else {
-    DCHECK(cont->IsSet());
-    selector->Emit(opcode, g.DefineAsRegister(cont->result()), left, right);
+    DCHECK(cont->IsTrap());
+    Instruction* instr = selector->Emit(opcode, g.NoOutput(), left, right,
+                                        g.UseImmediate(cont->trap_id()));
+    selector->SetSourcePosition(instr, *cont->source_position());
   }
 }
 
 
 // Shared routine for multiple compare operations.
 void VisitCompare(InstructionSelector* selector, InstructionCode opcode,
                   Node* left, Node* right, FlagsContinuation* cont,
                   bool commutative) {
   X64OperandGenerator g(selector);
   if (commutative && g.CanBeBetterLeftOperand(right)) {
@@ skipping 129 matching lines @@
     if (mleft.object().Is(js_stack_limit) && mleft.index().Is(0)) {
       // Compare(Load(js_stack_limit), LoadStackPointer)
       if (!node->op()->HasProperty(Operator::kCommutative)) cont->Commute();
       InstructionCode opcode = cont->Encode(kX64StackCheck);
       if (cont->IsBranch()) {
         selector->Emit(opcode, g.NoOutput(), g.Label(cont->true_block()),
                        g.Label(cont->false_block()));
       } else if (cont->IsDeoptimize()) {
         selector->EmitDeoptimize(opcode, 0, nullptr, 0, nullptr, cont->reason(),
                                  cont->frame_state());
+      } else if (cont->IsSet()) {
+        selector->Emit(opcode, g.DefineAsRegister(cont->result()));
       } else {
-        DCHECK(cont->IsSet());
-        selector->Emit(opcode, g.DefineAsRegister(cont->result()));
+        DCHECK(cont->IsTrap());
+        Instruction* instr = selector->Emit(opcode, g.NoOutput(),
+                                            g.UseImmediate(cont->trap_id()));
+        selector->SetSourcePosition(instr, *cont->source_position());
       }
       return;
     }
   }
   VisitWordCompare(selector, node, kX64Cmp, cont);
 }
 
 
 // Shared routine for comparison with zero.
 void VisitCompareZero(InstructionSelector* selector, Node* node,
@@ skipping 187 matching lines @@
       kNotEqual, DeoptimizeReasonOf(node->op()), node->InputAt(1));
   VisitWordCompareZero(this, node, node->InputAt(0), &cont);
 }
 
 void InstructionSelector::VisitDeoptimizeUnless(Node* node) {
   FlagsContinuation cont = FlagsContinuation::ForDeoptimize(
       kEqual, DeoptimizeReasonOf(node->op()), node->InputAt(1));
   VisitWordCompareZero(this, node, node->InputAt(0), &cont);
 }
 
+void InstructionSelector::VisitTrapIf(Node* node) {
+  SourcePosition pos = source_positions_->GetSourcePosition(node);
+  FlagsContinuation cont = FlagsContinuation::ForTrap(
+      kNotEqual, OpParameter<Runtime::FunctionId>(node->op()), &pos,
+      node->InputAt(1));
+  VisitWordCompareZero(this, node, node->InputAt(0), &cont);
+}
+
+void InstructionSelector::VisitTrapUnless(Node* node) {
+  SourcePosition pos = source_positions_->GetSourcePosition(node);
+  FlagsContinuation cont = FlagsContinuation::ForTrap(
+      kEqual, OpParameter<Runtime::FunctionId>(node->op()), &pos,
+      node->InputAt(1));
+  VisitWordCompareZero(this, node, node->InputAt(0), &cont);
+}
+
 void InstructionSelector::VisitSwitch(Node* node, const SwitchInfo& sw) {
   X64OperandGenerator g(this);
   InstructionOperand value_operand = g.UseRegister(node->InputAt(0));
 
   // Emit either ArchTableSwitch or ArchLookupSwitch.
   size_t table_space_cost = 4 + sw.value_range;
   size_t table_time_cost = 3;
   size_t lookup_space_cost = 3 + 2 * sw.case_count;
   size_t lookup_time_cost = sw.case_count;
   if (sw.case_count > 4 &&
@@ skipping 349 matching lines @@
 // static
 MachineOperatorBuilder::AlignmentRequirements
 InstructionSelector::AlignmentRequirements() {
   return MachineOperatorBuilder::AlignmentRequirements::
       FullUnalignedAccessSupport();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8