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

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

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index b43d42679e449c9ee7b9f675e123988f9964946c..7a43bf8fa72aab74c24b2c43237f8c42bc9941f0 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -5,6 +5,7 @@
 #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"
@@ -1687,10 +1688,15 @@ void VisitCompareWithMemoryOperand(InstructionSelector* selector,
   } 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.

   }
 }
 
@@ -1706,9 +1712,13 @@ void VisitCompare(InstructionSelector* selector, InstructionCode opcode,
   } else if (cont->IsDeoptimize()) {
     selector->EmitDeoptimize(opcode, g.NoOutput(), left, right, cont->reason(),
                              cont->frame_state());
-  } else {
-    DCHECK(cont->IsSet());
+  } else if (cont->IsSet()) {
     selector->Emit(opcode, g.DefineAsRegister(cont->result()), left, right);
+  } else {
+    DCHECK(cont->IsTrap());
+    Instruction* instr = selector->Emit(opcode, g.NoOutput(), left, right,
+                                        g.UseImmediate(cont->trap_id()));
+    selector->SetSourcePosition(instr, *cont->source_position());
   }
 }
 
@@ -1858,9 +1868,13 @@ void VisitWord64Compare(InstructionSelector* selector, Node* node,
       } else if (cont->IsDeoptimize()) {
         selector->EmitDeoptimize(opcode, 0, nullptr, 0, nullptr, cont->reason(),
                                  cont->frame_state());
-      } else {
-        DCHECK(cont->IsSet());
+      } else if (cont->IsSet()) {
         selector->Emit(opcode, g.DefineAsRegister(cont->result()));
+      } else {
+        DCHECK(cont->IsTrap());
+        Instruction* instr = selector->Emit(opcode, g.NoOutput(),
+                                            g.UseImmediate(cont->trap_id()));
+        selector->SetSourcePosition(instr, *cont->source_position());
       }
       return;
     }
@@ -2068,6 +2082,22 @@ void InstructionSelector::VisitDeoptimizeUnless(Node* node) {
   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));