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

src/compiler/x64/code-generator-x64.cc

Index: src/compiler/x64/code-generator-x64.cc
diff --git a/src/compiler/x64/code-generator-x64.cc b/src/compiler/x64/code-generator-x64.cc
index 0a14781921a660bec6dead9866d0e3e67a7cf326..da4df55875d16bf2d4eb7e5a4be61ee529b814ec 100644
--- a/src/compiler/x64/code-generator-x64.cc
+++ b/src/compiler/x64/code-generator-x64.cc
@@ -2226,61 +2226,67 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
   return kSuccess;
 }  // NOLINT(readability/fn_size)
 
-
-// Assembles branches after this instruction.
-void CodeGenerator::AssembleArchBranch(Instruction* instr, BranchInfo* branch) {
-  X64OperandConverter i(this, instr);
-  Label::Distance flabel_distance =
-      branch->fallthru ? Label::kNear : Label::kFar;
-  Label* tlabel = branch->true_label;
-  Label* flabel = branch->false_label;
-  switch (branch->condition) {
+static Condition ToCC(FlagsCondition condition) {
+  switch (condition) {
     case kUnorderedEqual:
-      __ j(parity_even, flabel, flabel_distance);
-    // Fall through.
     case kEqual:
-      __ j(equal, tlabel);
+      return equal;
       break;
     case kUnorderedNotEqual:
-      __ j(parity_even, tlabel);
-    // Fall through.
     case kNotEqual:
-      __ j(not_equal, tlabel);
+      return not_equal;
       break;
     case kSignedLessThan:
-      __ j(less, tlabel);
+      return less;
       break;
     case kSignedGreaterThanOrEqual:
-      __ j(greater_equal, tlabel);
+      return greater_equal;
       break;
     case kSignedLessThanOrEqual:
-      __ j(less_equal, tlabel);
+      return less_equal;
       break;
     case kSignedGreaterThan:
-      __ j(greater, tlabel);
+      return greater;
       break;
     case kUnsignedLessThan:
-      __ j(below, tlabel);
+      return below;
       break;
     case kUnsignedGreaterThanOrEqual:
-      __ j(above_equal, tlabel);
+      return above_equal;
       break;
     case kUnsignedLessThanOrEqual:
-      __ j(below_equal, tlabel);
+      return below_equal;
       break;
     case kUnsignedGreaterThan:
-      __ j(above, tlabel);
+      return above;
       break;
     case kOverflow:
-      __ j(overflow, tlabel);
+      return overflow;
       break;
     case kNotOverflow:
-      __ j(no_overflow, tlabel);
+      return no_overflow;
       break;
     default:
       UNREACHABLE();
+      return no_condition;
       break;
   }
+}
+
+// Assembles branches after this instruction.
+void CodeGenerator::AssembleArchBranch(Instruction* instr, BranchInfo* branch) {
+  X64OperandConverter i(this, instr);
+  Label::Distance flabel_distance =
+      branch->fallthru ? Label::kNear : Label::kFar;
+  Label* tlabel = branch->true_label;
+  Label* flabel = branch->false_label;
+  if (branch->condition == kUnorderedEqual) {
+    __ j(parity_even, flabel, flabel_distance);
+  } else if (branch->condition == kUnorderedNotEqual) {
+    __ j(parity_even, tlabel);
+  }
+  __ j(ToCC(branch->condition), tlabel);
+
   if (!branch->fallthru) __ jmp(flabel, flabel_distance);
 }
 
@@ -2289,6 +2295,59 @@ void CodeGenerator::AssembleArchJump(RpoNumber target) {
   if (!IsNextInAssemblyOrder(target)) __ jmp(GetLabel(target));
 }
 
+void CodeGenerator::AssembleArchTrap(Instruction* instr,
+                                     FlagsCondition condition) {
+  class OutOfLineTrap final : public OutOfLineCode {
+   public:
+    OutOfLineTrap(CodeGenerator* gen, bool frame_elided, Instruction* instr)
+        : OutOfLineCode(gen),
+          frame_elided_(frame_elided),
+          instr_(instr),
+          gen_(gen) {}
+
+    void Generate() final {
+      X64OperandConverter i(gen_, instr_);
+
+      Runtime::FunctionId trap_id = static_cast<Runtime::FunctionId>(
+          i.InputInt32(instr_->InputCount() - 1));
+      if (frame_elided_) {

[titzer, 2016/12/12 14:21:34]

We don't need the frame teardown, since the call to the runtime should never
return. (Although we do need it in the testing case).

+        FrameScope f(masm(), StackFrame::WASM);
+        GenerateCallToTrap(trap_id);
+      } else {
+        GenerateCallToTrap(trap_id);
+      }
+    }
+
+   private:
+    void GenerateCallToTrap(Runtime::FunctionId trap_id) {
+      if (trap_id == Runtime::kNumFunctions) {

[titzer, 2016/12/12 14:21:33]

You should probably leave a comment here that this is for testing.

+        __ PrepareCallCFunction(0);
+        __ CallCFunction(
+            ExternalReference::wasm_call_trap_callback_for_testing(isolate()),
+            0);
+      } else {
+        __ Move(rsi, isolate()->native_context());
+        gen_->AssembleSourcePosition(instr_);

[titzer, 2016/12/12 14:21:33]

Should the source position recording be after the call? (or maybe it doesn't
matter in that the PC is not actually used?)

[ahaas, 2016/12/13 12:38:59]

I looked up other code, and there it is recorded before the call. In addition,
some tests fail if it is recorded after the call.

+        __ CallRuntime(trap_id);
+      }
+    }
+
+    bool frame_elided_;
+    Instruction* instr_;
+    CodeGenerator* gen_;
+  };
+  bool frame_elided = !frame_access_state()->has_frame();
+  auto ool = new (zone()) OutOfLineTrap(this, frame_elided, instr);
+  Label* tlabel = ool->entry();
+  Label end;
+  if (condition == kUnorderedEqual) {
+    __ j(parity_even, &end);
+  } else if (condition == kUnorderedNotEqual) {
+    __ j(parity_even, tlabel);
+  }
+  __ j(ToCC(condition), tlabel);
+  __ bind(&end);
+}
 
 // Assembles boolean materializations after this instruction.
 void CodeGenerator::AssembleArchBoolean(Instruction* instr,
@@ -2301,60 +2360,17 @@ void CodeGenerator::AssembleArchBoolean(Instruction* instr,
   Label check;
   DCHECK_NE(0u, instr->OutputCount());
   Register reg = i.OutputRegister(instr->OutputCount() - 1);
-  Condition cc = no_condition;
-  switch (condition) {
-    case kUnorderedEqual:
-      __ j(parity_odd, &check, Label::kNear);
-      __ movl(reg, Immediate(0));
-      __ jmp(&done, Label::kNear);
-    // Fall through.
-    case kEqual:
-      cc = equal;
-      break;
-    case kUnorderedNotEqual:
-      __ j(parity_odd, &check, Label::kNear);
-      __ movl(reg, Immediate(1));
-      __ jmp(&done, Label::kNear);
-    // Fall through.
-    case kNotEqual:
-      cc = not_equal;
-      break;
-    case kSignedLessThan:
-      cc = less;
-      break;
-    case kSignedGreaterThanOrEqual:
-      cc = greater_equal;
-      break;
-    case kSignedLessThanOrEqual:
-      cc = less_equal;
-      break;
-    case kSignedGreaterThan:
-      cc = greater;
-      break;
-    case kUnsignedLessThan:
-      cc = below;
-      break;
-    case kUnsignedGreaterThanOrEqual:
-      cc = above_equal;
-      break;
-    case kUnsignedLessThanOrEqual:
-      cc = below_equal;
-      break;
-    case kUnsignedGreaterThan:
-      cc = above;
-      break;
-    case kOverflow:
-      cc = overflow;
-      break;
-    case kNotOverflow:
-      cc = no_overflow;
-      break;
-    default:
-      UNREACHABLE();
-      break;
+  if (condition == kUnorderedEqual) {
+    __ j(parity_odd, &check, Label::kNear);
+    __ movl(reg, Immediate(0));
+    __ jmp(&done, Label::kNear);
+  } else if (condition == kUnorderedNotEqual) {
+    __ j(parity_odd, &check, Label::kNear);
+    __ movl(reg, Immediate(1));
+    __ jmp(&done, Label::kNear);
   }
   __ bind(&check);
-  __ setcc(cc, reg);
+  __ setcc(ToCC(condition), reg);
   __ movzxbl(reg, reg);
   __ bind(&done);
 }