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

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

 // Copyright 2013 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 "src/compiler/code-generator.h"
 
 #include <limits>
 
 #include "src/compilation-info.h"
 #include "src/compiler/code-generator-impl.h"
@@ skipping 2208 matching lines @@
     case kAtomicLoadWord32:
     case kAtomicStoreWord8:
     case kAtomicStoreWord16:
     case kAtomicStoreWord32:
       UNREACHABLE();  // Won't be generated by instruction selector.
       break;
   }
   return kSuccess;
 }  // NOLINT(readability/fn_size)
 
+static Condition ToCC(FlagsCondition condition) {
+  switch (condition) {
+    case kUnorderedEqual:
+    case kEqual:
+      return equal;
+      break;
+    case kUnorderedNotEqual:
+    case kNotEqual:
+      return not_equal;
+      break;
+    case kSignedLessThan:
+      return less;
+      break;
+    case kSignedGreaterThanOrEqual:
+      return greater_equal;
+      break;
+    case kSignedLessThanOrEqual:
+      return less_equal;
+      break;
+    case kSignedGreaterThan:
+      return greater;
+      break;
+    case kUnsignedLessThan:
+      return below;
+      break;
+    case kUnsignedGreaterThanOrEqual:
+      return above_equal;
+      break;
+    case kUnsignedLessThanOrEqual:
+      return below_equal;
+      break;
+    case kUnsignedGreaterThan:
+      return above;
+      break;
+    case kOverflow:
+      return overflow;
+      break;
+    case kNotOverflow:
+      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;
-  switch (branch->condition) {
-    case kUnorderedEqual:
-      __ j(parity_even, flabel, flabel_distance);
-    // Fall through.
-    case kEqual:
-      __ j(equal, tlabel);
-      break;
-    case kUnorderedNotEqual:
-      __ j(parity_even, tlabel);
-    // Fall through.
-    case kNotEqual:
-      __ j(not_equal, tlabel);
-      break;
-    case kSignedLessThan:
-      __ j(less, tlabel);
-      break;
-    case kSignedGreaterThanOrEqual:
-      __ j(greater_equal, tlabel);
-      break;
-    case kSignedLessThanOrEqual:
-      __ j(less_equal, tlabel);
-      break;
-    case kSignedGreaterThan:
-      __ j(greater, tlabel);
-      break;
-    case kUnsignedLessThan:
-      __ j(below, tlabel);
-      break;
-    case kUnsignedGreaterThanOrEqual:
-      __ j(above_equal, tlabel);
-      break;
-    case kUnsignedLessThanOrEqual:
-      __ j(below_equal, tlabel);
-      break;
-    case kUnsignedGreaterThan:
-      __ j(above, tlabel);
-      break;
-    case kOverflow:
-      __ j(overflow, tlabel);
-      break;
-    case kNotOverflow:
-      __ j(no_overflow, tlabel);
-      break;
-    default:
-      UNREACHABLE();
-      break;
+  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);
 }
 
 
 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,
                                         FlagsCondition condition) {
   X64OperandConverter i(this, instr);
   Label done;
 
   // Materialize a full 64-bit 1 or 0 value. The result register is always the
   // last output of the instruction.
   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);
 }
 
 
 void CodeGenerator::AssembleArchLookupSwitch(Instruction* instr) {
   X64OperandConverter i(this, instr);
   Register input = i.InputRegister(0);
   for (size_t index = 2; index < instr->InputCount(); index += 2) {
     __ cmpl(input, Immediate(i.InputInt32(index + 0)));
@@ skipping 452 matching lines @@
     int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     __ Nop(padding_size);
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8