VM-codegen: Clean up the way we emit code for comparison instructions.

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "vm/compiler.h"
@@ skipping 147 matching lines @@
 
 
 void IfThenElseInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   ASSERT(locs()->out(0).reg() == RDX);
 
   // Clear upper part of the out register. We are going to use setcc on it
   // which is a byte move.
   __ xorq(RDX, RDX);
 
   // Emit comparison code. This must not overwrite the result register.
+  // IfThenElseInstr::Supports() should prevent EmitComparisonCode from using
+  // the labels or returning an invalid condition.
   BranchLabels labels = {NULL, NULL, NULL};
   Condition true_condition = comparison()->EmitComparisonCode(compiler, labels);
+  ASSERT(true_condition != INVALID_CONDITION);
 
   const bool is_power_of_two_kind = IsPowerOfTwoKind(if_true_, if_false_);
 
   intptr_t true_value = if_true_;
   intptr_t false_value = if_false_;
 
   if (is_power_of_two_kind) {
     if (true_value == 0) {
       // We need to have zero in RDX on true_condition.
       true_condition = NegateCondition(true_condition);
@@ skipping 386 matching lines @@
                                                    BranchLabels labels) {
   if ((operation_cid() == kSmiCid) || (operation_cid() == kMintCid)) {
     return EmitInt64ComparisonOp(compiler, *locs(), kind());
   } else {
     ASSERT(operation_cid() == kDoubleCid);
     return EmitDoubleComparisonOp(compiler, *locs(), kind(), labels);
   }
 }
 
 
-void EqualityCompareInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  ASSERT((kind() == Token::kEQ) || (kind() == Token::kNE));
-
+void ComparisonInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Label is_true, is_false;
   BranchLabels labels = {&is_true, &is_false, &is_false};
   Condition true_condition = EmitComparisonCode(compiler, labels);
-  EmitBranchOnCondition(compiler, true_condition, labels);
+  if (true_condition != INVALID_CONDITION) {
+    EmitBranchOnCondition(compiler, true_condition, labels);
+  }
 
   Register result = locs()->out(0).reg();
   Label done;
   __ Bind(&is_false);
   __ LoadObject(result, Bool::False());
   __ jmp(&done);
   __ Bind(&is_true);
   __ LoadObject(result, Bool::True());
   __ Bind(&done);
 }
 
 
-void EqualityCompareInstr::EmitBranchCode(FlowGraphCompiler* compiler,
-                                          BranchInstr* branch) {
-  ASSERT((kind() == Token::kNE) || (kind() == Token::kEQ));
-
+void ComparisonInstr::EmitBranchCode(FlowGraphCompiler* compiler,
+                                     BranchInstr* branch) {
   BranchLabels labels = compiler->CreateBranchLabels(branch);
   Condition true_condition = EmitComparisonCode(compiler, labels);
-  EmitBranchOnCondition(compiler, true_condition, labels);
+  if (true_condition != INVALID_CONDITION) {
+    EmitBranchOnCondition(compiler, true_condition, labels);
+  }
 }
 
 
 LocationSummary* TestSmiInstr::MakeLocationSummary(Zone* zone, bool opt) const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps = 0;
   LocationSummary* locs = new (zone)
       LocationSummary(zone, kNumInputs, kNumTemps, LocationSummary::kNoCall);
   locs->set_in(0, Location::RequiresRegister());
   // Only one input can be a constant operand. The case of two constant
@@ skipping 12 matching lines @@
     const int64_t imm = reinterpret_cast<int64_t>(right.constant().raw());
     __ TestImmediate(left_reg, Immediate(imm));
   } else {
     __ testq(left_reg, right.reg());
   }
   Condition true_condition = (kind() == Token::kNE) ? NOT_ZERO : ZERO;
   return true_condition;
 }
 
 
-void TestSmiInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  // Never emitted outside of the BranchInstr.
-  UNREACHABLE();
-}
-
-
-void TestSmiInstr::EmitBranchCode(FlowGraphCompiler* compiler,
-                                  BranchInstr* branch) {
-  BranchLabels labels = compiler->CreateBranchLabels(branch);
-  Condition true_condition = EmitComparisonCode(compiler, labels);
-  EmitBranchOnCondition(compiler, true_condition, labels);
-}
-
-
 LocationSummary* TestCidsInstr::MakeLocationSummary(Zone* zone,
                                                     bool opt) const {
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps = 1;
   LocationSummary* locs = new (zone)
       LocationSummary(zone, kNumInputs, kNumTemps, LocationSummary::kNoCall);
   locs->set_in(0, Location::RequiresRegister());
   locs->set_temp(0, Location::RequiresRegister());
   locs->set_out(0, Location::RequiresRegister());
   return locs;
@@ skipping 31 matching lines @@
     // If the cid is not in the list, jump to the opposite label from the cids
     // that are in the list.  These must be all the same (see asserts in the
     // constructor).
     Label* target = result ? labels.false_label : labels.true_label;
     if (target != labels.fall_through) {
       __ jmp(target);
     }
   } else {
     __ jmp(deopt);
   }
-  // Dummy result as the last instruction is a jump, any conditional
-  // branch using the result will therefore be skipped.
-  return ZERO;
+  // Dummy result as this method already did the jump, there's no need
+  // for the caller to branch on a condition.
+  return INVALID_CONDITION;
 }
 
 
-void TestCidsInstr::EmitBranchCode(FlowGraphCompiler* compiler,
-                                   BranchInstr* branch) {
-  BranchLabels labels = compiler->CreateBranchLabels(branch);
-  EmitComparisonCode(compiler, labels);
-}
-
-
-void TestCidsInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  Register result_reg = locs()->out(0).reg();
-  Label is_true, is_false, done;
-  BranchLabels labels = {&is_true, &is_false, &is_false};
-  EmitComparisonCode(compiler, labels);
-  __ Bind(&is_false);
-  __ LoadObject(result_reg, Bool::False());
-  __ jmp(&done, Assembler::kNearJump);
-  __ Bind(&is_true);
-  __ LoadObject(result_reg, Bool::True());
-  __ Bind(&done);
-}
-
-
 LocationSummary* RelationalOpInstr::MakeLocationSummary(Zone* zone,
                                                         bool opt) const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps = 0;
   if (operation_cid() == kDoubleCid) {
     LocationSummary* summary = new (zone)
         LocationSummary(zone, kNumInputs, kNumTemps, LocationSummary::kNoCall);
     summary->set_in(0, Location::RequiresFpuRegister());
     summary->set_in(1, Location::RequiresFpuRegister());
     summary->set_out(0, Location::RequiresRegister());
@@ skipping 24 matching lines @@
                                                 BranchLabels labels) {
   if ((operation_cid() == kSmiCid) || (operation_cid() == kMintCid)) {
     return EmitInt64ComparisonOp(compiler, *locs(), kind());
   } else {
     ASSERT(operation_cid() == kDoubleCid);
     return EmitDoubleComparisonOp(compiler, *locs(), kind(), labels);
   }
 }
 
 
-void RelationalOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  Label is_true, is_false;
-  BranchLabels labels = {&is_true, &is_false, &is_false};
-  Condition true_condition = EmitComparisonCode(compiler, labels);
-  EmitBranchOnCondition(compiler, true_condition, labels);
-
-  Register result = locs()->out(0).reg();
-  Label done;
-  __ Bind(&is_false);
-  __ LoadObject(result, Bool::False());
-  __ jmp(&done);
-  __ Bind(&is_true);
-  __ LoadObject(result, Bool::True());
-  __ Bind(&done);
-}
-
-
-void RelationalOpInstr::EmitBranchCode(FlowGraphCompiler* compiler,
-                                       BranchInstr* branch) {
-  BranchLabels labels = compiler->CreateBranchLabels(branch);
-  Condition true_condition = EmitComparisonCode(compiler, labels);
-  EmitBranchOnCondition(compiler, true_condition, labels);
-}
-
-
 LocationSummary* NativeCallInstr::MakeLocationSummary(Zone* zone,
                                                       bool opt) const {
   return MakeCallSummary(zone);
 }
 
 
 void NativeCallInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   SetupNative();
   Register result = locs()->out(0).reg();
   const intptr_t argc_tag = NativeArguments::ComputeArgcTag(function());
@@ skipping 2297 matching lines @@
 
 void CheckedSmiComparisonInstr::EmitBranchCode(FlowGraphCompiler* compiler,
                                                BranchInstr* branch) {
   BranchLabels labels = compiler->CreateBranchLabels(branch);
   CheckedSmiComparisonSlowPath* slow_path = new CheckedSmiComparisonSlowPath(
       this, compiler->CurrentTryIndex(), labels,
       /* merged = */ true);
   compiler->AddSlowPathCode(slow_path);
   EMIT_SMI_CHECK;
   Condition true_condition = EmitComparisonCode(compiler, labels);
+  ASSERT(true_condition != INVALID_CONDITION);
   EmitBranchOnCondition(compiler, true_condition, labels);
   __ Bind(slow_path->exit_label());
 }
 
 
 void CheckedSmiComparisonInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Label true_label, false_label, done;
   BranchLabels labels = {&true_label, &false_label, &false_label};
   CheckedSmiComparisonSlowPath* slow_path = new CheckedSmiComparisonSlowPath(
       this, compiler->CurrentTryIndex(), labels,
       /* merged = */ false);
   compiler->AddSlowPathCode(slow_path);
   EMIT_SMI_CHECK;
   Condition true_condition = EmitComparisonCode(compiler, labels);
+  ASSERT(true_condition != INVALID_CONDITION);
   EmitBranchOnCondition(compiler, true_condition, labels);
   Register result = locs()->out(0).reg();
   __ Bind(&false_label);
   __ LoadObject(result, Bool::False());
   __ jmp(&done);
   __ Bind(&true_label);
   __ LoadObject(result, Bool::True());
   __ Bind(&done);
   __ Bind(slow_path->exit_label());
 }
@@ skipping 808 matching lines @@
     __ AddImmediate(RSP, Immediate(kDoubleSize));
     // Mask off the sign.
     __ AndImmediate(temp, Immediate(0x7FFFFFFFFFFFFFFFLL));
     // Compare with +infinity.
     __ CompareImmediate(temp, Immediate(0x7FF0000000000000LL));
     return is_negated ? NOT_EQUAL : EQUAL;
   }
 }
 
 
-void DoubleTestOpInstr::EmitBranchCode(FlowGraphCompiler* compiler,
-                                       BranchInstr* branch) {
-  ASSERT(compiler->is_optimizing());
-  BranchLabels labels = compiler->CreateBranchLabels(branch);
-  Condition true_condition = EmitComparisonCode(compiler, labels);
-  EmitBranchOnCondition(compiler, true_condition, labels);
-}
-
-
-void DoubleTestOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  Label is_true, is_false;
-  BranchLabels labels = {&is_true, &is_false, &is_false};
-  Condition true_condition = EmitComparisonCode(compiler, labels);
-  EmitBranchOnCondition(compiler, true_condition, labels);
-
-  Register result = locs()->out(0).reg();
-  Label done;
-  __ Bind(&is_false);
-  __ LoadObject(result, Bool::False());
-  __ jmp(&done);
-  __ Bind(&is_true);
-  __ LoadObject(result, Bool::True());
-  __ Bind(&done);
-}
-
-
 LocationSummary* BinaryFloat32x4OpInstr::MakeLocationSummary(Zone* zone,
                                                              bool opt) const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps = 0;
   LocationSummary* summary = new (zone)
       LocationSummary(zone, kNumInputs, kNumTemps, LocationSummary::kNoCall);
   summary->set_in(0, Location::RequiresFpuRegister());
   summary->set_in(1, Location::RequiresFpuRegister());
   summary->set_out(0, Location::SameAsFirstInput());
   return summary;
@@ skipping 2641 matching lines @@
         left.reg(), right.reg(), needs_number_check(), token_pos(), deopt_id_);
   }
   if (kind() != Token::kEQ_STRICT) {
     ASSERT(kind() == Token::kNE_STRICT);
     true_condition = NegateCondition(true_condition);
   }
   return true_condition;
 }
 
 
-void StrictCompareInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  ASSERT(kind() == Token::kEQ_STRICT || kind() == Token::kNE_STRICT);
-
-  Label is_true, is_false;
-  BranchLabels labels = {&is_true, &is_false, &is_false};
-
-  Condition true_condition = EmitComparisonCode(compiler, labels);
-  EmitBranchOnCondition(compiler, true_condition, labels);
-
-  Register result = locs()->out(0).reg();
-  Label done;
-  __ Bind(&is_false);
-  __ LoadObject(result, Bool::False());
-  __ jmp(&done);
-  __ Bind(&is_true);
-  __ LoadObject(result, Bool::True());
-  __ Bind(&done);
-}
-
-
-void StrictCompareInstr::EmitBranchCode(FlowGraphCompiler* compiler,
-                                        BranchInstr* branch) {
-  ASSERT(kind() == Token::kEQ_STRICT || kind() == Token::kNE_STRICT);
-
-  BranchLabels labels = compiler->CreateBranchLabels(branch);
-  Condition true_condition = EmitComparisonCode(compiler, labels);
-  EmitBranchOnCondition(compiler, true_condition, labels);
-}
-
-
 LocationSummary* ClosureCallInstr::MakeLocationSummary(Zone* zone,
                                                        bool opt) const {
   const intptr_t kNumInputs = 1;
   const intptr_t kNumTemps = 0;
   LocationSummary* summary = new (zone)
       LocationSummary(zone, kNumInputs, kNumTemps, LocationSummary::kCall);
   summary->set_in(0, Location::RegisterLocation(RAX));  // Function.
   summary->set_out(0, Location::RegisterLocation(RAX));
   return summary;
 }
@@ skipping 100 matching lines @@
   __ Drop(1);
   __ popq(result);
 }
 
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64