Generalize if-conversion to arbitrary smi comparisons.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 30464)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -131,16 +131,7 @@
 
 
 LocationSummary* IfThenElseInstr::MakeLocationSummary() const {
-  const intptr_t kNumInputs = 2;
-  const intptr_t kNumTemps = 0;
-  LocationSummary* locs =
-      new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
-  locs->set_in(0, Location::RegisterOrConstant(left()));
-  // Only one of the inputs can be a constant. Choose register if the first one
-  // is a constant.
-  locs->set_in(1, locs->in(0).IsConstant()
-                      ? Location::RequiresRegister()
-                      : Location::RegisterOrConstant(right()));
+  LocationSummary* locs = comparison()->MakeLocationSummary();
   // TODO(vegorov): support byte register constraints in the register allocator.
   locs->set_out(Location::RegisterLocation(RDX));
   return locs;
@@ -149,31 +140,15 @@
 
 void IfThenElseInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   ASSERT(locs()->out().reg() == RDX);
-  ASSERT(Token::IsEqualityOperator(kind()));
 
-  Location left = locs()->in(0);
-  Location right = locs()->in(1);
-  ASSERT(!left.IsConstant() || !right.IsConstant());
-
   // Clear upper part of the out register. We are going to use setcc on it
   // which is a byte move.
   __ xorq(RDX, RDX);
 
-  // Compare left and right. For now only equality comparison is supported.
-  // TODO(vegorov): reuse code from the other comparison instructions instead of
-  // generating it inline here.
-  if (left.IsConstant()) {
-    __ CompareObject(right.reg(), left.constant(), PP);
-  } else if (right.IsConstant()) {
-    __ CompareObject(left.reg(), right.constant(), PP);
-  } else {
-    __ cmpq(left.reg(), right.reg());
-  }
+  // Emit comparison code. This must not overwrite the result register.
+  BranchLabels labels = { NULL, NULL, NULL };
+  Condition true_condition = comparison()->EmitComparisonCode(compiler, labels);
 
-  Condition true_condition =
-      ((kind_ == Token::kEQ_STRICT) || (kind_ == Token::kEQ)) ? EQUAL
-                                                              : NOT_EQUAL;
-
   const bool is_power_of_two_kind = IsPowerOfTwoKind(if_true_, if_false_);
 
   intptr_t true_value = if_true_;
@@ -420,10 +395,10 @@
 }
 
 
-static void EmitSmiComparisonOp(FlowGraphCompiler* compiler,
-                                const LocationSummary& locs,
-                                Token::Kind kind,
-                                BranchLabels labels) {
+static Condition EmitSmiComparisonOp(FlowGraphCompiler* compiler,
+                                     const LocationSummary& locs,
+                                     Token::Kind kind,
+                                     BranchLabels labels) {
   Location left = locs.in(0);
   Location right = locs.in(1);
   ASSERT(!left.IsConstant() || !right.IsConstant());
@@ -440,7 +415,7 @@
   } else {
     __ cmpq(left.reg(), right.reg());
   }
-  EmitBranchOnCondition(compiler, true_condition, labels);
+  return true_condition;
 }
 
 
@@ -459,10 +434,10 @@
 }
 
 
-static void EmitDoubleComparisonOp(FlowGraphCompiler* compiler,
-                                   const LocationSummary& locs,
-                                   Token::Kind kind,
-                                   BranchLabels labels) {
+static Condition EmitDoubleComparisonOp(FlowGraphCompiler* compiler,
+                                        const LocationSummary& locs,
+                                        Token::Kind kind,
+                                        BranchLabels labels) {
   XmmRegister left = locs.in(0).fpu_reg();
   XmmRegister right = locs.in(1).fpu_reg();
 
@@ -472,22 +447,29 @@
   Label* nan_result = (true_condition == NOT_EQUAL)
       ? labels.true_label : labels.false_label;
   __ j(PARITY_EVEN, nan_result);
-  EmitBranchOnCondition(compiler, true_condition, labels);
+  return true_condition;
 }
 
 
+Condition EqualityCompareInstr::EmitComparisonCode(FlowGraphCompiler* compiler,
+                                                   BranchLabels labels) {
+  if (operation_cid() == kSmiCid) {
+    return EmitSmiComparisonOp(compiler, *locs(), kind(), labels);
+  } else {
+    ASSERT(operation_cid() == kDoubleCid);
+    return EmitDoubleComparisonOp(compiler, *locs(), kind(), labels);
+  }
+}
+
+
 void EqualityCompareInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   ASSERT((kind() == Token::kEQ) || (kind() == Token::kNE));
 
   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 (operation_cid() == kSmiCid) {
-    EmitSmiComparisonOp(compiler, *locs(), kind(), labels);
-  } else {
-    ASSERT(operation_cid() == kDoubleCid);
-    EmitDoubleComparisonOp(compiler, *locs(), kind(), labels);
-  }
   Register result = locs()->out().reg();
   Label done;
   __ Bind(&is_false);
@@ -504,13 +486,8 @@
   ASSERT((kind() == Token::kNE) || (kind() == Token::kEQ));
 
   BranchLabels labels = compiler->CreateBranchLabels(branch);
-
-  if (operation_cid() == kSmiCid) {
-    EmitSmiComparisonOp(compiler, *locs(), kind(), labels);
-  } else  {
-    ASSERT(operation_cid() == kDoubleCid);
-    EmitDoubleComparisonOp(compiler, *locs(), kind(), labels);
-  }
+  Condition true_condition = EmitComparisonCode(compiler, labels);
+  EmitBranchOnCondition(compiler, true_condition, labels);
 }
 
 
@@ -527,17 +504,8 @@
 }
 
 
-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 branch_condition = (kind() == Token::kNE) ? NOT_ZERO : ZERO;
+Condition TestSmiInstr::EmitComparisonCode(FlowGraphCompiler* compiler,
+                                           BranchLabels labels) {
   Register left_reg = locs()->in(0).reg();
   Location right = locs()->in(1);
   if (right.IsConstant()) {
@@ -548,10 +516,25 @@
   } else {
     __ testq(left_reg, right.reg());
   }
-  EmitBranchOnCondition(compiler, branch_condition, labels);
+  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* RelationalOpInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 2;
   const intptr_t kNumTemps = 0;
@@ -577,16 +560,23 @@
 }
 
 
-void RelationalOpInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
-  Label is_true, is_false;
-  BranchLabels labels = { &is_true, &is_false, &is_false };
-
+Condition RelationalOpInstr::EmitComparisonCode(FlowGraphCompiler* compiler,
+                                                BranchLabels labels) {
   if (operation_cid() == kSmiCid) {
-    EmitSmiComparisonOp(compiler, *locs(), kind(), labels);
+    return EmitSmiComparisonOp(compiler, *locs(), kind(), labels);
   } else {
     ASSERT(operation_cid() == kDoubleCid);
-    EmitDoubleComparisonOp(compiler, *locs(), kind(), labels);
+    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().reg();
   Label done;
   __ Bind(&is_false);
@@ -601,13 +591,8 @@
 void RelationalOpInstr::EmitBranchCode(FlowGraphCompiler* compiler,
                                        BranchInstr* branch) {
   BranchLabels labels = compiler->CreateBranchLabels(branch);
-
-  if (operation_cid() == kSmiCid) {
-    EmitSmiComparisonOp(compiler, *locs(), kind(), labels);
-  } else {
-    ASSERT(operation_cid() == kDoubleCid);
-    EmitDoubleComparisonOp(compiler, *locs(), kind(), labels);
-  }
+  Condition true_condition = EmitComparisonCode(compiler, labels);
+  EmitBranchOnCondition(compiler, true_condition, labels);
 }
 
 
@@ -4402,46 +4387,41 @@
 }
 
 
-static void EmitStrictComparison(FlowGraphCompiler* compiler,
-                                 StrictCompareInstr* compare,
-                                 BranchLabels labels) {
-  LocationSummary* locs = compare->locs();
-  bool needs_number_check = compare->needs_number_check();
-  intptr_t token_pos = compare->token_pos();
-  Token::Kind kind = compare->kind();
-  Location left = locs->in(0);
-  Location right = locs->in(1);
+Condition StrictCompareInstr::EmitComparisonCode(FlowGraphCompiler* compiler,
+                                                 BranchLabels labels) {
+  Location left = locs()->in(0);
+  Location right = locs()->in(1);
   ASSERT(!left.IsConstant() || !right.IsConstant());
   if (left.IsConstant()) {
     compiler->EmitEqualityRegConstCompare(right.reg(),
                                           left.constant(),
-                                          needs_number_check,
-                                          token_pos);
+                                          needs_number_check(),
+                                          token_pos());
   } else if (right.IsConstant()) {
     compiler->EmitEqualityRegConstCompare(left.reg(),
                                           right.constant(),
-                                          needs_number_check,
-                                          token_pos);
+                                          needs_number_check(),
+                                          token_pos());
   } else {
     compiler->EmitEqualityRegRegCompare(left.reg(),
                                         right.reg(),
-                                        needs_number_check,
-                                        token_pos);
+                                        needs_number_check(),
+                                        token_pos());
   }
 
-  Condition true_condition = (kind == Token::kEQ_STRICT) ? EQUAL : NOT_EQUAL;
-  EmitBranchOnCondition(compiler, true_condition, labels);
+  Condition true_condition = (kind() == Token::kEQ_STRICT) ? EQUAL : NOT_EQUAL;
+  return true_condition;
 }
 
 
-// Special code for numbers (compare values instead of references.)
 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 };
 
-  EmitStrictComparison(compiler, this, labels);
+  Condition true_condition = EmitComparisonCode(compiler, labels);
+  EmitBranchOnCondition(compiler, true_condition, labels);
 
   Register result = locs()->out().reg();
   Label done;
@@ -4459,8 +4439,8 @@
   ASSERT(kind() == Token::kEQ_STRICT || kind() == Token::kNE_STRICT);
 
   BranchLabels labels = compiler->CreateBranchLabels(branch);
-
-  EmitStrictComparison(compiler, this, labels);
+  Condition true_condition = EmitComparisonCode(compiler, labels);
+  EmitBranchOnCondition(compiler, true_condition, labels);
 }