[x64/ia32] Deal with the non-transitivity of InstructionSelector::CanCover() when folding loads int…

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 8e68b96d7a529514b514448f305c9d72f186e3f8..7aba7913aef5b503b7033d24a84d84344219dadc 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -37,11 +37,15 @@ class X64OperandGenerator final : public OperandGenerator {
     }
   }
 
-  bool CanBeMemoryOperand(InstructionCode opcode, Node* node, Node* input) {
+  bool CanBeMemoryOperand(InstructionCode opcode, Node* node, Node* input,
+                          int effect_level) {
     if (input->opcode() != IrOpcode::kLoad ||
         !selector()->CanCover(node, input)) {
       return false;
     }
+    if (effect_level != selector()->GetEffectLevel(input)) {
+      return false;
+    }
     MachineRepresentation rep =
         LoadRepresentationOf(input->op()).representation();
     switch (opcode) {
@@ -1548,16 +1552,22 @@ void VisitWordCompare(InstructionSelector* selector, Node* node,
 
   // If one of the two inputs is an immediate, make sure it's on the right, or
   // if one of the two inputs is a memory operand, make sure it's on the left.
+  int effect_level = selector->GetEffectLevel(node);
+  if (cont->IsBranch()) {
+    effect_level = selector->GetEffectLevel(
+        cont->true_block()->PredecessorAt(0)->control_input());
+  }
+
   if ((!g.CanBeImmediate(right) && g.CanBeImmediate(left)) ||
-      (g.CanBeMemoryOperand(opcode, node, right) &&
-       !g.CanBeMemoryOperand(opcode, node, left))) {
+      (g.CanBeMemoryOperand(opcode, node, right, effect_level) &&
+       !g.CanBeMemoryOperand(opcode, node, left, effect_level))) {
     if (!node->op()->HasProperty(Operator::kCommutative)) cont->Commute();
     std::swap(left, right);
   }
 
   // Match immediates on right side of comparison.
   if (g.CanBeImmediate(right)) {
-    if (g.CanBeMemoryOperand(opcode, node, left)) {
+    if (g.CanBeMemoryOperand(opcode, node, left, effect_level)) {
       return VisitCompareWithMemoryOperand(selector, opcode, left,
                                            g.UseImmediate(right), cont);
     }
@@ -1566,7 +1576,7 @@ void VisitWordCompare(InstructionSelector* selector, Node* node,
   }
 
   // Match memory operands on left side of comparison.
-  if (g.CanBeMemoryOperand(opcode, node, left)) {
+  if (g.CanBeMemoryOperand(opcode, node, left, effect_level)) {
     return VisitCompareWithMemoryOperand(selector, opcode, left,
                                          g.UseRegister(right), cont);
   }