A64: Truncate booleans to 0 or 1 in LTaggedToI.

src/a64/lithium-codegen-a64.cc

Index: src/a64/lithium-codegen-a64.cc
diff --git a/src/a64/lithium-codegen-a64.cc b/src/a64/lithium-codegen-a64.cc
index 3a58f021e4b7c1115906e7957105b01a27e4f62d..e4e47c6a1f8d7771e00ddfe34d2466e9f864f123 100644
--- a/src/a64/lithium-codegen-a64.cc
+++ b/src/a64/lithium-codegen-a64.cc
@@ -5118,7 +5118,7 @@ void LCodeGen::DoDeferredTaggedToI(LTaggedToI* instr,
   if (instr->truncating()) {
     Register output = ToRegister(instr->result());
     Register scratch2 = ToRegister(temp2);
-    Label check_bools, undefined;
+    Label check_bools;
 
     // If it's not a heap number, jump to undefined check.
     __ JumpIfNotRoot(scratch1, Heap::kHeapNumberMapRootIndex, &check_bools);
@@ -5130,15 +5130,18 @@ void LCodeGen::DoDeferredTaggedToI(LTaggedToI* instr,
 
     __ Bind(&check_bools);
 
-    TODO_UNIMPLEMENTED("LTaggedToI: Truncate booleans to 0 or 1.");
+    Register true_root = output;
+    Register false_root = scratch2;
+    __ LoadTrueFalseRoots(true_root, false_root);
+    __ Cmp(scratch1, true_root);
+    __ Cset(output, eq);
+    __ Ccmp(scratch1, false_root, ZFlag, ne);
+    __ B(eq, &done);
 
-    // Check for undefined. Undefined is converted to zero for truncating
+    // Output contains zero, undefined is converted to zero for truncating
     // conversions.
-    __ Bind(&undefined);
-
     DeoptimizeIfNotRoot(input, Heap::kUndefinedValueRootIndex,
                         instr->environment());
-    __ Mov(output, 0);
   } else {
     Register output = ToRegister32(instr->result());