[turbofan] Allow 0.0 as immediate for floating-point comparison on arm/arm64.

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

Index: src/compiler/arm/code-generator-arm.cc
diff --git a/src/compiler/arm/code-generator-arm.cc b/src/compiler/arm/code-generator-arm.cc
index 81298aaeca8e28970aa5ee874d346283734c7c93..5616337a6d8c63cd83123a76d8edf9f177cbb2e4 100644
--- a/src/compiler/arm/code-generator-arm.cc
+++ b/src/compiler/arm/code-generator-arm.cc
@@ -494,8 +494,15 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       DCHECK_EQ(SetCC, i.OutputSBit());
       break;
     case kArmVcmpF64:
-      __ VFPCompareAndSetFlags(i.InputFloat64Register(0),
-                               i.InputFloat64Register(1));
+      if (instr->InputAt(1)->IsDoubleRegister()) {
+        __ VFPCompareAndSetFlags(i.InputFloat64Register(0),
+                                 i.InputFloat64Register(1));
+      } else {
+        DCHECK(instr->InputAt(1)->IsImmediate());
+        // 0.0 is the only immediate supported by vcmp instructions.
+        DCHECK(i.InputDouble(1) == 0.0);
+        __ VFPCompareAndSetFlags(i.InputFloat64Register(0), i.InputDouble(1));
+      }
       DCHECK_EQ(SetCC, i.OutputSBit());
       break;
     case kArmVaddF64: