ARM: Enable VFP default NaN mode

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index a3379d59f54297975a57ba03e7a93a009984d7a3..7df0c0a1ff0514457fb37754902cc6072f789503 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -773,6 +773,23 @@ void MacroAssembler::Strd(Register src1, Register src2,
 }
 
 
+void MacroAssembler::VFPEnsureFPSCRState(Register scratch) {
+  // If needed, restore wanted bits of FPSCR.
+  Label fpscr_done;
+  vmrs(scratch);
+  tst(scratch, Operand(kVFPDefaultNaNModeControlBit));
+  b(ne, &fpscr_done);
+  orr(scratch, scratch, Operand(kVFPDefaultNaNModeControlBit));
+  vmsr(scratch);
+  bind(&fpscr_done);
+}
+
+void MacroAssembler::VFPCanonicalizeNaN(const DwVfpRegister value,
+                                        const Condition cond) {
+  vsub(value, value, kDoubleRegZero, cond);
+}
+
+
 void MacroAssembler::VFPCompareAndSetFlags(const DwVfpRegister src1,
                                            const DwVfpRegister src2,
                                            const Condition cond) {
@@ -1983,7 +2000,7 @@ void MacroAssembler::StoreNumberToDoubleElements(Register value_reg,
                                                  Register scratch4,
                                                  Label* fail,
                                                  int elements_offset) {
-  Label smi_value, maybe_nan, have_double_value, is_nan, done;
+  Label smi_value, store;
   Register mantissa_reg = scratch2;
   Register exponent_reg = scratch3;
 
@@ -1997,68 +2014,28 @@ void MacroAssembler::StoreNumberToDoubleElements(Register value_reg,
            fail,
            DONT_DO_SMI_CHECK);
 
-  // Check for nan: all NaN values have a value greater (signed) than 0x7ff00000
-  // in the exponent.
-  mov(scratch1, Operand(kNaNOrInfinityLowerBoundUpper32));
-  ldr(exponent_reg, FieldMemOperand(value_reg, HeapNumber::kExponentOffset));
-  cmp(exponent_reg, scratch1);
-  b(ge, &maybe_nan);
-
-  ldr(mantissa_reg, FieldMemOperand(value_reg, HeapNumber::kMantissaOffset));
-
-  bind(&have_double_value);
-  add(scratch1, elements_reg,
-      Operand(key_reg, LSL, kDoubleSizeLog2 - kSmiTagSize));
-  str(mantissa_reg, FieldMemOperand(
-      scratch1, FixedDoubleArray::kHeaderSize - elements_offset));
-  uint32_t offset = FixedDoubleArray::kHeaderSize - elements_offset +
-      sizeof(kHoleNanLower32);
-  str(exponent_reg, FieldMemOperand(scratch1, offset));
-  jmp(&done);
-
-  bind(&maybe_nan);
-  // Could be NaN or Infinity. If fraction is not zero, it's NaN, otherwise
-  // it's an Infinity, and the non-NaN code path applies.
-  b(gt, &is_nan);
-  ldr(mantissa_reg, FieldMemOperand(value_reg, HeapNumber::kMantissaOffset));
-  cmp(mantissa_reg, Operand::Zero());
-  b(eq, &have_double_value);
-  bind(&is_nan);
-  // Load canonical NaN for storing into the double array.
-  uint64_t nan_int64 = BitCast<uint64_t>(
-      FixedDoubleArray::canonical_not_the_hole_nan_as_double());
-  mov(mantissa_reg, Operand(static_cast<uint32_t>(nan_int64)));
-  mov(exponent_reg, Operand(static_cast<uint32_t>(nan_int64 >> 32)));
-  jmp(&have_double_value);
+  vldr(d0, FieldMemOperand(value_reg, HeapNumber::kValueOffset));
+  // Force a canonical NaN.
+  if (emit_debug_code()) {
+    vmrs(ip);
+    tst(ip, Operand(kVFPDefaultNaNModeControlBit));
+    Assert(ne, "Default NaN mode not set");
+  }
+  VFPCanonicalizeNaN(d0);
+  b(&store);
 
   bind(&smi_value);
+  Register untagged_value = scratch1;
+  SmiUntag(untagged_value, value_reg);
+  FloatingPointHelper::ConvertIntToDouble(
+          this, untagged_value, FloatingPointHelper::kVFPRegisters, d0,
+          mantissa_reg, exponent_reg, scratch4, s2);
+
+  bind(&store);
   add(scratch1, elements_reg,
-      Operand(FixedDoubleArray::kHeaderSize - kHeapObjectTag -
-              elements_offset));
-  add(scratch1, scratch1,
       Operand(key_reg, LSL, kDoubleSizeLog2 - kSmiTagSize));
-  // scratch1 is now effective address of the double element
-
-  FloatingPointHelper::Destination destination;
-  destination = FloatingPointHelper::kVFPRegisters;
-
-  Register untagged_value = elements_reg;
-  SmiUntag(untagged_value, value_reg);
-  FloatingPointHelper::ConvertIntToDouble(this,
-                                          untagged_value,
-                                          destination,
-                                          d0,
-                                          mantissa_reg,
-                                          exponent_reg,
-                                          scratch4,
-                                          s2);
-  if (destination == FloatingPointHelper::kVFPRegisters) {
-    vstr(d0, scratch1, 0);
-  } else {
-    str(mantissa_reg, MemOperand(scratch1, 0));
-    str(exponent_reg, MemOperand(scratch1, Register::kSizeInBytes));
-  }
-  bind(&done);
+  vstr(d0, FieldMemOperand(scratch1,
+                           FixedDoubleArray::kHeaderSize - elements_offset));
 }