ARM: Fix comparison of NaN values....

src/arm/lithium-codegen-arm.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1058 matching lines @@
   int true_block = chunk_->LookupDestination(instr->true_block_id());
   int false_block = chunk_->LookupDestination(instr->false_block_id());
 
   Representation r = instr->hydrogen()->representation();
   if (r.IsInteger32()) {
     Register reg = ToRegister(instr->input());
     __ cmp(reg, Operand(0));
     EmitBranch(true_block, false_block, nz);
   } else if (r.IsDouble()) {
     DoubleRegister reg = ToDoubleRegister(instr->input());
+    Register scratch = scratch0();
+
+    // Test for the double value. Zero and NaN are false.
+    // Clear the Invalid cumulative exception flags.

[Søren Thygesen Gjesse, 2011/01/07 11:44:32]

I will suggest a macro assembler instruction for this:

__ ClearFPCSRBit(kVFPInvalidExceptionBit, scratch);

[Alexandre, 2011/01/07 18:34:49]

Added the ClearFPSCRBits Masm instruction.
On 2011/01/07 11:44:32, Søren Gjesse wrote:

+    __ vmrs(scratch);
+    __ bic(scratch, scratch, Operand(kVFPInvalidExceptionBit));
+    __ vmsr(scratch);
     __ vcmp(reg, 0.0);
-    __ vmrs(pc);  // Move vector status bits to normal status bits.
+    __ vmrs(scratch);  // Retrieve the exception and status flags.
+    // Check for zero or an invalid exception.
+    __ tst(scratch, Operand(kVFPZConditionFlagBit | kVFPInvalidExceptionBit));
     EmitBranch(true_block, false_block, ne);
   } else {
     ASSERT(r.IsTagged());
     Register reg = ToRegister(instr->input());
     if (instr->hydrogen()->type().IsBoolean()) {
       __ LoadRoot(ip, Heap::kTrueValueRootIndex);
       __ cmp(reg, ip);
       EmitBranch(true_block, false_block, eq);
     } else {
       Label* true_label = chunk_->GetAssemblyLabel(true_block);
       Label* false_label = chunk_->GetAssemblyLabel(false_block);
 
       __ LoadRoot(ip, Heap::kUndefinedValueRootIndex);
       __ cmp(reg, ip);
       __ b(eq, false_label);
       __ LoadRoot(ip, Heap::kTrueValueRootIndex);
       __ cmp(reg, ip);
       __ b(eq, true_label);
       __ LoadRoot(ip, Heap::kFalseValueRootIndex);
       __ cmp(reg, ip);
       __ b(eq, false_label);
       __ cmp(reg, Operand(0));
       __ b(eq, false_label);
       __ tst(reg, Operand(kSmiTagMask));
       __ b(eq, true_label);
 
-      // Test for double values. Zero is false.
+      // Test for double values. Zero and NaN are false.
       Label call_stub;
       DoubleRegister dbl_scratch = d0;
       Register scratch = scratch0();
       __ ldr(scratch, FieldMemOperand(reg, HeapObject::kMapOffset));
       __ LoadRoot(ip, Heap::kHeapNumberMapRootIndex);
       __ cmp(scratch, Operand(ip));
       __ b(ne, &call_stub);
       __ sub(ip, reg, Operand(kHeapObjectTag));
       __ vldr(dbl_scratch, ip, HeapNumber::kValueOffset);
+      // Clear the Invalid cumulative exception flags.

[Søren Thygesen Gjesse, 2011/01/07 11:44:32]

Ditto.

[Alexandre, 2011/01/07 18:34:49]

Used the new pseudo instruction.
On 2011/01/07 11:44:32, Søren Gjesse wrote:

+      __ vmrs(scratch);
+      __ bic(scratch, scratch, Operand(kVFPInvalidExceptionBit));
+      __ vmsr(scratch);
       __ vcmp(dbl_scratch, 0.0);
-      __ vmrs(pc);  // Move vector status bits to normal status bits.
-      __ b(eq, false_label);
+      __ vmrs(scratch);  // Retrieve the exception and status flags.
+      // Check for zero or an invalid exception.
+      __ tst(scratch, Operand(kVFPZConditionFlagBit | kVFPInvalidExceptionBit));
+      __ b(ne, false_label);
       __ b(true_label);
 
       // The conversion stub doesn't cause garbage collections so it's
       // safe to not record a safepoint after the call.
       __ bind(&call_stub);
       ToBooleanStub stub(reg);
       RegList saved_regs = kJSCallerSaved | kCalleeSaved;
       __ stm(db_w, sp, saved_regs);
       __ CallStub(&stub);
       __ cmp(reg, Operand(0));
@@ skipping 1461 matching lines @@
 
 
 void LCodeGen::DoOsrEntry(LOsrEntry* instr) {
   Abort("DoOsrEntry unimplemented.");
 }
 
 
 #undef __
 
 } }  // namespace v8::internal