ARM: Correctness fix to Math.pow optimization...

src/arm/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 4328 matching lines @@
 
     // Run through all the bits in the exponent. The result is calculated in d0
     // and d1 holds base^(bit^2).
     Label more_bits;
     __ bind(&more_bits);
     __ mov(scratch1, Operand(scratch1, LSR, 1), SetCC);
     __ vmul(d0, d0, d1, cs);  // Multiply with base^(bit^2) if bit is set.
     __ vmul(d1, d1, d1, ne);  // Don't bother calculating next d1 if done.
     __ b(ne, &more_bits);
 
+    // If exponent is positive we are done.
+    __ cmp(exponent, Operand(0));
+    __ b(ge, &allocate_return);
+
     // If exponent is negative result is 1/result (d2 already holds 1.0 in that
-    // case).
-    __ cmp(exponent, Operand(0));
-    __ vdiv(d0, d2, d0, mi);
+    // case). However if d0 has reached infinity this will not provide the
+    // correct result, so call runtime if that is the case.
+    __ mov(scratch2, Operand(0x7FF00000));
+    __ mov(scratch1, Operand(0));
+    __ vmov(d1, scratch1, scratch2);  // Load infinity into d1.
+    __ vcmp(d0, d1);
+    __ vmrs(pc);
+    runtime.Branch(eq);  // d0 reached infinity.
+    __ vdiv(d0, d2, d0);
     __ b(&allocate_return);
 
     __ bind(&exponent_nonsmi);
     // Special handling of raising to the power of -0.5 and 0.5. First check
     // that the value is a heap number and that the lower bits (which for both
     // values are zero).
     heap_number_map = r6;
     __ LoadRoot(heap_number_map, Heap::kHeapNumberMapRootIndex);
     __ ldr(scratch1, FieldMemOperand(exponent, HeapObject::kMapOffset));
     __ ldr(scratch2, FieldMemOperand(exponent, HeapNumber::kMantissaOffset));
@@ skipping 6749 matching lines @@
   __ bind(&string_add_runtime);
   __ TailCallRuntime(Runtime::kStringAdd, 2, 1);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM