Revert 17963, 17962 and 17955: Random number generator in JS changes

src/ia32/full-codegen-ia32.cc

Index: src/ia32/full-codegen-ia32.cc
diff --git a/src/ia32/full-codegen-ia32.cc b/src/ia32/full-codegen-ia32.cc
index e067c903091c4e6064d8e9702341792270154985..86c525d7f63e034af66868d20a94b34338cf6d3a 100644
--- a/src/ia32/full-codegen-ia32.cc
+++ b/src/ia32/full-codegen-ia32.cc
@@ -3296,6 +3296,57 @@ void FullCodeGenerator::EmitLog(CallRuntime* expr) {
 }
 
 
+void FullCodeGenerator::EmitRandomHeapNumber(CallRuntime* expr) {
+  ASSERT(expr->arguments()->length() == 0);
+
+  Label slow_allocate_heapnumber;
+  Label heapnumber_allocated;
+
+  __ AllocateHeapNumber(edi, ebx, ecx, &slow_allocate_heapnumber);
+  __ jmp(&heapnumber_allocated);
+
+  __ bind(&slow_allocate_heapnumber);
+  // Allocate a heap number.
+  __ CallRuntime(Runtime::kNumberAlloc, 0);
+  __ mov(edi, eax);
+
+  __ bind(&heapnumber_allocated);
+
+  __ PrepareCallCFunction(1, ebx);
+  __ mov(eax, ContextOperand(context_register(), Context::GLOBAL_OBJECT_INDEX));
+  __ mov(eax, FieldOperand(eax, GlobalObject::kNativeContextOffset));
+  __ mov(Operand(esp, 0), eax);
+  __ CallCFunction(ExternalReference::random_uint32_function(isolate()), 1);
+
+  // Convert 32 random bits in eax to 0.(32 random bits) in a double
+  // by computing:
+  // ( 1.(20 0s)(32 random bits) x 2^20 ) - (1.0 x 2^20)).
+  // This is implemented on both SSE2 and FPU.
+  if (CpuFeatures::IsSupported(SSE2)) {
+    CpuFeatureScope fscope(masm(), SSE2);
+    __ mov(ebx, Immediate(0x49800000));  // 1.0 x 2^20 as single.
+    __ movd(xmm1, ebx);
+    __ movd(xmm0, eax);
+    __ cvtss2sd(xmm1, xmm1);
+    __ xorps(xmm0, xmm1);
+    __ subsd(xmm0, xmm1);
+    __ movsd(FieldOperand(edi, HeapNumber::kValueOffset), xmm0);
+  } else {
+    // 0x4130000000000000 is 1.0 x 2^20 as a double.
+    __ mov(FieldOperand(edi, HeapNumber::kExponentOffset),
+           Immediate(0x41300000));
+    __ mov(FieldOperand(edi, HeapNumber::kMantissaOffset), eax);
+    __ fld_d(FieldOperand(edi, HeapNumber::kValueOffset));
+    __ mov(FieldOperand(edi, HeapNumber::kMantissaOffset), Immediate(0));
+    __ fld_d(FieldOperand(edi, HeapNumber::kValueOffset));
+    __ fsubp(1);
+    __ fstp_d(FieldOperand(edi, HeapNumber::kValueOffset));
+  }
+  __ mov(eax, edi);
+  context()->Plug(eax);
+}
+
+
 void FullCodeGenerator::EmitSubString(CallRuntime* expr) {
   // Load the arguments on the stack and call the stub.
   SubStringStub stub;