Port r10939 to x64 and arm (inline Math.random in crankshaft).

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 985cdc6d98e49c6fd377a9b94edc97e1d3bbbe15..893ec597d42bd43ee9c1b1c82399483a33e8fa1a 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -2966,6 +2966,18 @@ void LCodeGen::DoPower(LPower* instr) {
 
 
 void LCodeGen::DoRandom(LRandom* instr) {
+  class DeferredDoRandom: public LDeferredCode {
+   public:
+    DeferredDoRandom(LCodeGen* codegen, LRandom* instr)
+        : LDeferredCode(codegen), instr_(instr) { }
+    virtual void Generate() { codegen()->DoDeferredRandom(instr_); }
+    virtual LInstruction* instr() { return instr_; }
+   private:
+    LRandom* instr_;
+  };
+
+  DeferredDoRandom* deferred = new DeferredDoRandom(this, instr);
+
   // Having marked this instruction as a call we can use any
   // registers.
   ASSERT(ToDoubleRegister(instr->result()).is(xmm1));
@@ -2980,12 +2992,49 @@ void LCodeGen::DoRandom(LRandom* instr) {
   Register global_object = rdi;
 #endif
 
-  __ PrepareCallCFunction(1);
+  static const int kSeedSize = sizeof(uint32_t);
+  STATIC_ASSERT(kPointerSize == 2 * kSeedSize);
+
   __ movq(global_object,
           FieldOperand(global_object, GlobalObject::kGlobalContextOffset));
-  __ CallCFunction(ExternalReference::random_uint32_function(isolate()), 1);
-  __ movq(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
+  static const int kRandomSeedOffset =
+      FixedArray::kHeaderSize + Context::RANDOM_SEED_INDEX * kPointerSize;
+  __ movq(rbx, FieldOperand(global_object, kRandomSeedOffset));
+  // rbx: FixedArray of the global context's random seeds
+
+  // Load state[0].
+  __ movl(rax, FieldOperand(rbx, ByteArray::kHeaderSize));
+  // If state[0] == 0, call runtime to initialize seeds.
+  __ testl(rax, rax);
+  __ j(zero, deferred->entry());
+  // Load state[1].
+  __ movl(rcx, FieldOperand(rbx, ByteArray::kHeaderSize + kSeedSize));
+
+  // state[0] = 18273 * (state[0] & 0xFFFF) + (state[0] >> 16)
+  // Only operate on the lower 32 bit of rax.
+  __ movl(rdx, rax);
+  __ andl(rdx, Immediate(0xFFFF));
+  __ imull(rdx, rdx, Immediate(18273));
+  __ shrl(rax, Immediate(16));
+  __ addl(rax, rdx);
+  // Save state[0].
+  __ movl(FieldOperand(rbx, ByteArray::kHeaderSize), rax);
+
+  // state[1] = 36969 * (state[1] & 0xFFFF) + (state[1] >> 16)
+  __ movl(rdx, rcx);
+  __ andl(rdx, Immediate(0xFFFF));
+  __ imull(rdx, rdx, Immediate(36969));
+  __ shrl(rcx, Immediate(16));
+  __ addl(rcx, rdx);
+  // Save state[1].
+  __ movl(FieldOperand(rbx, ByteArray::kHeaderSize + kSeedSize), rcx);
+
+  // Random bit pattern = (state[0] << 14) + (state[1] & 0x3FFFF)
+  __ shll(rax, Immediate(14));
+  __ andl(rcx, Immediate(0x3FFFF));
+  __ addl(rax, rcx);
 
+  __ bind(deferred->exit());
   // Convert 32 random bits in rax to 0.(32 random bits) in a double
   // by computing:
   // ( 1.(20 0s)(32 random bits) x 2^20 ) - (1.0 x 2^20)).
@@ -2998,6 +3047,14 @@ void LCodeGen::DoRandom(LRandom* instr) {
 }
 
 
+void LCodeGen::DoDeferredRandom(LRandom* instr) {
+  __ PrepareCallCFunction(1);
+  __ CallCFunction(ExternalReference::random_uint32_function(isolate()), 1);
+  __ movq(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
+  // Return value is in rax.
+}
+
+
 void LCodeGen::DoMathLog(LUnaryMathOperation* instr) {
   ASSERT(ToDoubleRegister(instr->result()).is(xmm1));
   TranscendentalCacheStub stub(TranscendentalCache::LOG,