Unbox phis that were proven to be of type Double.

runtime/vm/stub_code_x64.cc

Index: runtime/vm/stub_code_x64.cc
diff --git a/runtime/vm/stub_code_x64.cc b/runtime/vm/stub_code_x64.cc
index 2b2029197aafec7bdf44adefb71c11030eab8da4..98779359078a83f48c0b9a77f7a1c65ca2428eb7 100644
--- a/runtime/vm/stub_code_x64.cc
+++ b/runtime/vm/stub_code_x64.cc
@@ -470,7 +470,7 @@ void StubCode::GenerateInstanceFunctionLookupStub(Assembler* assembler) {
 
 DECLARE_LEAF_RUNTIME_ENTRY(intptr_t, DeoptimizeCopyFrame,
                            intptr_t deopt_reason,
-                           intptr_t* saved_registers_address);
+                           uword saved_registers_address);
 
 DECLARE_LEAF_RUNTIME_ENTRY(void, DeoptimizeFillFrame, uword last_fp);
 
@@ -500,6 +500,14 @@ void StubCode::GenerateDeoptimizeStub(Assembler* assembler) {
   for (intptr_t i = kNumberOfCpuRegisters - 1; i >= 0; i--) {
     __ pushq(static_cast<Register>(i));
   }
+  __ subq(RSP, Immediate(kNumberOfXmmRegisters * kDoubleSize));
+  intptr_t offset = 0;
+  for (intptr_t reg_idx = 0; reg_idx < kNumberOfXmmRegisters; ++reg_idx) {
+    XmmRegister xmm_reg = static_cast<XmmRegister>(reg_idx);
+    __ movsd(Address(RSP, offset), xmm_reg);
+    offset += kDoubleSize;
+  }
+
   __ movq(RCX, RSP);  // Saved saved registers block.
   __ ReserveAlignedFrameSpace(0);
   __ SmiUntag(RAX);
@@ -519,6 +527,11 @@ void StubCode::GenerateDeoptimizeStub(Assembler* assembler) {
   __ movq(RDI, RCX);  // Set up argument 1 last_fp.
   __ CallRuntime(kDeoptimizeFillFrameRuntimeEntry);
   __ LeaveFrame();
+
+  __ EnterFrame(0);
+  __ CallRuntime(kDeoptimizeMaterializeDoublesRuntimeEntry);
+  __ LeaveFrame();
+
   __ ret();
 }