Unbox phis that were proven to be of type Double.

runtime/vm/stub_code_x64.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/assembler_macros.h"
 #include "vm/compiler.h"
@@ skipping 452 matching lines @@
   __ popq(RAX);  // Get result into RAX.
 
   // Remove the stub frame as we are about to return.
   __ LeaveFrame();
   __ ret();
 }
 
 
 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);
 
 // This stub translates optimized frame into unoptimized frame. The optimized
 // frame can contain values in registers and on stack, the unoptimized
 // frame contains all values on stack.
 // Deoptimization occurs in following steps:
 // - Push all registers that can contain values.
 // - Call C routine to copy the stack and saved registers into temporary buffer.
 // - Adjust caller's frame to correct unoptimized frame size.
 // - Fill the unoptimized frame.
+// - Materialize objects that require allocation (e.g. Double instances).
+// GC can occur only after frame is fully rewritten.
 // Stack:
 //   +------------------+
 //   | 0 as PC marker   | <- TOS
 //   +------------------+
 //   | Saved FP         |
 //   +------------------+
 //   | return-address   |  (deoptimization point)
 //   +------------------+
 //   | optimized frame  |
 //   |  ...             |
 //
 void StubCode::GenerateDeoptimizeStub(Assembler* assembler) {
   __ EnterFrame(0);
   // Push registers in their enumeration order: lowest register number at
   // lowest address.
   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);
   __ movq(RDI, RCX);  // Set up argument 1 saved_registers_address.
 
   __ CallRuntime(kDeoptimizeCopyFrameRuntimeEntry);
   // Result (RAX) is stack-size (FP - SP) in bytes, incl. the return address.
   __ LeaveFrame();
   __ popq(RCX);   // Preserve return address.
   __ movq(RSP, RBP);
   __ subq(RSP, RAX);
   __ movq(Address(RSP, 0), RCX);
 
   __ EnterFrame(0);
   __ movq(RCX, RSP);  // Get last FP address.
   __ ReserveAlignedFrameSpace(0);
   __ movq(RDI, RCX);  // Set up argument 1 last_fp.
   __ CallRuntime(kDeoptimizeFillFrameRuntimeEntry);
   __ LeaveFrame();
+
+  // Frame is fully rewritten at this point and it is safe to perform a GC.
+  // Materialize any objects that were deferred by FillFrame because they
+  // require allocation.
+  __ EnterFrame(0);
+  __ CallRuntime(kDeoptimizeMaterializeDoublesRuntimeEntry);
+  __ LeaveFrame();
+
   __ ret();
 }
 
 
 // Called for inline allocation of arrays.
 // Input parameters:
 //   R10 : Array length as Smi.
 //   RBX : array element type (either NULL or an instantiated type).
 // NOTE: R10 cannot be clobbered here as the caller relies on it being saved.
 // The newly allocated object is returned in RAX.
@@ skipping 1315 matching lines @@
 void StubCode::GenerateJumpToErrorHandlerStub(Assembler* assembler) {
   __ movq(RAX, RCX);  // error object.
   __ movq(RBP, RDX);  // target frame_pointer.
   __ movq(RSP, RSI);  // target stack_pointer.
   __ jmp(RDI);  // Jump to the exception handler code.
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64