Saves callee-saved fpu registers on MIPS.

runtime/vm/stub_code_mips.cc

 // Copyright (c) 2013, 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_MIPS)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 893 matching lines @@
 //   A1 : arguments descriptor array.
 //   A2 : arguments array.
 //   A3 : new context containing the current isolate pointer.
 void StubCode::GenerateInvokeDartCodeStub(Assembler* assembler) {
   // Save frame pointer coming in.
   __ TraceSimMsg("InvokeDartCodeStub");
   __ EnterStubFrame();
 
   // Save new context and C++ ABI callee-saved registers.
   const intptr_t kNewContextOffset =
-      -(1 + kAbiPreservedCpuRegCount) * kWordSize;
+      -(1 + kAbiPreservedCpuRegCount + kAbiPreservedFpuRegCount) * kWordSize;
+  const intptr_t kPreservedRegSpace =
+      (kAbiPreservedCpuRegCount + kAbiPreservedFpuRegCount + 3) * kWordSize;

[regis, 2013/08/30 01:53:39]

What are these 3 registers you save? 1 is the new context, but what are the
other 2? These must be top exit frame and old context. A comment would help.
Also a defined constant for 3 that you can reuse several times below would be
cleaner. This predated this cl...

[zra, 2013/09/03 15:09:11]

Done.

 
-  __ addiu(SP, SP, Immediate(-(3 + kAbiPreservedCpuRegCount) * kWordSize));
+  __ addiu(SP, SP, Immediate(-kPreservedRegSpace));
   for (int i = S0; i <= S7; i++) {
     Register r = static_cast<Register>(i);
     __ sw(r, Address(SP, (i - S0 + 3) * kWordSize));
   }
+
+  for (intptr_t i = F20; i <= F31; i++) {
+    FRegister r = static_cast<FRegister>(i);
+    __ swc1(r,
+        Address(SP, (kAbiPreservedCpuRegCount + 3 + i - F20) * kWordSize));
+  }
+
   __ sw(A3, Address(SP, 2 * kWordSize));
 
   // The new Context structure contains a pointer to the current Isolate
   // structure. Cache the Context pointer in the CTX register so that it is
   // available in generated code and calls to Isolate::Current() need not be
   // done. The assumption is that this register will never be clobbered by
   // compiled or runtime stub code.
 
   // Cache the new Context pointer into CTX while executing Dart code.
   __ lw(CTX, Address(A3, VMHandles::kOffsetOfRawPtrInHandle));
 
   // Load Isolate pointer from Context structure into temporary register R8.
   __ lw(T2, FieldAddress(CTX, Context::isolate_offset()));
 
   // Save the top exit frame info. Use T0 as a temporary register.
   // StackFrameIterator reads the top exit frame info saved in this frame.
   __ lw(T0, Address(T2, Isolate::top_exit_frame_info_offset()));
   __ sw(ZR, Address(T2, Isolate::top_exit_frame_info_offset()));
 
   // Save the old Context pointer. Use T1 as a temporary register.
   // Note that VisitObjectPointers will find this saved Context pointer during
   // GC marking, since it traverses any information between SP and
   // FP - kExitLinkSlotFromEntryFp.
   // EntryFrame::SavedContext reads the context saved in this frame.
   __ lw(T1, Address(T2, Isolate::top_context_offset()));
 
   // The constants kSavedContextSlotFromEntryFp and
   // kExitLinkSlotFromEntryFp must be kept in sync with the code below.
-  ASSERT(kExitLinkSlotFromEntryFp == -10);
-  ASSERT(kSavedContextSlotFromEntryFp == -11);
+  ASSERT(kExitLinkSlotFromEntryFp == -22);
+  ASSERT(kSavedContextSlotFromEntryFp == -23);
   __ sw(T0, Address(SP, 1 * kWordSize));
   __ sw(T1, Address(SP, 0 * kWordSize));
 
   // After the call, The stack pointer is restored to this location.
-  // Pushed A3, S0-7, T0, T1 = 11.
+  // Pushed A3, S0-7, F20-31, T0, T1 = 23.
 
   // Load arguments descriptor array into S4, which is passed to Dart code.
   __ lw(S4, Address(A1, VMHandles::kOffsetOfRawPtrInHandle));
 
   // Load number of arguments into S5.
   __ lw(T1, FieldAddress(S4, ArgumentsDescriptor::count_offset()));
   __ SmiUntag(T1);
 
   // Compute address of 'arguments array' data area into A2.
   __ lw(A2, Address(A2, VMHandles::kOffsetOfRawPtrInHandle));
@@ skipping 35 matching lines @@
   __ lw(T1, Address(SP, 0 * kWordSize));
   __ lw(T0, Address(SP, 1 * kWordSize));
   __ sw(T1, Address(CTX, Isolate::top_context_offset()));
   __ sw(T0, Address(CTX, Isolate::top_exit_frame_info_offset()));
 
   // Restore C++ ABI callee-saved registers.
   for (int i = S0; i <= S7; i++) {
     Register r = static_cast<Register>(i);
     __ lw(r, Address(SP, (i - S0 + 3) * kWordSize));
   }
+
+  for (intptr_t i = F20; i <= F31; i++) {
+    FRegister r = static_cast<FRegister>(i);
+    __ lwc1(r,
+        Address(SP, (kAbiPreservedCpuRegCount + 3 + i - F20) * kWordSize));

[regis, 2013/08/30 01:53:39]

3 -> named constant defined above.

[zra, 2013/09/03 15:09:11]

Done.

+  }
+
   __ lw(A3, Address(SP, 2 * kWordSize));
-  __ addiu(SP, SP, Immediate((3 + kAbiPreservedCpuRegCount) * kWordSize));
+  __ addiu(SP, SP, Immediate(kPreservedRegSpace));
 
   // Restore the frame pointer and return.
   __ LeaveStubFrameAndReturn();
 }
 
 
 // Called for inline allocation of contexts.
 // Input:
 //   T1: number of context variables.
 // Output:
@@ skipping 1440 matching lines @@
   __ lw(left, Address(SP, 1 * kWordSize));
   __ lw(temp2, Address(SP, 2 * kWordSize));
   __ lw(temp1, Address(SP, 3 * kWordSize));
   __ Ret();
   __ delay_slot()->addiu(SP, SP, Immediate(4 * kWordSize));
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_MIPS