[Liftoff] Implement {MoveToReturnRegister} platform independent

Now that wasm-linkage.h is split off, we can easily implement
{MoveToReturnRegister} in platform independent code.

R=titzer@chromium.org

Bug: v8:6600
Change-Id: I072a0ee48d58ed29e0df489016f838915c3f2cb2
Reviewed-on: https://chromium-review.googlesource.com/1041690
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52939}

src/wasm/baseline/arm/liftoff-assembler-arm.h

@@ -79,11 +79,6 @@ void LiftoffAssembler::MoveStackValue(uint32_t dst_index, uint32_t src_index,
   BAILOUT("MoveStackValue");
 }
 
-void LiftoffAssembler::MoveToReturnRegister(LiftoffRegister reg,
-                                            ValueType type) {
-  BAILOUT("MoveToReturnRegister");
-}
-
 void LiftoffAssembler::Move(Register dst, Register src, ValueType type) {
   BAILOUT("Move Register");
 }

src/wasm/baseline/arm64/liftoff-assembler-arm64.h

@@ -306,15 +306,6 @@ void LiftoffAssembler::MoveStackValue(uint32_t dst_index, uint32_t src_index,
   Str(scratch, liftoff::GetStackSlot(dst_index));
 }
 
-void LiftoffAssembler::MoveToReturnRegister(LiftoffRegister reg,
-                                            ValueType type) {
-  if (reg.is_gp()) {
-    Move(x0, reg.gp(), type);
-  } else {
-    Move(d0, reg.fp(), type);
-  }
-}
-
 void LiftoffAssembler::Move(Register dst, Register src, ValueType type) {
   if (type == kWasmI32) {
     Mov(dst.W(), src.W());

src/wasm/baseline/ia32/liftoff-assembler-ia32.h

@@ -357,16 +357,6 @@ void LiftoffAssembler::MoveStackValue(uint32_t dst_index, uint32_t src_index,
   }
 }
 
-void LiftoffAssembler::MoveToReturnRegister(LiftoffRegister reg,
-                                            ValueType type) {
-  // TODO(wasm): Extract the destination register from the CallDescriptor.
-  // TODO(wasm): Add multi-return support.
-  LiftoffRegister dst = reg.is_pair() ? LiftoffRegister::ForPair(eax, edx)
-                                      : reg.is_gp() ? LiftoffRegister(eax)
-                                                    : LiftoffRegister(xmm1);
-  if (reg != dst) Move(dst, reg, type);
-}
-
 void LiftoffAssembler::Move(Register dst, Register src, ValueType type) {
   DCHECK_NE(dst, src);
   DCHECK_EQ(kWasmI32, type);

src/wasm/baseline/liftoff-assembler.h

@@ -372,7 +372,6 @@ class LiftoffAssembler : public TurboAssembler {
                                   ValueType);
   inline void MoveStackValue(uint32_t dst_index, uint32_t src_index, ValueType);
 
-  inline void MoveToReturnRegister(LiftoffRegister src, ValueType);
   inline void Move(Register dst, Register src, ValueType);
   inline void Move(DoubleRegister dst, DoubleRegister src, ValueType);
 

src/wasm/baseline/liftoff-compiler.cc

@@ -1074,7 +1074,14 @@ class LiftoffCompiler {
     if (!values.is_empty()) {
       if (values.size() > 1) return unsupported(decoder, "multi-return");
       LiftoffRegister reg = __ PopToRegister();
-      __ MoveToReturnRegister(reg, values[0].type);
+      LiftoffRegister return_reg =
+          kNeedI64RegPair && values[0].type == kWasmI64
+              ? LiftoffRegister::ForPair(kGpReturnRegisters[0],
+                                         kGpReturnRegisters[1])
+              : reg_class_for(values[0].type) == kGpReg
+                    ? LiftoffRegister(kGpReturnRegisters[0])
+                    : LiftoffRegister(kFpReturnRegisters[0]);
+      if (reg != return_reg) __ Move(return_reg, reg, values[0].type);
     }
     __ LeaveFrame(StackFrame::WASM_COMPILED);
     __ DropStackSlotsAndRet(

src/wasm/baseline/mips/liftoff-assembler-mips.h

@@ -458,16 +458,6 @@ void LiftoffAssembler::MoveStackValue(uint32_t dst_index, uint32_t src_index,
   Spill(dst_index, reg, type);
 }
 
-void LiftoffAssembler::MoveToReturnRegister(LiftoffRegister reg,
-                                            ValueType type) {
-  // TODO(wasm): Extract the destination register from the CallDescriptor.
-  // TODO(wasm): Add multi-return support.
-  LiftoffRegister dst =
-      reg.is_pair() ? LiftoffRegister::ForPair(v0, v1)
-                    : reg.is_gp() ? LiftoffRegister(v0) : LiftoffRegister(f2);
-  if (reg != dst) Move(dst, reg, type);
-}
-
 void LiftoffAssembler::Move(Register dst, Register src, ValueType type) {
   DCHECK_NE(dst, src);
   TurboAssembler::mov(dst, src);

src/wasm/baseline/mips64/liftoff-assembler-mips64.h

@@ -391,12 +391,6 @@ void LiftoffAssembler::MoveStackValue(uint32_t dst_index, uint32_t src_index,
   Spill(dst_index, reg, type);
 }
 
-void LiftoffAssembler::MoveToReturnRegister(LiftoffRegister reg,
-                                            ValueType type) {
-  LiftoffRegister dst = reg.is_gp() ? LiftoffRegister(v0) : LiftoffRegister(f2);
-  if (reg != dst) Move(dst, reg, type);
-}
-
 void LiftoffAssembler::Move(Register dst, Register src, ValueType type) {
   DCHECK_NE(dst, src);
   // TODO(ksreten): Handle different sizes here.

src/wasm/baseline/ppc/liftoff-assembler-ppc.h

@@ -79,11 +79,6 @@ void LiftoffAssembler::MoveStackValue(uint32_t dst_index, uint32_t src_index,
   BAILOUT("MoveStackValue");
 }
 
-void LiftoffAssembler::MoveToReturnRegister(LiftoffRegister reg,
-                                            ValueType type) {
-  BAILOUT("MoveToReturnRegister");
-}
-
 void LiftoffAssembler::Move(Register dst, Register src, ValueType type) {
   BAILOUT("Move Register");
 }

src/wasm/baseline/s390/liftoff-assembler-s390.h

@@ -79,11 +79,6 @@ void LiftoffAssembler::MoveStackValue(uint32_t dst_index, uint32_t src_index,
   BAILOUT("MoveStackValue");
 }
 
-void LiftoffAssembler::MoveToReturnRegister(LiftoffRegister reg,
-                                            ValueType type) {
-  BAILOUT("MoveToReturnRegister");
-}
-
 void LiftoffAssembler::Move(Register dst, Register src, ValueType type) {
   BAILOUT("Move Register");
 }

src/wasm/baseline/x64/liftoff-assembler-x64.h

@@ -302,15 +302,6 @@ void LiftoffAssembler::MoveStackValue(uint32_t dst_index, uint32_t src_index,
   }
 }
 
-void LiftoffAssembler::MoveToReturnRegister(LiftoffRegister reg,
-                                            ValueType type) {
-  // TODO(wasm): Extract the destination register from the CallDescriptor.
-  // TODO(wasm): Add multi-return support.
-  LiftoffRegister dst =
-      reg.is_gp() ? LiftoffRegister(rax) : LiftoffRegister(xmm1);
-  if (reg != dst) Move(dst, reg, type);
-}
-
 void LiftoffAssembler::Move(Register dst, Register src, ValueType type) {
   DCHECK_NE(dst, src);
   if (type == kWasmI32) {