[Liftoff] Unify name of frame size constant

Some architectures used {kConstantStackSpace}, others used
{kInstanceOffset}. This CL unifies it to {kInstanceOffset} and uses that
constant consistently (in {GetInstanceOperand}).

R=zhin@chromium.org

Bug: v8:10019
Change-Id: Ia2b6908e289591e2dbc48e559e11407877b7c4ad
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2000146Reviewed-by: Zhi An Ng <zhin@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65780}

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

@@ -51,9 +51,7 @@ inline MemOperand GetHalfStackSlot(int offset, RegPairHalf half) {
   return MemOperand(fp, -offset + half_offset);
 }
 
-inline MemOperand GetInstanceOperand() {
-  return MemOperand(fp, -kInstanceOffset);
-}
+inline MemOperand GetInstanceOperand() { return GetStackSlot(kInstanceOffset); }
 
 inline MemOperand GetMemOp(LiftoffAssembler* assm,
                            UseScratchRegisterScope* temps, Register addr,

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

@@ -43,9 +43,7 @@ constexpr int kInstanceOffset = 2 * kSystemPointerSize;
 
 inline MemOperand GetStackSlot(int offset) { return MemOperand(fp, -offset); }
 
-inline MemOperand GetInstanceOperand() {
-  return MemOperand(fp, -kInstanceOffset);
-}
+inline MemOperand GetInstanceOperand() { return GetStackSlot(kInstanceOffset); }
 
 inline CPURegister GetRegFromType(const LiftoffRegister& reg, ValueType type) {
   switch (type) {

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

@@ -20,9 +20,8 @@ namespace wasm {
 
 namespace liftoff {
 
-// ebp-4 holds the stack marker, ebp-8 is the instance parameter, first stack
-// slot is located at ebp-8-offset.
-constexpr int kConstantStackSpace = 8;
+// ebp-4 holds the stack marker, ebp-8 is the instance parameter.
+constexpr int kInstanceOffset = 8;
 
 inline Operand GetStackSlot(int offset) { return Operand(ebp, -offset); }
 
@@ -33,7 +32,7 @@ inline MemOperand GetHalfStackSlot(int offset, RegPairHalf half) {
 }
 
 // TODO(clemensb): Make this a constexpr variable once Operand is constexpr.
-inline Operand GetInstanceOperand() { return Operand(ebp, -8); }
+inline Operand GetInstanceOperand() { return GetStackSlot(kInstanceOffset); }
 
 static constexpr LiftoffRegList kByteRegs =
     LiftoffRegList::FromBits<Register::ListOf(eax, ecx, edx)>();
@@ -192,7 +191,7 @@ void LiftoffAssembler::AbortCompilation() {}
 
 // static
 constexpr int LiftoffAssembler::StaticStackFrameSize() {
-  return liftoff::kConstantStackSpace;
+  return liftoff::kInstanceOffset;
 }
 
 int LiftoffAssembler::SlotSizeForType(ValueType type) {

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

@@ -43,9 +43,8 @@ constexpr int32_t kLowWordOffset = 0;
 constexpr int32_t kHighWordOffset = 4;
 #endif
 
-// fp-4 holds the stack marker, fp-8 is the instance parameter, first stack
-// slot is located at fp-8-offset.
-constexpr int kConstantStackSpace = 8;
+// fp-4 holds the stack marker, fp-8 is the instance parameter.
+constexpr int kInstanceOffset = 8;
 
 inline MemOperand GetStackSlot(int offset) { return MemOperand(fp, -offset); }
 
@@ -55,7 +54,7 @@ inline MemOperand GetHalfStackSlot(int offset, RegPairHalf half) {
   return MemOperand(fp, -offset + half_offset);
 }
 
-inline MemOperand GetInstanceOperand() { return MemOperand(fp, -8); }
+inline MemOperand GetInstanceOperand() { return GetStackSlot(kInstanceOffset); }
 
 inline void Load(LiftoffAssembler* assm, LiftoffRegister dst, Register base,
                  int32_t offset, ValueType type) {

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

@@ -39,13 +39,12 @@ namespace liftoff {
 //  -----+--------------------+  <-- stack ptr (sp)
 //
 
-// fp-8 holds the stack marker, fp-16 is the instance parameter, first stack
-// slot is located at fp-16-offset.
-constexpr int kConstantStackSpace = 16;
+// fp-8 holds the stack marker, fp-16 is the instance parameter.
+constexpr int kInstanceOffset = 16;
 
 inline MemOperand GetStackSlot(int offset) { return MemOperand(fp, -offset); }
 
-inline MemOperand GetInstanceOperand() { return MemOperand(fp, -16); }
+inline MemOperand GetInstanceOperand() { return GetStackSlot(kInstanceOffset); }
 
 inline void Load(LiftoffAssembler* assm, LiftoffRegister dst, MemOperand src,
                  ValueType type) {
@@ -253,7 +252,7 @@ void LiftoffAssembler::AbortCompilation() {}
 
 // static
 constexpr int LiftoffAssembler::StaticStackFrameSize() {
-  return liftoff::kConstantStackSpace;
+  return liftoff::kInstanceOffset;
 }
 
 int LiftoffAssembler::SlotSizeForType(ValueType type) {

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

@@ -33,14 +33,13 @@ static_assert((kLiftoffAssemblerFpCacheRegs &
                   0,
               "scratch registers must not be used as cache registers");
 
-// rbp-8 holds the stack marker, rbp-16 is the instance parameter, first stack
-// slot is located at rbp-16-offset.
-constexpr int kConstantStackSpace = 16;
+// rbp-8 holds the stack marker, rbp-16 is the instance parameter.
+constexpr int kInstanceOffset = 16;
 
 inline Operand GetStackSlot(int offset) { return Operand(rbp, -offset); }
 
 // TODO(clemensb): Make this a constexpr variable once Operand is constexpr.
-inline Operand GetInstanceOperand() { return Operand(rbp, -16); }
+inline Operand GetInstanceOperand() { return GetStackSlot(kInstanceOffset); }
 
 inline Operand GetMemOp(LiftoffAssembler* assm, Register addr, Register offset,
                         uint32_t offset_imm) {
@@ -175,7 +174,7 @@ void LiftoffAssembler::AbortCompilation() {}
 
 // static
 constexpr int LiftoffAssembler::StaticStackFrameSize() {
-  return liftoff::kConstantStackSpace;
+  return liftoff::kInstanceOffset;
 }
 
 int LiftoffAssembler::SlotSizeForType(ValueType type) {