[wasm] Use a name for the lazy compile func index

Pure refactoring CL. Introduce a symbolic name for the register
used to hold the function index when calling the lazy compile stub.
This makes it easier to see this contract when looking at the
macro assembler.

R=ahaas@chromium.org
CC=clemensh@chromium.org

Change-Id: I714f978883ced001a1435338dcefd96744bfb2ae
Reviewed-on: https://chromium-review.googlesource.com/c/1273099
Commit-Queue: Ben Titzer <titzer@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56516}

src/arm/macro-assembler-arm.h

@@ -38,6 +38,7 @@ constexpr Register kRuntimeCallFunctionRegister = r1;
 constexpr Register kRuntimeCallArgCountRegister = r0;
 constexpr Register kRuntimeCallArgvRegister = r2;
 constexpr Register kWasmInstanceRegister = r3;
+constexpr Register kWasmLazyCompileFuncIndexRegister = r4;
 
 // ----------------------------------------------------------------------------
 // Static helper functions

src/arm64/macro-assembler-arm64.h

@@ -65,6 +65,7 @@ constexpr Register kRuntimeCallFunctionRegister = x1;
 constexpr Register kRuntimeCallArgCountRegister = x0;
 constexpr Register kRuntimeCallArgvRegister = x11;
 constexpr Register kWasmInstanceRegister = x7;
+constexpr Register kWasmCompileLazyFuncIndexRegister = x8;
 
 #define LS_MACRO_LIST(V)                                     \
   V(Ldrb, Register&, rt, LDRB_w)                             \

src/builtins/arm/builtins-arm.cc

@@ -2187,9 +2187,10 @@ void Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
 }
 
 void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
-  // The function index was put in r4 by the jump table trampoline.
+  // The function index was put in a register by the jump table trampoline.
   // Convert to Smi for the runtime call.
-  __ SmiTag(r4, r4);
+  __ SmiTag(kWasmLazyCompileFuncIndexRegister,
+            kWasmLazyCompileFuncIndexRegister);
   {
     HardAbortScope hard_abort(masm);  // Avoid calls to Abort.
     FrameAndConstantPoolScope scope(masm, StackFrame::WASM_COMPILE_LAZY);
@@ -2207,7 +2208,7 @@ void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
     // Pass instance and function index as explicit arguments to the runtime
     // function.
     __ push(kWasmInstanceRegister);
-    __ push(r4);
+    __ push(kWasmLazyCompileFuncIndexRegister);
     // Load the correct CEntry builtin from the instance object.
     __ ldr(r2, FieldMemOperand(kWasmInstanceRegister,
                                WasmInstanceObject::kCEntryStubOffset));

src/builtins/arm64/builtins-arm64.cc

@@ -2647,8 +2647,10 @@ void Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
 void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
   // The function index was put in w8 by the jump table trampoline.
   // Sign extend and convert to Smi for the runtime call.
-  __ sxtw(x8, w8);
-  __ SmiTag(x8, x8);
+  __ sxtw(kWasmCompileLazyFuncIndexRegister,
+          kWasmCompileLazyFuncIndexRegister.W());
+  __ SmiTag(kWasmCompileLazyFuncIndexRegister,
+            kWasmCompileLazyFuncIndexRegister);
   {
     HardAbortScope hard_abort(masm);  // Avoid calls to Abort.
     FrameScope scope(masm, StackFrame::WASM_COMPILE_LAZY);
@@ -2665,7 +2667,7 @@ void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
 
     // Pass instance and function index as explicit arguments to the runtime
     // function.
-    __ Push(kWasmInstanceRegister, x8);
+    __ Push(kWasmInstanceRegister, kWasmCompileLazyFuncIndexRegister);
     // Load the correct CEntry builtin from the instance object.
     __ Ldr(x2, FieldMemOperand(kWasmInstanceRegister,
                                WasmInstanceObject::kCEntryStubOffset));

src/builtins/ia32/builtins-ia32.cc

@@ -2482,7 +2482,7 @@ void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
 
   // The function index was put in edi by the jump table trampoline.
   // Convert to Smi for the runtime call.
-  __ SmiTag(edi);
+  __ SmiTag(kWasmCompileLazyFuncIndexRegister);
   {
     HardAbortScope hard_abort(masm);  // Avoid calls to Abort.
     FrameScope scope(masm, StackFrame::WASM_COMPILE_LAZY);
@@ -2510,7 +2510,7 @@ void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
     // Push the WASM instance as an explicit argument to WasmCompileLazy.
     __ Push(kWasmInstanceRegister);
     // Push the function index as second argument.
-    __ Push(edi);
+    __ Push(kWasmCompileLazyFuncIndexRegister);
     // Load the correct CEntry builtin from the instance object.
     __ mov(ecx, FieldOperand(kWasmInstanceRegister,
                              WasmInstanceObject::kCEntryStubOffset));

src/builtins/mips/builtins-mips.cc

@@ -2245,7 +2245,7 @@ void Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
 void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
   // The function index was put in t0 by the jump table trampoline.
   // Convert to Smi for the runtime call.
-  __ SmiTag(t0);
+  __ SmiTag(kWasmCompileLazyFuncIndexRegister);
   {
     HardAbortScope hard_abort(masm);  // Avoid calls to Abort.
     FrameScope scope(masm, StackFrame::WASM_COMPILE_LAZY);
@@ -2261,7 +2261,7 @@ void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
 
     // Pass instance and function index as an explicit arguments to the runtime
     // function.
-    __ Push(kWasmInstanceRegister, t0);
+    __ Push(kWasmInstanceRegister, kWasmCompileLazyFuncIndexRegister);
     // Load the correct CEntry builtin from the instance object.
     __ lw(a2, FieldMemOperand(kWasmInstanceRegister,
                               WasmInstanceObject::kCEntryStubOffset));

src/builtins/mips64/builtins-mips64.cc

@@ -2262,7 +2262,7 @@ void Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
 void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
   // The function index was put in t0 by the jump table trampoline.
   // Convert to Smi for the runtime call
-  __ SmiTag(t0);
+  __ SmiTag(kWasmCompileLazyFuncIndexRegister);
   {
     HardAbortScope hard_abort(masm);  // Avoid calls to Abort.
     FrameScope scope(masm, StackFrame::WASM_COMPILE_LAZY);
@@ -2279,7 +2279,7 @@ void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
 
     // Pass instance and function index as an explicit arguments to the runtime
     // function.
-    __ Push(kWasmInstanceRegister, t0);
+    __ Push(kWasmInstanceRegister, kWasmCompileLazyFuncIndexRegister);
     // Load the correct CEntry builtin from the instance object.
     __ Ld(a2, FieldMemOperand(kWasmInstanceRegister,
                               WasmInstanceObject::kCEntryStubOffset));

src/builtins/ppc/builtins-ppc.cc

@@ -2269,9 +2269,10 @@ void Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
 }
 
 void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
-  // The function index was put in r15 by the jump table trampoline.
+  // The function index was put in a register by the jump table trampoline.
   // Convert to Smi for the runtime call.
-  __ SmiTag(r15, r15);
+  __ SmiTag(kWasmCompileLazyFuncIndexRegister,
+            kWasmCompileLazyFuncIndexRegister);
   {
     HardAbortScope hard_abort(masm);  // Avoid calls to Abort.
     FrameAndConstantPoolScope scope(masm, StackFrame::WASM_COMPILE_LAZY);
@@ -2288,7 +2289,7 @@ void Builtins::Generate_WasmCompileLazy(MacroAssembler* masm) {
 
     // Pass instance and function index as explicit arguments to the runtime
     // function.
-    __ Push(kWasmInstanceRegister, r15);
+    __ Push(kWasmInstanceRegister, kWasmCompileLazyFuncIndexRegister);
     // Load the correct CEntry builtin from the instance object.
     __ LoadP(r5, FieldMemOperand(kWasmInstanceRegister,
                                  WasmInstanceObject::kCEntryStubOffset));

src/ia32/macro-assembler-ia32.h

@@ -45,6 +45,7 @@ constexpr Register kRuntimeCallFunctionRegister = edx;
 constexpr Register kRuntimeCallArgCountRegister = eax;
 constexpr Register kRuntimeCallArgvRegister = ecx;
 constexpr Register kWasmInstanceRegister = esi;
+constexpr Register kWasmCompileLazyFuncIndexRegister = edi;
 
 // TODO(v8:6666): Implement full support.
 constexpr Register kRootRegister = ebx;

src/mips/macro-assembler-mips.h

@@ -37,6 +37,7 @@ constexpr Register kRuntimeCallFunctionRegister = a1;
 constexpr Register kRuntimeCallArgCountRegister = a0;
 constexpr Register kRuntimeCallArgvRegister = a2;
 constexpr Register kWasmInstanceRegister = a0;
+constexpr Register kWasmCompileLazyFuncIndexRegister = t0;
 
 // Forward declarations
 enum class AbortReason : uint8_t;

src/mips64/macro-assembler-mips64.h

@@ -37,6 +37,7 @@ constexpr Register kRuntimeCallFunctionRegister = a1;
 constexpr Register kRuntimeCallArgCountRegister = a0;
 constexpr Register kRuntimeCallArgvRegister = a2;
 constexpr Register kWasmInstanceRegister = a0;
+constexpr Register kWasmCompileLazyFuncIndexRegister = t0;
 
 // Forward declarations.
 enum class AbortReason : uint8_t;

src/ppc/macro-assembler-ppc.h

@@ -39,6 +39,7 @@ constexpr Register kRuntimeCallFunctionRegister = r4;
 constexpr Register kRuntimeCallArgCountRegister = r3;
 constexpr Register kRuntimeCallArgvRegister = r5;
 constexpr Register kWasmInstanceRegister = r10;
+constexpr Register kWasmCompileLazyFuncIndexRegister = r15;
 
 // ----------------------------------------------------------------------------
 // Static helper functions

src/wasm/jump-table-assembler.cc

@@ -53,7 +53,7 @@ void JumpTableAssembler::NopBytes(int bytes) {
 #elif V8_TARGET_ARCH_IA32
 void JumpTableAssembler::EmitLazyCompileJumpSlot(uint32_t func_index,
                                                  Address lazy_compile_target) {
-  mov(edi, func_index);                       // 5 bytes
+  mov(kWasmCompileLazyFuncIndexRegister, func_index);  // 5 bytes
   jmp(lazy_compile_target, RelocInfo::NONE);  // 5 bytes
 }
 
@@ -69,10 +69,10 @@ void JumpTableAssembler::NopBytes(int bytes) {
 #elif V8_TARGET_ARCH_ARM
 void JumpTableAssembler::EmitLazyCompileJumpSlot(uint32_t func_index,
                                                  Address lazy_compile_target) {
-  // Load function index to r4.
+  // Load function index to a register.
   // This generates [movw, movt] on ARMv7 and later, [ldr, constant pool marker,
   // constant] on ARMv6.
-  Move32BitImmediate(r4, Operand(func_index));
+  Move32BitImmediate(kWasmLazyCompileFuncIndexRegister, Operand(func_index));
   // EmitJumpSlot emits either [b], [movw, movt, mov] (ARMv7+), or [ldr,
   // constant].
   // In total, this is <=5 instructions on all architectures.
@@ -99,7 +99,7 @@ void JumpTableAssembler::NopBytes(int bytes) {
 #elif V8_TARGET_ARCH_ARM64
 void JumpTableAssembler::EmitLazyCompileJumpSlot(uint32_t func_index,
                                                  Address lazy_compile_target) {
-  Mov(w8, func_index);                         // max. 2 instr
+  Mov(kWasmCompileLazyFuncIndexRegister.W(), func_index);  // max. 2 instr
   Jump(lazy_compile_target, RelocInfo::NONE);  // 1 instr
 }
 
@@ -144,7 +144,7 @@ void JumpTableAssembler::NopBytes(int bytes) {
 #elif V8_TARGET_ARCH_MIPS || V8_TARGET_ARCH_MIPS64
 void JumpTableAssembler::EmitLazyCompileJumpSlot(uint32_t func_index,
                                                  Address lazy_compile_target) {
-  li(t0, func_index);  // max. 2 instr
+  li(kWasmCompileLazyFuncIndexRegister, func_index);  // max. 2 instr
   // Jump produces max. 4 instructions for 32-bit platform
   // and max. 6 instructions for 64-bit platform.
   Jump(lazy_compile_target, RelocInfo::NONE);
@@ -165,8 +165,8 @@ void JumpTableAssembler::NopBytes(int bytes) {
 #elif V8_TARGET_ARCH_PPC
 void JumpTableAssembler::EmitLazyCompileJumpSlot(uint32_t func_index,
                                                  Address lazy_compile_target) {
-  // Load function index to r8. max 5 instrs
-  mov(r15, Operand(func_index));
+  // Load function index to register. max 5 instrs
+  mov(kWasmCompileLazyFuncIndexRegister, Operand(func_index));
   // Jump to {lazy_compile_target}. max 5 instrs
   mov(r0, Operand(lazy_compile_target));
   mtctr(r0);