[liftoff] Remove unused kNoParamRegister

R=titzer@chromium.org

Bug: v8:6600
Change-Id: Ib926c068b468df6fcbaab9ef4734e9cd90ba553c
Reviewed-on: https://chromium-review.googlesource.com/c/1309814Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57167}

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

@@ -21,8 +21,6 @@ constexpr RegList kLiftoffAssemblerGpCacheRegs =
 constexpr RegList kLiftoffAssemblerFpCacheRegs =
     DoubleRegister::ListOf<xmm0, xmm1, xmm2, xmm3, xmm4, xmm5, xmm6>();
 
-constexpr Register kNoParamRegister = edi;
-
 #elif V8_TARGET_ARCH_X64
 
 constexpr RegList kLiftoffAssemblerGpCacheRegs =
@@ -31,8 +29,6 @@ constexpr RegList kLiftoffAssemblerGpCacheRegs =
 constexpr RegList kLiftoffAssemblerFpCacheRegs =
     DoubleRegister::ListOf<xmm0, xmm1, xmm2, xmm3, xmm4, xmm5, xmm6, xmm7>();
 
-constexpr Register kNoParamRegister = r8;
-
 #elif V8_TARGET_ARCH_MIPS
 
 constexpr RegList kLiftoffAssemblerGpCacheRegs =
@@ -42,8 +38,6 @@ constexpr RegList kLiftoffAssemblerFpCacheRegs =
     DoubleRegister::ListOf<f0, f2, f4, f6, f8, f10, f12, f14, f16, f18, f20,
                            f22, f24>();
 
-constexpr Register kNoParamRegister = t0;
-
 #elif V8_TARGET_ARCH_MIPS64
 
 constexpr RegList kLiftoffAssemblerGpCacheRegs =
@@ -53,8 +47,6 @@ constexpr RegList kLiftoffAssemblerFpCacheRegs =
     DoubleRegister::ListOf<f0, f2, f4, f6, f8, f10, f12, f14, f16, f18, f20,
                            f22, f24, f26>();
 
-constexpr Register kNoParamRegister = t0;
-
 #elif V8_TARGET_ARCH_ARM64
 
 // x16: ip0, x17: ip1, x26: root, x27: cp, x29: fp, x30: lr, x31: xzr.
@@ -69,18 +61,12 @@ constexpr RegList kLiftoffAssemblerFpCacheRegs =
                         d13, d14, d16, d17, d18, d19, d20, d21, d22, d23, d24,
                         d25, d26, d27, d28, d29>();
 
-constexpr Register kNoParamRegister = x28;
-
 #else
 
 constexpr RegList kLiftoffAssemblerGpCacheRegs = 0xff;
 
 constexpr RegList kLiftoffAssemblerFpCacheRegs = 0xff;
 
-// This should be an allocatable, general purpose register
-// that is not used for parameters, see {wasm-linkage.cc}.
-constexpr Register kNoParamRegister = Register::no_reg();
-
 #endif
 
 #if V8_TARGET_ARCH_IA32 || V8_TARGET_ARCH_X64