PPC/S390 [simd]: optimize S128Const on codegen

Change-Id: I6e72c56bb71d0d227b5556139dc687a78da6fb31
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2892257Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#74541}

src/compiler/backend/ppc/code-generator-ppc.cc

@@ -2795,15 +2795,11 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       break;
     }
     case kPPC_S128Const: {
-      Simd128Register dst = i.OutputSimd128Register();
-      constexpr int lane_width_in_bytes = 8;
       uint64_t low = make_uint64(i.InputUint32(1), i.InputUint32(0));
       uint64_t high = make_uint64(i.InputUint32(3), i.InputUint32(2));
       __ mov(r0, Operand(low));
       __ mov(ip, Operand(high));
-      __ mtvsrd(dst, ip);
-      __ mtvsrd(kScratchSimd128Reg, r0);
-      __ vinsertd(dst, kScratchSimd128Reg, Operand(1 * lane_width_in_bytes));
+      __ mtvsrdd(i.OutputSimd128Register(), ip, r0);
       break;
     }
     case kPPC_S128Zero: {

src/compiler/backend/s390/code-generator-s390.cc

@@ -3280,11 +3280,11 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
       break;
     }
     case kS390_S128Const: {
-      for (int index = 0, j = 0; index < 2; index++, j = +2) {
-        __ mov(index < 1 ? ip : r0, Operand(i.InputInt32(j)));
-        __ iihf(index < 1 ? ip : r0, Operand(i.InputInt32(j + 1)));
-      }
-      __ vlvgp(i.OutputSimd128Register(), r0, ip);
+      uint64_t low = make_uint64(i.InputUint32(1), i.InputUint32(0));
+      uint64_t high = make_uint64(i.InputUint32(3), i.InputUint32(2));
+      __ mov(r0, Operand(low));
+      __ mov(ip, Operand(high));
+      __ vlvgp(i.OutputSimd128Register(), ip, r0);
       break;
     }
     case kS390_S128Zero: {