PPC/s390: [wasm-simd] [liftoff] Implement rounding average on x64 and ia32

Port bd04ee08

R=fanchen.kong@intel.com, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: I3b8e2625816a8517a0557882d6acdb6d6f28766b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2147029Reviewed-by: Junliang Yan <jyan@ca.ibm.com>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#67100}

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

@@ -822,6 +822,18 @@ void LiftoffAssembler::emit_i8x16_max_u(LiftoffRegister dst,
   bailout(kUnsupportedArchitecture, "emit_i8x16_max_u");
 }
 
+void LiftoffAssembler::emit_i8x16_rounding_average_u(LiftoffRegister dst,
+                                                     LiftoffRegister lhs,
+                                                     LiftoffRegister rhs) {
+  bailout(kUnsupportedArchitecture, "emit_i8x16_rounding_average_u");
+}
+
+void LiftoffAssembler::emit_i16x8_rounding_average_u(LiftoffRegister dst,
+                                                     LiftoffRegister lhs,
+                                                     LiftoffRegister rhs) {
+  bailout(kUnsupportedArchitecture, "emit_i16x8_rounding_average_u");
+}
+
 void LiftoffAssembler::emit_i8x16_sub(LiftoffRegister dst, LiftoffRegister lhs,
                                       LiftoffRegister rhs) {
   bailout(kUnsupportedArchitecture, "emit_i8x16sub");

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

@@ -842,6 +842,18 @@ void LiftoffAssembler::emit_i8x16_max_u(LiftoffRegister dst,
   bailout(kUnsupportedArchitecture, "emit_i8x16_max_u");
 }
 
+void LiftoffAssembler::emit_i8x16_rounding_average_u(LiftoffRegister dst,
+                                                     LiftoffRegister lhs,
+                                                     LiftoffRegister rhs) {
+  bailout(kUnsupportedArchitecture, "emit_i8x16_rounding_average_u");
+}
+
+void LiftoffAssembler::emit_i16x8_rounding_average_u(LiftoffRegister dst,
+                                                     LiftoffRegister lhs,
+                                                     LiftoffRegister rhs) {
+  bailout(kUnsupportedArchitecture, "emit_i16x8_rounding_average_u");
+}
+
 void LiftoffAssembler::StackCheck(Label* ool_code, Register limit_address) {
   bailout(kUnsupportedArchitecture, "StackCheck");
 }