PPC/s390: [liftoff][mv] Remove multi-value overhead

Port 2332ebd8

Original Commit Message:

    - Add a separate function to load return slots, instead of encoding this
    in the offset,
    - Add fast path for single return.

R=thibaudm@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=
LOG=N

Change-Id: Ia302772478b58fd25ee53a18e6ee03ac4b2ea9f5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2267477Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Milad Farazmand <miladfar@ca.ibm.com>
Cr-Commit-Position: refs/heads/master@{#68546}

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

@@ -198,6 +198,11 @@ void LiftoffAssembler::StoreCallerFrameSlot(LiftoffRegister src,
   bailout(kUnsupportedArchitecture, "StoreCallerFrameSlot");
 }
 
+void LiftoffAssembler::LoadReturnStackSlot(LiftoffRegister dst, int offset,
+                                           ValueType type) {
+  bailout(kUnsupportedArchitecture, "LoadReturnStackSlot");
+}
+
 void LiftoffAssembler::MoveStackValue(uint32_t dst_offset, uint32_t src_offset,
                                       ValueType type) {
   bailout(kUnsupportedArchitecture, "MoveStackValue");

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

@@ -197,6 +197,11 @@ void LiftoffAssembler::StoreCallerFrameSlot(LiftoffRegister src,
   bailout(kUnsupportedArchitecture, "StoreCallerFrameSlot");
 }
 
+void LiftoffAssembler::LoadReturnStackSlot(LiftoffRegister dst, int offset,
+                                           ValueType type) {
+  bailout(kUnsupportedArchitecture, "LoadReturnStackSlot");
+}
+
 void LiftoffAssembler::MoveStackValue(uint32_t dst_offset, uint32_t src_offset,
                                       ValueType type) {
   bailout(kUnsupportedArchitecture, "MoveStackValue");