PPC: [builtins] Add 'RestartFrameTrampoline'

Port b0118171

Original Commit Message:

    This CL adds a new builtin called "RestartFrameTrampoline". This
    trampoline is relatively simple: It leaves the current frame and
    re-invokes the function. This essentially restarts the function and
    is one of the key components required to bring back the "Restart
    frame" DevTools debugging feature.

    The builtin is closely related to the "FrameDropperTrampoline"
    removed in the CL https://crrev.com/c/2854750. The key difference
    is that the "FrameDropperTrampoline" dropped to an "arbitrary"
    frame pointer before restarting the function (arbitrary in the
    sense that it was provided as an argument). This caused issues
    as the feature was implemented in a way that the frame pointer
    wasn't necessarily valid anymore.

    In comparison, the "RestartFrameTrampoline" relies on the V8
    unwinder to drop it in the correct frame first and is then
    invoked via either the CEntry stub or the deoptimizer
    (see design doc for details).

R=szuend@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: Id742eeaa59a540ec206a92308fb72bb50413e267
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3613391Reviewed-by: Simon Zünd <szuend@chromium.org>
Commit-Queue: Milad Farazmand <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#80264}

src/builtins/ppc/builtins-ppc.cc

@@ -3887,8 +3887,8 @@ void Builtins::Generate_RestartFrameTrampoline(MacroAssembler* masm) {
   // - Leave the frame.
   // - Restart the frame by calling the function.
 
-  __ LoadP(r4, MemOperand(fp, StandardFrameConstants::kFunctionOffset));
-  __ LoadP(r3, MemOperand(fp, StandardFrameConstants::kArgCOffset));
+  __ LoadU64(r4, MemOperand(fp, StandardFrameConstants::kFunctionOffset));
+  __ LoadU64(r3, MemOperand(fp, StandardFrameConstants::kArgCOffset));
   __ LeaveFrame(StackFrame::INTERPRETED);
 
   // The arguments are already in the stack (including any necessary padding),