[sparkplug] Add scratch register for arm64

We didn't have enough scratch registers for a suspend generator
whose field write offsets exceeded the immediate value range.

Bug: v8:11420, chromium:1193493
Change-Id: Iee90db4ef1ec00924bcc4791a8e6ffb9138bb388
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2794424
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73739}

src/baseline/arm64/baseline-assembler-arm64-inl.h

@@ -23,6 +23,7 @@ class BaselineAssembler::ScratchRegisterScope {
       // If we haven't opened a scratch scope yet, for the first one add a
       // couple of extra registers.
       wrapped_scope_.Include(x14, x15);
+      wrapped_scope_.Include(x19);
     }
     assembler_->scratch_register_scope_ = this;
   }

test/mjsunit/baseline/test-baseline.js

@@ -268,6 +268,19 @@ for (let val of gen) {
 }
 assertEquals(4, i);
 
+// Generator with a lot of locals
+let gen_func_with_a_lot_of_locals = eval(`(function*() {
+  ${ Array(32*1024).fill().map((x,i)=>`let local_${i};`).join("\n") }
+  yield 1;
+  yield 2;
+  yield 3;
+})`);
+i = 1;
+for (let val of run(gen_func_with_a_lot_of_locals)) {
+  assertEquals(i++, val);
+}
+assertEquals(4, i);
+
 // Async await
 run(async function() {
   await 1;