PPC: Assembler changes for enabling GrowHeap in Wasm

Port e1a7c1e7

Original commit message:
    - New RelocInfo mode WASM_MEMORY_REFERENCE as a marker for wasm code objects that need to be relocated on a heap change
    - RelocInfo mode recorded for immediates that use the memory buffer as base
    - Tests to verify address patching works

R=joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1845283004

Cr-Commit-Position: refs/heads/master@{#35204}

src/ppc/assembler-ppc-inl.h

@@ -89,6 +89,10 @@ Address RelocInfo::target_address() {
   return Assembler::target_address_at(pc_, host_);
 }
 
+Address RelocInfo::wasm_memory_reference() {
+  DCHECK(IsWasmMemoryReference(rmode_));
+  return Assembler::target_address_at(pc_, host_);
+}
 
 Address RelocInfo::target_address_address() {
   DCHECK(IsCodeTarget(rmode_) || IsRuntimeEntry(rmode_) ||
@@ -179,6 +183,18 @@ Address Assembler::return_address_from_call_start(Address pc) {
   return pc + (len + 2) * kInstrSize;
 }
 
+void RelocInfo::update_wasm_memory_reference(
+    Address old_base, Address new_base, size_t old_size, size_t new_size,
+    ICacheFlushMode icache_flush_mode) {
+  DCHECK(IsWasmMemoryReference(rmode_));
+  DCHECK(old_base <= wasm_memory_reference() &&
+         wasm_memory_reference() < old_base + old_size);
+  Address updated_reference = new_base + (wasm_memory_reference() - old_base);
+  DCHECK(new_base <= updated_reference &&
+         updated_reference < new_base + new_size);
+  Assembler::set_target_address_at(isolate_, pc_, host_, updated_reference,
+                                   icache_flush_mode);
+}
 
 Object* RelocInfo::target_object() {
   DCHECK(IsCodeTarget(rmode_) || rmode_ == EMBEDDED_OBJECT);