PPC: Disable CP on builtins

Also updated LoadConstantPoolPointerRegisterFromCodeTargetAddress
to add instruction size to the new constant_pool_offset.

Bug: v8:11036
Change-Id: Ib92a1b0606c60f82628d3e63ade54b312e4cf196
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2508691
Commit-Queue: Junliang Yan <junyan@redhat.com>
Reviewed-by: Milad Fa <mfarazma@redhat.com>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70929}

src/codegen/assembler.h

@@ -240,7 +240,9 @@ class V8_EXPORT_PRIVATE AssemblerBase : public Malloced {
 
   bool is_constant_pool_available() const {
     if (FLAG_enable_embedded_constant_pool) {
-      return constant_pool_available_;
+      // We need to disable constant pool here for embeded builtins
+      // because the metadata section is not adjacent to instructions
+      return constant_pool_available_ && !options().isolate_independent_code;
     } else {
       // Embedded constant pool not supported on this architecture.
       UNREACHABLE();

src/codegen/ppc/macro-assembler-ppc.cc

@@ -1053,10 +1053,16 @@ void TurboAssembler::ShiftRightAlgPair(Register dst_low, Register dst_high,
 
 void TurboAssembler::LoadConstantPoolPointerRegisterFromCodeTargetAddress(
     Register code_target_address) {
+  // Builtins do not use the constant pool (see is_constant_pool_available).
+  STATIC_ASSERT(Code::kOnHeapBodyIsContiguous);
+
+  lwz(r0, MemOperand(code_target_address,
+                     Code::kInstructionSizeOffset - Code::kHeaderSize));
   lwz(kConstantPoolRegister,
       MemOperand(code_target_address,
                  Code::kConstantPoolOffsetOffset - Code::kHeaderSize));
   add(kConstantPoolRegister, kConstantPoolRegister, code_target_address);
+  add(kConstantPoolRegister, kConstantPoolRegister, r0);
 }
 
 void TurboAssembler::LoadPC(Register dst) {
@@ -1072,6 +1078,10 @@ void TurboAssembler::ComputeCodeStartAddress(Register dst) {
 }
 
 void TurboAssembler::LoadConstantPoolPointerRegister() {
+  //
+  // Builtins do not use the constant pool (see is_constant_pool_available).
+  STATIC_ASSERT(Code::kOnHeapBodyIsContiguous);
+
   LoadPC(kConstantPoolRegister);
   int32_t delta = -pc_offset() + 4;
   add_label_offset(kConstantPoolRegister, kConstantPoolRegister,