Use cross to compile mmtk-v8

.github/scripts/args-debug.gn

@@ -15,6 +15,12 @@ v8_enable_fast_mksnapshot = true
 v8_enable_verify_csa = true
 v8_enable_slow_dchecks = false
 v8_optimized_debug = false
+# If we enable external code space, this error shows up.
+# ERROR at //BUILD.gn:560:1: Assertion failed.
+# assert(!v8_enable_external_code_space || v8_enable_pointer_compression,
+# ^-----
+# External code space feature requires pointer compression
+v8_enable_external_code_space = false
 
 v8_enable_third_party_heap = true
 v8_third_party_heap_files = [
@@ -23,4 +29,4 @@ v8_third_party_heap_files = [
     "$the_root/v8/third_party/heap/mmtk/mmtkUpcalls.h",
     "$the_root/v8/third_party/heap/mmtk/mmtkUpcalls.cc"
 ]
-v8_third_party_heap_libs = [ "$the_root/mmtk/target/debug/libmmtk_v8.so" ]
+v8_third_party_heap_libs = [ "$the_root/mmtk/target/x86_64-unknown-linux-gnu/debug/libmmtk_v8.so" ]

.github/scripts/args-optdebug.gn

@@ -14,6 +14,12 @@ v8_enable_backtrace = true
 v8_enable_fast_mksnapshot = true
 v8_enable_verify_heap = true
 v8_optimized_debug = true
+# If we enable external code space, this error shows up.
+# ERROR at //BUILD.gn:560:1: Assertion failed.
+# assert(!v8_enable_external_code_space || v8_enable_pointer_compression,
+# ^-----
+# External code space feature requires pointer compression
+v8_enable_external_code_space = false
 
 v8_enable_third_party_heap = true
 v8_third_party_heap_files = [
@@ -22,4 +28,4 @@ v8_third_party_heap_files = [
     "$the_root/v8/third_party/heap/mmtk/mmtkUpcalls.h",
     "$the_root/v8/third_party/heap/mmtk/mmtkUpcalls.cc"
 ]
-v8_third_party_heap_libs = [ "$the_root/mmtk/target/debug/libmmtk_v8.so" ]
+v8_third_party_heap_libs = [ "$the_root/mmtk/target/x86_64-unknown-linux-gnu/debug/libmmtk_v8.so" ]

.github/scripts/build-mmtk.sh

@@ -2,6 +2,15 @@ set -xe
 
 . $(dirname "$0")/common.sh
 
+export PATH=~/.cargo/bin:$PATH
+# Check if we have cross available
+if ! [ -x "$(command -v cross)" ]; then
+  echo 'Cross is not available. Will install cross.' >&2
+  # lock to version 0.2.4. This version uses libc 2.31 for x86_64.
+  # This matches the version in the sysroot used by V8 (debian bullseye)
+  cargo install cross --tag v0.2.4 --git https://github.com/cross-rs/cross
+fi
+
 # simply build mmtk-v8 with nogc
 cd $THE_ROOT/mmtk
-rustup run $RUSTUP_TOOLCHAIN cargo build --features nogc
+cross build --target x86_64-unknown-linux-gnu --features nogc

.github/scripts/common.sh

@@ -5,8 +5,8 @@ export THE_ROOT=`realpath $(dirname "$0")/../..`
 export V8_ROOT=$THE_ROOT/deps
 
 # Test with a specific revision.
-export V8_VERSION=`cargo read-manifest --manifest-path=$THE_ROOT/mmtk/Cargo.toml | python -c 'import json,sys; print(json.load(sys.stdin)["metadata"]["v8"]["v8_version"])'`
+export V8_VERSION=`cargo read-manifest --manifest-path=$THE_ROOT/mmtk/Cargo.toml | python3 -c 'import json,sys; print(json.load(sys.stdin)["metadata"]["v8"]["v8_version"])'`
 # The commit after this requires python 3.7. This is the only reason we fix to this revision.
-export DEPOT_TOOLS_VERSION=`cargo read-manifest --manifest-path=$THE_ROOT/mmtk/Cargo.toml | python -c 'import json,sys; print(json.load(sys.stdin)["metadata"]["v8"]["depot_tools_version"])'`
+export DEPOT_TOOLS_VERSION=`cargo read-manifest --manifest-path=$THE_ROOT/mmtk/Cargo.toml | python3 -c 'import json,sys; print(json.load(sys.stdin)["metadata"]["v8"]["depot_tools_version"])'`
 
 export RUSTUP_TOOLCHAIN=`cat $THE_ROOT/mmtk/rust-toolchain`

mmtk/Cargo.toml

@@ -13,7 +13,7 @@ crate-type = ["cdylib"]
 lto = true
 
 [package.metadata.v8]
-v8_version = "191b637f28c0e2c6ca5f2d6ac89377039a754337"
+v8_version = "bc0e7c8722b81d92fe3c2e35da5457c25574e07e"
 depot_tools_version = "b674278ce71b2ee683b8b0c98c9a64152988ecdb"
 
 [dependencies]

mmtk/src/scanning.rs

@@ -4,8 +4,8 @@ use mmtk::vm::EdgeVisitor;
 use mmtk::vm::RootsWorkFactory;
 use mmtk::vm::Scanning;
 use mmtk::Mutator;
-use V8;
 use V8Edge;
+use V8;
 
 pub struct VMScanning {}
 

v8/third_party/heap/mmtk/mmtk.cc

@@ -119,7 +119,7 @@ AllocationResult Heap::Allocate(size_t size_in_bytes, AllocationType type, Alloc
   CheckMutator(this);
   TPHData* tph_data_ = get_tph_data(this);
   bool large_object = size_in_bytes > kMaxRegularHeapObjectSize;
-  size_t align_bytes = (type == AllocationType::kCode) ? kCodeAlignment : (align == kWordAligned) ? kSystemPointerSize : (align == kDoubleAligned) ? kDoubleSize : kSystemPointerSize;
+  size_t align_bytes = (type == AllocationType::kCode) ? kCodeAlignment : (align == kTaggedAligned) ? kTaggedSize : (align == kDoubleAligned) ? kDoubleSize : kSystemPointerSize;
   // Get MMTk space that the object should be allocated to.
   Address result =
       reinterpret_cast<Address>(alloc(tph_mutator_, size_in_bytes, align_bytes, 0, 0));
@@ -136,7 +136,7 @@ AllocationResult Heap::Allocate(size_t size_in_bytes, AllocationType type, Alloc
   }
   tph_archive_insert(tph_data_->archive(), reinterpret_cast<void*>(result), tph_data_->isolate(), uint8_t(allocation_space));
   HeapObject rtn = HeapObject::FromAddress(result);
-  return rtn;
+  return AllocationResult::FromObject(rtn);
 }
 
 Address Heap::GetObjectFromInnerPointer(Address inner_pointer) {
@@ -155,7 +155,7 @@ bool Heap::CollectGarbage() {
 }
 
 // Uninitialized space tag
-constexpr AllocationSpace kNoSpace = AllocationSpace(255);
+constexpr AllocationSpace kNoSpace = AllocationSpace(7);
 
 // Checks whether the address is *logically* in the allocation_space.
 // This does not related the real MMTk space that contains the address,
@@ -176,9 +176,21 @@ bool Heap::InOldSpace(Address address) {
   return InSpace(address, OLD_SPACE);
 }
 
+bool Heap::IsValidCodeObject(HeapObject object) {
+  return InSpace(object.address(), CODE_SPACE);
+}
+
+bool Heap::IsImmovable(HeapObject object) {
+  // FIXME: we need to check with MMTK
+  return true;
+}
 
-bool Heap::InCodeSpace(Address address) {
-  return InSpace(address, CODE_SPACE);
+// Check if the given object was recently allocated and its fields may appear
+// as uninitialized to background threads.
+bool Heap::IsPendingAllocation(HeapObject object) {
+  // Initializing fields should be the responsibility of the runtime.
+  // MMTk won't know that?
+  return false;
 }
 
 bool Heap::InReadOnlySpace(Address address) {