[maglev] Add UNSUPPORTED macro for codegen

Allows incremental test, while some codegen paths are not available.

Bug: v8:7700
Change-Id: Icc24cf8e85464587f9eee6175107093a25b76da9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3512794Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79423}

src/maglev/maglev-code-gen-state.h

@@ -72,6 +72,14 @@ class MaglevCodeGenState {
   }
   MaglevCompilationUnit* compilation_unit() const { return compilation_unit_; }
 
+  // TODO(v8:7700): Clean up after all code paths are supported.
+  void set_found_unsupported_code_paths(bool val) {
+    found_unsupported_code_paths_ = val;
+  }
+  bool found_unsupported_code_paths() const {
+    return found_unsupported_code_paths_;
+  }
+
  private:
   MaglevCompilationUnit* const compilation_unit_;
   SafepointTableBuilder* const safepoint_table_builder_;
@@ -79,6 +87,11 @@ class MaglevCodeGenState {
   MacroAssembler masm_;
   std::vector<DeferredCodeInfo*> deferred_code_;
   int vreg_slots_ = 0;
+
+  // Allow marking some codegen paths as unsupported, so that we can test maglev
+  // incrementally.
+  // TODO(v8:7700): Clean up after all code paths are supported.
+  bool found_unsupported_code_paths_ = false;
 };
 
 // Some helpers for codegen.

src/maglev/maglev-code-generator.cc

@@ -323,6 +323,7 @@ class MaglevCodeGeneratorImpl final {
 
   MaybeHandle<Code> Generate() {
     EmitCode();
+    if (code_gen_state_.found_unsupported_code_paths()) return {};
     EmitMetadata();
     return BuildCodeObject();
   }

src/maglev/maglev-graph-builder.cc

@@ -18,13 +18,16 @@ namespace internal {
 namespace maglev {
 
 // TODO(v8:7700): Clean up after all bytecodes are supported.
-#define MAGLEV_UNIMPLEMENTED_BYTECODE(Name)                             \
-  void MaglevGraphBuilder::Visit##Name() {                              \
-    std::cerr << "Maglev: Can't compile, bytecode " #Name               \
+#define MAGLEV_UNIMPLEMENTED(BytecodeName)                              \
+  do {                                                                  \
+    std::cerr << "Maglev: Can't compile, bytecode " #BytecodeName       \
                  " is not supported\n";                                 \
     found_unsupported_bytecode_ = true;                                 \
     this_field_will_be_unused_once_all_bytecodes_are_supported_ = true; \
-  }
+  } while (false)
+
+#define MAGLEV_UNIMPLEMENTED_BYTECODE(Name) \
+  void MaglevGraphBuilder::Visit##Name() { MAGLEV_UNIMPLEMENTED(Name); }
 
 void MaglevGraphBuilder::VisitLdar() { SetAccumulator(LoadRegister(0)); }
 
@@ -164,7 +167,7 @@ void MaglevGraphBuilder::VisitSetNamedProperty() {
   }
 
   // TODO(victorgomes): Generic store.
-  UNREACHABLE();
+  MAGLEV_UNIMPLEMENTED(VisitSetNamedProperty);
 }
 
 MAGLEV_UNIMPLEMENTED_BYTECODE(DefineNamedOwnProperty)

src/maglev/maglev-ir.cc

@@ -30,6 +30,15 @@ const char* ToString(Opcode opcode) {
 
 #define __ code_gen_state->masm()->
 
+// TODO(v8:7700): Clean up after all code paths are supported.
+static bool g_this_field_will_be_unused_once_all_code_paths_are_supported;
+#define UNSUPPORTED()                                                     \
+  do {                                                                    \
+    std::cerr << "Maglev: Can't compile, unsuppored codegen path.\n";     \
+    code_gen_state->set_found_unsupported_code_paths(true);               \
+    g_this_field_will_be_unused_once_all_code_paths_are_supported = true; \
+  } while (false)
+
 namespace {
 
 // ---
@@ -576,11 +585,11 @@ void LoadField::GenerateCode(MaglevCodeGenState* code_gen_state,
     __ DecompressAnyTagged(ToRegister(result()), input_field_operand);
     if (LoadHandler::IsDoubleBits::decode(handler)) {
       // TODO(leszeks): Copy out the value, either as a double or a HeapNumber.
-      UNREACHABLE();
+      UNSUPPORTED();
     }
   } else {
     // TODO(leszeks): Handle out-of-object properties.
-    UNREACHABLE();
+    UNSUPPORTED();
   }
 }
 void LoadField::PrintParams(std::ostream& os,
@@ -605,7 +614,7 @@ void StoreField::GenerateCode(MaglevCodeGenState* code_gen_state,
     __ StoreTaggedField(operand, value);
   } else {
     // TODO(victorgomes): Out-of-object properties.
-    UNREACHABLE();
+    UNSUPPORTED();
   }
 }