[turbo-assembler] Add code comment for inlined trampolines

Trampolines to off-heap targets may get inlined. In this case, it is hard
to tell where the trampoline is going to; this CL adds code comments which
identify the target builtin by name.

Bug: v8:6666
Change-Id: Ib085ad118ad64551af2522f9187b4faaad6ce315
Reviewed-on: https://chromium-review.googlesource.com/1160536
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54874}

src/arm/macro-assembler-arm.cc

@@ -207,6 +207,7 @@ void TurboAssembler::Jump(Handle<Code> code, RelocInfo::Mode rmode,
     } else if (target_is_isolate_independent_builtin &&
                options().inline_offheap_trampolines) {
       // Inline the trampoline.
+      RecordCommentForOffHeapTrampoline(builtin_index);
       EmbeddedData d = EmbeddedData::FromBlob();
       Address entry = d.InstructionStartOfBuiltin(builtin_index);
       // Use ip directly instead of using UseScratchRegisterScope, as we do not
@@ -286,7 +287,7 @@ void TurboAssembler::Call(Handle<Code> code, RelocInfo::Mode rmode,
     } else if (target_is_isolate_independent_builtin &&
                options().inline_offheap_trampolines) {
       // Inline the trampoline.
-      DCHECK(Builtins::IsBuiltinId(builtin_index));
+      RecordCommentForOffHeapTrampoline(builtin_index);
       EmbeddedData d = EmbeddedData::FromBlob();
       Address entry = d.InstructionStartOfBuiltin(builtin_index);
       // Use ip directly instead of using UseScratchRegisterScope, as we do not

src/arm64/macro-assembler-arm64.cc

@@ -1950,6 +1950,7 @@ void TurboAssembler::Jump(Handle<Code> code, RelocInfo::Mode rmode,
       if (isolate()->builtins()->IsBuiltinHandle(code, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         CHECK_NE(builtin_index, Builtins::kNoBuiltinId);
         UseScratchRegisterScope temps(this);
         Register scratch = temps.AcquireX();
@@ -2007,6 +2008,7 @@ void TurboAssembler::Call(Handle<Code> code, RelocInfo::Mode rmode) {
       if (isolate()->builtins()->IsBuiltinHandle(code, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         CHECK_NE(builtin_index, Builtins::kNoBuiltinId);
         UseScratchRegisterScope temps(this);
         Register scratch = temps.AcquireX();

src/mips/macro-assembler-mips.cc

@@ -3782,6 +3782,7 @@ void TurboAssembler::Jump(Handle<Code> code, RelocInfo::Mode rmode,
       if (isolate()->builtins()->IsBuiltinHandle(code, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         CHECK_NE(builtin_index, Builtins::kNoBuiltinId);
         EmbeddedData d = EmbeddedData::FromBlob();
         Address entry = d.InstructionStartOfBuiltin(builtin_index);
@@ -3888,6 +3889,7 @@ void TurboAssembler::Call(Handle<Code> code, RelocInfo::Mode rmode,
       if (isolate()->builtins()->IsBuiltinHandle(code, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         CHECK_NE(builtin_index, Builtins::kNoBuiltinId);
         EmbeddedData d = EmbeddedData::FromBlob();
         Address entry = d.InstructionStartOfBuiltin(builtin_index);

src/mips64/macro-assembler-mips64.cc

@@ -4207,6 +4207,7 @@ void TurboAssembler::Jump(Handle<Code> code, RelocInfo::Mode rmode,
       if (isolate()->builtins()->IsBuiltinHandle(code, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         CHECK_NE(builtin_index, Builtins::kNoBuiltinId);
         EmbeddedData d = EmbeddedData::FromBlob();
         Address entry = d.InstructionStartOfBuiltin(builtin_index);
@@ -4266,6 +4267,7 @@ void TurboAssembler::Call(Handle<Code> code, RelocInfo::Mode rmode,
       if (isolate()->builtins()->IsBuiltinHandle(code, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         CHECK_NE(builtin_index, Builtins::kNoBuiltinId);
         EmbeddedData d = EmbeddedData::FromBlob();
         Address entry = d.InstructionStartOfBuiltin(builtin_index);

src/ppc/macro-assembler-ppc.cc

@@ -197,6 +197,7 @@ void TurboAssembler::Jump(Handle<Code> code, RelocInfo::Mode rmode,
       if (isolate()->builtins()->IsBuiltinHandle(code, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         EmbeddedData d = EmbeddedData::FromBlob();
         Address entry = d.InstructionStartOfBuiltin(builtin_index);
         // Use ip directly instead of using UseScratchRegisterScope, as we do
@@ -268,6 +269,7 @@ void TurboAssembler::Call(Handle<Code> code, RelocInfo::Mode rmode,
       if (isolate()->builtins()->IsBuiltinHandle(code, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         DCHECK(Builtins::IsBuiltinId(builtin_index));
         EmbeddedData d = EmbeddedData::FromBlob();
         Address entry = d.InstructionStartOfBuiltin(builtin_index);

src/s390/macro-assembler-s390.cc

@@ -192,6 +192,7 @@ void TurboAssembler::Jump(Handle<Code> code, RelocInfo::Mode rmode,
       if (isolate()->builtins()->IsBuiltinHandle(code, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         EmbeddedData d = EmbeddedData::FromBlob();
         Address entry = d.InstructionStartOfBuiltin(builtin_index);
         // Use ip directly instead of using UseScratchRegisterScope, as we do
@@ -253,6 +254,7 @@ void TurboAssembler::Call(Handle<Code> code, RelocInfo::Mode rmode,
       if (isolate()->builtins()->IsBuiltinHandle(code, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         DCHECK(Builtins::IsBuiltinId(builtin_index));
         EmbeddedData d = EmbeddedData::FromBlob();
         Address entry = d.InstructionStartOfBuiltin(builtin_index);

src/turbo-assembler.cc

@@ -7,6 +7,7 @@
 #include "src/builtins/builtins.h"
 #include "src/builtins/constants-table-builder.h"
 #include "src/heap/heap-inl.h"
+#include "src/lsan.h"
 #include "src/snapshot/serializer-common.h"
 
 namespace v8 {
@@ -117,5 +118,17 @@ int32_t TurboAssemblerBase::RootRegisterOffsetForBuiltinIndex(
          builtin_index * kPointerSize;
 }
 
+void TurboAssemblerBase::RecordCommentForOffHeapTrampoline(int builtin_index) {
+  if (!FLAG_code_comments) return;
+  size_t len = strlen("-- Inlined Trampoline to  --") +
+               strlen(Builtins::name(builtin_index)) + 1;
+  Vector<char> buffer = Vector<char>::New(static_cast<int>(len));
+  char* buffer_start = buffer.start();
+  LSAN_IGNORE_OBJECT(buffer_start);
+  SNPrintF(buffer, "-- Inlined Trampoline to %s --",
+           Builtins::name(builtin_index));
+  RecordComment(buffer_start);
+}
+
 }  // namespace internal
 }  // namespace v8

src/turbo-assembler.h

@@ -69,6 +69,8 @@ class V8_EXPORT_PRIVATE TurboAssemblerBase : public Assembler {
                      void* buffer, int buffer_size,
                      CodeObjectRequired create_code_object);
 
+  void RecordCommentForOffHeapTrampoline(int builtin_index);
+
   Isolate* const isolate_ = nullptr;
 
   // This handle will be patched with the code object on installation.

src/x64/macro-assembler-x64.cc

@@ -1494,6 +1494,7 @@ if (FLAG_embedded_builtins) {
     if (isolate()->builtins()->IsBuiltinHandle(code_object, &builtin_index) &&
         Builtins::IsIsolateIndependent(builtin_index)) {
       // Inline the trampoline.
+      RecordCommentForOffHeapTrampoline(builtin_index);
       CHECK_NE(builtin_index, Builtins::kNoBuiltinId);
       EmbeddedData d = EmbeddedData::FromBlob();
       Address entry = d.InstructionStartOfBuiltin(builtin_index);
@@ -1548,6 +1549,7 @@ void TurboAssembler::Call(Handle<Code> code_object, RelocInfo::Mode rmode) {
       if (isolate()->builtins()->IsBuiltinHandle(code_object, &builtin_index) &&
           Builtins::IsIsolateIndependent(builtin_index)) {
         // Inline the trampoline.
+        RecordCommentForOffHeapTrampoline(builtin_index);
         CHECK_NE(builtin_index, Builtins::kNoBuiltinId);
         EmbeddedData d = EmbeddedData::FromBlob();
         Address entry = d.InstructionStartOfBuiltin(builtin_index);