cppgc: Try to fix test IteratePointersFindsCalleeSavedRegisters, vol.2

The previous attempt has broken the tsan bot. The only reliable way to
make sure that registers are not clobbered is by doing direct call from
inline assembly, which is what this CL does.

Change-Id: I6adbd5e735949a7cc4cc7fc686ee8c428863ffb9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2859947
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74313}

test/unittests/heap/cppgc/stack-unittest.cc

@@ -308,6 +308,16 @@ TEST_F(GCStackTest, IteratePointersFindsParameterNesting8) {
 
 #ifdef FOR_ALL_CALLEE_SAVED_REGS
 
+namespace {
+#if !defined(V8_OS_WIN)
+__attribute__((visibility("hidden")))
+#endif
+extern "C" void
+IteratePointersNoMangling(Stack* stack, StackVisitor* visitor) {
+  stack->IteratePointers(visitor);
+}
+}  // namespace
+
 TEST_F(GCStackTest, IteratePointersFindsCalleeSavedRegisters) {
   auto scanner = std::make_unique<StackScanner>();
 
@@ -324,22 +334,35 @@ TEST_F(GCStackTest, IteratePointersFindsCalleeSavedRegisters) {
   auto* local_stack = GetStack();
   auto* local_scanner = scanner.get();
 
+#define MOVE_TO_REG_AND_CALL_IMPL(needle_reg, arg1, arg2)           \
+  asm volatile("mov %0, %%" needle_reg "\n mov %1, %%" arg1         \
+               "\n mov %2, %%" arg2                                 \
+               "\n call %P3"                                        \
+               "\n mov $0, %%" needle_reg                           \
+               :                                                    \
+               : "r"(local_scanner->needle()), "r"(local_stack),    \
+                 "r"(local_scanner), "i"(IteratePointersNoMangling) \
+               : "memory", needle_reg, arg1, arg2, "cc");
+
+#ifdef V8_OS_WIN
+#define MOVE_TO_REG_AND_CALL(reg) MOVE_TO_REG_AND_CALL_IMPL(reg, "rcx", "rdx")
+#else  // !V8_OS_WIN
+#define MOVE_TO_REG_AND_CALL(reg) MOVE_TO_REG_AND_CALL_IMPL(reg, "rdi", "rsi")
+#endif  // V8_OS_WIN
+
 // Moves |local_scanner->needle()| into a callee-saved register, leaving the
 // callee-saved register as the only register referencing the needle.
 // (Ignoring implementation-dependent dirty registers/stack.)
-#define KEEP_ALIVE_FROM_CALLEE_SAVED(reg)                                \
-  local_scanner->Reset();                                                \
-  /* This moves the temporary into the calee-saved register. */          \
-  asm("mov %0, %%" reg : : "r"(local_scanner->needle()) : reg);          \
-  /* Register is unprotected from here till the actual invocation. */    \
-  local_stack->IteratePointers(local_scanner);                           \
-  EXPECT_TRUE(local_scanner->found())                                    \
-      << "pointer in callee-saved register not found. register: " << reg \
-      << std::endl;                                                      \
-  /* Clear out the register again */                                     \
-  asm("mov $0, %%" reg : : : reg);
+#define KEEP_ALIVE_FROM_CALLEE_SAVED(reg)                                     \
+  local_scanner->Reset();                                                     \
+  [local_stack, local_scanner]() V8_NOINLINE { MOVE_TO_REG_AND_CALL(reg) }(); \
+  EXPECT_TRUE(local_scanner->found())                                         \
+      << "pointer in callee-saved register not found. register: " << reg      \
+      << std::endl;
 
   FOR_ALL_CALLEE_SAVED_REGS(KEEP_ALIVE_FROM_CALLEE_SAVED)
+#undef MOVE_TO_REG_AND_CALL
+#undef MOVE_TO_REG_AND_CALL_IMPL
 #undef KEEP_ALIVE_FROM_CALLEE_SAVED
 #undef FOR_ALL_CALLEE_SAVED_REGS
 }