[LSan] Fix `__sanitizer_print_stack_trace` via fast unwinder

[yln]

Summary

Quick follow-up to: https://reviews.llvm.org/D58156

[vitalybuka]

Thanks, LGTM

lib/lsan/lsan.h

 // The pc will be in the position 0 of the resulting stack trace.
 // The bp may refer to the current frame or to the caller's frame.
 ALWAYS_INLINE
 void GetStackTrace(__sanitizer::BufferedStackTrace *stack,
                    __sanitizer::uptr max_depth, __sanitizer::uptr pc,
                    __sanitizer::uptr bp, void *context, bool fast) {
   uptr stack_top = 0, stack_bottom = 0;
   ThreadContext *t;
-  if (fast && (t = CurrentThreadContext())) {
+  if (__sanitizer::StackTrace::WillUseFastUnwind(fast) &&
+      (t = CurrentThreadContext())) {
     stack_top = t->stack_end();
     stack_bottom = t->stack_begin();
   }
   if (!SANITIZER_MIPS || IsValidFrame(bp, stack_top, stack_bottom)) {
     stack->Unwind(max_depth, pc, bp, context, stack_top, stack_bottom, fast);
   }
 }
 
 }  // namespace __lsan
 
 extern bool lsan_inited;
 extern bool lsan_init_is_running;
 
 extern "C" SANITIZER_INTERFACE_ATTRIBUTE void __lsan_init();

test/sanitizer_common/TestCases/Darwin/print-stack-trace.cc

 // RUN: %clangxx -O0 %s -o %t && %env_tool_opts=stack_trace_format=DEFAULT %run %t 2>&1 | FileCheck %s
 // RUN: %env_tool_opts=stack_trace_format='"frame:%n lineno:%l"' %run %t 2>&1 | FileCheck %s --check-prefix=CUSTOM
 
-// FIXME(dliew): Make this test work on Darwin with LSan
-// XFAIL: darwin && lsan
-
 #include <sanitizer/common_interface_defs.h>
 
 static inline void FooBarBaz() {
   __sanitizer_print_stack_trace();
 }
 
 int main() {
   FooBarBaz();
   return 0;
 }
 // CHECK: {{    #0 0x.* in __sanitizer_print_stack_trace}}
 // CHECK: {{    #1 0x.* in FooBarBaz(\(\))? .*}}print-stack-trace.cc:[[@LINE-8]]
 // CHECK: {{    #2 0x.* in main.*}}print-stack-trace.cc:[[@LINE-5]]
 
 // CUSTOM: frame:1 lineno:[[@LINE-11]]
 // CUSTOM: frame:2 lineno:[[@LINE-8]]

test/sanitizer_common/TestCases/Posix/dedup_token_length_test.cc

 // Test dedup_token_length
 // RUN: %clangxx -O0 %s -o %t
 // RUN: env %tool_options='abort_on_error=0'                       not %run %t 2>&1   | FileCheck %s --check-prefix=CHECK0 --match-full-lines
 // RUN: env %tool_options='abort_on_error=0, dedup_token_length=0' not %run %t 2>&1   | FileCheck %s --check-prefix=CHECK0 --match-full-lines
 // RUN: env %tool_options='abort_on_error=0, dedup_token_length=1' not %run %t 2>&1   | FileCheck %s --check-prefix=CHECK1 --match-full-lines
 // RUN: env %tool_options='abort_on_error=0, dedup_token_length=2' not %run %t 2>&1   | FileCheck %s --check-prefix=CHECK2 --match-full-lines
 // RUN: env %tool_options='abort_on_error=0, dedup_token_length=3' not %run %t 2>&1   | FileCheck %s --check-prefix=CHECK3 --match-full-lines
 
 // REQUIRES: stable-runtime
 
 // XFAIL: netbsd && !asan
 
 // FIXME(dliew): Make this test work with other sanitizers
-// XFAIL: darwin && (lsan || tsan || ubsan)
+// XFAIL: darwin && (tsan || ubsan)
 
 volatile int *null = 0;
 
 namespace Xyz {
   template<class A, class B> void Abc() {
     *null = 0;
   }
 }

test/sanitizer_common/TestCases/symbolize_stack.cc

 // RUN: %clangxx -O0 %s -o %t && %run %t 2>&1 | FileCheck %s
 
 // Test that symbolizer does not crash on frame with large function name.
 
-// FIXME(dliew): Make this test work on Darwin with LSan
+// On Darwin LSan reports a false positive
 // XFAIL: darwin && lsan
 
 #include <sanitizer/common_interface_defs.h>
 #include <vector>
 
 template <int N> struct A {
   template <class T> void RecursiveTemplateFunction(const T &t);
 };