[sanitizer] Add compress_stack_depot flag

[vitalybuka]

Summary

Depends on D114494.

[vitalybuka]

rebase

[morehouse]

compiler-rt/lib/sanitizer_common/sanitizer_stackdepot.cpp

100

stackStore.Allocated() here is the total *after* compression. So we should probably add diff to it.

[vitalybuka]

fix

[morehouse]

compiler-rt/lib/sanitizer_common/sanitizer_stackdepot.cpp

100

I don't think this was addressed.

Suppose we compressed 100 KB down to 50 KB. The Printf is going to say we released 50 KB out of 50 KB, which is confusing and wrong.

[stevewan]

This is failing on clang-s390x-linux, https://lab.llvm.org/buildbot/#/builders/94/builds/6748, can you please take a look?

[vitalybuka]

fix total

[morehouse]

LGTM

compiler-rt/lib/sanitizer_common/sanitizer_flags.inc

COMMON_FLAG(int, dedup_token_length, 0,
             "If positive, after printing a stack trace also print a short "
             "string token based on this number of frames that will simplify "
             "deduplication of the reports. "
             "Example: 'DEDUP_TOKEN: foo-bar-main'. Default is 0.")
 COMMON_FLAG(const char *, stack_trace_format, "DEFAULT",
             "Format string used to render stack frames. "
             "See sanitizer_stacktrace_printer.h for the format description. "
             "Use DEFAULT to get default format.")
+COMMON_FLAG(int, compress_stack_depot, 0,
+            "Compress stack depot to save memory.")
 COMMON_FLAG(bool, no_huge_pages_for_shadow, true,
             "If true, the shadow is not allowed to use huge pages. ")
 COMMON_FLAG(bool, strict_string_checks, false,
             "If set check that string arguments are properly null-terminated")
 COMMON_FLAG(bool, intercept_strstr, true,
             "If set, uses custom wrappers for strstr and strcasestr functions "
             "to find more errors.")
 COMMON_FLAG(bool, intercept_strspn, true,

compiler-rt/lib/sanitizer_common/sanitizer_stackdepot.cpp

 void StackDepotHandle::inc_use_count_unsafe() {
   atomic_fetch_add(&useCounts[id_], 1, memory_order_relaxed);
 }
 
 uptr StackDepotNode::allocated() {
   return stackStore.Allocated() + useCounts.MemoryUsage();
 }
 
+static void CompressStackStore() {
+  u64 start = MonotonicNanoTime();
+  uptr diff = stackStore.Pack(static_cast<StackStore::Compression>(
+      common_flags()->compress_stack_depot));
+  if (!diff)
+    return;
+  u64 finish = MonotonicNanoTime();
+  uptr total_before = stackStore.Allocated() + diff;
+  VPrintf(1, "%s: StackDepot released %zu KiB out of %zu KiB in %llu ms\n",
+          SanitizerToolName, diff >> 10, total_before >> 10,
+          (finish - start) / 1000000);
+}
+
 void StackDepotNode::store(u32 id, const args_type &args, hash_type hash) {
   stack_hash = hash;
   uptr pack = 0;
   store_id = stackStore.Store(args, &pack);
-  if (pack)
-    stackStore.Pack(StackStore::Compression::None);
+  if (pack && common_flags()->compress_stack_depot)
+    CompressStackStore();
 }
 
 StackDepotNode::args_type StackDepotNode::load(u32 id) const {
   if (!store_id)
     return {};
   return stackStore.Load(store_id);
 }
 
 StackDepotStats StackDepotGetStats() { return theDepot.GetStats(); }
 
 u32 StackDepotPut(StackTrace stack) { return theDepot.Put(stack); }
 
 StackDepotHandle StackDepotPut_WithHandle(StackTrace stack) {
   return StackDepotNode::get_handle(theDepot.Put(stack));
 }

compiler-rt/test/sanitizer_common/TestCases/compress_stack_depot.cpp

+// RUN: %clangxx %s -fsanitize-memory-track-origins=1 -o %t
+// RUN: %env_tool_opts="compress_stack_depot=0:malloc_context_size=128:verbosity=1" %run %t 2>&1 | FileCheck %s --implicit-check-not="StackDepot released"
+// RUN: %env_tool_opts="compress_stack_depot=1:malloc_context_size=128:verbosity=1" %run %t 2>&1 | FileCheck %s --check-prefixes=COMPRESS
+
+// Ubsan does not store stacks.
+// UNSUPPORTED: ubsan
+
+// FIXME: Fails for unknown reason.
+// UNSUPPORTED: s390x
+
+#include <memory>
+
+__attribute__((noinline)) void a(unsigned v);
+__attribute__((noinline)) void b(unsigned v);
+
+std::unique_ptr<int[]> p;
+
+__attribute__((noinline)) void a(unsigned v) {
+  int x;
+  v >>= 1;
+  if (!v) {
+    p.reset(new int[100]);
+    p[1] = x;
+    return;
+  }
+  if (v & 1)
+    b(v);
+  else
+    a(v);
+}
+
+__attribute__((noinline)) void b(unsigned v) { return a(v); }
+
+int main(int argc, char *argv[]) {
+  for (unsigned i = 0; i < 100000; ++i)
+    a(i + (i << 16));
+  return 0;
+}
+
+// COMPRESS: StackDepot released {{[0-9]+}}