sanitizers: compile with -O1 under debug

[dvyukov]

Summary

Tsan's check_memcpy.c test was disabled under debug because it failed.
But it points to real issues and does not help to just disable it.
I tried to enable it and see what fail and the first hit was default ctor for:

struct ChainedOriginDepotDesc {
  u32 here_id;
  u32 prev_id;
};

initializing these fields to 0's help partially,
but compiler still emits memset before calling ctor.
I did not try to see what's the next failure, because if it fails
on such small structs, it won't be realistic to fix everything
and keep working.

Compile runtimes with -O1 under debug instead.
It seems to fix all current failures. At least I run check-tsan
under clang/gcc x debug/non-debug and all combinations passed.
-O1 does not usually use too aggressive optimizations
and sometimes even makes debugging easier because machine code
is not exceedingly verbose.

[vitalybuka]

compiler-rt/CMakeLists.txt

381

Doc string says: COMPILER_RT_DEBUG "Build runtimes with full debug info", but we never use it for -g flag and only for -O

Why don't we use regular CMAKE_BUILD_TYPE for that?

compiler-rt/test/tsan/Linux/check_memcpy.c

6

I am not sure we can assume availability of c++filt
why not to match to the mangled name?

[MaskRay]

When LLVM_OPTIMIZE_SANITIZED_BUILDS is on, the runtime also gets the -O1 option.

[dvyukov]

don't use c++filt

[dvyukov]

compiler-rt/CMakeLists.txt

381

The main effect of COMPILER_RT_DEBUG for me was always defining SANITIZER_DEBUG=1.

Why don't we use regular CMAKE_BUILD_TYPE for that?

You mean why don't enable -O1 based on CMAKE_BUILD_TYPE?
The problem is that the runtime is miscompiled with -O0, it's not up to user to select or not select -O0/-O1.
And test/tsan/Linux/check_memcpy.c fails with -O0, so if there is some bot w/o CMAKE_BUILD_TYPE, it will fail after this change.

compiler-rt/test/tsan/Linux/check_memcpy.c

6

Removed c++filt

[dvyukov]

In D107962#2942388, @MaskRay wrote:

When LLVM_OPTIMIZE_SANITIZED_BUILDS is on, the runtime also gets the -O1 option.

See my reply to Vitaly.

compiler-rt/CMakeLists.txt

 endif()
 
 # If we're using MSVC,
 # always respect the optimization flags set by CMAKE_BUILD_TYPE instead.
 if (NOT MSVC)
 
   # Build with optimization, unless we're in debug mode.
   if(COMPILER_RT_DEBUG)
-    list(APPEND SANITIZER_COMMON_CFLAGS -O0)
+    list(APPEND SANITIZER_COMMON_CFLAGS -O1)
   else()
     list(APPEND SANITIZER_COMMON_CFLAGS -O3)
   endif()
 endif()
 
 # Determine if we should restrict stack frame sizes.
 # Stack frames on PowerPC, Mips, SystemZ and in debug build can be much larger than
 # anticipated.

compiler-rt/test/tsan/Linux/check_memcpy.c

 // Test that verifies TSan runtime doesn't contain compiler-emitted
 // memcpy/memmove calls. It builds the binary with TSan and check's
 // its objdump.
 
 // RUN: %clang_tsan -O1 %s -o %t
-// RUN: llvm-objdump -d %t | FileCheck %s
-
-// REQUIRES: compiler-rt-optimized
+// RUN: llvm-objdump -d -l %t | FileCheck %s
 
 int main() {
   return 0;
 }
 
 // CHECK-NOT: callq {{.*<(__interceptor_)?mem(cpy|set)>}}
 // tail calls:
 // CHECK-NOT: jmpq {{.*<(__interceptor_)?mem(cpy|set)>}}