Merging r372038:

jcai19 · tstellar · commit 4e858e4ac00b · 2019-11-08T12:33:21.000-08:00
------------------------------------------------------------------------ r372038 | jcai19 | 2019-09-16 14:47:47 -0700 (Mon, 16 Sep 2019) | 15 lines [compiler-rt][crt] make test case nontrivial in check_cxx_section_exists Summary: .init_array gets optimized away when building with -O2 and as a result, check_cxx_section_exists failed to pass -DCOMPILER_RT_HAS_INITFINI_ARRAY when building crtbegin.o and crtend.o, which causes binaries linked with them encounter segmentation fault. See https://crbug.com/855759 for details. This change prevents .init_array section to be optimized away even with -O2 or higher optimization level. Subscribers: dberris, mgorny, #sanitizers, llvm-commits Tags: #sanitizers, #llvm Differential Revision: https://reviews.llvm.org/D67628 ------------------------------------------------------------------------
diff --git a/compiler-rt/lib/crt/CMakeLists.txt b/compiler-rt/lib/crt/CMakeLists.txt
@@ -69,7 +69,7 @@ function(check_cxx_section_exists section output)
 endfunction()
 
 check_cxx_section_exists(".init_array" COMPILER_RT_HAS_INITFINI_ARRAY
-  SOURCE "__attribute__((constructor)) void f() {}\nint main() { return 0; }\n")
+  SOURCE "volatile int x;\n__attribute__((constructor)) void f() {x = 0;}\nint main() { return 0; }\n")
 
 append_list_if(COMPILER_RT_HAS_STD_C11_FLAG -std=c11 CRT_CFLAGS)
 append_list_if(COMPILER_RT_HAS_INITFINI_ARRAY -DCRT_HAS_INITFINI_ARRAY CRT_CFLAGS)
