[gn build] Move -fno-builtin to crt_code

[aeubanks]

Summary

crt_code seems to correspond to SANITIZER_COMMON_CFLAGS which contains -fno-builtin.

[thakis]

Thanks!

[thakis]

I guess crt_code is maybe also used by lib/buildins (?) So maybe crt_code doesn't correspond to SANITIZER_COMMON_CFLAGS since it's (maybe) also used for non-sanitizer compiler-rt things. Didn't check, maybe do a quick check of that before committing :)

[aeubanks]

In D118288#3274377, @thakis wrote:

I guess crt_code is maybe also used by lib/buildins (?) So maybe crt_code doesn't correspond to SANITIZER_COMMON_CFLAGS since it's (maybe) also used for non-sanitizer compiler-rt things. Didn't check, maybe do a quick check of that before committing :)

crt_code isn't used in compiler-rt/lib/builtins, that specifies its own -fno-builtin/-fPIC.

llvm/utils/gn/build/BUILD.gn

 
 config("crt_code") {
   include_dirs = [ "//compiler-rt/lib" ]
   cflags = [
     "-fPIC",
     "-funwind-tables",
     "-gline-tables-only",
     "-fvisibility=hidden",
+    "-fno-builtin",
   ]
   if (is_clang) {
     cflags += [
       "-Werror=thread-safety",
       "-Werror=thread-safety-reference",
       "-Werror=thread-safety-beta",
     ]
   }

llvm/utils/gn/secondary/compiler-rt/lib/asan/BUILD.gn

sources = [
     "asan_thread.cpp",
     "asan_thread.h",
     "asan_win.cpp",
   ]
   if (target_os != "mac" && target_os != "win") {
     sources += [ "asan_interceptors_vfork.S" ]
   }
 
-  # FIXME: have SANITIZER_COMMON_CFLAGS thingy? should fno-builtin be in
-  # crt_code?
-  cflags = [ "-fno-builtin" ]
+  cflags = []
   if (target_os != "win") {
     cflags += [ "-ftls-model=initial-exec" ]
   }
 
   # FIXME: link rt dl m pthread log
   # FIXME: dep on libcxx-headers?
   # FIXME: add_sanitizer_rt_version_list (cf hwasan)
   # FIXME: need libclang_rt.asan*.a.syms?

llvm/utils/gn/secondary/compiler-rt/lib/msan/BUILD.gn

sources = [
     "msan_poisoning.cpp",
     "msan_poisoning.h",
     "msan_report.cpp",
     "msan_report.h",
     "msan_thread.cpp",
     "msan_thread.h",
   ]
 
-  # FIXME: have SANITIZER_COMMON_CFLAGS thingy? should fno-builtin be in
-  # crt_code?
-  cflags = [ "-fno-builtin" ]
-
-  cflags += [ "-fPIE" ]
+  cflags = [ "-fPIE" ]
 
   # Prevent clang from generating libc calls.
   cflags += [ "-ffreestanding" ]
 
   # FIXME: link rt dl m pthread log
   # FIXME: need libclang_rt.msan*.a.syms?
   # FIXME: msan_ignorelist.txt
 }

llvm/utils/gn/secondary/compiler-rt/lib/tsan/rtl/BUILD.gn

target(tsan_target_type, "rtl") {
   } else if (target_cpu == "powerpc64") {
     sources += [ "tsan_rtl_ppc64.S" ]
   } else if (target_cpu == "mips64") {
     sources += [ "tsan_rtl_mips64.S" ]
   } else if (target_cpu == "s390x") {
     sources += [ "tsan_rtl_s390x.S" ]
   }
 
-  # FIXME: have SANITIZER_COMMON_CFLAGS thingy? should fno-builtin be in
-  # crt_code?
-  cflags += [ "-fno-builtin" ]
-
   # FIXME: link rt dl m pthread log
   # FIXME: dep on libcxx-headers?
   # FIXME: add_sanitizer_rt_version_list (cf hwasan)
   # FIXME: need libclang_rt.tsan*.a.syms?
   # FIXME: tsan_ignorelist.txt
 
   if (target_os == "mac") {
     # The -U flags below correspond to the add_weak_symbols() calls in CMake.