[gcc r10-10020] sanitizer: cherry pick 414482751452e54710f16bae58458c66298aaf69

[gcc r10-10020] sanitizer: cherry pick 414482751452e54710f16bae58458c66298aaf69

[Martin Liska]

https://gcc.gnu.org/g:6bbaa64881715b8df2d717e418eeec7b7e974a22

commit r10-10020-g6bbaa64881715b8df2d717e418eeec7b7e974a22
Author: Martin Liska <mliska@suse.cz>
Date:   Thu Aug 5 10:43:17 2021 +0200

    sanitizer: cherry pick 414482751452e54710f16bae58458c66298aaf69
    
    The patch is needed in order to support recent glibc (2.34).
    
    libsanitizer/ChangeLog:
    
            PR sanitizer/101749
            * sanitizer_common/sanitizer_posix_libcdep.cpp: Prevent
            generation of dependency on _cxa_guard for static
            initialization.

Diff:
---
 libsanitizer/sanitizer_common/sanitizer_posix_libcdep.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/libsanitizer/sanitizer_common/sanitizer_posix_libcdep.cpp b/libsanitizer/sanitizer_common/sanitizer_posix_libcdep.cpp
index ac88fbe074e..44359b3d1ac 100644
--- a/libsanitizer/sanitizer_common/sanitizer_posix_libcdep.cpp
+++ b/libsanitizer/sanitizer_common/sanitizer_posix_libcdep.cpp
@@ -170,9 +170,10 @@ bool SupportsColoredOutput(fd_t fd) {
 #if !SANITIZER_GO
 // TODO(glider): different tools may require different altstack size.
 static uptr GetAltStackSize() {
-  // SIGSTKSZ is not enough.
-  static const uptr kAltStackSize = SIGSTKSZ * 4;
-  return kAltStackSize;
+  // Note: since GLIBC_2.31, SIGSTKSZ may be a function call, so this may be
+  // more costly that you think. However GetAltStackSize is only call 2-3 times
+  // per thread so don't cache the evaluation.
+  return SIGSTKSZ * 4;
 }
 
 void SetAlternateSignalStack() {