[PATCH] D45725: [sanitizer] Minor refactor of ThreadDescriptorSize
Kostya Kortchinsky via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Apr 17 08:50:48 PDT 2018
cryptoad created this revision.
cryptoad added reviewers: alekseyshl, eugenis, koriakin.
Herald added subscribers: Sanitizers, delcypher, kubamracek.
While I was sifting through dead code findings, I stumbled on this function.
First, for `__s390__` it always returned 0 for the 1st call, which doesn't seem
right. 2nd call & beyond would return the correct value though.
Then it duplicated the `atomic_store` multiple times, sometimes with a `if`,
sometimes without. Finally it used a capitalized variable name starting with `k`
which indicates a constant, and it is not.
So:
- rename the static global variable;
- change the atomic functions to their relaxed version;
- move the store to the end, and make sure we return `val` all the time.
Repository:
rCRT Compiler Runtime
https://reviews.llvm.org/D45725
Files:
lib/sanitizer_common/sanitizer_linux_libcdep.cc
Index: lib/sanitizer_common/sanitizer_linux_libcdep.cc
===================================================================
--- lib/sanitizer_common/sanitizer_linux_libcdep.cc
+++ lib/sanitizer_common/sanitizer_linux_libcdep.cc
@@ -219,10 +219,10 @@
defined(__arm__)) && \
SANITIZER_LINUX && !SANITIZER_ANDROID
// sizeof(struct pthread) from glibc.
-static atomic_uintptr_t kThreadDescriptorSize;
+static atomic_uintptr_t thread_descriptor_size;
uptr ThreadDescriptorSize() {
- uptr val = atomic_load(&kThreadDescriptorSize, memory_order_relaxed);
+ uptr val = atomic_load_relaxed(&thread_descriptor_size);
if (val)
return val;
#if defined(__x86_64__) || defined(__i386__) || defined(__arm__)
@@ -261,31 +261,22 @@
else
val = FIRST_32_SECOND_64(1216, 2304);
}
- if (val)
- atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
- return val;
}
#endif
#elif defined(__mips__)
// TODO(sagarthakur): add more values as per different glibc versions.
val = FIRST_32_SECOND_64(1152, 1776);
- if (val)
- atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
- return val;
#elif defined(__aarch64__)
// The sizeof (struct pthread) is the same from GLIBC 2.17 to 2.22.
val = 1776;
- atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
- return val;
#elif defined(__powerpc64__)
val = 1776; // from glibc.ppc64le 2.20-8.fc21
- atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
- return val;
#elif defined(__s390__)
val = FIRST_32_SECOND_64(1152, 1776); // valid for glibc 2.22
- atomic_store(&kThreadDescriptorSize, val, memory_order_relaxed);
#endif
- return 0;
+ if (val)
+ atomic_store_relaxed(&thread_descriptor_size, val);
+ return val;
}
// The offset at which pointer to self is located in the thread descriptor.
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