Author: compnerd
Date: Wed Aug 23 09:50:27 2017
New Revision: 311574
URL: http://llvm.org/viewvc/llvm-project?rev=311574&view=rev
Log:
ARM: explicitly specify the 8-byte alignment
It seems that GCC interprets `__attribute__((__aligned__))` as 8-byte
alignment on ARM, but clang does not. Explicitly specify the
double-word alignment value to ensure that the structure is properly
aligned.
Modified:
libunwind/trunk/include/unwind.h
libunwind/trunk/test/alignment.pass.cpp
Modified: libunwind/trunk/include/unwind.h
URL:
http://llvm.org/viewvc/llvm-project/libunwind/trunk/include/unwind.h?rev=311574&r1=311573&r2=311574&view=diff
==============================================================================
--- libunwind/trunk/include/unwind.h (original)
+++ libunwind/trunk/include/unwind.h Wed Aug 23 09:50:27 2017
@@ -100,7 +100,7 @@ struct _Unwind_Control_Block {
} pr_cache;
long long int :0; /* Enforce the 8-byte alignment */
-} __attribute__((__aligned__));
+} __attribute__((__aligned__(8)));
typedef _Unwind_Reason_Code (*_Unwind_Stop_Fn)
(_Unwind_State state,
Modified: libunwind/trunk/test/alignment.pass.cpp
URL:
http://llvm.org/viewvc/llvm-project/libunwind/trunk/test/alignment.pass.cpp?rev=311574&r1=311573&r2=311574&view=diff
==============================================================================
--- libunwind/trunk/test/alignment.pass.cpp (original)
+++ libunwind/trunk/test/alignment.pass.cpp Wed Aug 23 09:50:27 2017
@@ -13,8 +13,16 @@
#include <unwind.h>
-struct MaxAligned {} __attribute__((aligned));
-static_assert(alignof(_Unwind_Exception) == alignof(MaxAligned), "");
+// EHABI : 8-byte aligned
+// itanium: largest supported alignment for the system
+#if defined(_LIBUNWIND_ARM_EHABI)
+static_assert(alignof(_Unwind_Control_Block) == 8,
+ "_Unwind_Control_Block must be double-word aligned");
+#else
+struct MaxAligned {} __attribute__((__aligned__));
+static_assert(alignof(_Unwind_Exception) == alignof(MaxAligned),
+ "_Unwind_Exception must be maximally aligned");
+#endif
int main()
{
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