From b0342a66a005b72d42bdbf858969c208c08595ca Mon Sep 17 00:00:00 2001 From: Peter Zotov Date: Mon, 9 Nov 2015 06:57:29 +0000 Subject: Make it possible to use libunwind without heap. This patch allows to use libunwind on bare-metal systems that do not include malloc/free by conditionally turning off nonessential functionality that requires these functions. The disabled functionality includes: * the .cfi_remember_state and .cfi_restore_state instructions; * the DWARF FDE cache. The .cfi_{remember,restore}_state instructions don't seem to be used by contemporary compilers. None of the LLVM backends emit it. The DWARF FDE cache is bypassed if _LIBUNWIND_NO_HEAP is defined. Specifically, entries are never added to it, so the search begins and ends at the statically allocated, empty initial cache. Such heap-less libunwind on a bare metal system is successfully used in the ARTIQ project[1], and it is my hope that it will be useful elsewhere. [1]: http://m-labs.hk/artiq Differential Revision: http://reviews.llvm.org/D11897 llvm-svn: 252452 --- libunwind/src/UnwindCursor.hpp | 2 ++ 1 file changed, 2 insertions(+) (limited to 'libunwind/src/UnwindCursor.hpp') diff --git a/libunwind/src/UnwindCursor.hpp b/libunwind/src/UnwindCursor.hpp index 040d13e9256..90683164ff2 100644 --- a/libunwind/src/UnwindCursor.hpp +++ b/libunwind/src/UnwindCursor.hpp @@ -114,6 +114,7 @@ typename A::pint_t DwarfFDECache::findFDE(pint_t mh, pint_t pc) { template void DwarfFDECache::add(pint_t mh, pint_t ip_start, pint_t ip_end, pint_t fde) { +#if !defined(_LIBUNWIND_NO_HEAP) _LIBUNWIND_LOG_NON_ZERO(::pthread_rwlock_wrlock(&_lock)); if (_bufferUsed >= _bufferEnd) { size_t oldSize = (size_t)(_bufferEnd - _buffer); @@ -139,6 +140,7 @@ void DwarfFDECache::add(pint_t mh, pint_t ip_start, pint_t ip_end, } #endif _LIBUNWIND_LOG_NON_ZERO(::pthread_rwlock_unlock(&_lock)); +#endif } template -- cgit v1.2.3