Support generation of CFI in .debug_frame format.
.debug_frame section is almost identical to .eh_frame section.
There are only minor differences in the CIE and FDE headers.
The main difference is that .eh_frame is intended to be used
at runtime for exception handling and is therefore allocated
within the running program whereas .debug_frame is not.
This makes .debug_frame easier to remove using standard tools.
"objcopy --strip-debug" removes .debug_frame, but not .eh_frame.
(although objcopy can be still be forced to remove .eh_frame)
Similarly, we might want to separate the CFI to separate debug
file or include it as compressed .gnu_debugdata section.
It is more appropriate to use .debug_frame for this purpose.
Bug:20556771
Change-Id: I9d91a333b9fb37523fd6fafccfad89b21d2477af
diff --git a/compiler/dwarf/headers.h b/compiler/dwarf/headers.h
index 9f64766..ad315ee 100644
--- a/compiler/dwarf/headers.h
+++ b/compiler/dwarf/headers.h
@@ -35,17 +35,18 @@
// and compilers are expected *not* to use it by default.
// In particular, it is not related to machine architecture.
-// Write common information entry (CIE) to .eh_frame section.
+// Write common information entry (CIE) to .debug_frame or .eh_frame section.
template<typename Allocator>
-void WriteEhFrameCIE(bool is64bit,
- ExceptionHeaderValueApplication address_type,
- Reg return_address_register,
- const DebugFrameOpCodeWriter<Allocator>& opcodes,
- std::vector<uint8_t>* eh_frame) {
- Writer<> writer(eh_frame);
+void WriteDebugFrameCIE(bool is64bit,
+ ExceptionHeaderValueApplication address_type,
+ Reg return_address_register,
+ const DebugFrameOpCodeWriter<Allocator>& opcodes,
+ CFIFormat format,
+ std::vector<uint8_t>* debug_frame) {
+ Writer<> writer(debug_frame);
size_t cie_header_start_ = writer.data()->size();
writer.PushUint32(0); // Length placeholder.
- writer.PushUint32(0); // CIE id.
+ writer.PushUint32((format == DW_EH_FRAME_FORMAT) ? 0 : 0xFFFFFFFF); // CIE id.
writer.PushUint8(1); // Version.
writer.PushString("zR");
writer.PushUleb128(DebugFrameOpCodeWriter<Allocator>::kCodeAlignmentFactor);
@@ -62,20 +63,26 @@
writer.UpdateUint32(cie_header_start_, writer.data()->size() - cie_header_start_ - 4);
}
-// Write frame description entry (FDE) to .eh_frame section.
+// Write frame description entry (FDE) to .debug_frame or .eh_frame section.
template<typename Allocator>
-void WriteEhFrameFDE(bool is64bit, size_t cie_offset,
- uint64_t initial_address, uint64_t address_range,
- const std::vector<uint8_t, Allocator>* opcodes,
- std::vector<uint8_t>* eh_frame,
- std::vector<uintptr_t>* eh_frame_patches) {
- Writer<> writer(eh_frame);
+void WriteDebugFrameFDE(bool is64bit, size_t cie_offset,
+ uint64_t initial_address, uint64_t address_range,
+ const std::vector<uint8_t, Allocator>* opcodes,
+ CFIFormat format,
+ std::vector<uint8_t>* debug_frame,
+ std::vector<uintptr_t>* debug_frame_patches) {
+ Writer<> writer(debug_frame);
size_t fde_header_start = writer.data()->size();
writer.PushUint32(0); // Length placeholder.
- uint32_t cie_pointer = writer.data()->size() - cie_offset;
- writer.PushUint32(cie_pointer);
+ if (format == DW_EH_FRAME_FORMAT) {
+ uint32_t cie_pointer = writer.data()->size() - cie_offset;
+ writer.PushUint32(cie_pointer);
+ } else {
+ uint32_t cie_pointer = cie_offset;
+ writer.PushUint32(cie_pointer);
+ }
// Relocate initial_address, but not address_range (it is size).
- eh_frame_patches->push_back(writer.data()->size());
+ debug_frame_patches->push_back(writer.data()->size());
if (is64bit) {
writer.PushUint64(initial_address);
writer.PushUint64(address_range);