Implement post-review comments for r216730
Feedback was 'this could use better comments'.
git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@217459 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/Unwind/Unwind-EHABI.cpp b/src/Unwind/Unwind-EHABI.cpp
index 84dd0d1..eeefd39 100644
--- a/src/Unwind/Unwind-EHABI.cpp
+++ b/src/Unwind/Unwind-EHABI.cpp
@@ -218,11 +218,25 @@
decode_eht_entry(const uint32_t* data, size_t* off, size_t* len) {
if ((*data & 0x80000000) == 0) {
// 6.2: Generic Model
- *off = 1; // First byte is size data.
- *len = (((data[1] >> 24) & 0xff) + 1) * 4;
+ // EHT entry is a prel31 pointing to the PR, followed by data understood only
+ // by the personality routine. Since EHABI doesn't guarantee the location or
+ // availability of the unwind opcodes in the generic model, we have to check
+ // for them on a case-by-case basis:
+ _Unwind_Reason_Code __gxx_personality_v0(int version, _Unwind_Action actions,
+ uint64_t exceptionClass,
+ _Unwind_Exception* unwind_exception,
+ _Unwind_Context* context);
+ void *PR = (void*)signExtendPrel31(*data);
+ if (PR == &__gxx_personality_v0) {
+ *off = 1; // First byte is size data.
+ *len = (((data[1] >> 24) & 0xff) + 1) * 4;
+ } else
+ return nullptr;
data++; // Skip the first word, which is the prel31 offset.
} else {
// 6.3: ARM Compact Model
+ // EHT entries here correspond to the __aeabi_unwind_cpp_pr[012] PRs indeded
+ // by format:
Descriptor::Format format =
static_cast<Descriptor::Format>((*data & 0x0f000000) >> 24);
switch (format) {
