[libunwind] Support for leaf function unwinding.
Unwinding leaf function is useful in cases when the backtrace finds a
leaf function for example when it caused a signal.
This patch also add the support for the DW_CFA_undefined because it marks
the end of the frames.
Ryan Prichard provided code for the tests.
Reviewed By: #libunwind, mstorsjo
Differential Revision: https://reviews.llvm.org/D83573
Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 23bef7ee9923b1262326981960397e8cd95d6923
diff --git a/src/DwarfInstructions.hpp b/src/DwarfInstructions.hpp
index ee98f53..c39cabe 100644
--- a/src/DwarfInstructions.hpp
+++ b/src/DwarfInstructions.hpp
@@ -93,7 +93,8 @@
case CFI_Parser<A>::kRegisterInRegister:
return registers.getRegister((int)savedReg.value);
-
+ case CFI_Parser<A>::kRegisterUndefined:
+ return 0;
case CFI_Parser<A>::kRegisterUnused:
case CFI_Parser<A>::kRegisterOffsetFromCFA:
// FIX ME
@@ -117,6 +118,7 @@
case CFI_Parser<A>::kRegisterIsExpression:
case CFI_Parser<A>::kRegisterUnused:
+ case CFI_Parser<A>::kRegisterUndefined:
case CFI_Parser<A>::kRegisterOffsetFromCFA:
case CFI_Parser<A>::kRegisterInRegister:
// FIX ME
@@ -140,6 +142,7 @@
case CFI_Parser<A>::kRegisterIsExpression:
case CFI_Parser<A>::kRegisterUnused:
+ case CFI_Parser<A>::kRegisterUndefined:
case CFI_Parser<A>::kRegisterOffsetFromCFA:
case CFI_Parser<A>::kRegisterInRegister:
// FIX ME
@@ -190,6 +193,10 @@
prolog.savedRegisters[i]));
else
return UNW_EBADREG;
+ } else if (i == (int)cieInfo.returnAddressRegister) {
+ // Leaf function keeps the return address in register and there is no
+ // explicit intructions how to restore it.
+ returnAddress = registers.getRegister(cieInfo.returnAddressRegister);
}
}