Add support for artificial tail call frames

This patch teaches lldb to detect when there are missing frames in a
backtrace due to a sequence of tail calls, and to fill in the backtrace
with artificial tail call frames when this happens. This is only done
when the execution history can be determined from the call graph and
from the return PC addresses of calls on the stack. Ambiguous sequences
of tail calls (e.g anything involving tail calls and recursion) are
detected and ignored.

Depends on D49887.

Differential Revision: https://reviews.llvm.org/D50478

llvm-svn: 343900

1 files changed, 4 insertions, 2 deletions

diff --git a/lldb/source/Core/Debugger.cpp b/lldb/source/Core/Debugger.cpp
index 1c2d69cb58a..be72ac0b16e 100644
--- a/lldb/source/Core/Debugger.cpp
+++ b/lldb/source/Core/Debugger.cpp
@@ -123,6 +123,8 @@ static constexpr OptionEnumValueElement g_language_enumerators[] = {
   "{ at ${line.file.basename}:${line.number}{:${line.column}}}"
 #define IS_OPTIMIZED "{${function.is-optimized} [opt]}"
 
+#define IS_ARTIFICIAL "{${frame.is-artificial} [artificial]}"
+
 #define DEFAULT_THREAD_FORMAT                                                  \
   "thread #${thread.index}: tid = ${thread.id%tid}"                            \
   "{, ${frame.pc}}" MODULE_WITH_FUNC FILE_AND_LINE                             \
@@ -147,11 +149,11 @@ static constexpr OptionEnumValueElement g_language_enumerators[] = {
 
 #define DEFAULT_FRAME_FORMAT                                                   \
   "frame #${frame.index}: ${frame.pc}" MODULE_WITH_FUNC FILE_AND_LINE          \
-      IS_OPTIMIZED "\\n"
+      IS_OPTIMIZED IS_ARTIFICIAL "\\n"
 
 #define DEFAULT_FRAME_FORMAT_NO_ARGS                                           \
   "frame #${frame.index}: ${frame.pc}" MODULE_WITH_FUNC_NO_ARGS FILE_AND_LINE  \
-      IS_OPTIMIZED "\\n"
+      IS_OPTIMIZED IS_ARTIFICIAL "\\n"
 
 // Three parts to this disassembly format specification:
 //   1. If this is a new function/symbol (no previous symbol/function), print