Fix PC adjustment in StackFrame::GetSymbolContext

Summary:
Update StackFrame::GetSymbolContext to mirror the logic in
RegisterContextLLDB::InitializeNonZerothFrame that knows not to do the
pc decrement when the given frame is a signal trap handler frame or the
parent of one, because the pc may not follow a call in these frames.
Accomplish this by adding a behaves_like_zeroth_frame field to
lldb_private::StackFrame, set to true for the zeroth frame, for
signal handler frames, and for parents of signal handler frames.

Also add logic to propagate the signal handler flag from UnwindPlan to
the FrameType on the RegisterContextLLDB it generates, and factor out a
helper to resolve symbol and address range for an Address now that we
need to invoke it in four places.

Reviewers: jasonmolenda, clayborg, jfb

Reviewed By: jasonmolenda

Subscribers: labath, dexonsmith, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D64993

llvm-svn: 367691

1 files changed, 21 insertions, 13 deletions

diff --git a/lldb/source/Target/StackFrameList.cpp b/lldb/source/Target/StackFrameList.cpp
index 0723ed0b5a2..69445624a53 100644
--- a/lldb/source/Target/StackFrameList.cpp
+++ b/lldb/source/Target/StackFrameList.cpp
@@ -397,11 +397,13 @@ void StackFrameList::SynthesizeTailCallFrames(StackFrame &next_frame) {
     bool cfa_is_valid = false;
     addr_t pc =
         callee->GetAddressRange().GetBaseAddress().GetLoadAddress(&target);
+    constexpr bool behaves_like_zeroth_frame = false;
     SymbolContext sc;
     callee->CalculateSymbolContext(&sc);
     auto synth_frame = std::make_shared<StackFrame>(
         m_thread.shared_from_this(), frame_idx, concrete_frame_idx, cfa,
-        cfa_is_valid, pc, StackFrame::Kind::Artificial, &sc);
+        cfa_is_valid, pc, StackFrame::Kind::Artificial,
+        behaves_like_zeroth_frame, &sc);
     m_frames.push_back(synth_frame);
     LLDB_LOG(log, "Pushed frame {0}", callee->GetDisplayName());
   }
@@ -451,6 +453,7 @@ void StackFrameList::GetFramesUpTo(uint32_t end_idx) {
     uint32_t idx = m_concrete_frames_fetched++;
     lldb::addr_t pc = LLDB_INVALID_ADDRESS;
     lldb::addr_t cfa = LLDB_INVALID_ADDRESS;
+    bool behaves_like_zeroth_frame = (idx == 0);
     if (idx == 0) {
       // We might have already created frame zero, only create it if we need
       // to.
@@ -458,8 +461,9 @@ void StackFrameList::GetFramesUpTo(uint32_t end_idx) {
         RegisterContextSP reg_ctx_sp(m_thread.GetRegisterContext());
 
         if (reg_ctx_sp) {
-          const bool success =
-              unwinder && unwinder->GetFrameInfoAtIndex(idx, cfa, pc);
+          const bool success = unwinder &&
+                               unwinder->GetFrameInfoAtIndex(
+                                   idx, cfa, pc, behaves_like_zeroth_frame);
           // There shouldn't be any way not to get the frame info for frame
           // 0. But if the unwinder can't make one, lets make one by hand
           // with the SP as the CFA and see if that gets any further.
@@ -470,7 +474,7 @@ void StackFrameList::GetFramesUpTo(uint32_t end_idx) {
 
           unwind_frame_sp = std::make_shared<StackFrame>(
               m_thread.shared_from_this(), m_frames.size(), idx, reg_ctx_sp,
-              cfa, pc, nullptr);
+              cfa, pc, behaves_like_zeroth_frame, nullptr);
           m_frames.push_back(unwind_frame_sp);
         }
       } else {
@@ -478,8 +482,9 @@ void StackFrameList::GetFramesUpTo(uint32_t end_idx) {
         cfa = unwind_frame_sp->m_id.GetCallFrameAddress();
       }
     } else {
-      const bool success =
-          unwinder && unwinder->GetFrameInfoAtIndex(idx, cfa, pc);
+      const bool success = unwinder &&
+                           unwinder->GetFrameInfoAtIndex(
+                               idx, cfa, pc, behaves_like_zeroth_frame);
       if (!success) {
         // We've gotten to the end of the stack.
         SetAllFramesFetched();
@@ -488,7 +493,7 @@ void StackFrameList::GetFramesUpTo(uint32_t end_idx) {
       const bool cfa_is_valid = true;
       unwind_frame_sp = std::make_shared<StackFrame>(
           m_thread.shared_from_this(), m_frames.size(), idx, cfa, cfa_is_valid,
-          pc, StackFrame::Kind::Regular, nullptr);
+          pc, StackFrame::Kind::Regular, behaves_like_zeroth_frame, nullptr);
 
       // Create synthetic tail call frames between the previous frame and the
       // newly-found frame. The new frame's index may change after this call,
@@ -530,10 +535,11 @@ void StackFrameList::GetFramesUpTo(uint32_t end_idx) {
       while (unwind_sc.GetParentOfInlinedScope(
           curr_frame_address, next_frame_sc, next_frame_address)) {
         next_frame_sc.line_entry.ApplyFileMappings(target_sp);
-        StackFrameSP frame_sp(
-            new StackFrame(m_thread.shared_from_this(), m_frames.size(), idx,
-                           unwind_frame_sp->GetRegisterContextSP(), cfa,
-                           next_frame_address, &next_frame_sc));
+        behaves_like_zeroth_frame = false;
+        StackFrameSP frame_sp(new StackFrame(
+            m_thread.shared_from_this(), m_frames.size(), idx,
+            unwind_frame_sp->GetRegisterContextSP(), cfa, next_frame_address,
+            behaves_like_zeroth_frame, &next_frame_sc));
 
         m_frames.push_back(frame_sp);
         unwind_sc = next_frame_sc;
@@ -664,11 +670,13 @@ StackFrameSP StackFrameList::GetFrameAtIndex(uint32_t idx) {
       Unwind *unwinder = m_thread.GetUnwinder();
       if (unwinder) {
         addr_t pc, cfa;
-        if (unwinder->GetFrameInfoAtIndex(idx, cfa, pc)) {
+        bool behaves_like_zeroth_frame = (idx == 0);
+        if (unwinder->GetFrameInfoAtIndex(idx, cfa, pc,
+                                          behaves_like_zeroth_frame)) {
           const bool cfa_is_valid = true;
           frame_sp = std::make_shared<StackFrame>(
               m_thread.shared_from_this(), idx, idx, cfa, cfa_is_valid, pc,
-              StackFrame::Kind::Regular, nullptr);
+              StackFrame::Kind::Regular, behaves_like_zeroth_frame, nullptr);
 
           Function *function =
               frame_sp->GetSymbolContext(eSymbolContextFunction).function;