Filter on wanted backtrace entry types.

Author: maleadt

base/error.jl

@@ -65,33 +65,55 @@ struct InterpreterIP
     mod::Union{Module,Nothing}
 end
 
+# formatted backtrace buffers can contain all types of objects (none for now though)
+const BackTraceEntry = Union{Ptr{Nothing}, InterpreterIP}
+# but only some correspond with actual instruction pointers
+const InstructionPointer = Union{Ptr{Nothing}, InterpreterIP}
+
 # convert an array of raw backtrace entries to array of usable objects
-# (either native pointers or InterpreterIP objects)
-function _reformat_bt(bt)
-    ret = Vector{Union{Ptr{Cvoid},InterpreterIP}}()
+# (either native pointers, InterpreterIP objects, or AllocationInfo objects)
+function _reformat_bt(bt, Wanted::Type=BackTraceEntry)
+    # NOTE: Ptr{Cvoid} is always part of the output container type,
+    #       as end-of-block markers are encoded as a NULL pointer
+    # TODO: use Nothing/nothing for that?
+    ret = Vector{Union{Ptr{Cvoid}, Wanted}}()
     i = 1
     while i <= length(bt)
         ip = bt[i]::Ptr{Cvoid}
-        if UInt(ip) != (-1 % UInt) # See also jl_bt_is_native
-            # native frame
+
+        # end-of-block marker
+        if UInt(ip) == 0
             push!(ret, ip)
             i += 1
             continue
         end
+
+        # native frame
+        if UInt(ip) != (-1 % UInt)
+            # See also jl_bt_is_native
+            if Ptr{Cvoid} <: Wanted
+                push!(ret, ip)
+                i += 1
+            end
+            continue
+        end
+
         # Extended backtrace entry
         entry_metadata = reinterpret(UInt, bt[i+1])
         njlvalues =  entry_metadata & 0x7
         nuintvals = (entry_metadata >> 3) & 0x7
         tag       = (entry_metadata >> 6) & 0xf
         header    =  entry_metadata >> 10
         if tag == 1 # JL_BT_INTERP_FRAME_TAG
-            code = unsafe_pointer_to_objref(convert(Ptr{Any}, bt[i+2]))
-            mod = if njlvalues == 2
-                unsafe_pointer_to_objref(convert(Ptr{Any}, bt[i+3]))
-            else
-                nothing
+            if InterpreterIP <: Wanted
+                code = unsafe_pointer_to_objref(convert(Ptr{Any}, bt[i+2]))
+                mod = if njlvalues == 2
+                    unsafe_pointer_to_objref(convert(Ptr{Any}, bt[i+3]))
+                else
+                    nothing
+                end
+                push!(ret, InterpreterIP(code, header, mod))
             end
-            push!(ret, InterpreterIP(code, header, mod))
         else
             # Tags we don't know about are an error
             throw(ArgumentError("Unexpected extended backtrace entry tag $tag at bt[$i]"))
@@ -114,7 +136,7 @@ function backtrace()
     skip = 1
     bt1, bt2 = ccall(:jl_backtrace_from_here, Ref{SimpleVector}, (Cint, Cint), false, skip)
     t = @_gc_preserve_begin bt2
-    bt = _reformat_bt(bt1::Vector{Ptr{Cvoid}})
+    bt = _reformat_bt(bt1::Vector{Ptr{Cvoid}}, InstructionPointer)
     @_gc_preserve_end t
     return bt
 end
@@ -127,7 +149,7 @@ Get the backtrace of the current exception, for use within `catch` blocks.
 function catch_backtrace()
     bt1, bt2 = ccall(:jl_get_backtrace, Ref{SimpleVector}, ())
     t = @_gc_preserve_begin bt2
-    bt = _reformat_bt(bt1::Vector{Ptr{Cvoid}})
+    bt = _reformat_bt(bt1::Vector{Ptr{Cvoid}}, InstructionPointer)
     @_gc_preserve_end t
     return bt
 end
@@ -158,7 +180,7 @@ function catch_stack(task=current_task(); include_bt=true)
         if include_bt
             bt1, bt2 = raw[i+1], raw[i+2]
             t = @_gc_preserve_begin bt2
-            push!(formatted, (e, Base._reformat_bt(bt1)))
+            push!(formatted, (e, Base._reformat_bt(bt1, InstructionPointer)))
             @_gc_preserve_end t
         else
             push!(formatted, e)