[DLCov] Origin-Tracking: Add config options

llvm/CMakeLists.txt

@@ -569,8 +569,8 @@ endif()
 option(LLVM_ENABLE_CRASH_DUMPS "Turn on memory dumps on crashes. Currently only implemented on Windows." OFF)
 
 set(LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING "DISABLED" CACHE STRING
-  "Enhance Debugify's line number coverage tracking; enabling this is ABI-breaking. Can be DISABLED, or COVERAGE.")
-set_property(CACHE LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING PROPERTY STRINGS DISABLED COVERAGE)
+  "Enhance Debugify's line number coverage tracking; enabling this is ABI-breaking. Can be DISABLED, COVERAGE, or COVERAGE_AND_ORIGIN.")
+set_property(CACHE LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING PROPERTY STRINGS DISABLED COVERAGE COVERAGE_AND_ORIGIN)
 
 option(LLVM_EXPERIMENTAL_KEY_INSTRUCTIONS
   "Add additional fields to DILocations to support Key Instructions" OFF)

llvm/cmake/modules/HandleLLVMOptions.cmake

@@ -200,6 +200,9 @@ string(TOUPPER "${LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING}" uppercase_LLVM_ENABLE
 
 if( uppercase_LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING STREQUAL "COVERAGE" )
   set( LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING 1 )
+elseif( uppercase_LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING STREQUAL "COVERAGE_AND_ORIGIN" )
+  set( LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING 1 )
+  set( LLVM_ENABLE_DEBUGLOC_ORIGIN_TRACKING 1 )
 elseif( uppercase_LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING STREQUAL "DISABLED" OR NOT DEFINED LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING )
   # The DISABLED setting is default and requires no additional defines.
 else()

llvm/docs/CMake.rst

@@ -482,11 +482,14 @@ enabled sub-projects. Nearly all of these variable names begin with
 **LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING**:STRING
   Enhances Debugify's ability to detect line number errors by storing extra
   information inside Instructions, removing false positives from Debugify's
-  results at the cost of performance. Allowed values are `DISABLED` (default)
-  and `COVERAGE`. `COVERAGE` tracks whether and why a line number was
-  intentionally dropped or not generated for an instruction, allowing Debugify
-  to avoid reporting these as errors; this comes with a small performance cost
-  of ~0.1%. `COVERAGE` is an ABI-breaking option.
+  results at the cost of performance. Allowed values are `DISABLED` (default),
+  `COVERAGE`, and `COVERAGE_AND_ORIGIN`. `COVERAGE` tracks whether and why a
+  line number was intentionally dropped or not generated for an instruction,
+  allowing Debugify to avoid reporting these as errors; this comes with a small
+  performance cost of ~0.1%. `COVERAGE_AND_ORIGIN` additionally stores a
+  stacktrace of the point where each DebugLoc is unintentionally dropped,
+  allowing for much easier bug triaging at the cost of a ~10x performance
+  slowdown. `COVERAGE` and `COVERAGE_AND_ORIGIN` are ABI-breaking options.
 
 **LLVM_ENABLE_DIA_SDK**:BOOL
   Enable building with MSVC DIA SDK for PDB debugging support. Available

llvm/include/llvm/Config/llvm-config.h.cmake

@@ -133,4 +133,8 @@
    and to 0 otherwise. */
 #cmakedefine01 LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING
 
+/* Define to 1 to enable expensive tracking of the origin of debug location
+   coverage bugs, and to 0 otherwise. */
+#cmakedefine01 LLVM_ENABLE_DEBUGLOC_ORIGIN_TRACKING
+
 #endif