Reapply "[DLCov] Implement DebugLoc coverage tracking (#107279)"

Reapplied after fixing the config issue that was causing issues following
the previous merge.

This reverts commit fdbf073a86573c9ac4d595fac8e06d252ce1469f.

1 files changed, 16 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 2271f01..c9ceb49 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -962,6 +962,22 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
       Debugify.setOrigDIVerifyBugsReportFilePath(
           CodeGenOpts.DIBugsReportFilePath);
     Debugify.registerCallbacks(PIC, MAM);
+
+#if LLVM_ENABLE_DEBUGLOC_COVERAGE_TRACKING
+    // If we're using debug location coverage tracking, mark all the
+    // instructions coming out of the frontend without a DebugLoc as being
+    // compiler-generated, to prevent both those instructions and new
+    // instructions that inherit their location from being treated as
+    // incorrectly empty locations.
+    for (Function &F : *TheModule) {
+      if (!F.getSubprogram())
+        continue;
+      for (BasicBlock &BB : F)
+        for (Instruction &I : BB)
+          if (!I.getDebugLoc())
+            I.setDebugLoc(DebugLoc::getCompilerGenerated());
+    }
+#endif
   }
   // Attempt to load pass plugins and register their callbacks with PB.
   for (auto &PluginFN : CodeGenOpts.PassPlugins) {