[llvm] [BOLT][rewrite] warn about functions without CFG before binary analyses. (PR #197294)

[Anatoly Trosinenko via llvm-commits]

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@@ -3888,8 +3888,24 @@ void RewriteInstance::runBinaryAnalyses() {
   NamedRegionTimer T("runBinaryAnalyses", "run binary analysis passes",
                      TimerGroupName, TimerGroupDesc, opts::TimeRewrite);
   BinaryFunctionPassManager Manager(*BC);
-  // FIXME: add a pass that warns about which functions do not have CFG,
-  // and therefore, analysis is most likely to be less accurate.
+
+  // Warn about functions without a reconstructed CFG: binary analyses degrade
+  // in accuracy on those and may produce false negatives.
+  uint64_t NoCFGCount = 0;
+  for (const auto &BFI : BC->getBinaryFunctions()) {
+    const BinaryFunction &BF = BFI.second;
+    if (BF.isIgnored() || BF.hasCFG())
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atrosinenko wrote:

Hmm, I wonder why `PAuthGadgetScanner.cpp` does not check `isIgnored()` as well - was it by design or should we skip `ignored` functions there too? Maybe @kbeyls remembers something on this decision.

https://github.com/llvm/llvm-project/pull/197294