[llvm] [HWASan] optimize AttrInfer fix for selective HWASan (PR #108111)

[Vitaly Buka via llvm-commits]

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@@ -591,47 +609,81 @@ void HWAddressSanitizer::createHwasanCtorComdat() {
   appendToCompilerUsed(M, Dummy);
 }
 
-/// Module-level initialization.
-///
-/// inserts a call to __hwasan_init to the module's constructor list.
-void HWAddressSanitizer::initializeModule() {
-  LLVM_DEBUG(dbgs() << "Init " << M.getName() << "\n");
-  TargetTriple = Triple(M.getTargetTriple());
-
-  for (auto &F : M.functions()) {
-    // Remove memory attributes that are invalid with HWASan.
-    // HWASan checks read from shadow, which invalidates memory(argmem: *)
-    // Short granule checks on function arguments read from the argument memory
-    // (last byte of the granule), which invalidates writeonly.
-    //
-    // This is not only true for sanitized functions, because AttrInfer can
-    // infer those attributes on libc functions, which is not true if those
-    // are instrumented (Android) or intercepted.
-
-    // The API is weird. `onlyReadsMemory` actually means "does not write", and
-    // `onlyWritesMemory` actually means "does not read". So we reconstruct
-    // "accesses memory" && "does not read" <=> "writes".
-    bool Changed = false;
-    if (!F.doesNotAccessMemory()) {
-      bool WritesMemory = !F.onlyReadsMemory();
-      bool ReadsMemory = !F.onlyWritesMemory();
-      if ((WritesMemory && !ReadsMemory) || F.onlyAccessesArgMemory()) {
-        F.removeFnAttr(Attribute::Memory);
-        Changed = true;
-      }
+void HWAddressSanitizer::removeFnAttributes(Function *F) {
+  if (!F || ChangedFns.contains(F))
+    return;
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vitalybuka wrote:

most of the patch can be extracted into NFC refactorings

https://github.com/llvm/llvm-project/pull/108111