[llvm] [ASan] Don't mark alloca as safe if address escapes to callee (PR #178591)

[Florian Mayer via llvm-commits]

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@@ -920,7 +920,11 @@ const StackSafetyGlobalInfo::InfoTy &StackSafetyGlobalInfo::getInfo() const {
         ++NumAllocaTotal;
         const AllocaInst *AI = KV.first;
         auto AIRange = getStaticAllocaSizeRange(*AI);
-        if (AIRange.contains(KV.second.Range)) {
+        // An alloca is safe if all accesses are in-bounds AND the address
+        // doesn't escape to other functions. If the address is passed to
+        // another function, ASan may instrument accesses in the callee, which
+        // requires the caller to properly initialize shadow memory.
+        if (AIRange.contains(KV.second.Range) && KV.second.Calls.empty()) {
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fmayer wrote:

I think this unnecessarily degrades Stack Safety for HWASan, which doesn't have this problem.

https://github.com/llvm/llvm-project/pull/178591