[clang] [compiler-rt] [UBSAN] add null and alignment checks for aggregates (PR #164548)

[Hubert Tong via cfe-commits]

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@@ -2249,6 +2249,24 @@ void CodeGenFunction::EmitAggregateCopy(LValue Dest, LValue Src, QualType Ty,
                                         bool isVolatile) {
   assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
 
+  // Sanitizer checks to verify source and destination pointers are
+  // non-null and properly aligned before copying.
+  // Without these checks, undefined behavior from invalid pointers goes undetected.
+  if (SanOpts.hasOneOf(SanitizerKind::Null | SanitizerKind::Alignment)) {
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hubert-reinterpretcast wrote:

I recommend omitting this check and leaving `sanitizePerformTypeCheck` to do its work.

https://github.com/llvm/llvm-project/pull/164548