[llvm] [DataFlowSanitizer] Properly add ext attributes on arguments as needed. (PR #225443)

[Jonas Paulsson via llvm-commits]

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@@ -3138,6 +3167,26 @@ bool DFSanVisitor::visitWrappedCallBase(Function &F, CallBase &CB) {
     if (Function *CustomFn = dyn_cast<Function>(CustomF.getCallee())) {
       CustomFn->copyAttributesFrom(&F);
 
+      // Ensure all narrow integer arguments (both original and added
+      // shadow/origin) have an extension attribute on the function
+      // declaration. If none is present, add the right attribute for zero
+      // extend as all DFSan args are unsigned. TODO: Avoid getting here with
+      // missing attributes in the first place (use TLI/emitLibFunc()?).
----------------
JonPsson1 wrote:

I actually also get this in compiler-rt (trace-cmp.c): 
```

# .---command stderr------------      
# | ERROR: Missing extension attribute of passed value in call to function:       
# | Callee:  void @__dfsw___sanitizer_cov_trace_const_cmp4(i8 zeroext, i8 zeroext, i8, i8)     
# | Caller:  void @dfsw$__dfsw___sanitizer_cov_trace_const_cmp4(i8 zeroext, i8 zeroext, i8 zeroext, i8 zeroext) 
# |    
```

https://github.com/llvm/llvm-project/pull/225443