[clang] [clang][bytecode] Don't deref() non-dereferencable pointers (PR #200774)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Timm Baeder (tbaederr)

<details>
<summary>Changes</summary>

That shouldn't happen and the isDummy() check wasn't enough.

---
Full diff: https://github.com/llvm/llvm-project/pull/200774.diff


2 Files Affected:

- (modified) clang/lib/AST/ByteCode/Interp.h (+1-1) 
- (modified) clang/test/AST/ByteCode/invalid.cpp (+11) 


``````````diff
diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index 86795e13a14ff..fa77e19afce66 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -2599,7 +2599,7 @@ bool SubOffset(InterpState &S, CodePtr OpPC) {
 template <ArithOp Op>
 static inline bool IncDecPtrHelper(InterpState &S, CodePtr OpPC,
                                    const Pointer &Ptr) {
-  if (Ptr.isDummy())
+  if (!Ptr.isDereferencable())
     return false;
 
   using OneT = Char<false>;
diff --git a/clang/test/AST/ByteCode/invalid.cpp b/clang/test/AST/ByteCode/invalid.cpp
index 9513645a74794..fb209d353c4a1 100644
--- a/clang/test/AST/ByteCode/invalid.cpp
+++ b/clang/test/AST/ByteCode/invalid.cpp
@@ -198,3 +198,14 @@ namespace InvalidUnaryOperator {
       ;
   }
 }
+
+namespace IncNonDereferencable {
+  struct S {};
+
+  void foo() {
+    S *s = (foo *)malloc(sizeof(*s)); // both-error {{expected expression}}
+    S *&sref = s;
+    for (int i = 0; i < 2; sref++)
+      ;
+  }
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/200774