[compiler-rt] [TySan] Fixed false positive when accessing offset member variables (PR #120406)

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``````````bash
git-clang-format --diff 95eb49a0905568a13c840b7866ce5d9c47e022f0 4d70fda2f8047cb7145776be78b9caf260ea67cf --extensions cpp,c -- compiler-rt/test/tysan/global-struct-members.c compiler-rt/lib/tysan/tysan.cpp
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View the diff from clang-format here.
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``````````diff
diff --git a/compiler-rt/lib/tysan/tysan.cpp b/compiler-rt/lib/tysan/tysan.cpp
index 8595d9014d..d8aee2278c 100644
--- a/compiler-rt/lib/tysan/tysan.cpp
+++ b/compiler-rt/lib/tysan/tysan.cpp
@@ -227,20 +227,21 @@ __tysan_check(void *addr, int size, tysan_type_descriptor *td, int flags) {
     int i = -((sptr)OldTD);
     OldTDPtr -= i;
     OldTD = *OldTDPtr;
-  
+
     tysan_type_descriptor *AccessedType = OldTD;
-    
+
     // Only check if we are accessing members if the type exists
-    if(OldTD != nullptr){
-      // When shadow memory is set for global objects, the entire object is tagged
-      // with the struct type This means that when you access a member variable,
-      // tysan reads that as you accessing a struct midway through, with 'i' being
-      // the offset Therefore, if you are accessing a struct, we need to find the
-      // member type. We can go through the members of the struct type and see if
-      // there is a member at the offset you are accessing the struct by. If there
-      // is indeed a member starting at offset 'i' in the struct, we should check
-      // aliasing legality with that type. If there isn't, we run alias checking
-      // on the struct which will give us the correct error.
+    if (OldTD != nullptr) {
+      // When shadow memory is set for global objects, the entire object is
+      // tagged with the struct type This means that when you access a member
+      // variable, tysan reads that as you accessing a struct midway through,
+      // with 'i' being the offset Therefore, if you are accessing a struct, we
+      // need to find the member type. We can go through the members of the
+      // struct type and see if there is a member at the offset you are
+      // accessing the struct by. If there is indeed a member starting at offset
+      // 'i' in the struct, we should check aliasing legality with that type. If
+      // there isn't, we run alias checking on the struct which will give us the
+      // correct error.
       if (OldTD->Tag == TYSAN_STRUCT_TD) {
         for (int j = 0; j < OldTD->Struct.MemberCount; ++j) {
           if (OldTD->Struct.Members[j].Offset == i) {

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https://github.com/llvm/llvm-project/pull/120406