[style] Tidied up comments, formatting, and polished test

Author: gbMattN

compiler-rt/lib/tysan/tysan.cpp

@@ -228,24 +228,26 @@ __tysan_check(void *addr, int size, tysan_type_descriptor *td, int flags) {
     OldTDPtr -= i;
     OldTD = *OldTDPtr;
 
-    // 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 with will give us the correct error.
-    tysan_type_descriptor *InternalMember = OldTD;
+    // 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.
+    tysan_type_descriptor *AccessedType = OldTD;
     if (OldTD->Tag == TYSAN_STRUCT_TD) {
-      for (int j = 0; j < OldTD->Struct.MemberCount; j++) {
+      for (int j = 0; j < OldTD->Struct.MemberCount; ++j) {
         if (OldTD->Struct.Members[j].Offset == i) {
-          InternalMember = OldTD->Struct.Members[j].Type;
+          AccessedType = OldTD->Struct.Members[j].Type;
           break;
         }
       }
     }
 
-    if (!isAliasingLegal(td, InternalMember, i))
+    if (!isAliasingLegal(td, AccessedType, i))
       reportError(addr, size, td, OldTD, AccessStr,
                   "accesses part of an existing object", -i, pc, bp, sp);
 

compiler-rt/test/tysan/global-struct-members.c

@@ -1,5 +1,5 @@
 // RUN: %clang_tysan -O0 %s -o %t && %run %t >%t.out 2>&1
-// RUN: FileCheck %s < %t.out
+// RUN: FileCheck %s --implicit-check-not ERROR < %t.out
 
 #include <stdio.h>
 
@@ -15,7 +15,6 @@ int main() {
   x.c = 3;
 
   printf("%d %d %d\n", x.a, x.b, x.c);
-  // CHECK-NOT: ERROR: TypeSanitizer: type-aliasing-violation
 
   for (size_t i = 0; i < 2; i++) {
     xArray[i].a = 1;
@@ -26,6 +25,6 @@ int main() {
   struct X *xPtr = (struct X *)&(xArray[0].c);
   xPtr->a = 1;
   // CHECK: ERROR: TypeSanitizer: type-aliasing-violation
-  // CHECK: WRITE of size 4 at {{.*}} with type int (in X at offset 0) accesses an existing object of type int (in X at offset 8)
-  // CHECK: {{#0 0x.* in main .*struct-members.c:}}[[@LINE-3]]
+  // CHECK-NEXT: WRITE of size 4 at {{.*}} with type int (in X at offset 0) accesses an existing object of type int (in X at offset 8)
+  // CHECK-NEXT: #0 0x{{.*}} in main {{.*}}struct-members.c:[[@LINE-3]]
 }