[compiler-rt] 450ec77 - [NFC][asan] Move a few precondition checks

[Vitaly Buka via llvm-commits]

Author: Vitaly Buka
Date: 2022-11-27T23:00:42-08:00
New Revision: 450ec77037294594c5e7cbbd780e93a97c957132

URL: https://github.com/llvm/llvm-project/commit/450ec77037294594c5e7cbbd780e93a97c957132
DIFF: https://github.com/llvm/llvm-project/commit/450ec77037294594c5e7cbbd780e93a97c957132.diff

LOG: [NFC][asan] Move a few precondition checks

Added: 
    

Modified: 
    compiler-rt/lib/asan/asan_poisoning.cpp

Removed: 
    


################################################################################
diff  --git a/compiler-rt/lib/asan/asan_poisoning.cpp b/compiler-rt/lib/asan/asan_poisoning.cpp
index abb8ff4d2580..558ec9d1f13e 100644
--- a/compiler-rt/lib/asan/asan_poisoning.cpp
+++ b/compiler-rt/lib/asan/asan_poisoning.cpp
@@ -492,6 +492,12 @@ void __sanitizer_annotate_double_ended_contiguous_container(
     ReportBadParamsToAnnotateDoubleEndedContiguousContainer(
         storage_beg, storage_end, old_beg, old_end, new_beg, new_end, &stack);
   }
+  CHECK_LE(storage_end - storage_beg,
+           FIRST_32_SECOND_64(1UL << 30, 1ULL << 40));  // Sanity check.
+
+  if ((old_beg == old_end && new_beg == new_end) ||
+      (old_beg == new_beg && old_end == new_end))
+    return;  // Nothing to do here.
 
   // Right now, the function does not support:
   // - unaligned storage beginning
@@ -513,9 +519,6 @@ void __sanitizer_annotate_double_ended_contiguous_container(
   }
 
   if (old_beg != new_beg) {
-    CHECK_LE(storage_end - storage_beg,
-             FIRST_32_SECOND_64(1UL << 30, 1ULL << 40));  // Sanity check.
-
     // There are two situations: we are poisoning or unpoisoning.
     // WARNING: at the moment we do not poison prefixes of blocks described by
     // one byte in shadow memory, so we have to unpoison prefixes of blocks with
@@ -566,9 +569,6 @@ void __sanitizer_annotate_double_ended_contiguous_container(
   }
 
   if (old_end != new_end) {
-    CHECK_LE(storage_end - storage_beg,
-             FIRST_32_SECOND_64(1UL << 30, 1ULL << 40));  // Sanity check.
-
     if (old_end < new_end) {  // We are unpoisoning memory
       uptr a = RoundDownTo(old_end, granularity);
       uptr c = RoundDownTo(new_end, granularity);