[compiler-rt] DO_NOT_MERGE (PR #66682)

[Florian Mayer via llvm-commits]

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@@ -446,8 +458,51 @@ class BaseReport {
   const HeapChunk heap;
   const Allocations allocations;
   const OverflowCandidate candidate;
+
+  struct {
+    uptr addr = 0;
+    tag_t tags[512] = {};
+    tag_t short_tags[ARRAY_SIZE(tags)] = {};
+  } shadow;
 };
 
+void BaseReport::CopyShadow() {
+  if (!MemIsApp(untagged_addr))
+    return;
+
+  shadow.addr = MemToShadow(untagged_addr) - ARRAY_SIZE(shadow.tags) / 2;
+  for (uptr i = 0; i < ARRAY_SIZE(shadow.tags); ++i) {
+    uptr tag_addr = shadow.addr + i;
+    if (!MemIsShadow(tag_addr))
+      continue;
+    shadow.tags[i] = *reinterpret_cast<tag_t *>(tag_addr);
+    uptr granule_addr = ShadowToMem(tag_addr);
+    if (1 <= shadow.tags[i] && shadow.tags[i] <= kShadowAlignment &&
+        IsAccessibleMemoryRange(granule_addr, kShadowAlignment)) {
+      shadow.short_tags[i] =
+          *reinterpret_cast<tag_t *>(granule_addr + kShadowAlignment - 1);
+    }
+  }
+}
+
+tag_t BaseReport::GetTagCopy(uptr addr) const {
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fmayer wrote:

Why do we expect for those to be called out of range? Should the checks be assert instead? `0` tag is not the same as "we don't know" really.

https://github.com/llvm/llvm-project/pull/66682