[lld] [AArch64][GCS][LLD] Introduce -zgcs-report-dynamic Command Line Option (PR #127787)

[Fangrui Song via llvm-commits]

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@@ -1418,6 +1438,37 @@ std::vector<uint32_t> SharedFile::parseVerneed(const ELFFile<ELFT> &obj,
   return verneeds;
 }
 
+// To determine if a shared file can support any of the GNU Attributes,
+// the .note.gnu.properties section need to be read. The appropriate
+// location in memory is located then the GnuPropertyNote can be parsed.
+// This is the same process as is used for readGnuProperty, however we
+// do not pass the data variable as, without an InputSection, its value
+// is unknown in a SharedFile. This is ok as the information that would
+// be collected from this is irrelevant for a dynamic object.
+template <typename ELFT>
+void SharedFile::parseGnuAndFeatures(const uint8_t *base,
+                                     const typename ELFT::PhdrRange headers) {
+  if (headers.size() == 0)
+    return;
+  uint32_t featureAndType = ctx.arg.emachine == EM_AARCH64
+                                ? GNU_PROPERTY_AARCH64_FEATURE_1_AND
+                                : GNU_PROPERTY_X86_FEATURE_1_AND;
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MaskRay wrote:

This PR should not change the behavior of x86. DSOs are ignored for `GNU_PROPERTY_X86_FEATURE_1_AND` and I think we should continue ignoring it. 

https://github.com/llvm/llvm-project/pull/127787