[llvm] [BOLT] Overwrite .eh_frame and .gcc_except_table (PR #116755)

[Davide Italiano via llvm-commits]

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@@ -3887,6 +3887,43 @@ void RewriteInstance::mapCodeSections(BOLTLinker::SectionMapper MapSection) {
 
 void RewriteInstance::mapAllocatableSections(
     BOLTLinker::SectionMapper MapSection) {
+
+  if (opts::UseOldText || opts::StrictMode) {
+    auto tryRewriteSection = [&](BinarySection &OldSection,
+                                 BinarySection &NewSection) {
+      if (OldSection.getSize() < NewSection.getOutputSize())
+        return;
+
+      BC->outs() << "BOLT-INFO: rewriting " << OldSection.getName()
+                 << " in-place\n";
+
+      NewSection.setOutputAddress(OldSection.getAddress());
+      NewSection.setOutputFileOffset(OldSection.getInputFileOffset());
+      MapSection(NewSection, OldSection.getAddress());
+
+      // Pad contents with zeros.
+      NewSection.addPadding(OldSection.getSize() - NewSection.getOutputSize());
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dcci wrote:

I guess the padding is required to make sure the size match? We can add that in a comment

https://github.com/llvm/llvm-project/pull/116755