[lld] [llvm] [WebAssembly] Add segment NO_STRIP flag to support private retained data (PR #81539)

[Yuta Saito via llvm-commits]

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@@ -70,6 +70,8 @@ void MCSectionWasm::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
     OS << 'S';
   if (SegmentFlags & wasm::WASM_SEG_FLAG_TLS)
     OS << 'T';
+  if (SegmentFlags & wasm::WASM_SEG_FLAG_NO_STRIP)
+    OS << 'R';
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kateinoigakukun wrote:

Based on how `WASM_SYMBOL_NO_STRIP ` is chosen as a symbol flag name in https://reviews.llvm.org/D62542#1519799, I agree we don't need to align with it because the segment flag is not based on `.no_dead_strip`. Now I feel `WASM_SEG_FLAG_RETAIN` makes more sense 👍 

https://github.com/llvm/llvm-project/pull/81539