[clang] [llvm] [Clang] Support `--offload-compress` for offload binaries (PR #227765)

[Yaxun Liu via cfe-commits]

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@@ -143,10 +143,13 @@ static Error bundleImages() {
 
   SmallString<0> Buffer;
   if (Compress) {
-    if (const char *Reason =
-            compression::getReasonIfUnsupported(CompressionFormat))
+    compression::Format Format = CompressionFormat;
+    if (!CompressionFormat.getNumOccurrences() &&
+        !compression::zstd::isAvailable())
+      Format = compression::Format::Zlib;
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yxsamliu wrote:

A quick reminder: the new level check still rejects valid values. zlib accepts `-1`, and zstd accepts `-10`. Could you update the check and add tests for both?

https://github.com/llvm/llvm-project/pull/227765