[llvm] [AMDGPU] Replace some uses of raw_svector_ostream with Twine. NFC. (PR #137627)

[via llvm-commits]

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@@ -261,11 +261,8 @@ void AMDGPUPALMetadata::setEntryPoint(unsigned CC, StringRef Name) {
 
   // Set .entry_point which is defined
   // to be _amdgpu_<stage> and _amdgpu_cs for non-shader functions
-  SmallString<16> EPName("_amdgpu_");
-  raw_svector_ostream EPNameOS(EPName);
-  EPNameOS << getStageName(CC) + 1;
-  getHwStage(CC)[".entry_point"] =
-      MsgPackDoc.getNode(EPNameOS.str(), /*Copy=*/true);
+  getHwStage(CC)[".entry_point"] = MsgPackDoc.getNode(
+      (Twine("_amdgpu_") + getStageName(CC).drop_front()).str(), /*Copy=*/true);
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LU-JOHN wrote:

FWIW, I feel like the new code is more readable.

https://github.com/llvm/llvm-project/pull/137627