[llvm] [LLVM][TableGen] Move DecoderEmitter output to anonymous namespace (PR #136214)

[Rahul Joshi via llvm-commits]

https://github.com/jurahul updated https://github.com/llvm/llvm-project/pull/136214

>From bc87d29c22b560899c1fb8fe00cce032209340d0 Mon Sep 17 00:00:00 2001
From: Rahul Joshi <rjoshi at nvidia.com>
Date: Thu, 17 Apr 2025 14:03:48 -0700
Subject: [PATCH] [LLVM][TableGen] Move DecoderEmitter output to anonymous
 namespace

- Move the code generated by DecoderEmitter to anonymous nespace.
- Move AMDGPU's usage of this code from header file to .cpp file.
---
 .../Disassembler/AMDGPUDisassembler.cpp       | 40 +++++++++++++++++++
 .../AMDGPU/Disassembler/AMDGPUDisassembler.h  | 34 +---------------
 llvm/utils/TableGen/DecoderEmitter.cpp        |  4 +-
 3 files changed, 44 insertions(+), 34 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp b/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp
index 847121f251361..3fbba17159375 100644
--- a/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp
+++ b/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.cpp
@@ -487,6 +487,46 @@ static DecodeStatus decodeVersionImm(MCInst &Inst, unsigned Imm,
 //
 //===----------------------------------------------------------------------===//
 
+template <typename InsnType>
+DecodeStatus AMDGPUDisassembler::tryDecodeInst(const uint8_t *Table, MCInst &MI,
+                                               InsnType Inst, uint64_t Address,
+                                               raw_ostream &Comments) const {
+  assert(MI.getOpcode() == 0);
+  assert(MI.getNumOperands() == 0);
+  MCInst TmpInst;
+  HasLiteral = false;
+  const auto SavedBytes = Bytes;
+
+  SmallString<64> LocalComments;
+  raw_svector_ostream LocalCommentStream(LocalComments);
+  CommentStream = &LocalCommentStream;
+
+  DecodeStatus Res =
+      decodeInstruction(Table, TmpInst, Inst, Address, this, STI);
+
+  CommentStream = nullptr;
+
+  if (Res != MCDisassembler::Fail) {
+    MI = TmpInst;
+    Comments << LocalComments;
+    return MCDisassembler::Success;
+  }
+  Bytes = SavedBytes;
+  return MCDisassembler::Fail;
+}
+
+template <typename InsnType>
+DecodeStatus
+AMDGPUDisassembler::tryDecodeInst(const uint8_t *Table1, const uint8_t *Table2,
+                                  MCInst &MI, InsnType Inst, uint64_t Address,
+                                  raw_ostream &Comments) const {
+  for (const uint8_t *T : {Table1, Table2}) {
+    if (DecodeStatus Res = tryDecodeInst(T, MI, Inst, Address, Comments))
+      return Res;
+  }
+  return MCDisassembler::Fail;
+}
+
 template <typename T> static inline T eatBytes(ArrayRef<uint8_t>& Bytes) {
   assert(Bytes.size() >= sizeof(T));
   const auto Res =
diff --git a/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.h b/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.h
index 29452166e21a0..498ef655b7f45 100644
--- a/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.h
+++ b/llvm/lib/Target/AMDGPU/Disassembler/AMDGPUDisassembler.h
@@ -130,41 +130,11 @@ class AMDGPUDisassembler : public MCDisassembler {
 
   template <typename InsnType>
   DecodeStatus tryDecodeInst(const uint8_t *Table, MCInst &MI, InsnType Inst,
-                             uint64_t Address, raw_ostream &Comments) const {
-    assert(MI.getOpcode() == 0);
-    assert(MI.getNumOperands() == 0);
-    MCInst TmpInst;
-    HasLiteral = false;
-    const auto SavedBytes = Bytes;
-
-    SmallString<64> LocalComments;
-    raw_svector_ostream LocalCommentStream(LocalComments);
-    CommentStream = &LocalCommentStream;
-
-    DecodeStatus Res =
-        decodeInstruction(Table, TmpInst, Inst, Address, this, STI);
-
-    CommentStream = nullptr;
-
-    if (Res != Fail) {
-      MI = TmpInst;
-      Comments << LocalComments;
-      return MCDisassembler::Success;
-    }
-    Bytes = SavedBytes;
-    return MCDisassembler::Fail;
-  }
-
+                             uint64_t Address, raw_ostream &Comments) const;
   template <typename InsnType>
   DecodeStatus tryDecodeInst(const uint8_t *Table1, const uint8_t *Table2,
                              MCInst &MI, InsnType Inst, uint64_t Address,
-                             raw_ostream &Comments) const {
-    for (const uint8_t *T : {Table1, Table2}) {
-      if (DecodeStatus Res = tryDecodeInst(T, MI, Inst, Address, Comments))
-        return Res;
-    }
-    return MCDisassembler::Fail;
-  }
+                             raw_ostream &Comments) const;
 
   Expected<bool> onSymbolStart(SymbolInfoTy &Symbol, uint64_t &Size,
                                ArrayRef<uint8_t> Bytes,
diff --git a/llvm/utils/TableGen/DecoderEmitter.cpp b/llvm/utils/TableGen/DecoderEmitter.cpp
index 9c6015cc24576..35c928fae7b2b 100644
--- a/llvm/utils/TableGen/DecoderEmitter.cpp
+++ b/llvm/utils/TableGen/DecoderEmitter.cpp
@@ -2417,7 +2417,7 @@ void DecoderEmitter::run(raw_ostream &o) {
 #include "llvm/TargetParser/SubtargetFeature.h"
 #include <assert.h>
 
-namespace llvm {
+namespace {
 )";
 
   emitFieldFromInstruction(OS);
@@ -2561,7 +2561,7 @@ namespace llvm {
   // Emit the main entry point for the decoder, decodeInstruction().
   emitDecodeInstruction(OS, IsVarLenInst);
 
-  OS << "\n} // end namespace llvm\n";
+  OS << "\n} // end anonymous namespace\n";
 }
 
 void llvm::EmitDecoder(const RecordKeeper &RK, raw_ostream &OS,