[llvm] [DAGISel][NFC] Add XForm/Convert/CopyToReg Comments (PR #178379)

[Sam Elliott via llvm-commits]

https://github.com/lenary created https://github.com/llvm/llvm-project/pull/178379

Thus updates the TableGen comments (both in the TableGen source, and the code that TableGen produces) to make it clearer what is being represented by the ConvertToTarget emitter, the XForm emitter, and the CopyToReg emitter.

>From a027d912c8034cb74932626bea4321ad6381366f Mon Sep 17 00:00:00 2001
From: Sam Elliott <aelliott at qti.qualcomm.com>
Date: Wed, 28 Jan 2026 00:10:54 -0800
Subject: [PATCH] [DAGISel][NFC] Add XForm/Convert/CopyToReg Comments

Thus updates the TableGen comments (both in the TableGen source, and the
code that TableGen produces) to make it clearer what is being
represented by the ConvertToTarget emitter, the XForm emitter, and the
CopyToReg emitter.
---
 llvm/utils/TableGen/DAGISelMatcher.h          |  9 ++++++++-
 llvm/utils/TableGen/DAGISelMatcherEmitter.cpp | 15 +++++++++------
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/llvm/utils/TableGen/DAGISelMatcher.h b/llvm/utils/TableGen/DAGISelMatcher.h
index 40de956a3646b..5b1452e44857e 100644
--- a/llvm/utils/TableGen/DAGISelMatcher.h
+++ b/llvm/utils/TableGen/DAGISelMatcher.h
@@ -885,8 +885,10 @@ class EmitRegisterMatcher : public Matcher {
 /// recorded node and converts it from being a ISD::Constant to
 /// ISD::TargetConstant, likewise for ConstantFP.
 class EmitConvertToTargetMatcher : public Matcher {
+  // Recorded Node
   unsigned Slot;
 
+  // Result
   unsigned ResultNo;
 
 public:
@@ -940,7 +942,9 @@ class EmitMergeInputChainsMatcher : public Matcher {
 /// pushing the chain and glue results.
 ///
 class EmitCopyToRegMatcher : public Matcher {
-  unsigned SrcSlot; // Value to copy into the physreg.
+  // Value to copy into the physreg.
+  unsigned SrcSlot;
+  // Register Destination
   const CodeGenRegister *DestPhysReg;
 
 public:
@@ -965,9 +969,12 @@ class EmitCopyToRegMatcher : public Matcher {
 /// EmitNodeXFormMatcher - Emit an operation that runs an SDNodeXForm on a
 /// recorded node and records the result.
 class EmitNodeXFormMatcher : public Matcher {
+  // Recorded Node
   unsigned Slot;
+  // Transform
   const Record *NodeXForm;
 
+  // Result
   unsigned ResultNo;
 
 public:
diff --git a/llvm/utils/TableGen/DAGISelMatcherEmitter.cpp b/llvm/utils/TableGen/DAGISelMatcherEmitter.cpp
index 0ab19d686714f..082d6fce3abe3 100644
--- a/llvm/utils/TableGen/DAGISelMatcherEmitter.cpp
+++ b/llvm/utils/TableGen/DAGISelMatcherEmitter.cpp
@@ -946,7 +946,7 @@ unsigned MatcherTableEmitter::EmitMatcher(const Matcher *N,
       OS << ", ";
     OS << Slot << ',';
     if (!OmitComments)
-      OS << " // #" << CTTM->getResultNo();
+      OS << " // #" << CTTM->getResultNo() << " = ConvertToTarget #" << Slot;
     OS << '\n';
     return 1 + (Slot >= 8);
   }
@@ -975,19 +975,22 @@ unsigned MatcherTableEmitter::EmitMatcher(const Matcher *N,
     if (Reg->EnumValue > 255) {
       assert(isUInt<16>(Reg->EnumValue) && "not handled");
       OS << "OPC_EmitCopyToRegTwoByte, " << Slot << ", "
-         << "TARGET_VAL(" << getQualifiedName(Reg->TheDef) << "),\n";
+         << "TARGET_VAL(" << getQualifiedName(Reg->TheDef) << "),";
       ++Bytes;
     } else {
       if (Slot < 8) {
         OS << "OPC_EmitCopyToReg" << Slot << ", "
-           << getQualifiedName(Reg->TheDef) << ",\n";
+           << getQualifiedName(Reg->TheDef) << ",";
         --Bytes;
       } else {
         OS << "OPC_EmitCopyToReg, " << Slot << ", "
-           << getQualifiedName(Reg->TheDef) << ",\n";
+           << getQualifiedName(Reg->TheDef) << ",";
       }
     }
+    if (!OmitComments)
+      OS << " // = #" << Slot;
 
+    OS << '\n';
     return Bytes;
   }
   case Matcher::EmitNodeXForm: {
@@ -995,8 +998,8 @@ unsigned MatcherTableEmitter::EmitMatcher(const Matcher *N,
     OS << "OPC_EmitNodeXForm, " << getNodeXFormID(XF->getNodeXForm()) << ", "
        << XF->getSlot() << ',';
     if (!OmitComments)
-      OS << " // " << XF->getNodeXForm()->getName() << " #"
-         << XF->getResultNo();
+      OS << " // #" << XF->getResultNo() << " = "
+         << XF->getNodeXForm()->getName() << " #" << XF->getSlot();
     OS << '\n';
     return 3;
   }