[llvm] [SelectionDAG] Add space-optimized forms of OPC_EmitConvertToTarget (PR #73286)

[Wang Pengcheng via llvm-commits]

https://github.com/wangpc-pp created https://github.com/llvm/llvm-project/pull/73286

These new opcodes implicitly indicate the RecNo.

Overall this reduces the llc binary size with all in-tree targets by
about 13K.


>From 1b027dcbf350df9943650c28f24dbb92c1cbaea3 Mon Sep 17 00:00:00 2001
From: wangpc <wangpengcheng.pp at bytedance.com>
Date: Fri, 24 Nov 2023 14:09:40 +0800
Subject: [PATCH] [SelectionDAG] Add space-optimized forms of
 OPC_EmitConvertToTarget

These new opcodes implicitly indicate the RecNo.

Overall this reduces the llc binary size with all in-tree targets by
about 13K.
---
 llvm/include/llvm/CodeGen/SelectionDAGISel.h       |  8 ++++++++
 llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp | 14 ++++++++++++--
 llvm/utils/TableGen/DAGISelMatcherEmitter.cpp      | 11 ++++++++---
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/llvm/include/llvm/CodeGen/SelectionDAGISel.h b/llvm/include/llvm/CodeGen/SelectionDAGISel.h
index e6513eb6abc8749..aa23d68a7570b31 100644
--- a/llvm/include/llvm/CodeGen/SelectionDAGISel.h
+++ b/llvm/include/llvm/CodeGen/SelectionDAGISel.h
@@ -187,6 +187,14 @@ class SelectionDAGISel : public MachineFunctionPass {
     OPC_EmitRegister,
     OPC_EmitRegister2,
     OPC_EmitConvertToTarget,
+    OPC_EmitConvertToTarget0,
+    OPC_EmitConvertToTarget1,
+    OPC_EmitConvertToTarget2,
+    OPC_EmitConvertToTarget3,
+    OPC_EmitConvertToTarget4,
+    OPC_EmitConvertToTarget5,
+    OPC_EmitConvertToTarget6,
+    OPC_EmitConvertToTarget7,
     OPC_EmitMergeInputChains,
     OPC_EmitMergeInputChains1_0,
     OPC_EmitMergeInputChains1_1,
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 7d9bebdca127224..6f1f0bb5947c997 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -3486,9 +3486,19 @@ void SelectionDAGISel::SelectCodeCommon(SDNode *NodeToMatch,
       continue;
     }
 
-    case OPC_EmitConvertToTarget:  {
+    case OPC_EmitConvertToTarget:
+    case OPC_EmitConvertToTarget0:
+    case OPC_EmitConvertToTarget1:
+    case OPC_EmitConvertToTarget2:
+    case OPC_EmitConvertToTarget3:
+    case OPC_EmitConvertToTarget4:
+    case OPC_EmitConvertToTarget5:
+    case OPC_EmitConvertToTarget6:
+    case OPC_EmitConvertToTarget7: {
       // Convert from IMM/FPIMM to target version.
-      unsigned RecNo = MatcherTable[MatcherIndex++];
+      unsigned RecNo = Opcode == OPC_EmitConvertToTarget
+                           ? MatcherTable[MatcherIndex++]
+                           : Opcode - OPC_EmitConvertToTarget0;
       assert(RecNo < RecordedNodes.size() && "Invalid EmitConvertToTarget");
       SDValue Imm = RecordedNodes[RecNo].first;
 
diff --git a/llvm/utils/TableGen/DAGISelMatcherEmitter.cpp b/llvm/utils/TableGen/DAGISelMatcherEmitter.cpp
index 4a11991036efc11..4a39f07c00e9049 100644
--- a/llvm/utils/TableGen/DAGISelMatcherEmitter.cpp
+++ b/llvm/utils/TableGen/DAGISelMatcherEmitter.cpp
@@ -707,10 +707,15 @@ EmitMatcher(const Matcher *N, const unsigned Indent, unsigned CurrentIdx,
     }
   }
 
-  case Matcher::EmitConvertToTarget:
-    OS << "OPC_EmitConvertToTarget, "
-       << cast<EmitConvertToTargetMatcher>(N)->getSlot() << ",\n";
+  case Matcher::EmitConvertToTarget: {
+    unsigned Slot = cast<EmitConvertToTargetMatcher>(N)->getSlot();
+    if (Slot < 8) {
+      OS << "OPC_EmitConvertToTarget" << Slot << ",\n";
+      return 1;
+    }
+    OS << "OPC_EmitConvertToTarget, " << Slot << ",\n";
     return 2;
+  }
 
   case Matcher::EmitMergeInputChains: {
     const EmitMergeInputChainsMatcher *MN =