[llvm] [llvm][AArch64][TableGen] Create a ProcessorAlias record. NFC (PR #96249)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: Jon Roelofs (jroelofs)

<details>
<summary>Changes</summary>

... and use it to organize all of the Apple CPU aliases.

---
Full diff: https://github.com/llvm/llvm-project/pull/96249.diff


2 Files Affected:

- (modified) llvm/lib/Target/AArch64/AArch64Processors.td (+16-19) 
- (modified) llvm/utils/TableGen/ARMTargetDefEmitter.cpp (+22-3) 


``````````diff
diff --git a/llvm/lib/Target/AArch64/AArch64Processors.td b/llvm/lib/Target/AArch64/AArch64Processors.td
index 53b46ff42b72f..46f665cb15a9a 100644
--- a/llvm/lib/Target/AArch64/AArch64Processors.td
+++ b/llvm/lib/Target/AArch64/AArch64Processors.td
@@ -930,6 +930,12 @@ def ProcessorFeatures {
   list<SubtargetFeature> Generic = [FeatureFPARMv8, FeatureNEON, FeatureETE];
 }
 
+// Define an alternative name for a given Processor.
+class ProcessorAlias<string n, string alias> {
+  string Name = n;
+  string Alias = alias;
+}
+
 // FeatureFuseAdrpAdd is enabled under Generic to allow linker merging
 // optimizations.
 def : ProcessorModel<"generic", CortexA510Model, ProcessorFeatures.Generic,
@@ -1050,15 +1056,12 @@ def : ProcessorModel<"tsv110", TSV110Model, ProcessorFeatures.TSV110,
 
 // Apple CPUs
 
-// Support cyclone as an alias for apple-a7 so we can still LTO old bitcode.
-def : ProcessorModel<"cyclone", CycloneModel, ProcessorFeatures.AppleA7,
-                     [TuneAppleA7]>;
 def : ProcessorModel<"apple-a7", CycloneModel, ProcessorFeatures.AppleA7,
                      [TuneAppleA7]>;
-def : ProcessorModel<"apple-a8", CycloneModel, ProcessorFeatures.AppleA7,
-                     [TuneAppleA7]>;
-def : ProcessorModel<"apple-a9", CycloneModel, ProcessorFeatures.AppleA7,
-                     [TuneAppleA7]>;
+// Support cyclone as an alias for apple-a7 so we can still LTO old bitcode.
+def : ProcessorAlias<"cyclone", "apple-a7">;
+def : ProcessorAlias<"apple-a8", "apple-a7">;
+def : ProcessorAlias<"apple-a9", "apple-a7">;
 
 def : ProcessorModel<"apple-a10", CycloneModel, ProcessorFeatures.AppleA10,
                      [TuneAppleA10]>;
@@ -1068,28 +1071,23 @@ def : ProcessorModel<"apple-a11", CycloneModel, ProcessorFeatures.AppleA11,
 
 def : ProcessorModel<"apple-a12", CycloneModel, ProcessorFeatures.AppleA12,
                      [TuneAppleA12]>;
-def : ProcessorModel<"apple-s4", CycloneModel, ProcessorFeatures.AppleA12,
-                     [TuneAppleA12]>;
-def : ProcessorModel<"apple-s5", CycloneModel, ProcessorFeatures.AppleA12,
-                     [TuneAppleA12]>;
+def : ProcessorAlias<"apple-s4", "apple-a12">;
+def : ProcessorAlias<"apple-s5", "apple-a12">;
 
 def : ProcessorModel<"apple-a13", CycloneModel, ProcessorFeatures.AppleA13,
                      [TuneAppleA13]>;
 
 def : ProcessorModel<"apple-a14", CycloneModel, ProcessorFeatures.AppleA14,
                      [TuneAppleA14]>;
-def : ProcessorModel<"apple-m1", CycloneModel, ProcessorFeatures.AppleA14,
-                     [TuneAppleA14]>;
+def : ProcessorAlias<"apple-m1", "apple-a14">;
 
 def : ProcessorModel<"apple-a15", CycloneModel, ProcessorFeatures.AppleA15,
                      [TuneAppleA15]>;
-def : ProcessorModel<"apple-m2", CycloneModel, ProcessorFeatures.AppleA15,
-                     [TuneAppleA15]>;
+def : ProcessorAlias<"apple-m2", "apple-a15">;
 
 def : ProcessorModel<"apple-a16", CycloneModel, ProcessorFeatures.AppleA16,
                      [TuneAppleA16]>;
-def : ProcessorModel<"apple-m3", CycloneModel, ProcessorFeatures.AppleA16,
-                     [TuneAppleA16]>;
+def : ProcessorAlias<"apple-m3", "apple-a16">;
 
 def : ProcessorModel<"apple-a17", CycloneModel, ProcessorFeatures.AppleA17,
                      [TuneAppleA17]>;
@@ -1098,8 +1096,7 @@ def : ProcessorModel<"apple-m4", CycloneModel, ProcessorFeatures.AppleM4,
                      [TuneAppleM4]>;
 
 // Alias for the latest Apple processor model supported by LLVM.
-def : ProcessorModel<"apple-latest", CycloneModel, ProcessorFeatures.AppleM4,
-                     [TuneAppleM4]>;
+def : ProcessorAlias<"apple-latest", "apple-m4">;
 
 
 // Fujitsu A64FX
diff --git a/llvm/utils/TableGen/ARMTargetDefEmitter.cpp b/llvm/utils/TableGen/ARMTargetDefEmitter.cpp
index e22f353b451f9..3e111813280a3 100644
--- a/llvm/utils/TableGen/ARMTargetDefEmitter.cpp
+++ b/llvm/utils/TableGen/ARMTargetDefEmitter.cpp
@@ -221,8 +221,28 @@ static void EmitARMTargetDef(RecordKeeper &RK, raw_ostream &OS) {
   OS << "#ifdef EMIT_CPU_INFO\n"
      << "inline constexpr CpuInfo CpuInfos[] = {\n";
 
+  std::map<std::string, std::pair<std::string, const Record *>> ProcessorModels;
   for (const Record *Rec : RK.getAllDerivedDefinitions("ProcessorModel")) {
     auto Name = Rec->getValueAsString("Name");
+    ProcessorModels.insert(std::make_pair(Name, std::make_pair(Name, Rec)));
+  }
+
+  for (const Record *Rec : RK.getAllDerivedDefinitions("ProcessorAlias")) {
+    std::string Name = Rec->getValueAsString("Name").str();
+    auto Alias = Rec->getValueAsString("Alias");
+    auto It = ProcessorModels.find(Alias.str());
+    if (!ProcessorModels
+             .insert(
+                 std::make_pair(Name, std::make_pair(Alias, It->second.second)))
+             .second)
+      PrintFatalError(
+          Rec, "Alias duplicates an existing ProcessorAlias or ProcessorModel");
+  }
+
+  for (auto &[K, V] : ProcessorModels) {
+    auto Name = K;
+    auto Alias = V.first;
+    auto *Rec = V.second;
     auto Features = Rec->getValueAsListOfDefs("Features");
 
     // "apple-latest" is backend-only, should not be accepted by TargetParser.
@@ -253,9 +273,8 @@ static void EmitARMTargetDef(RecordKeeper &RK, raw_ostream &OS) {
     auto Profile = Arch->getValueAsString("Profile");
     auto ArchInfo = ArchInfoName(Major, Minor, Profile);
 
-    // The apple-latest alias is backend only, do not expose it to -mcpu.
-    if (Name == "apple-latest")
-      continue;
+    if (Name != Alias)
+      OS << "  // Alias: " << Name << " -> " << Alias << "\n";
 
     OS << "  {\n"
        << "    \"" << Name << "\",\n"

``````````

</details>


https://github.com/llvm/llvm-project/pull/96249