[llvm] [Exegesis] CPU selection, when native arch and target mismatch (PR #131014)

[via llvm-commits]

https://github.com/AnastasiyaChernikova created https://github.com/llvm/llvm-project/pull/131014

None

>From 0e3afaf36233421ecaa2dadeecd0dbc2a11984c5 Mon Sep 17 00:00:00 2001
From: Anastasiya Chernikova <anastasiya.chernikova at syntacore.com>
Date: Wed, 12 Mar 2025 19:48:15 +0300
Subject: [PATCH] [Exegesis] CPU selection, when native arch and target
 mismatch

---
 llvm/tools/llvm-exegesis/lib/LlvmState.cpp | 6 ++++++
 llvm/tools/llvm-exegesis/llvm-exegesis.cpp | 5 +++++
 2 files changed, 11 insertions(+)

diff --git a/llvm/tools/llvm-exegesis/lib/LlvmState.cpp b/llvm/tools/llvm-exegesis/lib/LlvmState.cpp
index 9502cae993f67..af885a764124b 100644
--- a/llvm/tools/llvm-exegesis/lib/LlvmState.cpp
+++ b/llvm/tools/llvm-exegesis/lib/LlvmState.cpp
@@ -45,6 +45,12 @@ Expected<LLVMState> LLVMState::Create(std::string TripleName,
   if (CpuName == "native")
     CpuName = std::string(sys::getHostCPUName());
 
+  if (CpuName.empty()) {
+    std::unique_ptr<MCSubtargetInfo> Empty_STI(
+        TheTarget->createMCSubtargetInfo(TripleName, "", ""));
+    CpuName = Empty_STI->getAllProcessorDescriptions().begin()->Key;
+  }
+
   std::unique_ptr<MCSubtargetInfo> STI(
       TheTarget->createMCSubtargetInfo(TripleName, CpuName, ""));
   assert(STI && "Unable to create subtarget info!");
diff --git a/llvm/tools/llvm-exegesis/llvm-exegesis.cpp b/llvm/tools/llvm-exegesis/llvm-exegesis.cpp
index babcffeb9666a..6a37637dcebee 100644
--- a/llvm/tools/llvm-exegesis/llvm-exegesis.cpp
+++ b/llvm/tools/llvm-exegesis/llvm-exegesis.cpp
@@ -44,6 +44,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/TargetSelect.h"
 #include "llvm/TargetParser/Host.h"
+#include "llvm/TargetParser/Triple.h"
 #include <algorithm>
 #include <string>
 
@@ -479,6 +480,10 @@ void benchmarkMain() {
 #endif
   }
 
+  // case for cross generating, when native arch and target mismatch
+  if (Triple(sys::getProcessTriple()).getArch() != Triple(TripleName).getArch())
+    MCPU = "";
+
   InitializeAllExegesisTargets();
 #define LLVM_EXEGESIS(TargetName)                                              \
   LLVMInitialize##TargetName##AsmPrinter();                                    \