[Mlir-commits] [mlir] [mlir] Avoid parallel code in single-threaded builds (PR #229794)

[Anutosh Bhat]

https://github.com/anutosh491 updated https://github.com/llvm/llvm-project/pull/229794

>From a56f3d2e9861dae549bef5ee73d34bcc5243afad Mon Sep 17 00:00:00 2001
From: anutosh491 <andersonbhat491 at gmail.com>
Date: Wed, 7 Oct 2026 20:46:07 +0530
Subject: [PATCH 1/2] [mlir] Inline the threading query when threads are
 disabled

---
 mlir/include/mlir/IR/MLIRContext.h | 5 +++++
 mlir/lib/IR/MLIRContext.cpp        | 4 +++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/mlir/include/mlir/IR/MLIRContext.h b/mlir/include/mlir/IR/MLIRContext.h
index ce195518066d9..d63c863de6544 100644
--- a/mlir/include/mlir/IR/MLIRContext.h
+++ b/mlir/include/mlir/IR/MLIRContext.h
@@ -12,6 +12,7 @@
 #include "mlir/Support/LLVM.h"
 #include "mlir/Support/TypeID.h"
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/Config/llvm-config.h"
 #include <functional>
 #include <memory>
 #include <vector>
@@ -189,7 +190,11 @@ class MLIRContext {
   };
 
   /// Return true if multi-threading is enabled by the context.
+#if LLVM_ENABLE_THREADS
   bool isMultithreadingEnabled();
+#else
+  bool isMultithreadingEnabled() { return false; }
+#endif
 
   /// Set the flag specifying if multi-threading is disabled by the context.
   /// The command line debugging flag `--mlir-disable-threading` is overriding
diff --git a/mlir/lib/IR/MLIRContext.cpp b/mlir/lib/IR/MLIRContext.cpp
index 94cf420070131..68589d8c4c192 100644
--- a/mlir/lib/IR/MLIRContext.cpp
+++ b/mlir/lib/IR/MLIRContext.cpp
@@ -608,9 +608,11 @@ void MLIRContext::allowUnregisteredDialects(bool allowing) {
 }
 
 /// Return true if multi-threading is enabled by the context.
+#if LLVM_ENABLE_THREADS
 bool MLIRContext::isMultithreadingEnabled() {
-  return impl->threadingIsEnabled && llvm::llvm_is_multithreaded();
+  return impl->threadingIsEnabled;
 }
+#endif
 
 /// Set the flag specifying if multi-threading is disabled by the context.
 void MLIRContext::disableMultithreading(bool disable) {

>From 2cce64961b141b411e2ba58205436a76dae140c7 Mon Sep 17 00:00:00 2001
From: Anutosh Bhat <andersonbhat491 at gmail.com>
Date: Thu, 8 Oct 2026 09:41:10 +0530
Subject: [PATCH 2/2] formatting

---
 mlir/lib/IR/MLIRContext.cpp | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mlir/lib/IR/MLIRContext.cpp b/mlir/lib/IR/MLIRContext.cpp
index 68589d8c4c192..c5d66c27557c5 100644
--- a/mlir/lib/IR/MLIRContext.cpp
+++ b/mlir/lib/IR/MLIRContext.cpp
@@ -609,9 +609,7 @@ void MLIRContext::allowUnregisteredDialects(bool allowing) {
 
 /// Return true if multi-threading is enabled by the context.
 #if LLVM_ENABLE_THREADS
-bool MLIRContext::isMultithreadingEnabled() {
-  return impl->threadingIsEnabled;
-}
+bool MLIRContext::isMultithreadingEnabled() { return impl->threadingIsEnabled; }
 #endif
 
 /// Set the flag specifying if multi-threading is disabled by the context.