Pass: Do not use llvm::array_pod_sort to sort OpPassManagers.

[pcc]

OpPassManager contains a field of type std::unique_ptr which
is not guaranteed to be trivially relocatable so we cannot use
llvm::array_pod_sort.

[llvmbot]

@llvm/pr-subscribers-mlir

@llvm/pr-subscribers-mlir-core

Author: Peter Collingbourne (pcc)

Changes

OpPassManager contains a field of type std::unique_ptr which
is not guaranteed to be trivially relocatable so we cannot use
llvm::array_pod_sort.

---

Full diff: https://github.com/llvm/llvm-project/pull/129968.diff

1 Files Affected:

• (modified) mlir/lib/Pass/Pass.cpp (+7-7)

diff --git a/mlir/lib/Pass/Pass.cpp b/mlir/lib/Pass/Pass.cpp
index 6fd51c1e3cb53..67c18189b85e0 100644
--- a/mlir/lib/Pass/Pass.cpp
+++ b/mlir/lib/Pass/Pass.cpp
@@ -678,16 +678,16 @@ LogicalResult OpToOpPassAdaptor::tryMergeInto(MLIRContext *ctx,
   mgrs.clear();
 
   // After coalescing, sort the pass managers within rhs by name.
-  auto compareFn = [](const OpPassManager *lhs, const OpPassManager *rhs) {
+  auto compareFn = [](const OpPassManager &lhs, const OpPassManager &rhs) {
     // Order op-specific pass managers first and op-agnostic pass managers last.
-    if (std::optional<StringRef> lhsName = lhs->getOpName()) {
-      if (std::optional<StringRef> rhsName = rhs->getOpName())
-        return lhsName->compare(*rhsName);
-      return -1; // lhs(op-specific) < rhs(op-agnostic)
+    if (std::optional<StringRef> lhsName = lhs.getOpName()) {
+      if (std::optional<StringRef> rhsName = rhs.getOpName())
+        return *lhsName < *rhsName;
+      return true; // lhs(op-specific) < rhs(op-agnostic)
     }
-    return 1; // lhs(op-agnostic) > rhs(op-specific)
+    return false; // lhs(op-agnostic) > rhs(op-specific)
   };
-  llvm::array_pod_sort(rhs.mgrs.begin(), rhs.mgrs.end(), compareFn);
+  std::sort(rhs.mgrs.begin(), rhs.mgrs.end(), compareFn);
   return success();
 }
 

[joker-eph]

There is no C++ trait that allows to check this at compile time?

[pcc]

There is no C++ trait that allows to check this at compile time?

There is one but libc++ doesn't use it because it has the wrong semantics:

llvm-project/libcxx/include/__type_traits/is_trivially_relocatable.h

Line 29 in 5f70ed5

#if __has_builtin(__is_trivially_relocatable) && 0