From 303e63dbd87fcd700990d9c79ee80be7896e529c Mon Sep 17 00:00:00 2001
From: Marc Auberer <marc.auberer@chillibits.com>
Date: Sun, 2 Aug 2026 02:32:48 +0200
Subject: [PATCH] [JITLink] Remove LTmp workaround now that LLVM requires C++17
 (#213428)

C++17 guarantees the postfix-expression naming the called function is
sequenced before evaluation of its arguments, so
L->linkPhase1(std::move(L)) is well-formed without the LTmp indirection.
This should also be implemented by MSVC now. See here (P0145R3 and
P0400R0):

https://learn.microsoft.com/ar-sa/cpp/overview/visual-cpp-language-conformance?view=msvc-170
Disclaimer: As I have no LLVM Windows machine with MSVC at hand, I was
not able to test it myself.

Co-authored-by: Claude <noreply@anthropic.com>
---
 .../JITLink/JITLinkGeneric.cpp                | 30 +++----------------
 .../ExecutionEngine/JITLink/JITLinkGeneric.h  |  8 ++---
 2 files changed, 7 insertions(+), 31 deletions(-)

diff --git a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
index 17050b0a5248..c160f9d4e7f0 100644
--- a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.cpp
@@ -54,11 +54,7 @@ void JITLinkerBase::linkPhase1(std::unique_ptr<JITLinkerBase> Self) {
   Ctx->getMemoryManager().allocate(
       Ctx->getJITLinkDylib(), *G,
       [S = std::move(Self)](AllocResult AR) mutable {
-        // FIXME: Once MSVC implements c++17 order of evaluation rules for calls
-        // this can be simplified to
-        //          S->linkPhase2(std::move(S), std::move(AR));
-        auto *TmpSelf = S.get();
-        TmpSelf->linkPhase2(std::move(S), std::move(AR));
+        S->linkPhase2(std::move(S), std::move(AR));
       });
 }
 
@@ -95,10 +91,7 @@ void JITLinkerBase::linkPhase2(std::unique_ptr<JITLinkerBase> Self,
       dbgs() << "No external symbols for " << G->getName()
              << ". Proceeding immediately with link phase 3.\n";
     });
-    // FIXME: Once MSVC implements c++17 order of evaluation rules for calls
-    // this can be simplified. See below.
-    auto &TmpSelf = *Self;
-    TmpSelf.linkPhase3(std::move(Self), AsyncLookupResult());
+    Self->linkPhase3(std::move(Self), AsyncLookupResult());
     return;
   }
 
@@ -108,22 +101,11 @@ void JITLinkerBase::linkPhase2(std::unique_ptr<JITLinkerBase> Self,
            << " (may trigger materialization/linking of other graphs)...\n";
   });
 
-  // We're about to hand off ownership of ourself to the continuation. Grab a
-  // pointer to the context so that we can call it to initiate the lookup.
-  //
-  // FIXME: Once MSVC implements c++17 order of evaluation rules for calls this
-  // can be simplified to:
-  //
-  // Ctx->lookup(std::move(UnresolvedExternals),
-  //             [Self=std::move(Self)](Expected<AsyncLookupResult> Result) {
-  //               Self->linkPhase3(std::move(Self), std::move(Result));
-  //             });
   Ctx->lookup(std::move(ExternalSymbols),
               createLookupContinuation(
                   [S = std::move(Self)](
                       Expected<AsyncLookupResult> LookupResult) mutable {
-                    auto &TmpSelf = *S;
-                    TmpSelf.linkPhase3(std::move(S), std::move(LookupResult));
+                    S->linkPhase3(std::move(S), std::move(LookupResult));
                   }));
 }
 
@@ -171,11 +153,7 @@ void JITLinkerBase::linkPhase3(std::unique_ptr<JITLinkerBase> Self,
   }
 
   Alloc->finalize([S = std::move(Self)](FinalizeResult FR) mutable {
-    // FIXME: Once MSVC implements c++17 order of evaluation rules for calls
-    // this can be simplified to
-    //          S->linkPhase2(std::move(S), std::move(AR));
-    auto *TmpSelf = S.get();
-    TmpSelf->linkPhase4(std::move(S), std::move(FR));
+    S->linkPhase4(std::move(S), std::move(FR));
   });
 }
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h
index 0bf714d6fcdf..4892a394d9e5 100644
--- a/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h
+++ b/llvm/lib/ExecutionEngine/JITLink/JITLinkGeneric.h
@@ -116,12 +116,10 @@ public:
     // Ownership of the linker is passed into the linker's doLink function to
     // allow it to be passed on to async continuations.
     //
-    // FIXME: Remove LTmp once we have c++17.
     // C++17 sequencing rules guarantee that function name expressions are
-    // sequenced before arguments, so L->linkPhase1(std::move(L), ...) will be
-    // well formed.
-    auto &LTmp = *L;
-    LTmp.linkPhase1(std::move(L));
+    // sequenced before arguments, so L->linkPhase1(std::move(L)) is well
+    // formed.
+    L->linkPhase1(std::move(L));
   }
 
 private: