[llvm] [NVPTX] Make GlobalUniqueCallSite a member of NVPTXISelLowering (PR #130212)

[Alex MacLean via llvm-commits]

https://github.com/AlexMaclean created https://github.com/llvm/llvm-project/pull/130212

Moving GlobalUniqueCallSite into NVPTXISelLowering ensures that in processes where multiple compilations occur, race conditions do not impact the generated PTX.

>From fa21654dc6eedbd4e277f3eee68bcde4a3bd5527 Mon Sep 17 00:00:00 2001
From: Alex Maclean <amaclean at nvidia.com>
Date: Thu, 6 Mar 2025 22:07:50 +0000
Subject: [PATCH] [NVPTX] Make GlobalUniqueCallSite a member of
 NVPTXISelLowering

---
 llvm/lib/Target/NVPTX/NVPTXISelLowering.cpp | 6 ++----
 llvm/lib/Target/NVPTX/NVPTXISelLowering.h   | 2 ++
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Target/NVPTX/NVPTXISelLowering.cpp b/llvm/lib/Target/NVPTX/NVPTXISelLowering.cpp
index 3e755c25fd91a..b62c15ddb97d3 100644
--- a/llvm/lib/Target/NVPTX/NVPTXISelLowering.cpp
+++ b/llvm/lib/Target/NVPTX/NVPTXISelLowering.cpp
@@ -73,8 +73,6 @@
 
 using namespace llvm;
 
-static std::atomic<unsigned> GlobalUniqueCallSite;
-
 static cl::opt<bool> sched4reg(
     "nvptx-sched4reg",
     cl::desc("NVPTX Specific: schedule for register pressue"), cl::init(false));
@@ -500,7 +498,7 @@ static SDValue MaybeBitcast(SelectionDAG &DAG, SDLoc DL, EVT VT,
 // NVPTXTargetLowering Constructor.
 NVPTXTargetLowering::NVPTXTargetLowering(const NVPTXTargetMachine &TM,
                                          const NVPTXSubtarget &STI)
-    : TargetLowering(TM), nvTM(&TM), STI(STI) {
+    : TargetLowering(TM), nvTM(&TM), STI(STI), GlobalUniqueCallSite(0) {
   // always lower memset, memcpy, and memmove intrinsics to load/store
   // instructions, rather
   // then generating calls to memset, mempcy or memmove.
@@ -1474,7 +1472,7 @@ SDValue NVPTXTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   unsigned FirstVAArg = CLI.NumFixedArgs; // position of the first variadic
   unsigned VAOffset = 0;                  // current offset in the param array
 
-  unsigned UniqueCallSite = GlobalUniqueCallSite.fetch_add(1);
+  const unsigned UniqueCallSite = GlobalUniqueCallSite++;
   SDValue TempChain = Chain;
   Chain = DAG.getCALLSEQ_START(Chain, UniqueCallSite, 0, dl);
   SDValue InGlue = Chain.getValue(1);
diff --git a/llvm/lib/Target/NVPTX/NVPTXISelLowering.h b/llvm/lib/Target/NVPTX/NVPTXISelLowering.h
index f41c569a65544..ff0241886223b 100644
--- a/llvm/lib/Target/NVPTX/NVPTXISelLowering.h
+++ b/llvm/lib/Target/NVPTX/NVPTXISelLowering.h
@@ -273,6 +273,8 @@ class NVPTXTargetLowering : public TargetLowering {
 
 private:
   const NVPTXSubtarget &STI; // cache the subtarget here
+  mutable unsigned GlobalUniqueCallSite;
+
   SDValue getParamSymbol(SelectionDAG &DAG, int idx, EVT) const;
 
   SDValue LowerADDRSPACECAST(SDValue Op, SelectionDAG &DAG) const;