[llvm] AMDGPU: Refactor unsafe atomicrmw remark emission (PR #89379)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm created https://github.com/llvm/llvm-project/pull/89379

Defers some of the setup work until the remark is actually emitted. Move big lambda into a helper function, and only use value capture of a pointer. Prepare to have different messages.

>From 47dda9a8a7a8c3fb8177cb452c2d02e1bb11b7a7 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Fri, 19 Apr 2024 08:41:31 +0200
Subject: [PATCH] AMDGPU: Refactor unsafe atomicrmw remark emission

Defers some of the setup work until the remark is actually emitted.
Move big lambda into a helper function, and only use value capture
of a pointer. Prepare to have different messages.
---
 llvm/lib/Target/AMDGPU/SIISelLowering.cpp | 33 ++++++++++++-----------
 1 file changed, 18 insertions(+), 15 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
index 0c706d51cb665f..c4592d43f4f8a8 100644
--- a/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIISelLowering.cpp
@@ -15996,32 +15996,35 @@ bool unsafeFPAtomicsDisabled(Function *F) {
          "true";
 }
 
+static OptimizationRemark emitAtomicRMWLegalRemark(const AtomicRMWInst *RMW) {
+  LLVMContext &Ctx = RMW->getContext();
+  SmallVector<StringRef> SSNs;
+  Ctx.getSyncScopeNames(SSNs);
+  StringRef MemScope = SSNs[RMW->getSyncScopeID()].empty()
+                           ? "system"
+                           : SSNs[RMW->getSyncScopeID()];
+
+  return OptimizationRemark(DEBUG_TYPE, "Passed", RMW)
+         << "Hardware instruction generated for atomic "
+         << RMW->getOperationName(RMW->getOperation())
+         << " operation at memory scope " << MemScope;
+}
+
 TargetLowering::AtomicExpansionKind
 SITargetLowering::shouldExpandAtomicRMWInIR(AtomicRMWInst *RMW) const {
   unsigned AS = RMW->getPointerAddressSpace();
   if (AS == AMDGPUAS::PRIVATE_ADDRESS)
     return AtomicExpansionKind::NotAtomic;
 
-  auto SSID = RMW->getSyncScopeID();
-
-  auto ReportUnsafeHWInst = [&](TargetLowering::AtomicExpansionKind Kind) {
+  auto ReportUnsafeHWInst = [=](TargetLowering::AtomicExpansionKind Kind) {
     OptimizationRemarkEmitter ORE(RMW->getFunction());
-    LLVMContext &Ctx = RMW->getFunction()->getContext();
-    SmallVector<StringRef> SSNs;
-    Ctx.getSyncScopeNames(SSNs);
-    auto MemScope = SSNs[RMW->getSyncScopeID()].empty()
-                        ? "system"
-                        : SSNs[RMW->getSyncScopeID()];
-    ORE.emit([&]() {
-      return OptimizationRemark(DEBUG_TYPE, "Passed", RMW)
-             << "Hardware instruction generated for atomic "
-             << RMW->getOperationName(RMW->getOperation())
-             << " operation at memory scope " << MemScope
-             << " due to an unsafe request.";
+    ORE.emit([=]() {
+      return emitAtomicRMWLegalRemark(RMW) << " due to an unsafe request.";
     });
     return Kind;
   };
 
+  auto SSID = RMW->getSyncScopeID();
   bool HasSystemScope =
       SSID == SyncScope::System ||
       SSID == RMW->getContext().getOrInsertSyncScopeID("one-as");