[llvm] [NFC][SPIRV] Move `SPIRVStripConvergenceIntrinsics` to Utils (PR #188537)

[Nathan Gauër via llvm-commits]

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@@ -0,0 +1,97 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass strips convergence intrinsics and convergencectrl operand bundles,
+// as those are only useful when modifying the CFG during IR passes.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/StripConvergenceIntrinsics.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/Utils.h"
+
+using namespace llvm;
+
+static bool stripConvergenceIntrinsics(Function &F) {
+  SmallVector<IntrinsicInst *> ConvergenceIntrinsics;
+  bool Changed = false;
+
+  for (BasicBlock &BB : F) {
+    for (Instruction &I : make_early_inc_range(BB)) {
+      auto *CI = dyn_cast<CallInst>(&I);
+      if (!CI)
+        continue;
+
+      // Strip a convergencectrl operand bundle if present. Note that
+      // convergence intrinsics (e.g. convergence.loop) may use a
+      // convergencectrl bundle.
+      if (CI->getOperandBundle(LLVMContext::OB_convergencectrl)) {
+        auto *NewCall = CallBase::removeOperandBundle(
+            CI, LLVMContext::OB_convergencectrl, CI->getIterator());
+        NewCall->copyMetadata(*CI);
+        CI->replaceAllUsesWith(NewCall);
+        CI->eraseFromParent();
+        CI = cast<CallInst>(NewCall);
+        Changed = true;
+      }
+
+      // Collect convergence intrinsics for deferred removal.
+      if (auto *II = dyn_cast<IntrinsicInst>(CI))
+        if (II->getIntrinsicID() == Intrinsic::experimental_convergence_entry ||
+            II->getIntrinsicID() == Intrinsic::experimental_convergence_loop ||
+            II->getIntrinsicID() == Intrinsic::experimental_convergence_anchor)
+          ConvergenceIntrinsics.push_back(II);
+    }
+  }
+
+  // Erase all convergence intrinsics now that convergence tokens are no
+  // longer in use.
+  for (IntrinsicInst *II : ConvergenceIntrinsics)
+    II->eraseFromParent();
+  Changed |= !ConvergenceIntrinsics.empty();
+
+  return Changed;
+}
+
+PreservedAnalyses
+StripConvergenceIntrinsicsPass::run(Function &F, FunctionAnalysisManager &) {
+  if (!stripConvergenceIntrinsics(F))
+    return PreservedAnalyses::all();
+  return PreservedAnalyses::none();
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Keenuts wrote:

I think this pass preserves almost all analysis:
 - loop analysis is ok
 - CFG, domtree, etc

https://github.com/llvm/llvm-project/pull/188537