[llvm] PreISelIntrinsicLowering: Lower llvm.exp to a loop if scalable vec arg (PR #117568)

[Matt Arsenault via llvm-commits]

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@@ -0,0 +1,70 @@
+//===- LowerMathIntrinsics.cpp ---------------------------------*- C++ -*--===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/LowerMathIntrinsics.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "lower-math-intrinsics"
+
+using namespace llvm;
+
+bool llvm::lowerUnaryMathIntrinsicWithScalableVecArgAsLoop(Module &M,
+                                                           CallInst *CI) {
+  ScalableVectorType *ScalableTy =
+      dyn_cast<ScalableVectorType>(CI->getArgOperand(0)->getType());
+  if (!ScalableTy) {
+    return false;
+  }
+
+  BasicBlock *PreLoopBB = CI->getParent();
+  BasicBlock *PostLoopBB = nullptr;
+  Function *ParentFunc = PreLoopBB->getParent();
+  LLVMContext &Ctx = PreLoopBB->getContext();
+
+  PostLoopBB = PreLoopBB->splitBasicBlock(CI);
+  BasicBlock *LoopBB = BasicBlock::Create(Ctx, "", ParentFunc, PostLoopBB);
+  PreLoopBB->getTerminator()->setSuccessor(0, LoopBB);
+
+  // loop preheader
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arsenm wrote:

Capitalize comments

https://github.com/llvm/llvm-project/pull/117568