[CodeGen] Properly update insertion point of the builder

[danilaml]

Summary

Other code assumes that it can use passed Builder parameter to
generate new instructions but this code path created its own IRBuilder
instance, leaving the passed builder with an old insertion point.

Fixes https://github.com/llvm/llvm-project/issues/65044

[danilaml]

llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp

1955

Not sure if it's the good/proper place to fix it, but at least it ensures that callers of replaceNode will insert their instructions after it.

[igor.kirillov]

llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp

1955

It's a good idea, but unfortunately, this won't work out because Builder.GetInsertPoint() might be from a different block than InsertPoint. I added a review with a fix - https://reviews.llvm.org/D159209

[danilaml]

Superseded by D159209

llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp

 //===- ComplexDeinterleavingPass.cpp --------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 //
case ComplexDeinterleavingOperation::Splat: {
     auto *I = dyn_cast<Instruction>(Node->Imag);
     if (R && I) {
       // Splats that are not constant are interleaved where they are located
       Instruction *InsertPoint = (I->comesBefore(R) ? R : I)->getNextNode();
       IRBuilder<> IRB(InsertPoint);
       ReplacementNode =
           IRB.CreateIntrinsic(Intrinsic::experimental_vector_interleave2, NewTy,
                               {Node->Real, Node->Imag});
+      if (Builder.GetInsertPoint()->comesBefore(InsertPoint))
+        Builder.SetInsertPoint(InsertPoint);
     } else {
       ReplacementNode =
           Builder.CreateIntrinsic(Intrinsic::experimental_vector_interleave2,
                                   NewTy, {Node->Real, Node->Imag});
     }
     break;
   }
   case ComplexDeinterleavingOperation::ReductionPHI: {

llvm/test/CodeGen/AArch64/complex-deinterleaving-crash.ll

-; XFAIL: *
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 2
 ; RUN: llc %s --mattr=+complxnum -o - | FileCheck %s
 
 target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128-ni:1-p2:32:8:8:32-ni:2"
 target triple = "aarch64-none-linux-gnu"
 
 ; Check that deinterleaving pass doesn't generate broken IR
 define void @check_deinterleave_crash() #0 {
+; CHECK-LABEL: check_deinterleave_crash:
+; CHECK:       // %bb.0: // %bb
+; CHECK-NEXT:    mov x8, xzr
+; CHECK-NEXT:    str wzr, [x8]
 bb:
   br label %bb173
 
 bb173:                                            ; preds = %bb173, %bb
   %phi177 = phi <2 x i32> [ %add190, %bb173 ], [ zeroinitializer, %bb ]
   %phi178 = phi <2 x i32> [ %add187, %bb173 ], [ zeroinitializer, %bb ]
   %add185 = add <2 x i32> %phi178, <i32 1, i32 1>
   %add186 = add <2 x i32> %phi177, <i32 1, i32 1>