[llvm] [ConstantHoisting] Don't attempt to hoist ConstantInt vectors. (PR #85416)

[Paul Walker via llvm-commits]

https://github.com/paulwalker-arm created https://github.com/llvm/llvm-project/pull/85416

The pass uses the TTI hook getIntImmCostIntrin that only supports scalar integer types. Whilst hoisting expensive vector constant is likely worthwhile, this is new behaviour and so I've followed the path taken by the GEP variant of collectConstantCandidates and simply bail for vector types.

>From 6be9b753065d3324869885145ab02d82da7dd46c Mon Sep 17 00:00:00 2001
From: Paul Walker <paul.walker at arm.com>
Date: Wed, 13 Mar 2024 14:46:59 +0000
Subject: [PATCH] [ConstantHoisting] Don't attempt to hoist ConstantInt
 vectors.

The pass uses the TTI hook getIntImmCostIntrin that only supports
scalar integer types. Whilst hoisting expensive vector constant is
likely worthwhile, this is new behaviour and so I've followed the
path taken by the GEP variant of collectConstantCandidates and
simply bail for vector types.
---
 .../Transforms/Scalar/ConstantHoisting.cpp    |  3 ++
 .../AArch64/large-immediate.ll                | 37 ++++++++++++++++---
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp b/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
index 49f8761a139232..c12dc281b0e3c4 100644
--- a/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
@@ -363,6 +363,9 @@ SetVector<Instruction *> ConstantHoistingPass::findConstantInsertionPoint(
 void ConstantHoistingPass::collectConstantCandidates(
     ConstCandMapType &ConstCandMap, Instruction *Inst, unsigned Idx,
     ConstantInt *ConstInt) {
+  if (ConstInt->getType()->isVectorTy())
+    return;
+
   InstructionCost Cost;
   // Ask the target about the cost of materializing the constant for the given
   // instruction and operand index.
diff --git a/llvm/test/Transforms/ConstantHoisting/AArch64/large-immediate.ll b/llvm/test/Transforms/ConstantHoisting/AArch64/large-immediate.ll
index 196a104adc0233..6d8890d71e2be9 100644
--- a/llvm/test/Transforms/ConstantHoisting/AArch64/large-immediate.ll
+++ b/llvm/test/Transforms/ConstantHoisting/AArch64/large-immediate.ll
@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
-; RUN: opt -mtriple=arm64-darwin-unknown -S -passes=consthoist < %s | FileCheck %s
+; RUN: opt -mtriple=arm64-darwin-unknown -S -passes=consthoist < %s | FileCheck %s --check-prefixes=CHECK,CV
+; RUN: opt -mtriple=arm64-darwin-unknown -S -passes=consthoist -use-constant-int-for-fixed-length-splat -use-constant-int-for-scalable-splat < %s | FileCheck %s --check-prefixes=CHECK,CI
 
 define i128 @test1(i128 %a) {
 ; CHECK-LABEL: define i128 @test1(
@@ -122,13 +123,37 @@ define i64 @sdiv_minsize(i64 %a) minsize {
 }
 
 define <2 x i64> @sdiv_v2i64(<2 x i64> %a) {
-; CHECK-LABEL: define <2 x i64> @sdiv_v2i64(
-; CHECK-SAME: <2 x i64> [[A:%.*]]) {
-; CHECK-NEXT:    [[TMP1:%.*]] = sdiv <2 x i64> [[A]], <i64 4294967087, i64 4294967087>
-; CHECK-NEXT:    [[TMP2:%.*]] = add <2 x i64> [[TMP1]], <i64 4294967087, i64 4294967087>
-; CHECK-NEXT:    ret <2 x i64> [[TMP2]]
+; CV-LABEL: define <2 x i64> @sdiv_v2i64(
+; CV-SAME: <2 x i64> [[A:%.*]]) {
+; CV-NEXT:    [[TMP1:%.*]] = sdiv <2 x i64> [[A]], <i64 4294967087, i64 4294967087>
+; CV-NEXT:    [[TMP2:%.*]] = add <2 x i64> [[TMP1]], <i64 4294967087, i64 4294967087>
+; CV-NEXT:    ret <2 x i64> [[TMP2]]
+;
+; CI-LABEL: define <2 x i64> @sdiv_v2i64(
+; CI-SAME: <2 x i64> [[A:%.*]]) {
+; CI-NEXT:    [[TMP1:%.*]] = sdiv <2 x i64> [[A]], splat (i64 4294967087)
+; CI-NEXT:    [[TMP2:%.*]] = add <2 x i64> [[TMP1]], splat (i64 4294967087)
+; CI-NEXT:    ret <2 x i64> [[TMP2]]
 ;
   %1 = sdiv <2 x i64> %a, <i64 4294967087, i64 4294967087>
   %2 = add <2 x i64> %1, <i64 4294967087, i64 4294967087>
   ret <2 x i64> %2
 }
+
+define <vscale x 2 x i64> @sdiv_nxv2i64(<vscale x 2 x i64> %a) {
+; CV-LABEL: define <vscale x 2 x i64> @sdiv_nxv2i64(
+; CV-SAME: <vscale x 2 x i64> [[A:%.*]]) {
+; CV-NEXT:    [[TMP1:%.*]] = sdiv <vscale x 2 x i64> [[A]], shufflevector (<vscale x 2 x i64> insertelement (<vscale x 2 x i64> poison, i64 4294967087, i64 0), <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer)
+; CV-NEXT:    [[TMP2:%.*]] = add <vscale x 2 x i64> [[TMP1]], shufflevector (<vscale x 2 x i64> insertelement (<vscale x 2 x i64> poison, i64 4294967087, i64 0), <vscale x 2 x i64> poison, <vscale x 2 x i32> zeroinitializer)
+; CV-NEXT:    ret <vscale x 2 x i64> [[TMP2]]
+;
+; CI-LABEL: define <vscale x 2 x i64> @sdiv_nxv2i64(
+; CI-SAME: <vscale x 2 x i64> [[A:%.*]]) {
+; CI-NEXT:    [[TMP1:%.*]] = sdiv <vscale x 2 x i64> [[A]], splat (i64 4294967087)
+; CI-NEXT:    [[TMP2:%.*]] = add <vscale x 2 x i64> [[TMP1]], splat (i64 4294967087)
+; CI-NEXT:    ret <vscale x 2 x i64> [[TMP2]]
+;
+  %1 = sdiv <vscale x 2 x i64> %a, splat (i64 4294967087)
+  %2 = add <vscale x 2 x i64> %1, splat (i64 4294967087)
+  ret <vscale x 2 x i64> %2
+}