[llvm] [LoopVectorize] Add support for vectorisation of simple early exit loops (PR #88385)
David Sherwood via llvm-commits
llvm-commits at lists.llvm.org
Wed May 1 01:55:15 PDT 2024
================
@@ -0,0 +1,2544 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt -S < %s -p loop-vectorize -mattr=+sve -mtriple aarch64-linux-gnu | FileCheck %s --check-prefixes=CHECK,MAY_FAULT
+; RUN: opt -S < %s -p loop-vectorize -vectorizer-no-mem-fault -mattr=+sve -mtriple aarch64-linux-gnu | FileCheck %s --check-prefixes=CHECK,NO_FAULT
+
+
+define i64 @same_exit_block_pre_inc_use1() {
+; CHECK-LABEL: define i64 @same_exit_block_pre_inc_use1(
+; CHECK-SAME: ) #[[ATTR0:[0-9]+]] {
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[P1:%.*]] = alloca [1024 x i8], align 4
+; CHECK-NEXT: [[P2:%.*]] = alloca [1024 x i8], align 4
+; CHECK-NEXT: [[TMP2:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT: [[TMP3:%.*]] = mul i64 [[TMP2]], 16
+; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 40, [[TMP3]]
+; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_PH:%.*]]
+; CHECK: vector.ph:
+; CHECK-NEXT: [[TMP4:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT: [[TMP5:%.*]] = mul i64 [[TMP4]], 16
+; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 40, [[TMP5]]
+; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 40, [[N_MOD_VF]]
+; CHECK-NEXT: [[IND_END:%.*]] = add i64 3, [[N_VEC]]
+; CHECK-NEXT: [[TMP6:%.*]] = call i64 @llvm.vscale.i64()
+; CHECK-NEXT: [[TMP7:%.*]] = mul i64 [[TMP6]], 16
+; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
+; CHECK: vector.body:
+; CHECK-NEXT: [[INDEX1:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT4:%.*]], [[FOR_INC3:%.*]] ]
+; CHECK-NEXT: [[OFFSET_IDX:%.*]] = add i64 3, [[INDEX1]]
+; CHECK-NEXT: [[TMP8:%.*]] = call <vscale x 16 x i64> @llvm.experimental.stepvector.nxv16i64()
+; CHECK-NEXT: [[DOTSPLATINSERT:%.*]] = insertelement <vscale x 16 x i64> poison, i64 [[OFFSET_IDX]], i64 0
+; CHECK-NEXT: [[DOTSPLAT:%.*]] = shufflevector <vscale x 16 x i64> [[DOTSPLATINSERT]], <vscale x 16 x i64> poison, <vscale x 16 x i32> zeroinitializer
+; CHECK-NEXT: [[TMP9:%.*]] = add <vscale x 16 x i64> zeroinitializer, [[TMP8]]
+; CHECK-NEXT: [[TMP10:%.*]] = mul <vscale x 16 x i64> [[TMP9]], shufflevector (<vscale x 16 x i64> insertelement (<vscale x 16 x i64> poison, i64 1, i64 0), <vscale x 16 x i64> poison, <vscale x 16 x i32> zeroinitializer)
+; CHECK-NEXT: [[TMP11:%.*]] = add <vscale x 16 x i64> [[DOTSPLAT]], [[TMP10]]
+; CHECK-NEXT: [[TMP12:%.*]] = add i64 [[OFFSET_IDX]], 0
+; CHECK-NEXT: [[TMP13:%.*]] = add i64 [[OFFSET_IDX]], 1
+; CHECK-NEXT: [[TMP14:%.*]] = add i64 [[OFFSET_IDX]], 2
+; CHECK-NEXT: [[TMP15:%.*]] = add i64 [[OFFSET_IDX]], 3
+; CHECK-NEXT: [[TMP16:%.*]] = add i64 [[OFFSET_IDX]], 4
+; CHECK-NEXT: [[TMP17:%.*]] = add i64 [[OFFSET_IDX]], 5
+; CHECK-NEXT: [[TMP18:%.*]] = add i64 [[OFFSET_IDX]], 6
+; CHECK-NEXT: [[TMP19:%.*]] = add i64 [[OFFSET_IDX]], 7
+; CHECK-NEXT: [[TMP20:%.*]] = add i64 [[OFFSET_IDX]], 8
+; CHECK-NEXT: [[TMP21:%.*]] = add i64 [[OFFSET_IDX]], 9
+; CHECK-NEXT: [[TMP22:%.*]] = add i64 [[OFFSET_IDX]], 10
+; CHECK-NEXT: [[TMP23:%.*]] = add i64 [[OFFSET_IDX]], 11
+; CHECK-NEXT: [[TMP24:%.*]] = add i64 [[OFFSET_IDX]], 12
+; CHECK-NEXT: [[TMP25:%.*]] = add i64 [[OFFSET_IDX]], 13
+; CHECK-NEXT: [[TMP26:%.*]] = add i64 [[OFFSET_IDX]], 14
+; CHECK-NEXT: [[TMP27:%.*]] = add i64 [[OFFSET_IDX]], 15
+; CHECK-NEXT: [[TMP28:%.*]] = getelementptr inbounds i8, ptr [[P1]], i64 [[TMP12]]
+; CHECK-NEXT: [[TMP29:%.*]] = getelementptr inbounds i8, ptr [[TMP28]], i32 0
+; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <vscale x 16 x i8>, ptr [[TMP29]], align 1
+; CHECK-NEXT: [[TMP30:%.*]] = getelementptr inbounds i8, ptr [[P2]], i64 [[TMP12]]
+; CHECK-NEXT: [[TMP31:%.*]] = getelementptr inbounds i8, ptr [[TMP30]], i32 0
+; CHECK-NEXT: [[WIDE_LOAD2:%.*]] = load <vscale x 16 x i8>, ptr [[TMP31]], align 1
+; CHECK-NEXT: [[TMP32:%.*]] = icmp eq <vscale x 16 x i8> [[WIDE_LOAD]], [[WIDE_LOAD2]]
+; CHECK-NEXT: [[TMP33:%.*]] = xor <vscale x 16 x i1> [[TMP32]], shufflevector (<vscale x 16 x i1> insertelement (<vscale x 16 x i1> poison, i1 true, i64 0), <vscale x 16 x i1> poison, <vscale x 16 x i32> zeroinitializer)
+; CHECK-NEXT: [[TMP34:%.*]] = call i1 @llvm.vector.reduce.or.nxv16i1(<vscale x 16 x i1> [[TMP33]])
+; CHECK-NEXT: br i1 [[TMP34]], label [[VECTOR_EARLY_EXIT:%.*]], label [[FOR_INC3]]
+; CHECK: loop.inc3:
+; CHECK-NEXT: [[INDEX_NEXT4]] = add nuw i64 [[INDEX1]], [[TMP7]]
+; CHECK-NEXT: [[TMP35:%.*]] = icmp eq i64 [[INDEX_NEXT4]], [[N_VEC]]
+; CHECK-NEXT: br i1 [[TMP35]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK: vector.early.exit:
+; CHECK-NEXT: [[TMP36:%.*]] = call i64 @llvm.experimental.cttz.elts.i64.nxv16i1(<vscale x 16 x i1> [[TMP33]], i1 true)
+; CHECK-NEXT: [[TMP37:%.*]] = add i64 [[TMP36]], [[INDEX1]]
+; CHECK-NEXT: [[IND_EARLY_ESCAPE:%.*]] = add i64 3, [[TMP37]]
+; CHECK-NEXT: br label [[FOR_END_LOOPEXIT:%.*]]
+; CHECK: middle.block:
+; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 40, [[N_VEC]]
+; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_END_LOOPEXIT]], label [[SCALAR_PH]]
+; CHECK: scalar.ph:
+; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[IND_END]], [[MIDDLE_BLOCK]] ], [ 3, [[ENTRY:%.*]] ]
+; CHECK-NEXT: br label [[LAND_RHS:%.*]]
+; CHECK: loop:
+; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ [[INDEX_NEXT:%.*]], [[FOR_INC:%.*]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
+; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds i8, ptr [[P1]], i64 [[INDEX]]
+; CHECK-NEXT: [[TMP38:%.*]] = load i8, ptr [[ARRAYIDX]], align 1
+; CHECK-NEXT: [[ARRAYIDX1:%.*]] = getelementptr inbounds i8, ptr [[P2]], i64 [[INDEX]]
+; CHECK-NEXT: [[TMP39:%.*]] = load i8, ptr [[ARRAYIDX1]], align 1
+; CHECK-NEXT: [[CMP3:%.*]] = icmp eq i8 [[TMP38]], [[TMP39]]
+; CHECK-NEXT: br i1 [[CMP3]], label [[FOR_INC]], label [[FOR_END_LOOPEXIT]]
+; CHECK: loop.inc:
+; CHECK-NEXT: [[INDEX_NEXT]] = add i64 [[INDEX]], 1
+; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne i64 [[INDEX_NEXT]], 43
+; CHECK-NEXT: br i1 [[EXITCOND]], label [[LAND_RHS]], label [[FOR_END_LOOPEXIT]], !llvm.loop [[LOOP3:![0-9]+]]
+; CHECK: loop.end:
+; CHECK-NEXT: [[START_0_LCSSA:%.*]] = phi i64 [ [[INDEX]], [[LAND_RHS]] ], [ 43, [[FOR_INC]] ], [ [[IND_EARLY_ESCAPE]], [[VECTOR_EARLY_EXIT]] ], [ 43, [[MIDDLE_BLOCK]] ]
+; CHECK-NEXT: ret i64 [[START_0_LCSSA]]
+;
----------------
david-arm wrote:
I will independently create a separate patch that improves the cost model for the cttz.elts intrinsic. For now I've disabled early-exit autovectorisation until we've got a better cost model, but that shouldn't hold up this patch.
https://github.com/llvm/llvm-project/pull/88385
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