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llvm-mirror/test/Transforms/LoopVectorize/multiple-strides-vectorization.ll
Florian Hahn 3f021fa672 [LV] Mark increment of main vector loop induction variable as NUW. 
This patch marks the induction increment of the main induction variable
of the vector loop as NUW when not folding the tail.

If the tail is not folded, we know that End - Start >= Step (either
statically or through the minimum iteration checks). We also know that both
Start % Step == 0 and End % Step == 0. We exit the vector loop if %IV +
%Step == %End. Hence we must exit the loop before %IV + %Step unsigned
overflows and we can mark the induction increment as NUW.

This should make SCEV return more precise bounds for the created vector
loops, used by later optimizations, like late unrolling.

At the moment quite a few tests still need to be updated, but before
doing so I'd like to get initial feedback to make sure I am not missing
anything.

Note that this could probably be further improved by using information
from the original IV.

Attempt of modeling of the assumption in Alive2:
https://alive2.llvm.org/ce/z/H_DL_g

Part of a set of fixes required for PR50412.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D103255
2021-06-07 10:47:52 +01:00

140 lines
7.5 KiB
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -loop-vectorize -force-vector-width=4 -S < %s | FileCheck %s
; This is the test case from PR26314.
; When we were retrying dependence checking with memchecks only,
; the loop-invariant access in the inner loop was incorrectly determined to be wrapping
; because it was not strided in the inner loop.
; Improved wrapping detection allows vectorization in the following case.
; #define Z 32
; typedef struct s {
; int v1[Z];
; int v2[Z];
; int v3[Z][Z];
; } s;
;
; void slow_function (s* const obj, int z) {
; for (int j=0; j<Z; j++) {
; for (int k=0; k<z; k++) {
; int x = obj->v1[k] + obj->v2[j];
; obj->v3[j][k] += x;
; }
; }
; }
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
%struct.s = type { [32 x i32], [32 x i32], [32 x [32 x i32]] }
define void @Test(%struct.s* nocapture %obj, i64 %z) #0 {
; CHECK-LABEL: @Test(
; CHECK-NEXT: [[OBJ4:%.*]] = bitcast %struct.s* [[OBJ:%.*]] to i8*
; CHECK-NEXT: [[SCEVGEP5:%.*]] = getelementptr [[STRUCT_S:%.*]], %struct.s* [[OBJ]], i64 0, i32 0, i64 [[Z:%.*]]
; CHECK-NEXT: [[SCEVGEP56:%.*]] = bitcast i32* [[SCEVGEP5]] to i8*
; CHECK-NEXT: br label [[DOTOUTER_PREHEADER:%.*]]
; CHECK: .outer.preheader:
; CHECK-NEXT: [[I:%.*]] = phi i64 [ 0, [[TMP0:%.*]] ], [ [[I_NEXT:%.*]], [[DOTOUTER:%.*]] ]
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr [[STRUCT_S]], %struct.s* [[OBJ]], i64 0, i32 2, i64 [[I]], i64 0
; CHECK-NEXT: [[SCEVGEP1:%.*]] = bitcast i32* [[SCEVGEP]] to i8*
; CHECK-NEXT: [[SCEVGEP2:%.*]] = getelementptr [[STRUCT_S]], %struct.s* [[OBJ]], i64 0, i32 2, i64 [[I]], i64 [[Z]]
; CHECK-NEXT: [[SCEVGEP23:%.*]] = bitcast i32* [[SCEVGEP2]] to i8*
; CHECK-NEXT: [[SCEVGEP7:%.*]] = getelementptr [[STRUCT_S]], %struct.s* [[OBJ]], i64 0, i32 1, i64 [[I]]
; CHECK-NEXT: [[SCEVGEP78:%.*]] = bitcast i32* [[SCEVGEP7]] to i8*
; CHECK-NEXT: [[UGLYGEP:%.*]] = getelementptr i8, i8* [[SCEVGEP78]], i64 1
; CHECK-NEXT: [[TMP1:%.*]] = getelementptr inbounds [[STRUCT_S]], %struct.s* [[OBJ]], i64 0, i32 1, i64 [[I]]
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i64 [[Z]], 4
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_MEMCHECK:%.*]]
; CHECK: vector.memcheck:
; CHECK-NEXT: [[BOUND0:%.*]] = icmp ult i8* [[SCEVGEP1]], [[SCEVGEP56]]
; CHECK-NEXT: [[BOUND1:%.*]] = icmp ult i8* [[OBJ4]], [[SCEVGEP23]]
; CHECK-NEXT: [[FOUND_CONFLICT:%.*]] = and i1 [[BOUND0]], [[BOUND1]]
; CHECK-NEXT: [[BC:%.*]] = bitcast i32* [[TMP1]] to i8*
; CHECK-NEXT: [[BOUND09:%.*]] = icmp ult i8* [[SCEVGEP1]], [[UGLYGEP]]
; CHECK-NEXT: [[BOUND110:%.*]] = icmp ult i8* [[BC]], [[SCEVGEP23]]
; CHECK-NEXT: [[FOUND_CONFLICT11:%.*]] = and i1 [[BOUND09]], [[BOUND110]]
; CHECK-NEXT: [[CONFLICT_RDX:%.*]] = or i1 [[FOUND_CONFLICT]], [[FOUND_CONFLICT11]]
; CHECK-NEXT: [[MEMCHECK_CONFLICT:%.*]] = and i1 [[CONFLICT_RDX]], true
; CHECK-NEXT: br i1 [[MEMCHECK_CONFLICT]], label [[SCALAR_PH]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i64 [[Z]], 4
; CHECK-NEXT: [[N_VEC:%.*]] = sub i64 [[Z]], [[N_MOD_VF]]
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP2:%.*]] = add i64 [[INDEX]], 0
; CHECK-NEXT: [[TMP3:%.*]] = getelementptr inbounds [[STRUCT_S]], %struct.s* [[OBJ]], i64 0, i32 0, i64 [[TMP2]]
; CHECK-NEXT: [[TMP4:%.*]] = getelementptr inbounds i32, i32* [[TMP3]], i32 0
; CHECK-NEXT: [[TMP5:%.*]] = bitcast i32* [[TMP4]] to <4 x i32>*
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <4 x i32>, <4 x i32>* [[TMP5]], align 4, !alias.scope !0
; CHECK-NEXT: [[TMP6:%.*]] = load i32, i32* [[TMP1]], align 4, !alias.scope !3
; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i32> poison, i32 [[TMP6]], i32 0
; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i32> [[BROADCAST_SPLATINSERT]], <4 x i32> poison, <4 x i32> zeroinitializer
; CHECK-NEXT: [[TMP7:%.*]] = add nsw <4 x i32> [[BROADCAST_SPLAT]], [[WIDE_LOAD]]
; CHECK-NEXT: [[TMP8:%.*]] = getelementptr inbounds [[STRUCT_S]], %struct.s* [[OBJ]], i64 0, i32 2, i64 [[I]], i64 [[TMP2]]
; CHECK-NEXT: [[TMP9:%.*]] = getelementptr inbounds i32, i32* [[TMP8]], i32 0
; CHECK-NEXT: [[TMP10:%.*]] = bitcast i32* [[TMP9]] to <4 x i32>*
; CHECK-NEXT: [[WIDE_LOAD12:%.*]] = load <4 x i32>, <4 x i32>* [[TMP10]], align 4, !alias.scope !5, !noalias !7
; CHECK-NEXT: [[TMP11:%.*]] = add nsw <4 x i32> [[TMP7]], [[WIDE_LOAD12]]
; CHECK-NEXT: [[TMP12:%.*]] = bitcast i32* [[TMP9]] to <4 x i32>*
; CHECK-NEXT: store <4 x i32> [[TMP11]], <4 x i32>* [[TMP12]], align 4, !alias.scope !5, !noalias !7
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
; CHECK-NEXT: [[TMP13:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP13]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP8:!llvm.loop !.*]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[Z]], [[N_VEC]]
; CHECK-NEXT: br i1 [[CMP_N]], label [[DOTOUTER]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[DOTOUTER_PREHEADER]] ], [ 0, [[VECTOR_MEMCHECK]] ]
; CHECK-NEXT: br label [[DOTINNER:%.*]]
; CHECK: .exit:
; CHECK-NEXT: ret void
; CHECK: .outer:
; CHECK-NEXT: [[I_NEXT]] = add nuw nsw i64 [[I]], 1
; CHECK-NEXT: [[EXITCOND_OUTER:%.*]] = icmp eq i64 [[I_NEXT]], 32
; CHECK-NEXT: br i1 [[EXITCOND_OUTER]], label [[DOTEXIT:%.*]], label [[DOTOUTER_PREHEADER]]
; CHECK: .inner:
; CHECK-NEXT: [[J:%.*]] = phi i64 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[J_NEXT:%.*]], [[DOTINNER]] ]
; CHECK-NEXT: [[TMP14:%.*]] = getelementptr inbounds [[STRUCT_S]], %struct.s* [[OBJ]], i64 0, i32 0, i64 [[J]]
; CHECK-NEXT: [[TMP15:%.*]] = load i32, i32* [[TMP14]], align 4
; CHECK-NEXT: [[TMP16:%.*]] = load i32, i32* [[TMP1]], align 4
; CHECK-NEXT: [[TMP17:%.*]] = add nsw i32 [[TMP16]], [[TMP15]]
; CHECK-NEXT: [[TMP18:%.*]] = getelementptr inbounds [[STRUCT_S]], %struct.s* [[OBJ]], i64 0, i32 2, i64 [[I]], i64 [[J]]
; CHECK-NEXT: [[TMP19:%.*]] = load i32, i32* [[TMP18]], align 4
; CHECK-NEXT: [[TMP20:%.*]] = add nsw i32 [[TMP17]], [[TMP19]]
; CHECK-NEXT: store i32 [[TMP20]], i32* [[TMP18]], align 4
; CHECK-NEXT: [[J_NEXT]] = add nuw nsw i64 [[J]], 1
; CHECK-NEXT: [[EXITCOND_INNER:%.*]] = icmp eq i64 [[J_NEXT]], [[Z]]
; CHECK-NEXT: br i1 [[EXITCOND_INNER]], label [[DOTOUTER]], label [[DOTINNER]], [[LOOP10:!llvm.loop !.*]]
;
br label %.outer.preheader
.outer.preheader:
%i = phi i64 [ 0, %0 ], [ %i.next, %.outer ]
%1 = getelementptr inbounds %struct.s, %struct.s* %obj, i64 0, i32 1, i64 %i
br label %.inner
.exit:
ret void
.outer:
%i.next = add nuw nsw i64 %i, 1
%exitcond.outer = icmp eq i64 %i.next, 32
br i1 %exitcond.outer, label %.exit, label %.outer.preheader
.inner:
%j = phi i64 [ 0, %.outer.preheader ], [ %j.next, %.inner ]
%2 = getelementptr inbounds %struct.s, %struct.s* %obj, i64 0, i32 0, i64 %j
%3 = load i32, i32* %2
%4 = load i32, i32* %1
%5 = add nsw i32 %4, %3
%6 = getelementptr inbounds %struct.s, %struct.s* %obj, i64 0, i32 2, i64 %i, i64 %j
%7 = load i32, i32* %6
%8 = add nsw i32 %5, %7
store i32 %8, i32* %6
%j.next = add nuw nsw i64 %j, 1
%exitcond.inner = icmp eq i64 %j.next, %z
br i1 %exitcond.inner, label %.outer, label %.inner
}
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