23c2f2e6b2
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
109 lines
5.7 KiB
LLVM
109 lines
5.7 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt < %s -S -loop-vectorize -force-vector-width=4 -force-vector-interleave=1 | FileCheck %s
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; Check that we can vectorize this loop without crashing.
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define i8 @widget(i8* %arr, i8 %t9) {
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; CHECK-LABEL: @widget(
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; CHECK-NEXT: bb:
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; CHECK-NEXT: [[ARR1:%.*]] = ptrtoint i8* [[ARR:%.*]] to i64
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; CHECK-NEXT: br label [[BB6:%.*]]
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; CHECK: bb6:
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; CHECK-NEXT: [[T1_0:%.*]] = phi i8* [ [[ARR]], [[BB:%.*]] ], [ null, [[BB6]] ]
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; CHECK-NEXT: [[C:%.*]] = call i1 @cond()
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; CHECK-NEXT: br i1 [[C]], label [[FOR_PREHEADER:%.*]], label [[BB6]]
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; CHECK: for.preheader:
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; CHECK-NEXT: [[T1_0_LCSSA:%.*]] = phi i8* [ [[T1_0]], [[BB6]] ]
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; CHECK-NEXT: [[T1_0_LCSSA3:%.*]] = ptrtoint i8* [[T1_0_LCSSA]] to i64
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; CHECK-NEXT: [[TMP0:%.*]] = trunc i64 [[T1_0_LCSSA3]] to i32
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; CHECK-NEXT: [[TMP1:%.*]] = trunc i64 [[ARR1]] to i32
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; CHECK-NEXT: [[TMP2:%.*]] = sub i32 [[TMP0]], [[TMP1]]
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; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[TMP2]], 4
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; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_SCEVCHECK:%.*]]
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; CHECK: vector.scevcheck:
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; CHECK-NEXT: [[TMP3:%.*]] = sub i64 -1, [[ARR1]]
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; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, i8* [[T1_0_LCSSA]], i64 [[TMP3]]
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; CHECK-NEXT: [[SCEVGEP2:%.*]] = ptrtoint i8* [[SCEVGEP]] to i64
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; CHECK-NEXT: [[TMP4:%.*]] = trunc i64 [[SCEVGEP2]] to i8
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; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.umul.with.overflow.i8(i8 1, i8 [[TMP4]])
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; CHECK-NEXT: [[MUL_RESULT:%.*]] = extractvalue { i8, i1 } [[MUL]], 0
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; CHECK-NEXT: [[MUL_OVERFLOW:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
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; CHECK-NEXT: [[TMP5:%.*]] = add i8 1, [[MUL_RESULT]]
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; CHECK-NEXT: [[TMP6:%.*]] = sub i8 1, [[MUL_RESULT]]
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; CHECK-NEXT: [[TMP7:%.*]] = icmp sgt i8 [[TMP6]], 1
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; CHECK-NEXT: [[TMP8:%.*]] = icmp slt i8 [[TMP5]], 1
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; CHECK-NEXT: [[TMP9:%.*]] = select i1 false, i1 [[TMP7]], i1 [[TMP8]]
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; CHECK-NEXT: [[TMP10:%.*]] = icmp ugt i64 [[SCEVGEP2]], 255
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; CHECK-NEXT: [[TMP11:%.*]] = or i1 [[TMP9]], [[TMP10]]
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; CHECK-NEXT: [[TMP12:%.*]] = or i1 [[TMP11]], [[MUL_OVERFLOW]]
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; CHECK-NEXT: [[TMP13:%.*]] = or i1 false, [[TMP12]]
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; CHECK-NEXT: br i1 [[TMP13]], label [[SCALAR_PH]], label [[VECTOR_PH:%.*]]
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; CHECK: vector.ph:
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; CHECK-NEXT: [[N_MOD_VF:%.*]] = urem i32 [[TMP2]], 4
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; CHECK-NEXT: [[N_VEC:%.*]] = sub i32 [[TMP2]], [[N_MOD_VF]]
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; CHECK-NEXT: [[IND_END:%.*]] = trunc i32 [[N_VEC]] to i8
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; CHECK-NEXT: [[BROADCAST_SPLATINSERT:%.*]] = insertelement <4 x i8> poison, i8 [[T9:%.*]], i32 0
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; CHECK-NEXT: [[BROADCAST_SPLAT:%.*]] = shufflevector <4 x i8> [[BROADCAST_SPLATINSERT]], <4 x i8> poison, <4 x i32> zeroinitializer
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; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
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; CHECK: vector.body:
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; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
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; CHECK-NEXT: [[VEC_IND:%.*]] = phi <4 x i8> [ <i8 0, i8 1, i8 2, i8 3>, [[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], [[VECTOR_BODY]] ]
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; CHECK-NEXT: [[TMP14:%.*]] = add <4 x i8> [[VEC_IND]], <i8 1, i8 1, i8 1, i8 1>
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; CHECK-NEXT: [[TMP15:%.*]] = extractelement <4 x i8> [[TMP14]], i32 0
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; CHECK-NEXT: [[TMP16:%.*]] = getelementptr inbounds i8, i8* [[ARR]], i8 [[TMP15]]
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; CHECK-NEXT: [[TMP17:%.*]] = icmp slt <4 x i8> [[TMP14]], [[BROADCAST_SPLAT]]
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; CHECK-NEXT: [[TMP18:%.*]] = zext <4 x i1> [[TMP17]] to <4 x i8>
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; CHECK-NEXT: [[TMP19:%.*]] = getelementptr inbounds i8, i8* [[TMP16]], i32 0
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; CHECK-NEXT: [[TMP20:%.*]] = bitcast i8* [[TMP19]] to <4 x i8>*
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; CHECK-NEXT: store <4 x i8> [[TMP18]], <4 x i8>* [[TMP20]], align 1
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; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 4
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; CHECK-NEXT: [[VEC_IND_NEXT]] = add <4 x i8> [[VEC_IND]], <i8 4, i8 4, i8 4, i8 4>
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; CHECK-NEXT: [[TMP21:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
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; CHECK-NEXT: br i1 [[TMP21]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
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; CHECK: middle.block:
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; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[TMP2]], [[N_VEC]]
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; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_EXIT:%.*]], label [[SCALAR_PH]]
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; CHECK: scalar.ph:
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; CHECK-NEXT: [[BC_RESUME_VAL:%.*]] = phi i8 [ [[IND_END]], [[MIDDLE_BLOCK]] ], [ 0, [[FOR_PREHEADER]] ], [ 0, [[VECTOR_SCEVCHECK]] ]
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; CHECK-NEXT: br label [[FOR_BODY:%.*]]
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; CHECK: for.body:
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; CHECK-NEXT: [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
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; CHECK-NEXT: [[IV_NEXT]] = add i8 [[IV]], 1
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; CHECK-NEXT: [[PTR:%.*]] = getelementptr inbounds i8, i8* [[ARR]], i8 [[IV_NEXT]]
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; CHECK-NEXT: [[T3_I:%.*]] = icmp slt i8 [[IV_NEXT]], [[T9]]
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; CHECK-NEXT: [[T3_I8:%.*]] = zext i1 [[T3_I]] to i8
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; CHECK-NEXT: store i8 [[T3_I8]], i8* [[PTR]], align 1
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; CHECK-NEXT: [[EC:%.*]] = icmp eq i8* [[T1_0_LCSSA]], [[PTR]]
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; CHECK-NEXT: br i1 [[EC]], label [[FOR_EXIT]], label [[FOR_BODY]], !llvm.loop [[LOOP2:![0-9]+]]
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; CHECK: for.exit:
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; CHECK-NEXT: [[IV_NEXT_LCSSA:%.*]] = phi i8 [ [[IV_NEXT]], [[FOR_BODY]] ], [ [[IND_END]], [[MIDDLE_BLOCK]] ]
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; CHECK-NEXT: ret i8 [[IV_NEXT_LCSSA]]
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;
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bb:
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br label %bb6
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bb6:
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%t1.0 = phi i8* [ %arr, %bb ], [ null, %bb6 ]
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%c = call i1 @cond()
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br i1 %c, label %for.preheader, label %bb6
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for.preheader:
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br label %for.body
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for.body:
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%iv = phi i8 [ %iv.next, %for.body ], [ 0, %for.preheader ]
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%iv.next = add i8 %iv, 1
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%ptr = getelementptr inbounds i8, i8* %arr, i8 %iv.next
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%t3.i = icmp slt i8 %iv.next, %t9
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%t3.i8 = zext i1 %t3.i to i8
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store i8 %t3.i8, i8* %ptr
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%ec = icmp eq i8* %t1.0, %ptr
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br i1 %ec, label %for.exit, label %for.body
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for.exit:
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%iv.next.lcssa = phi i8 [ %iv.next, %for.body ]
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ret i8 %iv.next.lcssa
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}
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declare i1 @cond()
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