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llvm-mirror/test/Transforms/LoopVectorize/scalable-reduction-inloop.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

61 lines
3.7 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -loop-vectorize -force-target-supports-scalable-vectors=true -scalable-vectorization=on -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
define i8 @reduction_add_trunc(i8* noalias nocapture %A) {
; CHECK-LABEL: @reduction_add_trunc(
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i32 [ 0, %vector.ph ], [ [[INDEX_NEXT:%.*]], %vector.body ]
; CHECK-NEXT: [[VEC_PHI:%.*]] = phi <vscale x 8 x i32> [ insertelement (<vscale x 8 x i32> zeroinitializer, i32 255, i32 0), %vector.ph ], [ [[TMP34:%.*]], %vector.body ]
; CHECK-NEXT: [[VEC_PHI1:%.*]] = phi <vscale x 8 x i32> [ zeroinitializer, %vector.ph ], [ [[TMP36:%.*]], %vector.body ]
; CHECK: [[TMP14:%.*]] = and <vscale x 8 x i32> [[VEC_PHI]], shufflevector (<vscale x 8 x i32> insertelement (<vscale x 8 x i32> poison, i32 255, i32 0), <vscale x 8 x i32> poison, <vscale x 8 x i32> zeroinitializer)
; CHECK-NEXT: [[TMP15:%.*]] = and <vscale x 8 x i32> [[VEC_PHI1]], shufflevector (<vscale x 8 x i32> insertelement (<vscale x 8 x i32> poison, i32 255, i32 0), <vscale x 8 x i32> poison, <vscale x 8 x i32> zeroinitializer)
; CHECK: [[WIDE_LOAD:%.*]] = load <vscale x 8 x i8>, <vscale x 8 x i8>*
; CHECK: [[WIDE_LOAD2:%.*]] = load <vscale x 8 x i8>, <vscale x 8 x i8>*
; CHECK-NEXT: [[TMP26:%.*]] = zext <vscale x 8 x i8> [[WIDE_LOAD]] to <vscale x 8 x i32>
; CHECK-NEXT: [[TMP27:%.*]] = zext <vscale x 8 x i8> [[WIDE_LOAD2]] to <vscale x 8 x i32>
; CHECK-NEXT: [[TMP28:%.*]] = add <vscale x 8 x i32> [[TMP14]], [[TMP26]]
; CHECK-NEXT: [[TMP29:%.*]] = add <vscale x 8 x i32> [[TMP15]], [[TMP27]]
; CHECK-NEXT: [[TMP30:%.*]] = call i32 @llvm.vscale.i32()
; CHECK-NEXT: [[TMP31:%.*]] = mul i32 [[TMP30]], 16
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i32 [[INDEX]], [[TMP31]]
; CHECK-NEXT: [[TMP32:%.*]] = icmp eq i32 [[INDEX_NEXT]], {{%.*}}
; CHECK-NEXT: [[TMP33:%.*]] = trunc <vscale x 8 x i32> [[TMP28]] to <vscale x 8 x i8>
; CHECK-NEXT: [[TMP34]] = zext <vscale x 8 x i8> [[TMP33]] to <vscale x 8 x i32>
; CHECK-NEXT: [[TMP35:%.*]] = trunc <vscale x 8 x i32> [[TMP29]] to <vscale x 8 x i8>
; CHECK-NEXT: [[TMP36]] = zext <vscale x 8 x i8> [[TMP35]] to <vscale x 8 x i32>
; CHECK: middle.block:
; CHECK-NEXT: [[TMP37:%.*]] = trunc <vscale x 8 x i32> [[TMP34]] to <vscale x 8 x i8>
; CHECK-NEXT: [[TMP38:%.*]] = trunc <vscale x 8 x i32> [[TMP36]] to <vscale x 8 x i8>
; CHECK-NEXT: [[BIN_RDX:%.*]] = add <vscale x 8 x i8> [[TMP38]], [[TMP37]]
; CHECK-NEXT: [[TMP39:%.*]] = call i8 @llvm.vector.reduce.add.nxv8i8(<vscale x 8 x i8> [[BIN_RDX]])
; CHECK-NEXT: [[TMP40:%.*]] = zext i8 [[TMP39]] to i32
;
entry:
br label %loop
loop: ; preds = %entry, %loop
%indvars.iv = phi i32 [ %indvars.iv.next, %loop ], [ 0, %entry ]
%sum.02p = phi i32 [ %l9, %loop ], [ 255, %entry ]
%sum.02 = and i32 %sum.02p, 255
%l2 = getelementptr inbounds i8, i8* %A, i32 %indvars.iv
%l3 = load i8, i8* %l2, align 4
%l3e = zext i8 %l3 to i32
%l9 = add i32 %sum.02, %l3e
%indvars.iv.next = add i32 %indvars.iv, 1
%exitcond = icmp eq i32 %indvars.iv.next, 256
br i1 %exitcond, label %exit, label %loop, !llvm.loop !0
exit: ; preds = %loop
%sum.0.lcssa = phi i32 [ %l9, %loop ]
%ret = trunc i32 %sum.0.lcssa to i8
ret i8 %ret
}
!0 = distinct !{!0, !1, !2, !3, !4}
!1 = !{!"llvm.loop.vectorize.width", i32 8}
!2 = !{!"llvm.loop.vectorize.scalable.enable", i1 true}
!3 = !{!"llvm.loop.interleave.count", i32 2}
!4 = !{!"llvm.loop.vectorize.enable", i1 true}