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llvm-mirror/test/Transforms/LoopVectorize/if-conversion-nest.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

119 lines
6.7 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -loop-vectorize -force-vector-interleave=1 -force-vector-width=4 -enable-if-conversion -dce -instcombine -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 i32 @foo(i32* nocapture %A, i32* nocapture %B, i32 %n) {
; CHECK-LABEL: @foo(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CMP26:%.*]] = icmp sgt i32 [[N:%.*]], 0
; CHECK-NEXT: br i1 [[CMP26]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_END:%.*]]
; CHECK: for.body.preheader:
; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[N]], -1
; CHECK-NEXT: [[TMP1:%.*]] = zext i32 [[TMP0]] to i64
; CHECK-NEXT: [[TMP2:%.*]] = add nuw nsw i64 [[TMP1]], 1
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[TMP0]], 3
; CHECK-NEXT: br i1 [[MIN_ITERS_CHECK]], label [[SCALAR_PH:%.*]], label [[VECTOR_MEMCHECK:%.*]]
; CHECK: vector.memcheck:
; CHECK-NEXT: [[TMP3:%.*]] = add i32 [[N]], -1
; CHECK-NEXT: [[TMP4:%.*]] = zext i32 [[TMP3]] to i64
; CHECK-NEXT: [[TMP5:%.*]] = add nuw nsw i64 [[TMP4]], 1
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i32, i32* [[A:%.*]], i64 [[TMP5]]
; CHECK-NEXT: [[SCEVGEP4:%.*]] = getelementptr i32, i32* [[B:%.*]], i64 [[TMP5]]
; CHECK-NEXT: [[BOUND0:%.*]] = icmp ugt i32* [[SCEVGEP4]], [[A]]
; CHECK-NEXT: [[BOUND1:%.*]] = icmp ugt i32* [[SCEVGEP]], [[B]]
; CHECK-NEXT: [[FOUND_CONFLICT:%.*]] = and i1 [[BOUND0]], [[BOUND1]]
; CHECK-NEXT: br i1 [[FOUND_CONFLICT]], label [[SCALAR_PH]], label [[VECTOR_PH:%.*]]
; CHECK: vector.ph:
; CHECK-NEXT: [[N_VEC:%.*]] = and i64 [[TMP2]], 8589934588
; CHECK-NEXT: br label [[VECTOR_BODY:%.*]]
; CHECK: vector.body:
; CHECK-NEXT: [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
; CHECK-NEXT: [[TMP6:%.*]] = getelementptr inbounds i32, i32* [[A]], i64 [[INDEX]]
; CHECK-NEXT: [[TMP7:%.*]] = bitcast i32* [[TMP6]] to <4 x i32>*
; CHECK-NEXT: [[WIDE_LOAD:%.*]] = load <4 x i32>, <4 x i32>* [[TMP7]], align 4, !alias.scope !0, !noalias !3
; CHECK-NEXT: [[TMP8:%.*]] = getelementptr inbounds i32, i32* [[B]], i64 [[INDEX]]
; CHECK-NEXT: [[TMP9:%.*]] = bitcast i32* [[TMP8]] to <4 x i32>*
; CHECK-NEXT: [[WIDE_LOAD6:%.*]] = load <4 x i32>, <4 x i32>* [[TMP9]], align 4, !alias.scope !3
; CHECK-NEXT: [[TMP10:%.*]] = icmp sgt <4 x i32> [[WIDE_LOAD]], [[WIDE_LOAD6]]
; CHECK-NEXT: [[TMP11:%.*]] = icmp sgt <4 x i32> [[WIDE_LOAD]], <i32 19, i32 19, i32 19, i32 19>
; CHECK-NEXT: [[TMP12:%.*]] = icmp slt <4 x i32> [[WIDE_LOAD6]], <i32 4, i32 4, i32 4, i32 4>
; CHECK-NEXT: [[TMP13:%.*]] = select <4 x i1> [[TMP12]], <4 x i32> <i32 4, i32 4, i32 4, i32 4>, <4 x i32> <i32 5, i32 5, i32 5, i32 5>
; CHECK-NEXT: [[TMP14:%.*]] = and <4 x i1> [[TMP10]], [[TMP11]]
; CHECK-NEXT: [[TMP15:%.*]] = xor <4 x i1> [[TMP11]], <i1 true, i1 true, i1 true, i1 true>
; CHECK-NEXT: [[TMP16:%.*]] = and <4 x i1> [[TMP10]], [[TMP15]]
; CHECK-NEXT: [[PREDPHI:%.*]] = select <4 x i1> [[TMP14]], <4 x i32> <i32 3, i32 3, i32 3, i32 3>, <4 x i32> <i32 9, i32 9, i32 9, i32 9>
; CHECK-NEXT: [[PREDPHI7:%.*]] = select <4 x i1> [[TMP16]], <4 x i32> [[TMP13]], <4 x i32> [[PREDPHI]]
; CHECK-NEXT: [[TMP17:%.*]] = bitcast i32* [[TMP6]] to <4 x i32>*
; CHECK-NEXT: store <4 x i32> [[PREDPHI7]], <4 x i32>* [[TMP17]], align 4, !alias.scope !0, !noalias !3
; CHECK-NEXT: [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 4
; CHECK-NEXT: [[TMP18:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP18]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP5:!llvm.loop !.*]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[TMP2]], [[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 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[FOR_BODY_PREHEADER]] ], [ 0, [[VECTOR_MEMCHECK]] ]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[INDVARS_IV:%.*]] = phi i64 [ [[INDVARS_IV_NEXT:%.*]], [[IF_END14:%.*]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr inbounds i32, i32* [[A]], i64 [[INDVARS_IV]]
; CHECK-NEXT: [[TMP19:%.*]] = load i32, i32* [[ARRAYIDX]], align 4
; CHECK-NEXT: [[ARRAYIDX2:%.*]] = getelementptr inbounds i32, i32* [[B]], i64 [[INDVARS_IV]]
; CHECK-NEXT: [[TMP20:%.*]] = load i32, i32* [[ARRAYIDX2]], align 4
; CHECK-NEXT: [[CMP3:%.*]] = icmp sgt i32 [[TMP19]], [[TMP20]]
; CHECK-NEXT: br i1 [[CMP3]], label [[IF_THEN:%.*]], label [[IF_END14]]
; CHECK: if.then:
; CHECK-NEXT: [[CMP6:%.*]] = icmp sgt i32 [[TMP19]], 19
; CHECK-NEXT: br i1 [[CMP6]], label [[IF_END14]], label [[IF_ELSE:%.*]]
; CHECK: if.else:
; CHECK-NEXT: [[CMP10:%.*]] = icmp slt i32 [[TMP20]], 4
; CHECK-NEXT: [[DOT:%.*]] = select i1 [[CMP10]], i32 4, i32 5
; CHECK-NEXT: br label [[IF_END14]]
; CHECK: if.end14:
; CHECK-NEXT: [[X_0:%.*]] = phi i32 [ 9, [[FOR_BODY]] ], [ 3, [[IF_THEN]] ], [ [[DOT]], [[IF_ELSE]] ]
; CHECK-NEXT: store i32 [[X_0]], i32* [[ARRAYIDX]], align 4
; CHECK-NEXT: [[INDVARS_IV_NEXT]] = add i64 [[INDVARS_IV]], 1
; CHECK-NEXT: [[LFTR_WIDEIV:%.*]] = trunc i64 [[INDVARS_IV_NEXT]] to i32
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp eq i32 [[LFTR_WIDEIV]], [[N]]
; CHECK-NEXT: br i1 [[EXITCOND]], label [[FOR_END_LOOPEXIT]], label [[FOR_BODY]], [[LOOP7:!llvm.loop !.*]]
; CHECK: for.end.loopexit:
; CHECK-NEXT: br label [[FOR_END]]
; CHECK: for.end:
; CHECK-NEXT: ret i32 undef
;
entry:
%cmp26 = icmp sgt i32 %n, 0
br i1 %cmp26, label %for.body, label %for.end
for.body:
%indvars.iv = phi i64 [ %indvars.iv.next, %if.end14 ], [ 0, %entry ]
%arrayidx = getelementptr inbounds i32, i32* %A, i64 %indvars.iv
%0 = load i32, i32* %arrayidx, align 4
%arrayidx2 = getelementptr inbounds i32, i32* %B, i64 %indvars.iv
%1 = load i32, i32* %arrayidx2, align 4
%cmp3 = icmp sgt i32 %0, %1
br i1 %cmp3, label %if.then, label %if.end14
if.then:
%cmp6 = icmp sgt i32 %0, 19
br i1 %cmp6, label %if.end14, label %if.else
if.else:
%cmp10 = icmp slt i32 %1, 4
%. = select i1 %cmp10, i32 4, i32 5
br label %if.end14
if.end14:
%x.0 = phi i32 [ 9, %for.body ], [ 3, %if.then ], [ %., %if.else ] ; <------------- A PHI with 3 entries that we can still vectorize.
store i32 %x.0, i32* %arrayidx, align 4
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, %n
br i1 %exitcond, label %for.end, label %for.body
for.end:
ret i32 undef
}