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Revert "[SCEV][NFC] Check NoWrap flags before lexicographical comparison of SCEVs" 

This reverts r319889.

Unfortunately, wrapping flags are not a part of SCEV's identity (they
do not participate in computing a hash value or in equality
comparisons) and in fact they could be assigned after the fact w/o
rebuilding a SCEV.

Grep for const_cast's to see quite a few of examples, apparently all
for AddRec's at the moment.

So, if 2 expressions get built in 2 slightly different ways: one with
flags set in the beginning, the other with the flags attached later
on, we may end up with 2 expressions which are exactly the same but
have their operands swapped in one of the commutative N-ary
expressions, and at least one of them will have "sorted by complexity"
invariant broken.

2 identical SCEV's won't compare equal by pointer comparison as they
are supposed to.

A real-world reproducer is added as a regression test: the issue
described causes 2 identical SCEV expressions to have different order
of operands and therefore compare not equal, which in its turn
prevents LoadStoreVectorizer from vectorizing a pair of consecutive
loads.

On a larger example (the source of the test attached, which is a
bugpoint) I have seen even weirder behavior: adding a constant to an
existing SCEV changes the order of the existing terms, for instance,
getAddExpr(1, ((A * B) + (C * D))) returns (1 + (C * D) + (A * B)).

Differential Revision: https://reviews.llvm.org/D40645

llvm-svn: 340777
This commit is contained in:
Roman Tereshin 2018-08-27 21:41:37 +00:00
parent 4e039d64e2
commit 02320eee6b
5 changed files with 86 additions and 18 deletions
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8
llvm/lib/Analysis/ScalarEvolution.cpp
View File

@ -692,10 +692,6 @@ static int CompareSCEVComplexity(
if (LNumOps != RNumOps)
return (int)LNumOps - (int)RNumOps;
// Compare NoWrap flags.
if (LA->getNoWrapFlags() != RA->getNoWrapFlags())
return (int)LA->getNoWrapFlags() - (int)RA->getNoWrapFlags();
// Lexicographically compare.
for (unsigned i = 0; i != LNumOps; ++i) {
int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
@ -720,10 +716,6 @@ static int CompareSCEVComplexity(
if (LNumOps != RNumOps)
return (int)LNumOps - (int)RNumOps;
// Compare NoWrap flags.
if (LC->getNoWrapFlags() != RC->getNoWrapFlags())
return (int)LC->getNoWrapFlags() - (int)RC->getNoWrapFlags();
for (unsigned i = 0; i != LNumOps; ++i) {
int X = CompareSCEVComplexity(EqCacheSCEV, EqCacheValue, LI,
LC->getOperand(i), RC->getOperand(i), DT,

6
llvm/test/Transforms/IRCE/conjunctive-checks.ll
View File

@ -5,10 +5,10 @@ define void @f_0(i32 *%arr, i32 *%a_len_ptr, i32 %n, i1* %cond_buf) {
; CHECK-LABEL: @f_0(
; CHECK: loop.preheader:
; CHECK: [[not_safe_range_end:[^ ]+]] = sub i32 3, %len
; CHECK: [[not_n:[^ ]+]] = sub i32 -1, %n
; CHECK: [[not_exit_main_loop_at_hiclamp_cmp:[^ ]+]] = icmp sgt i32 [[not_safe_range_end]], [[not_n]]
; CHECK: [[not_exit_main_loop_at_hiclamp:[^ ]+]] = select i1 [[not_exit_main_loop_at_hiclamp_cmp]], i32 [[not_safe_range_end]], i32 [[not_n]]
; CHECK: [[not_safe_range_end:[^ ]+]] = sub i32 3, %len
; CHECK: [[not_exit_main_loop_at_hiclamp_cmp:[^ ]+]] = icmp sgt i32 [[not_n]], [[not_safe_range_end]]
; CHECK: [[not_exit_main_loop_at_hiclamp:[^ ]+]] = select i1 [[not_exit_main_loop_at_hiclamp_cmp]], i32 [[not_n]], i32 [[not_safe_range_end]]
; CHECK: [[exit_main_loop_at_hiclamp:[^ ]+]] = sub i32 -1, [[not_exit_main_loop_at_hiclamp]]
; CHECK: [[exit_main_loop_at_loclamp_cmp:[^ ]+]] = icmp sgt i32 [[exit_main_loop_at_hiclamp]], 0
; CHECK: [[exit_main_loop_at_loclamp:[^ ]+]] = select i1 [[exit_main_loop_at_loclamp_cmp]], i32 [[exit_main_loop_at_hiclamp]], i32 0

6
llvm/test/Transforms/IRCE/single-access-no-preloop.ll
View File

@ -86,10 +86,10 @@ define void @single_access_no_preloop_with_offset(i32 *%arr, i32 *%a_len_ptr, i3
; CHECK-LABEL: @single_access_no_preloop_with_offset(
; CHECK: loop.preheader:
; CHECK: [[not_safe_range_end:[^ ]+]] = sub i32 3, %len
; CHECK: [[not_n:[^ ]+]] = sub i32 -1, %n
; CHECK: [[not_exit_main_loop_at_hiclamp_cmp:[^ ]+]] = icmp sgt i32 [[not_safe_range_end]], [[not_n]]
; CHECK: [[not_exit_main_loop_at_hiclamp:[^ ]+]] = select i1 [[not_exit_main_loop_at_hiclamp_cmp]], i32 [[not_safe_range_end]], i32 [[not_n]]
; CHECK: [[not_safe_range_end:[^ ]+]] = sub i32 3, %len
; CHECK: [[not_exit_main_loop_at_hiclamp_cmp:[^ ]+]] = icmp sgt i32 [[not_n]], [[not_safe_range_end]]
; CHECK: [[not_exit_main_loop_at_hiclamp:[^ ]+]] = select i1 [[not_exit_main_loop_at_hiclamp_cmp]], i32 [[not_n]], i32 [[not_safe_range_end]]
; CHECK: [[exit_main_loop_at_hiclamp:[^ ]+]] = sub i32 -1, [[not_exit_main_loop_at_hiclamp]]
; CHECK: [[exit_main_loop_at_loclamp_cmp:[^ ]+]] = icmp sgt i32 [[exit_main_loop_at_hiclamp]], 0
; CHECK: [[exit_main_loop_at_loclamp:[^ ]+]] = select i1 [[exit_main_loop_at_loclamp_cmp]], i32 [[exit_main_loop_at_hiclamp]], i32 0

76
llvm/test/Transforms/LoadStoreVectorizer/X86/compare-scev-by-complexity.ll Normal file
View File

@ -0,0 +1,76 @@
; RUN: opt -load-store-vectorizer %s -S | FileCheck %s
; Check that setting wrapping flags after a SCEV node is created
; does not invalidate "sorted by complexity" invariant for
; operands of commutative and associative SCEV operators.
target triple = "x86_64--"
@global_value0 = external constant i32
@global_value1 = external constant i32
@other_value = external global float
@a = external global float
@b = external global float
@c = external global float
@d = external global float
@plus1 = external global i32
@cnd = external global i8
; Function Attrs: nounwind
define void @main() local_unnamed_addr #0 {
; CHECK-LABEL: @main()
; CHECK: [[PTR:%[0-9]+]] = bitcast float* %preheader.load0.address to <2 x float>*
; CHECK: = load <2 x float>, <2 x float>* [[PTR]]
; CHECK-LABEL: for.body23:
entry:
%tmp = load i32, i32* @global_value0, !range !0
%tmp2 = load i32, i32* @global_value1
%and.i.i = and i32 %tmp2, 2
%add.nuw.nsw.i.i = add nuw nsw i32 %and.i.i, 0
%mul.i.i = shl nuw nsw i32 %add.nuw.nsw.i.i, 1
%and6.i.i = and i32 %tmp2, 3
%and9.i.i = and i32 %tmp2, 4
%add.nuw.nsw10.i.i = add nuw nsw i32 %and6.i.i, %and9.i.i
%conv3.i42.i = add nuw nsw i32 %mul.i.i, 1
%reass.add346.7 = add nuw nsw i32 %add.nuw.nsw10.i.i, 56
%reass.mul347.7 = mul nuw nsw i32 %tmp, %reass.add346.7
%add7.i.7 = add nuw nsw i32 %reass.mul347.7, 0
%preheader.address0.idx = add nuw nsw i32 %add7.i.7, %mul.i.i
%preheader.address0.idx.zext = zext i32 %preheader.address0.idx to i64
%preheader.load0.address = getelementptr inbounds float, float* @other_value, i64 %preheader.address0.idx.zext
%preheader.load0. = load float, float* %preheader.load0.address, align 4, !tbaa !1
%common.address.idx = add nuw nsw i32 %add7.i.7, %conv3.i42.i
%preheader.header.common.address.idx.zext = zext i32 %common.address.idx to i64
%preheader.load1.address = getelementptr inbounds float, float* @other_value, i64 %preheader.header.common.address.idx.zext
%preheader.load1. = load float, float* %preheader.load1.address, align 4, !tbaa !1
br label %for.body23
for.body23: ; preds = %for.body23, %entry
%loop.header.load0.address = getelementptr inbounds float, float* @other_value, i64 %preheader.header.common.address.idx.zext
%loop.header.load0. = load float, float* %loop.header.load0.address, align 4, !tbaa !1
%reass.mul343.7 = mul nuw nsw i32 %reass.add346.7, 72
%add7.i286.7.7 = add nuw nsw i32 %reass.mul343.7, 56
%add9.i288.7.7 = add nuw nsw i32 %add7.i286.7.7, %mul.i.i
%loop.header.address1.idx = add nuw nsw i32 %add9.i288.7.7, 1
%loop.header.address1.idx.zext = zext i32 %loop.header.address1.idx to i64
%loop.header.load1.address = getelementptr inbounds float, float* @other_value, i64 %loop.header.address1.idx.zext
%loop.header.load1. = load float, float* %loop.header.load1.address, align 4, !tbaa !1
store float %preheader.load0., float* @a, align 4, !tbaa !1
store float %preheader.load1., float* @b, align 4, !tbaa !1
store float %loop.header.load0., float* @c, align 4, !tbaa !1
store float %loop.header.load1., float* @d, align 4, !tbaa !1
%loaded.cnd = load i8, i8* @cnd
%condition = trunc i8 %loaded.cnd to i1
br i1 %condition, label %for.body23, label %exit
exit:
ret void
}
attributes #0 = { nounwind }
!0 = !{i32 0, i32 65536}
!1 = !{!2, !2, i64 0}
!2 = !{!"float", !3, i64 0}
!3 = !{!"omnipotent char", !4, i64 0}
!4 = !{!"Simple C++ TBAA"}

8
llvm/test/Transforms/LoopVectorize/X86/pr35432.ll
View File

@ -40,8 +40,8 @@ define i32 @main() local_unnamed_addr #0 {
; CHECK-NEXT: [[TMP4:%.*]] = add i8 [[CONV3]], -1
; CHECK-NEXT: [[TMP5:%.*]] = zext i8 [[TMP4]] to i32
; CHECK-NEXT: [[TMP6:%.*]] = sub i32 -1, [[TMP5]]
; CHECK-NEXT: [[TMP7:%.*]] = icmp ugt i32 [[TMP6]], [[TMP3]]
; CHECK-NEXT: [[UMAX:%.*]] = select i1 [[TMP7]], i32 [[TMP6]], i32 [[TMP3]]
; CHECK-NEXT: [[TMP7:%.*]] = icmp ugt i32 [[TMP3]], [[TMP6]]
; CHECK-NEXT: [[UMAX:%.*]] = select i1 [[TMP7]], i32 [[TMP3]], i32 [[TMP6]]
; CHECK-NEXT: [[TMP8:%.*]] = add i32 [[UMAX]], 2
; CHECK-NEXT: [[TMP9:%.*]] = add i32 [[TMP8]], [[TMP5]]
; CHECK-NEXT: [[MIN_ITERS_CHECK:%.*]] = icmp ult i32 [[TMP9]], 8
@ -50,8 +50,8 @@ define i32 @main() local_unnamed_addr #0 {
; CHECK-NEXT: [[TMP10:%.*]] = add i8 [[CONV3]], -1
; CHECK-NEXT: [[TMP11:%.*]] = zext i8 [[TMP10]] to i32
; CHECK-NEXT: [[TMP12:%.*]] = sub i32 -1, [[TMP11]]
; CHECK-NEXT: [[TMP13:%.*]] = icmp ugt i32 [[TMP12]], [[TMP3]]
; CHECK-NEXT: [[UMAX1:%.*]] = select i1 [[TMP13]], i32 [[TMP12]], i32 [[TMP3]]
; CHECK-NEXT: [[TMP13:%.*]] = icmp ugt i32 [[TMP3]], [[TMP12]]
; CHECK-NEXT: [[UMAX1:%.*]] = select i1 [[TMP13]], i32 [[TMP3]], i32 [[TMP12]]
; CHECK-NEXT: [[TMP14:%.*]] = add i32 [[UMAX1]], 1
; CHECK-NEXT: [[TMP15:%.*]] = add i32 [[TMP14]], [[TMP11]]
; CHECK-NEXT: [[TMP16:%.*]] = trunc i32 [[TMP15]] to i8