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[LSR] Fixup canonicalization formula and its checker.

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According to definition of canonical form, it is a canonical
if scale reg does not contain addrec for loop L then none of bases
should contain addrec for this loop.

The critical word here is "contains".

Current checker of canonical form checks not "containing" property
but "is". So it does not check whether it contains but whether it is.

Fix the checker and canonicalizing utility to follow definition.

Without this fix in the test attached the base formula looking as
reg((-1 * {0,+,8}<nuw><nsw><%bb2>)<nsw>) + 1*reg((8 * (%arg /u 8))<nuw>)
is considered as conanocial while base contains an addrec.
And modified formula we want to insert
reg({0,+,8}<nuw><nsw><%bb2>) + 1*reg((-8 * (%arg /u 8)))
is considered as not canonical.

Reviewed By: mkazantsev
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D122457
This commit is contained in:
Serguei Katkov 2022-03-25 10:19:01 +07:00
parent 01be9be2f2
commit 6444a65514
2 changed files with 96 additions and 11 deletions
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23
llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
View File

@ -479,6 +479,12 @@ void Formula::initialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE) {
canonicalize(*L);
}
static bool containsAddRecDependentOnLoop(const SCEV *S, const Loop &L) {
return SCEVExprContains(S, [&L](const SCEV *S) {
return isa<SCEVAddRecExpr>(S) && (cast<SCEVAddRecExpr>(S)->getLoop() == &L);
});
}
/// Check whether or not this formula satisfies the canonical
/// representation.
/// \see Formula::BaseRegs.
@ -492,18 +498,15 @@ bool Formula::isCanonical(const Loop &L) const {
if (Scale == 1 && BaseRegs.empty())
return false;
const SCEVAddRecExpr *SAR = dyn_cast<const SCEVAddRecExpr>(ScaledReg);
if (SAR && SAR->getLoop() == &L)
if (containsAddRecDependentOnLoop(ScaledReg, L))
return true;
// If ScaledReg is not a recurrent expr, or it is but its loop is not current
// loop, meanwhile BaseRegs contains a recurrent expr reg related with current
// loop, we want to swap the reg in BaseRegs with ScaledReg.
auto I = find_if(BaseRegs, [&](const SCEV *S) {
return isa<const SCEVAddRecExpr>(S) &&
(cast<SCEVAddRecExpr>(S)->getLoop() == &L);
return none_of(BaseRegs, [&L](const SCEV *S) {
return containsAddRecDependentOnLoop(S, L);
});
return I == BaseRegs.end();
}
/// Helper method to morph a formula into its canonical representation.
@ -535,11 +538,9 @@ void Formula::canonicalize(const Loop &L) {
// If ScaledReg is an invariant with respect to L, find the reg from
// BaseRegs containing the recurrent expr related with Loop L. Swap the
// reg with ScaledReg.
const SCEVAddRecExpr *SAR = dyn_cast<const SCEVAddRecExpr>(ScaledReg);
if (!SAR || SAR->getLoop() != &L) {
auto I = find_if(BaseRegs, [&](const SCEV *S) {
return isa<const SCEVAddRecExpr>(S) &&
(cast<SCEVAddRecExpr>(S)->getLoop() == &L);
if (!containsAddRecDependentOnLoop(ScaledReg, L)) {
auto I = find_if(BaseRegs, [&L](const SCEV *S) {
return containsAddRecDependentOnLoop(S, L);
});
if (I != BaseRegs.end())
std::swap(ScaledReg, *I);

84
llvm/test/Transforms/LoopStrengthReduce/canonical-form.ll Normal file
View File

@ -0,0 +1,84 @@
; RUN: opt -S -loop-reduce < %s | FileCheck %s
; Check that no crash here.
; When GenerateICmpZeroScales transforms the base formula
; it can get non-canonical form.
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define void @hoge(i32 %arg) {
; CHECK: @hoge
bb:
%tmp = and i32 %arg, -8
br label %bb2
bb1: ; preds = %bb2
ret void
bb2: ; preds = %bb2, %bb
%tmp3 = phi i64 [ 0, %bb ], [ %tmp62, %bb2 ]
%tmp4 = phi i32 [ 1, %bb ], [ %tmp63, %bb2 ]
%tmp5 = phi i32 [ 0, %bb ], [ %tmp64, %bb2 ]
%tmp6 = add i64 %tmp3, 1
%tmp7 = trunc i64 %tmp6 to i32
%tmp8 = sub i32 %tmp4, %tmp7
%tmp9 = mul i32 %tmp8, %tmp8
%tmp10 = sub i32 %tmp9, %tmp8
%tmp11 = sext i32 %tmp10 to i64
%tmp12 = sub i64 %tmp6, %tmp11
%tmp13 = add nuw nsw i32 %tmp4, 1
%tmp14 = add i64 %tmp12, 1
%tmp15 = trunc i64 %tmp14 to i32
%tmp16 = sub i32 %tmp13, %tmp15
%tmp17 = mul i32 %tmp16, %tmp16
%tmp18 = sub i32 %tmp17, %tmp16
%tmp19 = sext i32 %tmp18 to i64
%tmp20 = sub i64 %tmp14, %tmp19
%tmp21 = add i64 %tmp20, 1
%tmp22 = sub i64 %tmp21, 0
%tmp23 = add nuw nsw i32 %tmp4, 3
%tmp24 = add i64 %tmp22, 1
%tmp25 = trunc i64 %tmp24 to i32
%tmp26 = sub i32 %tmp23, %tmp25
%tmp27 = mul i32 %tmp26, %tmp26
%tmp28 = sub i32 %tmp27, %tmp26
%tmp29 = sext i32 %tmp28 to i64
%tmp30 = sub i64 %tmp24, %tmp29
%tmp31 = add nuw nsw i32 %tmp4, 4
%tmp32 = add i64 %tmp30, 1
%tmp33 = trunc i64 %tmp32 to i32
%tmp34 = sub i32 %tmp31, %tmp33
%tmp35 = mul i32 %tmp34, %tmp34
%tmp36 = sub i32 %tmp35, %tmp34
%tmp37 = sext i32 %tmp36 to i64
%tmp38 = sub i64 %tmp32, %tmp37
%tmp39 = add nuw nsw i32 %tmp4, 5
%tmp40 = add i64 %tmp38, 1
%tmp41 = trunc i64 %tmp40 to i32
%tmp42 = sub i32 %tmp39, %tmp41
%tmp43 = mul i32 %tmp42, %tmp42
%tmp44 = sub i32 %tmp43, %tmp42
%tmp45 = sext i32 %tmp44 to i64
%tmp46 = sub i64 %tmp40, %tmp45
%tmp47 = add nuw nsw i32 %tmp4, 6
%tmp48 = add i64 %tmp46, 1
%tmp49 = trunc i64 %tmp48 to i32
%tmp50 = sub i32 %tmp47, %tmp49
%tmp51 = mul i32 %tmp50, %tmp50
%tmp52 = sub i32 %tmp51, %tmp50
%tmp53 = sext i32 %tmp52 to i64
%tmp54 = sub i64 %tmp48, %tmp53
%tmp55 = add nuw nsw i32 %tmp4, 7
%tmp56 = add i64 %tmp54, 1
%tmp57 = trunc i64 %tmp56 to i32
%tmp58 = sub i32 %tmp55, %tmp57
%tmp59 = mul i32 %tmp58, %tmp58
%tmp60 = sub i32 %tmp59, %tmp58
%tmp61 = sext i32 %tmp60 to i64
%tmp62 = sub i64 %tmp56, %tmp61
%tmp63 = add nuw nsw i32 %tmp4, 8
%tmp64 = add i32 %tmp5, 8
%tmp65 = icmp eq i32 %tmp64, %tmp
br i1 %tmp65, label %bb1, label %bb2
}