[llvm] r357320 - [SCEV] Check the cache in get{S|U}MaxExpr before doing any work
Sanjoy Das via llvm-commits
llvm-commits at lists.llvm.org
Fri Mar 29 15:00:13 PDT 2019
Author: sanjoy
Date: Fri Mar 29 15:00:12 2019
New Revision: 357320
URL: http://llvm.org/viewvc/llvm-project?rev=357320&view=rev
Log:
[SCEV] Check the cache in get{S|U}MaxExpr before doing any work
Summary:
This lets us avoid e.g. checking if A >=s B in getSMaxExpr(A, B) if we've
already established that (A smax B) is the best we can do.
Fixes PR41225.
Reviewers: asbirlea
Subscribers: mcrosier, jlebar, bixia, jdoerfert, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60010
Added:
llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll
Modified:
llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
llvm/trunk/lib/Analysis/ScalarEvolution.cpp
Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolution.h?rev=357320&r1=357319&r2=357320&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolution.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolution.h Fri Mar 29 15:00:12 2019
@@ -1871,6 +1871,16 @@ private:
/// Assign A and B to LHS and RHS, respectively.
bool matchURem(const SCEV *Expr, const SCEV *&LHS, const SCEV *&RHS);
+ /// Look for a SCEV expression with type `SCEVType` and operands `Ops` in
+ /// `UniqueSCEVs`.
+ ///
+ /// The first component of the returned tuple is the SCEV if found and null
+ /// otherwise. The second component is the `FoldingSetNodeID` that was
+ /// constructed to look up the SCEV and the third component is the insertion
+ /// point.
+ std::tuple<const SCEV *, FoldingSetNodeID, void *>
+ findExistingSCEVInCache(int SCEVType, ArrayRef<const SCEV *> Ops);
+
FoldingSet<SCEV> UniqueSCEVs;
FoldingSet<SCEVPredicate> UniquePreds;
BumpPtrAllocator SCEVAllocator;
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=357320&r1=357319&r2=357320&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Fri Mar 29 15:00:12 2019
@@ -3523,6 +3523,17 @@ const SCEV *ScalarEvolution::getSMaxExpr
return getSMaxExpr(Ops);
}
+std::tuple<const SCEV *, FoldingSetNodeID, void *>
+ScalarEvolution::findExistingSCEVInCache(int SCEVType,
+ ArrayRef<const SCEV *> Ops) {
+ FoldingSetNodeID ID;
+ void *IP = nullptr;
+ ID.AddInteger(SCEVType);
+ for (unsigned i = 0, e = Ops.size(); i != e; ++i)
+ ID.AddPointer(Ops[i]);
+ return {UniqueSCEVs.FindNodeOrInsertPos(ID, IP), std::move(ID), IP};
+}
+
const SCEV *
ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
assert(!Ops.empty() && "Cannot get empty smax!");
@@ -3537,6 +3548,11 @@ ScalarEvolution::getSMaxExpr(SmallVector
// Sort by complexity, this groups all similar expression types together.
GroupByComplexity(Ops, &LI, DT);
+ // Check if we have created the same SMax expression before.
+ if (const SCEV *S = std::get<0>(findExistingSCEVInCache(scSMaxExpr, Ops))) {
+ return S;
+ }
+
// If there are any constants, fold them together.
unsigned Idx = 0;
if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
@@ -3604,16 +3620,16 @@ ScalarEvolution::getSMaxExpr(SmallVector
// Okay, it looks like we really DO need an smax expr. Check to see if we
// already have one, otherwise create a new one.
+ const SCEV *ExistingSCEV;
FoldingSetNodeID ID;
- ID.AddInteger(scSMaxExpr);
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- ID.AddPointer(Ops[i]);
- void *IP = nullptr;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
+ void *IP;
+ std::tie(ExistingSCEV, ID, IP) = findExistingSCEVInCache(scSMaxExpr, Ops);
+ if (ExistingSCEV)
+ return ExistingSCEV;
const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
std::uninitialized_copy(Ops.begin(), Ops.end(), O);
- SCEV *S = new (SCEVAllocator) SCEVSMaxExpr(ID.Intern(SCEVAllocator),
- O, Ops.size());
+ SCEV *S =
+ new (SCEVAllocator) SCEVSMaxExpr(ID.Intern(SCEVAllocator), O, Ops.size());
UniqueSCEVs.InsertNode(S, IP);
addToLoopUseLists(S);
return S;
@@ -3639,6 +3655,11 @@ ScalarEvolution::getUMaxExpr(SmallVector
// Sort by complexity, this groups all similar expression types together.
GroupByComplexity(Ops, &LI, DT);
+ // Check if we have created the same UMax expression before.
+ if (const SCEV *S = std::get<0>(findExistingSCEVInCache(scUMaxExpr, Ops))) {
+ return S;
+ }
+
// If there are any constants, fold them together.
unsigned Idx = 0;
if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
@@ -3707,12 +3728,12 @@ ScalarEvolution::getUMaxExpr(SmallVector
// Okay, it looks like we really DO need a umax expr. Check to see if we
// already have one, otherwise create a new one.
+ const SCEV *ExistingSCEV;
FoldingSetNodeID ID;
- ID.AddInteger(scUMaxExpr);
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- ID.AddPointer(Ops[i]);
- void *IP = nullptr;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
+ void *IP;
+ std::tie(ExistingSCEV, ID, IP) = findExistingSCEVInCache(scUMaxExpr, Ops);
+ if (ExistingSCEV)
+ return ExistingSCEV;
const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
std::uninitialized_copy(Ops.begin(), Ops.end(), O);
SCEV *S = new (SCEVAllocator) SCEVUMaxExpr(ID.Intern(SCEVAllocator),
Added: llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll?rev=357320&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll (added)
+++ llvm/trunk/test/Analysis/ScalarEvolution/max-expr-cache.ll Fri Mar 29 15:00:12 2019
@@ -0,0 +1,156 @@
+; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
+
+; SCEV would take a long time to compute SCEV expressions for this IR. If SCEV
+; finishes in < 1 second then the bug is fixed.
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64--linux-gnu"
+
+define void @smax(i32 %tmp3) {
+ ; CHECK-LABEL: Printing analysis 'Scalar Evolution Analysis' for function 'smax'
+entry:
+ br label %bb4
+
+bb4:
+ %tmp5 = phi i64 [ %tmp62, %bb61 ], [ 0, %entry ]
+ %tmp6 = trunc i64 %tmp5 to i32
+ %tmp7 = shl nsw i32 %tmp6, 8
+ %tmp8 = sub nsw i32 %tmp3, %tmp7
+ %tmp9 = icmp slt i32 %tmp8, 256
+ %tmp10 = select i1 %tmp9, i32 %tmp8, i32 256
+ %tmp11 = add nsw i32 %tmp10, 1
+ %tmp12 = icmp sgt i32 %tmp8, %tmp11
+ %tmp13 = select i1 %tmp12, i32 %tmp11, i32 %tmp8
+ %tmp14 = icmp slt i32 %tmp13, 256
+ %tmp15 = select i1 %tmp14, i32 %tmp13, i32 256
+ %tmp16 = add nsw i32 %tmp15, 1
+ %tmp17 = icmp sgt i32 %tmp8, %tmp16
+ %tmp18 = select i1 %tmp17, i32 %tmp16, i32 %tmp8
+ %tmp19 = icmp slt i32 %tmp18, 256
+ %tmp20 = select i1 %tmp19, i32 %tmp18, i32 256
+ %tmp21 = add nsw i32 %tmp20, 1
+ %tmp22 = icmp sgt i32 %tmp8, %tmp21
+ %tmp23 = select i1 %tmp22, i32 %tmp21, i32 %tmp8
+ %tmp24 = icmp slt i32 %tmp23, 256
+ %tmp25 = select i1 %tmp24, i32 %tmp23, i32 256
+ %tmp26 = add nsw i32 %tmp25, 1
+ %tmp27 = icmp sgt i32 %tmp8, %tmp26
+ %tmp28 = select i1 %tmp27, i32 %tmp26, i32 %tmp8
+ %tmp29 = icmp slt i32 %tmp28, 256
+ %tmp30 = select i1 %tmp29, i32 %tmp28, i32 256
+ %tmp31 = add nsw i32 %tmp30, 1
+ %tmp32 = icmp sgt i32 %tmp8, %tmp31
+ %tmp33 = select i1 %tmp32, i32 %tmp31, i32 %tmp8
+ %tmp34 = icmp slt i32 %tmp33, 256
+ %tmp35 = select i1 %tmp34, i32 %tmp33, i32 256
+ %tmp36 = add nsw i32 %tmp35, 1
+ %tmp37 = icmp sgt i32 %tmp8, %tmp36
+ %tmp38 = select i1 %tmp37, i32 %tmp36, i32 %tmp8
+ %tmp39 = icmp slt i32 %tmp38, 256
+ %tmp40 = select i1 %tmp39, i32 %tmp38, i32 256
+ %tmp41 = add nsw i32 %tmp40, 1
+ %tmp42 = icmp sgt i32 %tmp8, %tmp41
+ %tmp43 = select i1 %tmp42, i32 %tmp41, i32 %tmp8
+ %tmp44 = add nsw i32 %tmp10, 7
+ %tmp45 = icmp slt i32 %tmp43, 256
+ %tmp46 = select i1 %tmp45, i32 %tmp43, i32 256
+; CHECK: %tmp46 = select i1 %tmp45, i32 %tmp43, i32 256
+; CHECK-NEXT: --> (-1 + (-1 * (-257 smax (-1 + (-257 smax (-1 + (-257 smax (-1 + (-257 smax (-1 + (-257 smax (-1 + (-257 smax (-1 + (-257 smax (-1 + (-257 smax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> smax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> smax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> smax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> smax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> smax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> smax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> smax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw>)<nsw>
+ %tmp47 = icmp sgt i32 %tmp44, %tmp46
+ %tmp48 = select i1 %tmp47, i32 %tmp44, i32 %tmp46
+ %tmp49 = ashr i32 %tmp48, 3
+ %tmp50 = icmp sgt i32 %tmp49, 0
+ %tmp51 = select i1 %tmp50, i32 %tmp49, i32 0
+ %tmp52 = zext i32 %tmp51 to i64
+ br label %bb53
+
+bb53:
+ %tmp54 = phi i64 [ undef, %bb4 ], [ %tmp59, %bb53 ]
+ %tmp55 = trunc i64 %tmp54 to i32
+ %tmp56 = shl nsw i32 %tmp55, 3
+ %tmp57 = sext i32 %tmp56 to i64
+ %tmp58 = getelementptr inbounds i8, i8* null, i64 %tmp57
+ store i8 undef, i8* %tmp58, align 8
+ %tmp59 = add nsw i64 %tmp54, 1
+ %tmp60 = icmp eq i64 %tmp59, %tmp52
+ br i1 %tmp60, label %bb61, label %bb53
+
+bb61:
+ %tmp62 = add nuw nsw i64 %tmp5, 1
+ br label %bb4
+}
+
+
+define void @umax(i32 %tmp3) {
+; CHECK-LABEL: Printing analysis 'Scalar Evolution Analysis' for function 'umax'
+entry:
+ br label %bb4
+
+bb4:
+ %tmp5 = phi i64 [ %tmp62, %bb61 ], [ 0, %entry ]
+ %tmp6 = trunc i64 %tmp5 to i32
+ %tmp7 = shl nsw i32 %tmp6, 8
+ %tmp8 = sub nsw i32 %tmp3, %tmp7
+ %tmp9 = icmp ult i32 %tmp8, 256
+ %tmp10 = select i1 %tmp9, i32 %tmp8, i32 256
+ %tmp11 = add nsw i32 %tmp10, 1
+ %tmp12 = icmp ugt i32 %tmp8, %tmp11
+ %tmp13 = select i1 %tmp12, i32 %tmp11, i32 %tmp8
+ %tmp14 = icmp ult i32 %tmp13, 256
+ %tmp15 = select i1 %tmp14, i32 %tmp13, i32 256
+ %tmp16 = add nsw i32 %tmp15, 1
+ %tmp17 = icmp ugt i32 %tmp8, %tmp16
+ %tmp18 = select i1 %tmp17, i32 %tmp16, i32 %tmp8
+ %tmp19 = icmp ult i32 %tmp18, 256
+ %tmp20 = select i1 %tmp19, i32 %tmp18, i32 256
+ %tmp21 = add nsw i32 %tmp20, 1
+ %tmp22 = icmp ugt i32 %tmp8, %tmp21
+ %tmp23 = select i1 %tmp22, i32 %tmp21, i32 %tmp8
+ %tmp24 = icmp ult i32 %tmp23, 256
+ %tmp25 = select i1 %tmp24, i32 %tmp23, i32 256
+ %tmp26 = add nsw i32 %tmp25, 1
+ %tmp27 = icmp ugt i32 %tmp8, %tmp26
+ %tmp28 = select i1 %tmp27, i32 %tmp26, i32 %tmp8
+ %tmp29 = icmp ult i32 %tmp28, 256
+ %tmp30 = select i1 %tmp29, i32 %tmp28, i32 256
+ %tmp31 = add nsw i32 %tmp30, 1
+ %tmp32 = icmp ugt i32 %tmp8, %tmp31
+ %tmp33 = select i1 %tmp32, i32 %tmp31, i32 %tmp8
+ %tmp34 = icmp ult i32 %tmp33, 256
+ %tmp35 = select i1 %tmp34, i32 %tmp33, i32 256
+ %tmp36 = add nsw i32 %tmp35, 1
+ %tmp37 = icmp ugt i32 %tmp8, %tmp36
+ %tmp38 = select i1 %tmp37, i32 %tmp36, i32 %tmp8
+ %tmp39 = icmp ult i32 %tmp38, 256
+ %tmp40 = select i1 %tmp39, i32 %tmp38, i32 256
+ %tmp41 = add nsw i32 %tmp40, 1
+ %tmp42 = icmp ugt i32 %tmp8, %tmp41
+ %tmp43 = select i1 %tmp42, i32 %tmp41, i32 %tmp8
+ %tmp44 = add nsw i32 %tmp10, 7
+ %tmp45 = icmp ult i32 %tmp43, 256
+ %tmp46 = select i1 %tmp45, i32 %tmp43, i32 256
+; CHECK: %tmp46 = select i1 %tmp45, i32 %tmp43, i32 256
+; CHECK-NEXT: --> (-1 + (-1 * (-257 umax (-1 + (-257 umax (-1 + (-257 umax (-1 + (-257 umax (-1 + (-257 umax (-1 + (-257 umax (-1 + (-257 umax (-1 + (-257 umax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> umax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> umax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> umax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> umax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> umax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> umax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw> umax {(-1 + (-1 * %tmp3)),+,256}<%bb4>))<nsw>)<nsw>
+ %tmp47 = icmp ugt i32 %tmp44, %tmp46
+ %tmp48 = select i1 %tmp47, i32 %tmp44, i32 %tmp46
+ %tmp49 = ashr i32 %tmp48, 3
+ %tmp50 = icmp ugt i32 %tmp49, 0
+ %tmp51 = select i1 %tmp50, i32 %tmp49, i32 0
+ %tmp52 = zext i32 %tmp51 to i64
+ br label %bb53
+
+bb53:
+ %tmp54 = phi i64 [ undef, %bb4 ], [ %tmp59, %bb53 ]
+ %tmp55 = trunc i64 %tmp54 to i32
+ %tmp56 = shl nsw i32 %tmp55, 3
+ %tmp57 = sext i32 %tmp56 to i64
+ %tmp58 = getelementptr inbounds i8, i8* null, i64 %tmp57
+ store i8 undef, i8* %tmp58, align 8
+ %tmp59 = add nsw i64 %tmp54, 1
+ %tmp60 = icmp eq i64 %tmp59, %tmp52
+ br i1 %tmp60, label %bb61, label %bb53
+
+bb61:
+ %tmp62 = add nuw nsw i64 %tmp5, 1
+ br label %bb4
+}
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