Skip to content

Commit 9f3d169

Browse files
authored
[SCEVExpander] Preserve gep nuw during expansion (#102133)
When expanding SCEV adds to geps, transfer the nuw flag to the resulting gep. (Note that this doesn't apply to IV increment GEPs, which go through a different code path.)
1 parent 383a670 commit 9f3d169

20 files changed

+42
-38
lines changed

llvm/include/llvm/Transforms/Utils/ScalarEvolutionExpander.h

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -451,7 +451,7 @@ class SCEVExpander : public SCEVVisitor<SCEVExpander, Value *> {
451451

452452
/// Expand a SCEVAddExpr with a pointer type into a GEP instead of using
453453
/// ptrtoint+arithmetic+inttoptr.
454-
Value *expandAddToGEP(const SCEV *Op, Value *V);
454+
Value *expandAddToGEP(const SCEV *Op, Value *V, SCEV::NoWrapFlags Flags);
455455

456456
/// Find a previous Value in ExprValueMap for expand.
457457
/// DropPoisonGeneratingInsts is populated with instructions for which

llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp

Lines changed: 10 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -352,16 +352,19 @@ Value *SCEVExpander::InsertBinop(Instruction::BinaryOps Opcode,
352352
/// loop-invariant portions of expressions, after considering what
353353
/// can be folded using target addressing modes.
354354
///
355-
Value *SCEVExpander::expandAddToGEP(const SCEV *Offset, Value *V) {
355+
Value *SCEVExpander::expandAddToGEP(const SCEV *Offset, Value *V,
356+
SCEV::NoWrapFlags Flags) {
356357
assert(!isa<Instruction>(V) ||
357358
SE.DT.dominates(cast<Instruction>(V), &*Builder.GetInsertPoint()));
358359

359360
Value *Idx = expand(Offset);
361+
GEPNoWrapFlags NW = (Flags & SCEV::FlagNUW) ? GEPNoWrapFlags::noUnsignedWrap()
362+
: GEPNoWrapFlags::none();
360363

361364
// Fold a GEP with constant operands.
362365
if (Constant *CLHS = dyn_cast<Constant>(V))
363366
if (Constant *CRHS = dyn_cast<Constant>(Idx))
364-
return Builder.CreatePtrAdd(CLHS, CRHS);
367+
return Builder.CreatePtrAdd(CLHS, CRHS, "", NW);
365368

366369
// Do a quick scan to see if we have this GEP nearby. If so, reuse it.
367370
unsigned ScanLimit = 6;
@@ -380,7 +383,7 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *Offset, Value *V) {
380383
GEP->getSourceElementType() == Builder.getInt8Ty() &&
381384
GEP->getOperand(1) == Idx) {
382385
rememberFlags(GEP);
383-
GEP->setNoWrapFlags(GEPNoWrapFlags::none());
386+
GEP->setNoWrapFlags(GEP->getNoWrapFlags() & NW);
384387
return &*IP;
385388
}
386389
}
@@ -402,7 +405,7 @@ Value *SCEVExpander::expandAddToGEP(const SCEV *Offset, Value *V) {
402405
}
403406

404407
// Emit a GEP.
405-
return Builder.CreatePtrAdd(V, Idx, "scevgep");
408+
return Builder.CreatePtrAdd(V, Idx, "scevgep", NW);
406409
}
407410

408411
/// PickMostRelevantLoop - Given two loops pick the one that's most relevant for
@@ -549,7 +552,7 @@ Value *SCEVExpander::visitAddExpr(const SCEVAddExpr *S) {
549552
X = SE.getSCEV(U->getValue());
550553
NewOps.push_back(X);
551554
}
552-
Sum = expandAddToGEP(SE.getAddExpr(NewOps), Sum);
555+
Sum = expandAddToGEP(SE.getAddExpr(NewOps), Sum, S->getNoWrapFlags());
553556
} else if (Op->isNonConstantNegative()) {
554557
// Instead of doing a negate and add, just do a subtract.
555558
Value *W = expand(SE.getNegativeSCEV(Op));
@@ -1251,7 +1254,8 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
12511254
if (!S->getStart()->isZero()) {
12521255
if (isa<PointerType>(S->getType())) {
12531256
Value *StartV = expand(SE.getPointerBase(S));
1254-
return expandAddToGEP(SE.removePointerBase(S), StartV);
1257+
return expandAddToGEP(SE.removePointerBase(S), StartV,
1258+
S->getNoWrapFlags(SCEV::FlagNUW));
12551259
}
12561260

12571261
SmallVector<const SCEV *, 4> NewOps(S->operands());

llvm/test/Analysis/ScalarEvolution/scev-expander-reuse-gep.ll

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
; RUN: opt -mtriple=i386-apple-macosx10.12.0 < %s -loop-reduce -S | FileCheck %s
44

55
; CHECK: %ptr4.ptr1 = select i1 %cmp.i, ptr %ptr4, ptr %ptr1
6-
; CHECK-NEXT: %scevgep = getelementptr i8, ptr %ptr4.ptr1, i32 1
6+
; CHECK-NEXT: %scevgep = getelementptr nuw i8, ptr %ptr4.ptr1, i32 1
77
; CHECK-NEXT: br label %while.cond.i
88

99
target datalayout = "e-m:o-p:32:32-f64:32:64-f80:128-n8:16:32-S128"

llvm/test/Transforms/IndVarSimplify/D108043.ll

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@ define internal fastcc void @func_2() unnamed_addr {
99
; CHECK-NEXT: lbl_2898.preheader:
1010
; CHECK-NEXT: br label [[LBL_2898:%.*]]
1111
; CHECK: lbl_2898.loopexit:
12-
; CHECK-NEXT: store ptr getelementptr inbounds (i8, ptr @g_2168, i64 76), ptr @g_1150, align 8
12+
; CHECK-NEXT: store ptr getelementptr inbounds nuw (i8, ptr @g_2168, i64 76), ptr @g_1150, align 8
1313
; CHECK-NEXT: br label [[LBL_2898]]
1414
; CHECK: lbl_2898:
1515
; CHECK-NEXT: br label [[FOR_COND884:%.*]]

llvm/test/Transforms/IndVarSimplify/lftr-dead-ivs.ll

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -112,7 +112,7 @@ define void @dom_store_preinc() #0 {
112112
; CHECK-NEXT: [[P_0:%.*]] = phi ptr [ @data, [[ENTRY:%.*]] ], [ [[TMP3:%.*]], [[LOOP]] ]
113113
; CHECK-NEXT: store volatile i8 0, ptr [[P_0]], align 1
114114
; CHECK-NEXT: [[TMP3]] = getelementptr inbounds i8, ptr [[P_0]], i64 1
115-
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne ptr [[P_0]], getelementptr (i8, ptr @data, i64 245)
115+
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne ptr [[P_0]], getelementptr nuw (i8, ptr @data, i64 245)
116116
; CHECK-NEXT: br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
117117
; CHECK: exit:
118118
; CHECK-NEXT: ret void
@@ -141,7 +141,7 @@ define void @dom_store_postinc() #0 {
141141
; CHECK-NEXT: [[P_0:%.*]] = phi ptr [ @data, [[ENTRY:%.*]] ], [ [[TMP3:%.*]], [[LOOP]] ]
142142
; CHECK-NEXT: [[TMP3]] = getelementptr inbounds i8, ptr [[P_0]], i64 1
143143
; CHECK-NEXT: store volatile i8 0, ptr [[TMP3]], align 1
144-
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne ptr [[TMP3]], getelementptr (i8, ptr @data, i64 246)
144+
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne ptr [[TMP3]], getelementptr nuw (i8, ptr @data, i64 246)
145145
; CHECK-NEXT: br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
146146
; CHECK: exit:
147147
; CHECK-NEXT: ret void
@@ -170,7 +170,7 @@ define i8 @dom_load() #0 {
170170
; CHECK-NEXT: [[P_0:%.*]] = phi ptr [ @data, [[ENTRY:%.*]] ], [ [[TMP3:%.*]], [[LOOP]] ]
171171
; CHECK-NEXT: [[TMP3]] = getelementptr inbounds i8, ptr [[P_0]], i64 1
172172
; CHECK-NEXT: [[V:%.*]] = load i8, ptr [[TMP3]], align 1
173-
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne ptr [[TMP3]], getelementptr (i8, ptr @data, i64 246)
173+
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne ptr [[TMP3]], getelementptr nuw (i8, ptr @data, i64 246)
174174
; CHECK-NEXT: br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
175175
; CHECK: exit:
176176
; CHECK-NEXT: [[V_LCSSA:%.*]] = phi i8 [ [[V]], [[LOOP]] ]

llvm/test/Transforms/IndVarSimplify/lftr.ll

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -196,7 +196,7 @@ define void @test_zext(ptr %a) #0 {
196196
; CHECK-NEXT: [[T2:%.*]] = load i8, ptr [[DOT0]], align 1
197197
; CHECK-NEXT: [[T3]] = getelementptr inbounds i8, ptr [[P_0]], i64 1
198198
; CHECK-NEXT: store i8 [[T2]], ptr [[P_0]], align 1
199-
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne ptr [[P_0]], getelementptr inbounds (i8, ptr @data, i64 239)
199+
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne ptr [[P_0]], getelementptr inbounds nuw (i8, ptr @data, i64 239)
200200
; CHECK-NEXT: br i1 [[EXITCOND]], label [[LOOP]], label [[EXIT:%.*]]
201201
; CHECK: exit:
202202
; CHECK-NEXT: ret void

llvm/test/Transforms/LoopIdiom/basic-address-space.ll

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@ define void @test10(ptr addrspace(2) %X) nounwind ssp {
1313
; CHECK: bb.nph:
1414
; CHECK-NEXT: [[I_04:%.*]] = phi i16 [ 0, [[ENTRY:%.*]] ], [ [[INC12:%.*]], [[FOR_INC10:%.*]] ]
1515
; CHECK-NEXT: [[TMP0:%.*]] = mul nuw nsw i16 [[I_04]], 100
16-
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, ptr addrspace(2) [[X]], i16 [[TMP0]]
16+
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr nuw i8, ptr addrspace(2) [[X]], i16 [[TMP0]]
1717
; CHECK-NEXT: br label [[FOR_BODY5:%.*]]
1818
; CHECK: for.body5:
1919
; CHECK-NEXT: [[J_02:%.*]] = phi i16 [ 0, [[BB_NPH]] ], [ [[INC:%.*]], [[FOR_BODY5]] ]

llvm/test/Transforms/LoopIdiom/basic.ll

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -481,7 +481,7 @@ define void @test10(ptr %X) nounwind ssp {
481481
; CHECK-NEXT: [[INDVAR:%.*]] = phi i64 [ [[INDVAR_NEXT:%.*]], [[FOR_INC10:%.*]] ], [ 0, [[ENTRY:%.*]] ]
482482
; CHECK-NEXT: [[I_04:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[INC12:%.*]], [[FOR_INC10]] ]
483483
; CHECK-NEXT: [[TMP0:%.*]] = mul nuw nsw i64 [[INDVAR]], 100
484-
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, ptr [[X]], i64 [[TMP0]]
484+
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr nuw i8, ptr [[X]], i64 [[TMP0]]
485485
; CHECK-NEXT: br label [[FOR_BODY5:%.*]]
486486
; CHECK: for.body5:
487487
; CHECK-NEXT: [[J_02:%.*]] = phi i32 [ 0, [[BB_NPH]] ], [ [[INC:%.*]], [[FOR_BODY5]] ]
@@ -682,7 +682,7 @@ define void @PR14241(ptr %s, i64 %size) {
682682
; CHECK-NEXT: entry:
683683
; CHECK-NEXT: [[END_IDX:%.*]] = add i64 [[SIZE:%.*]], -1
684684
; CHECK-NEXT: [[END_PTR:%.*]] = getelementptr inbounds i32, ptr [[S:%.*]], i64 [[END_IDX]]
685-
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, ptr [[S]], i64 4
685+
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr nuw i8, ptr [[S]], i64 4
686686
; CHECK-NEXT: [[TMP0:%.*]] = shl i64 [[SIZE]], 2
687687
; CHECK-NEXT: [[TMP1:%.*]] = add i64 [[TMP0]], -8
688688
; CHECK-NEXT: [[TMP2:%.*]] = lshr i64 [[TMP1]], 2

llvm/test/Transforms/LoopIdiom/memset-pr52104.ll

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -6,12 +6,12 @@ define void @f(ptr nocapture nonnull align 4 dereferenceable(20) %0, i32 %1) loc
66
; CHECK-NEXT: [[TMP3:%.*]] = trunc i32 [[TMP1:%.*]] to i2
77
; CHECK-NEXT: [[TMP4:%.*]] = zext i2 [[TMP3]] to i64
88
; CHECK-NEXT: [[TMP5:%.*]] = shl nuw nsw i64 [[TMP4]], 2
9-
; CHECK-NEXT: [[UGLYGEP:%.*]] = getelementptr i8, ptr [[TMP0:%.*]], i64 [[TMP5]]
9+
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr nuw i8, ptr [[TMP0:%.*]], i64 [[TMP5]]
1010
; CHECK-NEXT: [[TMP6:%.*]] = sub i2 -1, [[TMP3]]
1111
; CHECK-NEXT: [[TMP7:%.*]] = zext i2 [[TMP6]] to i64
1212
; CHECK-NEXT: [[TMP8:%.*]] = shl nuw nsw i64 [[TMP7]], 2
1313
; CHECK-NEXT: [[TMP9:%.*]] = add nuw nsw i64 [[TMP8]], 4
14-
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 4 [[UGLYGEP]], i8 0, i64 [[TMP9]], i1 false)
14+
; CHECK-NEXT: call void @llvm.memset.p0.i64(ptr align 4 [[SCEVGEP]], i8 0, i64 [[TMP9]], i1 false)
1515
; CHECK-NEXT: br label [[TMP10:%.*]]
1616
; CHECK: 10:
1717
; CHECK-NEXT: [[TMP11:%.*]] = phi i32 [ [[TMP15:%.*]], [[TMP10]] ], [ [[TMP1]], [[TMP2:%.*]] ]

llvm/test/Transforms/LoopStrengthReduce/2011-12-19-PostincQuadratic.ll

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,7 @@ define void @vb() nounwind {
1616
; CHECK-NEXT: for.cond.preheader:
1717
; CHECK-NEXT: br label [[FOR_BODY7:%.*]]
1818
; CHECK: for.body7:
19-
; CHECK-NEXT: [[LSR_IV1:%.*]] = phi ptr [ [[SCEVGEP:%.*]], [[FOR_BODY7]] ], [ getelementptr inbounds (i8, ptr @b, i32 4), [[FOR_COND_PREHEADER:%.*]] ]
19+
; CHECK-NEXT: [[LSR_IV1:%.*]] = phi ptr [ [[SCEVGEP:%.*]], [[FOR_BODY7]] ], [ getelementptr inbounds nuw (i8, ptr @b, i32 4), [[FOR_COND_PREHEADER:%.*]] ]
2020
; CHECK-NEXT: [[LSR_IV:%.*]] = phi i32 [ [[LSR_IV_NEXT:%.*]], [[FOR_BODY7]] ], [ 8, [[FOR_COND_PREHEADER]] ]
2121
; CHECK-NEXT: [[INDVARS_IV77:%.*]] = phi i32 [ [[INDVARS_IV_NEXT78:%.*]], [[FOR_BODY7]] ], [ 1, [[FOR_COND_PREHEADER]] ]
2222
; CHECK-NEXT: [[INDVARS_IV_NEXT78]] = add i32 [[INDVARS_IV77]], 1

0 commit comments

Comments
 (0)