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Recommit "[SCEV] Look through single value PHIs." 

This commit was originally because it was suspected to cause a crash,
but a reproducer did not surface.

A crash that was exposed by this change was fixed in 1d8f2e5292.

This reverts the revert commit 0581c0b0ee.
This commit is contained in:
Florian Hahn 2020-09-21 11:03:27 +01:00
parent 2d76274b99
commit 11dccf8d3a
4 changed files with 22 additions and 43 deletions
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7
llvm/lib/Analysis/ScalarEvolution.cpp
View File

@ -5114,13 +5114,8 @@ const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
if (const SCEV *S = createNodeFromSelectLikePHI(PN))
return S;
// If the PHI has a single incoming value, follow that value, unless the
// PHI's incoming blocks are in a different loop, in which case doing so
// risks breaking LCSSA form. Instcombine would normally zap these, but
// it doesn't have DominatorTree information, so it may miss cases.
if (Value *V = SimplifyInstruction(PN, {getDataLayout(), &TLI, &DT, &AC}))
if (LI.replacementPreservesLCSSAForm(PN, V))
return getSCEV(V);
return getSCEV(V);
// If it's not a loop phi, we can't handle it yet.
return getUnknown(PN);

4
llvm/test/Analysis/ScalarEvolution/solve-quadratic-i1.ll
View File

@ -58,9 +58,9 @@ b2: ; preds = %b1
; CHECK-NEXT: %v6 = add nuw nsw i32 %v1, 1
; CHECK-NEXT: --> {4,+,1}<nuw><nsw><%b1> U: [4,7) S: [4,7) Exits: 6 LoopDispositions: { %b1: Computable }
; CHECK-NEXT: %v7 = phi i32 [ %v1, %b1 ]
; CHECK-NEXT: --> %v7 U: [3,6) S: [3,6)
; CHECK-NEXT: --> {3,+,1}<nuw><nsw><%b1> U: [3,6) S: [3,6) --> 5 U: [5,6) S: [5,6)
; CHECK-NEXT: %v8 = phi i16 [ %v3, %b1 ]
; CHECK-NEXT: --> %v8 U: full-set S: full-set
; CHECK-NEXT: --> {3,+,4,+,1}<%b1> U: full-set S: full-set --> 12 U: [12,13) S: [12,13)
; CHECK-NEXT: Determining loop execution counts for: @f1
; CHECK-NEXT: Loop %b3: <multiple exits> Unpredictable backedge-taken count.
; CHECK-NEXT: Loop %b3: Unpredictable max backedge-taken count.

6
llvm/test/Analysis/ScalarEvolution/solve-quadratic-overflow.ll
View File

@ -13,11 +13,11 @@
; CHECK-NEXT: %v3 = mul i16 %v2, %v2
; CHECK-NEXT: --> {1,+,3,+,2}<%b1> U: full-set S: full-set Exits: 0 LoopDispositions: { %b1: Computable }
; CHECK-NEXT: %v5 = phi i16 [ %v2, %b1 ]
; CHECK-NEXT: --> %v5 U: [-256,0) S: [-256,0)
; CHECK-NEXT: --> {-1,+,-1}<%b1> U: [-256,0) S: [-256,0) --> -256 U: [-256,-255) S: [-256,-255)
; CHECK-NEXT: %v6 = phi i16 [ %v3, %b1 ]
; CHECK-NEXT: --> %v6 U: full-set S: full-set
; CHECK-NEXT: --> {1,+,3,+,2}<%b1> U: full-set S: full-set --> 0 U: [0,1) S: [0,1)
; CHECK-NEXT: %v7 = sext i16 %v5 to i32
; CHECK-NEXT: --> (sext i16 %v5 to i32) U: [-256,0) S: [-256,0)
; CHECK-NEXT: --> {-1,+,-1}<nsw><%b1> U: [-256,0) S: [-256,0) --> -256 U: [-256,-255) S: [-256,-255)
; CHECK-NEXT: Determining loop execution counts for: @f0
; CHECK-NEXT: Loop %b1: backedge-taken count is 255
; CHECK-NEXT: Loop %b1: max backedge-taken count is 255

48
llvm/test/Transforms/LoopStrengthReduce/funclet.ll
View File

@ -15,25 +15,21 @@ define void @f() personality i32 (...)* @_except_handler3 {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[THROW:%.*]]
; CHECK: throw:
; CHECK-NEXT: [[TMP96:%.*]] = getelementptr inbounds i8, i8* undef, i32 1
; CHECK-NEXT: invoke void @reserve()
; CHECK-NEXT: to label [[THROW]] unwind label [[PAD:%.*]]
; CHECK: pad:
; CHECK-NEXT: [[PHI2:%.*]] = phi i8* [ [[TMP96]], [[THROW]] ]
; CHECK-NEXT: [[CS:%.*]] = catchswitch within none [label %unreachable] unwind label [[BLAH2:%.*]]
; CHECK: unreachable:
; CHECK-NEXT: [[TMP0:%.*]] = catchpad within [[CS]] []
; CHECK-NEXT: unreachable
; CHECK: blah2:
; CHECK-NEXT: [[CLEANUPPADI4_I_I_I:%.*]] = cleanuppad within none []
; CHECK-NEXT: [[PHI21:%.*]] = ptrtoint i8* [[PHI2]] to i32
; CHECK-NEXT: [[TMP1:%.*]] = sub i32 1, [[PHI21]]
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, i8* undef, i32 [[TMP1]]
; CHECK-NEXT: br label [[LOOP_BODY:%.*]]
; CHECK: loop_body:
; CHECK-NEXT: [[LSR_IV:%.*]] = phi i8* [ [[SCEVGEP2:%.*]], [[ITER:%.*]] ], [ [[SCEVGEP]], [[BLAH2]] ]
; CHECK-NEXT: [[SCEVGEP2]] = getelementptr i8, i8* [[LSR_IV]], i32 -1
; CHECK-NEXT: [[TMP100:%.*]] = icmp eq i8* [[SCEVGEP2]], null
; CHECK-NEXT: [[LSR_IV:%.*]] = phi i32 [ [[LSR_IV_NEXT:%.*]], [[ITER:%.*]] ], [ 0, [[BLAH2]] ]
; CHECK-NEXT: [[LSR_IV_NEXT]] = add nuw nsw i32 [[LSR_IV]], -1
; CHECK-NEXT: [[LSR_IV_NEXT1:%.*]] = inttoptr i32 [[LSR_IV_NEXT]] to i8*
; CHECK-NEXT: [[TMP100:%.*]] = icmp eq i8* [[LSR_IV_NEXT1]], null
; CHECK-NEXT: br i1 [[TMP100]], label [[UNWIND_OUT:%.*]], label [[ITER]]
; CHECK: iter:
; CHECK-NEXT: br i1 true, label [[UNWIND_OUT]], label [[LOOP_BODY]]
@ -78,29 +74,25 @@ define void @g() personality i32 (...)* @_except_handler3 {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[THROW:%.*]]
; CHECK: throw:
; CHECK-NEXT: [[TMP96:%.*]] = getelementptr inbounds i8, i8* undef, i32 1
; CHECK-NEXT: invoke void @reserve()
; CHECK-NEXT: to label [[THROW]] unwind label [[PAD:%.*]]
; CHECK: pad:
; CHECK-NEXT: [[PHI2:%.*]] = phi i8* [ [[TMP96]], [[THROW]] ]
; CHECK-NEXT: [[CS:%.*]] = catchswitch within none [label [[UNREACHABLE:%.*]], label %blah] unwind to caller
; CHECK: unreachable:
; CHECK-NEXT: [[TMP0:%.*]] = catchpad within [[CS]] []
; CHECK-NEXT: unreachable
; CHECK: blah:
; CHECK-NEXT: [[CATCHPAD:%.*]] = catchpad within [[CS]] []
; CHECK-NEXT: [[PHI21:%.*]] = ptrtoint i8* [[PHI2]] to i32
; CHECK-NEXT: [[TMP1:%.*]] = sub i32 1, [[PHI21]]
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, i8* undef, i32 [[TMP1]]
; CHECK-NEXT: br label [[LOOP_BODY:%.*]]
; CHECK: unwind_out:
; CHECK-NEXT: catchret from [[CATCHPAD]] to label [[LEAVE:%.*]]
; CHECK: leave:
; CHECK-NEXT: ret void
; CHECK: loop_body:
; CHECK-NEXT: [[LSR_IV:%.*]] = phi i8* [ [[SCEVGEP2:%.*]], [[ITER:%.*]] ], [ [[SCEVGEP]], [[BLAH:%.*]] ]
; CHECK-NEXT: [[SCEVGEP2]] = getelementptr i8, i8* [[LSR_IV]], i32 -1
; CHECK-NEXT: [[TMP100:%.*]] = icmp eq i8* [[SCEVGEP2]], null
; CHECK-NEXT: [[LSR_IV:%.*]] = phi i32 [ [[LSR_IV_NEXT:%.*]], [[ITER:%.*]] ], [ 0, [[BLAH:%.*]] ]
; CHECK-NEXT: [[LSR_IV_NEXT]] = add nuw nsw i32 [[LSR_IV]], -1
; CHECK-NEXT: [[LSR_IV_NEXT1:%.*]] = inttoptr i32 [[LSR_IV_NEXT]] to i8*
; CHECK-NEXT: [[TMP100:%.*]] = icmp eq i8* [[LSR_IV_NEXT1]], null
; CHECK-NEXT: br i1 [[TMP100]], label [[UNWIND_OUT:%.*]], label [[ITER]]
; CHECK: iter:
; CHECK-NEXT: br i1 true, label [[UNWIND_OUT]], label [[LOOP_BODY]]
@ -146,7 +138,6 @@ define void @h() personality i32 (...)* @_except_handler3 {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[THROW:%.*]]
; CHECK: throw:
; CHECK-NEXT: [[TMP96:%.*]] = getelementptr inbounds i8, i8* undef, i32 1
; CHECK-NEXT: invoke void @reserve()
; CHECK-NEXT: to label [[THROW]] unwind label [[PAD:%.*]]
; CHECK: pad:
@ -155,20 +146,17 @@ define void @h() personality i32 (...)* @_except_handler3 {
; CHECK-NEXT: [[TMP0:%.*]] = catchpad within [[CS]] []
; CHECK-NEXT: unreachable
; CHECK: blug:
; CHECK-NEXT: [[PHI2:%.*]] = phi i8* [ [[TMP96]], [[PAD]] ]
; CHECK-NEXT: [[CATCHPAD:%.*]] = catchpad within [[CS]] []
; CHECK-NEXT: [[PHI21:%.*]] = ptrtoint i8* [[PHI2]] to i32
; CHECK-NEXT: [[TMP1:%.*]] = sub i32 1, [[PHI21]]
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, i8* undef, i32 [[TMP1]]
; CHECK-NEXT: br label [[LOOP_BODY:%.*]]
; CHECK: unwind_out:
; CHECK-NEXT: catchret from [[CATCHPAD]] to label [[LEAVE:%.*]]
; CHECK: leave:
; CHECK-NEXT: ret void
; CHECK: loop_body:
; CHECK-NEXT: [[LSR_IV:%.*]] = phi i8* [ [[SCEVGEP2:%.*]], [[ITER:%.*]] ], [ [[SCEVGEP]], [[BLUG:%.*]] ]
; CHECK-NEXT: [[SCEVGEP2]] = getelementptr i8, i8* [[LSR_IV]], i32 -1
; CHECK-NEXT: [[TMP100:%.*]] = icmp eq i8* [[SCEVGEP2]], null
; CHECK-NEXT: [[LSR_IV:%.*]] = phi i32 [ [[LSR_IV_NEXT:%.*]], [[ITER:%.*]] ], [ 0, [[BLUG:%.*]] ]
; CHECK-NEXT: [[LSR_IV_NEXT]] = add nuw nsw i32 [[LSR_IV]], -1
; CHECK-NEXT: [[LSR_IV_NEXT1:%.*]] = inttoptr i32 [[LSR_IV_NEXT]] to i8*
; CHECK-NEXT: [[TMP100:%.*]] = icmp eq i8* [[LSR_IV_NEXT1]], null
; CHECK-NEXT: br i1 [[TMP100]], label [[UNWIND_OUT:%.*]], label [[ITER]]
; CHECK: iter:
; CHECK-NEXT: br i1 true, label [[UNWIND_OUT]], label [[LOOP_BODY]]
@ -214,11 +202,9 @@ define void @i() personality i32 (...)* @_except_handler3 {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[THROW:%.*]]
; CHECK: throw:
; CHECK-NEXT: [[TMP96:%.*]] = getelementptr inbounds i8, i8* undef, i32 1
; CHECK-NEXT: invoke void @reserve()
; CHECK-NEXT: to label [[THROW]] unwind label [[CATCHPAD:%.*]]
; CHECK: catchpad:
; CHECK-NEXT: [[PHI2:%.*]] = phi i8* [ [[TMP96]], [[THROW]] ]
; CHECK-NEXT: [[CS:%.*]] = catchswitch within none [label %cp_body] unwind label [[CLEANUPPAD:%.*]]
; CHECK: cp_body:
; CHECK-NEXT: [[TMP0:%.*]] = catchpad within [[CS]] []
@ -227,14 +213,12 @@ define void @i() personality i32 (...)* @_except_handler3 {
; CHECK-NEXT: [[TMP1:%.*]] = cleanuppad within none []
; CHECK-NEXT: br label [[LOOP_HEAD]]
; CHECK: loop_head:
; CHECK-NEXT: [[PHI21:%.*]] = ptrtoint i8* [[PHI2]] to i32
; CHECK-NEXT: [[TMP2:%.*]] = sub i32 1, [[PHI21]]
; CHECK-NEXT: [[SCEVGEP:%.*]] = getelementptr i8, i8* undef, i32 [[TMP2]]
; CHECK-NEXT: br label [[LOOP_BODY:%.*]]
; CHECK: loop_body:
; CHECK-NEXT: [[LSR_IV:%.*]] = phi i8* [ [[SCEVGEP2:%.*]], [[ITER:%.*]] ], [ [[SCEVGEP]], [[LOOP_HEAD]] ]
; CHECK-NEXT: [[SCEVGEP2]] = getelementptr i8, i8* [[LSR_IV]], i32 -1
; CHECK-NEXT: [[TMP100:%.*]] = icmp eq i8* [[SCEVGEP2]], null
; CHECK-NEXT: [[LSR_IV:%.*]] = phi i32 [ [[LSR_IV_NEXT:%.*]], [[ITER:%.*]] ], [ 0, [[LOOP_HEAD]] ]
; CHECK-NEXT: [[LSR_IV_NEXT]] = add nuw nsw i32 [[LSR_IV]], -1
; CHECK-NEXT: [[LSR_IV_NEXT1:%.*]] = inttoptr i32 [[LSR_IV_NEXT]] to i8*
; CHECK-NEXT: [[TMP100:%.*]] = icmp eq i8* [[LSR_IV_NEXT1]], null
; CHECK-NEXT: br i1 [[TMP100]], label [[UNWIND_OUT:%.*]], label [[ITER]]
; CHECK: iter:
; CHECK-NEXT: br i1 true, label [[UNWIND_OUT]], label [[LOOP_BODY]]