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NewGVN: Fix PR 33185 by checking whether we need to recursively 

generate a phi of ops, which we don't currently support.

llvm-svn: 304272
This commit is contained in:
Daniel Berlin 2017-05-31 01:47:32 +00:00
parent 9ceafe267b
commit be3e7ba45e
2 changed files with 74 additions and 23 deletions
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38
llvm/lib/Transforms/Scalar/NewGVN.cpp
View File

@ -613,7 +613,7 @@ private:
return CClass;
}
void initializeCongruenceClasses(Function &F);
const Expression *makePossiblePhiOfOps(Instruction *, bool,
const Expression *makePossiblePhiOfOps(Instruction *,
SmallPtrSetImpl<Value *> &);
void addPhiOfOps(PHINode *Op, BasicBlock *BB, Instruction *ExistingValue);
@ -1937,7 +1937,8 @@ void NewGVN::touchAndErase(Map &M, const KeyType &Key) {
}
void NewGVN::addAdditionalUsers(Value *To, Value *User) const {
AdditionalUsers[To].insert(User);
if (isa<Instruction>(To))
AdditionalUsers[To].insert(User);
}
void NewGVN::markUsersTouched(Value *V) {
@ -2423,7 +2424,7 @@ static bool okayForPHIOfOps(const Instruction *I) {
// When we see an instruction that is an op of phis, generate the equivalent phi
// of ops form.
const Expression *
NewGVN::makePossiblePhiOfOps(Instruction *I, bool HasBackedge,
NewGVN::makePossiblePhiOfOps(Instruction *I,
SmallPtrSetImpl<Value *> &Visited) {
if (!okayForPHIOfOps(I))
return nullptr;
@ -2438,24 +2439,6 @@ NewGVN::makePossiblePhiOfOps(Instruction *I, bool HasBackedge,
return nullptr;
unsigned IDFSNum = InstrToDFSNum(I);
// Pretty much all of the instructions we can convert to phi of ops over a
// backedge that are adds, are really induction variables, and those are
// pretty much pointless to convert. This is very coarse-grained for a
// test, so if we do find some value, we can change it later.
// But otherwise, what can happen is we convert the induction variable from
//
// i = phi (0, tmp)
// tmp = i + 1
//
// to
// i = phi (0, tmpphi)
// tmpphi = phi(1, tmpphi+1)
//
// Which we don't want to happen. We could just avoid this for all non-cycle
// free phis, and we made go that route.
if (HasBackedge && I->getOpcode() == Instruction::Add)
return nullptr;
SmallPtrSet<const Value *, 8> ProcessedPHIs;
// TODO: We don't do phi translation on memory accesses because it's
// complicated. For a load, we'd need to be able to simulate a new memoryuse,
@ -2470,6 +2453,16 @@ NewGVN::makePossiblePhiOfOps(Instruction *I, bool HasBackedge,
// Convert op of phis to phi of ops
for (auto &Op : I->operands()) {
// TODO: We can't handle expressions that must be recursively translated
// IE
// a = phi (b, c)
// f = use a
// g = f + phi of something
// To properly make a phi of ops for g, we'd have to properly translate and
// use the instruction for f. We should add this by splitting out the
// instruction creation we do below.
if (isa<Instruction>(Op) && PHINodeUses.count(cast<Instruction>(Op)))
return nullptr;
if (!isa<PHINode>(Op))
continue;
auto *OpPHI = cast<PHINode>(Op);
@ -2782,8 +2775,7 @@ void NewGVN::valueNumberInstruction(Instruction *I) {
// Make a phi of ops if necessary
if (Symbolized && !isa<ConstantExpression>(Symbolized) &&
!isa<VariableExpression>(Symbolized) && PHINodeUses.count(I)) {
// FIXME: Backedge argument
auto *PHIE = makePossiblePhiOfOps(I, false, Visited);
auto *PHIE = makePossiblePhiOfOps(I, Visited);
if (PHIE)
Symbolized = PHIE;
}

59
llvm/test/Transforms/NewGVN/pr33185.ll Normal file
View File

@ -0,0 +1,59 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -newgvn -S %s | FileCheck %s
@a = local_unnamed_addr global i32 9, align 4
@.str4 = private unnamed_addr constant [6 x i8] c"D:%d\0A\00", align 1
define i32 @main() local_unnamed_addr {
; CHECK-LABEL: @main(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP:%.*]] = load i32, i32* @a, align 4
; CHECK-NEXT: [[CMP1_I:%.*]] = icmp ne i32 [[TMP]], 0
; CHECK-NEXT: br label [[FOR_BODY_I:%.*]]
; CHECK: for.body.i:
; CHECK-NEXT: [[TMP1:%.*]] = phi i1 [ true, [[ENTRY:%.*]] ], [ false, [[COND_END_I:%.*]] ]
; CHECK-NEXT: [[F_08_I:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[INC_I:%.*]], [[COND_END_I]] ]
; CHECK-NEXT: [[MUL_I:%.*]] = select i1 [[CMP1_I]], i32 [[F_08_I]], i32 0
; CHECK-NEXT: br i1 [[TMP1]], label [[COND_END_I]], label [[COND_TRUE_I:%.*]]
; CHECK: cond.true.i:
; CHECK-NEXT: [[DIV_I:%.*]] = udiv i32 [[MUL_I]], [[F_08_I]]
; CHECK-NEXT: br label [[COND_END_I]]
; CHECK: cond.end.i:
; CHECK-NEXT: [[COND_I:%.*]] = phi i32 [ [[DIV_I]], [[COND_TRUE_I]] ], [ 0, [[FOR_BODY_I]] ]
; CHECK-NEXT: [[INC_I]] = add nuw nsw i32 [[F_08_I]], 1
; CHECK-NEXT: [[EXITCOND_I:%.*]] = icmp eq i32 [[INC_I]], 4
; CHECK-NEXT: br i1 [[EXITCOND_I]], label [[FN1_EXIT:%.*]], label [[FOR_BODY_I]]
; CHECK: fn1.exit:
; CHECK-NEXT: [[CALL4:%.*]] = tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([6 x i8], [6 x i8]* @.str4, i64 0, i64 0), i32 [[COND_I]])
; CHECK-NEXT: ret i32 0
;
entry:
%tmp = load i32, i32* @a, align 4
%cmp1.i = icmp ne i32 %tmp, 0
br label %for.body.i
for.body.i:
%tmp1 = phi i1 [ true, %entry ], [ false, %cond.end.i ]
%f.08.i = phi i32 [ 0, %entry ], [ %inc.i, %cond.end.i ]
%mul.i = select i1 %cmp1.i, i32 %f.08.i, i32 0
br i1 %tmp1, label %cond.end.i, label %cond.true.i
cond.true.i:
;; Ensure we don't replace this divide with a phi of ops that merges the wrong loop iteration value
%div.i = udiv i32 %mul.i, %f.08.i
br label %cond.end.i
cond.end.i:
%cond.i = phi i32 [ %div.i, %cond.true.i ], [ 0, %for.body.i ]
%inc.i = add nuw nsw i32 %f.08.i, 1
%exitcond.i = icmp eq i32 %inc.i, 4
br i1 %exitcond.i, label %fn1.exit, label %for.body.i
fn1.exit:
%cond.i.lcssa = phi i32 [ %cond.i, %cond.end.i ]
%call4= tail call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([6 x i8], [6 x i8]* @.str4, i64 0, i64 0), i32 %cond.i.lcssa)
ret i32 0
}
declare i32 @printf(i8* nocapture readonly, ...)