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This transform only handles two-operand AddRec's. Prevent it from trying to

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handle anything more complex. Fixes PR10383 again!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139186 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2011-09-06 21:42:18 +00:00
parent 34c4485b74
commit c103a08a11
2 changed files with 43 additions and 14 deletions
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36
lib/Analysis/ScalarEvolution.cpp
View File

@ -1974,7 +1974,8 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
// multiplied together. If so, we can fold them.
for (unsigned OtherIdx = Idx+1;
OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
++OtherIdx)
++OtherIdx) {
bool Retry = false;
if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
// {A,+,B}<L> * {C,+,D}<L> --> {A*C,+,A*D + B*C + B*D,+,2*B*D}<L>
//
@ -1985,7 +1986,7 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
// Rearranging, X = x, Y = y+z, Z = 2z.
//
// x = A*C, y = (A*D + B*C), z = B*D.
// Therefore X = A*C, Y = (A*D + B*C) + B*D and Z = 2*B*D.
// Therefore X = A*C, Y = A*D + B*C + B*D and Z = 2*B*D.
for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
++OtherIdx)
if (const SCEVAddRecExpr *OtherAddRec =
@ -2002,19 +2003,28 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
const SCEV *NewSecondOrderStep =
getMulExpr(BD, getConstant(BD->getType(), 2));
SmallVector<const SCEV *, 3> AddRecOps;
AddRecOps.push_back(NewStart);
AddRecOps.push_back(NewStep);
AddRecOps.push_back(NewSecondOrderStep);
const SCEV *NewAddRec = getAddRecExpr(AddRecOps,
AddRec->getLoop(),
SCEV::FlagAnyWrap);
if (Ops.size() == 2) return NewAddRec;
Ops[Idx] = AddRec = cast<SCEVAddRecExpr>(NewAddRec);
Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
// This can happen when AddRec or OtherAddRec have >3 operands.
// TODO: support these add-recs.
if (isLoopInvariant(NewStart, AddRecLoop) &&
isLoopInvariant(NewStep, AddRecLoop) &&
isLoopInvariant(NewSecondOrderStep, AddRecLoop)) {
SmallVector<const SCEV *, 3> AddRecOps;
AddRecOps.push_back(NewStart);
AddRecOps.push_back(NewStep);
AddRecOps.push_back(NewSecondOrderStep);
const SCEV *NewAddRec = getAddRecExpr(AddRecOps,
AddRec->getLoop(),
SCEV::FlagAnyWrap);
if (Ops.size() == 2) return NewAddRec;
Ops[Idx] = AddRec = cast<SCEVAddRecExpr>(NewAddRec);
Ops.erase(Ops.begin() + OtherIdx); --OtherIdx;
Retry = true;
}
}
return getMulExpr(Ops);
if (Retry)
return getMulExpr(Ops);
}
}
// Otherwise couldn't fold anything into this recurrence. Move onto the
// next one.

21
test/Analysis/ScalarEvolution/SolveQuadraticEquation.ll
View File

@ -35,7 +35,7 @@ return: ; preds = %bb5
; PR10383
; This used to crash.
; These next two used to crash.
define void @test2(i1 %cmp, i64 %n) {
entry:
@ -61,3 +61,22 @@ end:
ret void
}
; CHECK: Determining loop execution counts for: @test2
define i32 @test3() {
if.then466:
br i1 undef, label %for.cond539.preheader, label %for.inc479
for.inc479:
%a2.07 = phi i32 [ %add495, %for.inc479 ], [ 0, %if.then466 ]
%j.36 = phi i32 [ %inc497, %for.inc479 ], [ undef, %if.then466 ]
%mul484 = mul nsw i32 %j.36, %j.36
%mul491 = mul i32 %j.36, %j.36
%mul493 = mul i32 %mul491, %mul484
%add495 = add nsw i32 %mul493, %a2.07
%inc497 = add nsw i32 %j.36, 1
br i1 undef, label %for.cond539.preheader, label %for.inc479
for.cond539.preheader:
unreachable
}
; CHECK: Determining loop execution counts for: @test3