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Don't crash analyzing certain quadratics (addrec of {X,+,Y,+,1}).

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We're still waiting on code that actually analyzes them properly.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58592 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2008-11-03 02:43:49 +00:00
parent ae61ca0206
commit 8f4d5eb9e5
2 changed files with 26 additions and 0 deletions
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5
lib/Analysis/ScalarEvolution.cpp
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@ -2604,6 +2604,11 @@ SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
// The divisions must be performed as signed divisions.
APInt NegB(-B);
APInt TwoA( A << 1 );
if (TwoA.isMinValue()) {
SCEV *CNC = new SCEVCouldNotCompute();
return std::make_pair(CNC, CNC);
}
ConstantInt *Solution1 = ConstantInt::get((NegB + SqrtVal).sdiv(TwoA));
ConstantInt *Solution2 = ConstantInt::get((NegB - SqrtVal).sdiv(TwoA));

21
test/Analysis/ScalarEvolution/2008-11-02-QuadraticCrash.ll Normal file
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@ -0,0 +1,21 @@
; RUN: llvm-as < %s | opt -analyze -scalar-evolution
; PR1827
declare void @use(i32)
define void @foo() {
entry:
br label %loop_1
loop_1: ; preds = %loop_1, %entry
%a = phi i32 [ 2, %entry ], [ %b, %loop_1 ] ; <i32> [#uses=2]
%c = phi i32 [ 5, %entry ], [ %d, %loop_1 ] ; <i32> [#uses=1]
%b = add i32 %a, 1 ; <i32> [#uses=1]
%d = add i32 %c, %a ; <i32> [#uses=3]
%A = icmp ult i32 %d, 50 ; <i1> [#uses=1]
br i1 %A, label %loop_1, label %endloop
endloop: ; preds = %loop_1
call void @use(i32 %d)
ret void
}