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Fix PR24354.

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`InstCombiner::OptimizeOverflowCheck` was asserting an
invariant (operands to binary operations are ordered by decreasing
complexity) that wasn't really an invariant.  Fix this by instead having
`InstCombiner::OptimizeOverflowCheck` establish the invariant if it does
not hold.

llvm-svn: 244676
This commit is contained in:
Sanjoy Das 2015-08-11 21:33:55 +00:00
parent f00996d130
commit 2078fb4d89
2 changed files with 35 additions and 3 deletions
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5
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -2112,9 +2112,8 @@ static Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
bool InstCombiner::OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS,
Value *RHS, Instruction &OrigI,
Value *&Result, Constant *&Overflow) {
assert((!OrigI.isCommutative() ||
!(isa<Constant>(LHS) && !isa<Constant>(RHS))) &&
"call with a constant RHS if possible!");
if (OrigI.isCommutative() && isa<Constant>(LHS) && !isa<Constant>(RHS))
std::swap(LHS, RHS);
auto SetResult = [&](Value *OpResult, Constant *OverflowVal, bool ReuseName) {
Result = OpResult;

33
test/Transforms/InstCombine/pr24354.ll Normal file
View File

@ -0,0 +1,33 @@
; RUN: opt -instcombine -S < %s | FileCheck %s
; This used to crash opt
@c = common global i32 0, align 4
@b = common global i32 0, align 4
@a = common global i16 0, align 2
@d = common global i32 0, align 4
define void @fn3() {
; CHECK: @fn3
bb:
%tmp = load i32, i32* @c, align 4
%tmp1 = icmp eq i32 %tmp, 0
br i1 %tmp1, label %bb2, label %bb6
bb2: ; preds = %bb
%tmp3 = load i32, i32* @b, align 4
%tmp.i = add nsw i32 255, %tmp3
%tmp5 = icmp ugt i32 %tmp.i, 254
br label %bb6
bb6: ; preds = %bb, %bb2
%tmp7 = phi i1 [ true, %bb ], [ %tmp5, %bb2 ]
%tmp8 = zext i1 %tmp7 to i32
%tmp10 = icmp eq i32 %tmp8, 0
%tmp12 = load i16, i16* @a, align 2
%tmp14 = icmp ne i16 %tmp12, 0
%tmp16 = select i1 %tmp10, i1 false, i1 %tmp14
%tmp17 = zext i1 %tmp16 to i32
store i32 %tmp17, i32* @d, align 4
ret void
}