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[InstCombine] SliceUpIllegalIntegerPHI - bail on out of range shifts

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trunc(lshr) handling - if the shift is out of range (undefined) then bail like we do for non-constant shifts.

Fixes OSS Fuzz #15217

llvm-svn: 364181
This commit is contained in:
Simon Pilgrim 2019-06-24 13:13:36 +00:00
parent fd320855ef
commit 8d6f027a2f
2 changed files with 31 additions and 0 deletions
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5
lib/Transforms/InstCombine/InstCombinePHI.cpp
View File

@ -1004,6 +1004,11 @@ Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &FirstPhi) {
!isa<ConstantInt>(UserI->getOperand(1)))
return nullptr;
// Bail on out of range shifts.
unsigned SizeInBits = UserI->getType()->getScalarSizeInBits();
if (cast<ConstantInt>(UserI->getOperand(1))->getValue().uge(SizeInBits))
return nullptr;
unsigned Shift = cast<ConstantInt>(UserI->getOperand(1))->getZExtValue();
PHIUsers.push_back(PHIUsageRecord(PHIId, Shift, UserI->user_back()));
}

26
test/Transforms/InstCombine/phi-shifts.ll Normal file
View File

@ -0,0 +1,26 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -S -instcombine | FileCheck %s
; OSS Fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=15217
define i64 @fuzz15217(i1 %cond, i8* %Ptr, i64 %Val) {
; CHECK-LABEL: @fuzz15217(
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 [[COND:%.*]], label [[END:%.*]], label [[TWO:%.*]]
; CHECK: two:
; CHECK-NEXT: br label [[END]]
; CHECK: end:
; CHECK-NEXT: ret i64 0
;
entry:
br i1 %cond, label %end, label %two
two:
br label %end
end:
%tmp869.0 = phi i128 [ 0, %entry ], [ 18446744073709551616, %two ]
%tmp29 = lshr i128 %tmp869.0, 64
%B1 = lshr i128 %tmp29, 170141183460469231731687303715884105727
%tmp30 = trunc i128 %B1 to i64
ret i64 %tmp30
}