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[ValueTracking] Check for ConstantExpr before using recursive helpers. 

Make sure we do not call
constainsConstantExpression/containsUndefElement on ConstantExpression,
which is not supported.

In particular, containsUndefElement/constainsConstantExpression are only
supported on constants which are supported by getAggregateElement.

Unfortunately there's no convenient way to check if a constant supports
getAggregateElement, so just check for non-constantexpressions with
vector type. Other users of those functions do so too.

Reviewers: spatel, nikic, craig.topper, lebedev.ri, jdoerfert, aqjune

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D84512
This commit is contained in:
Florian Hahn 2020-07-24 17:28:01 +01:00
parent 22c16360dd
commit 1c7c69c795
2 changed files with 25 additions and 2 deletions
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4
llvm/lib/Analysis/ValueTracking.cpp
View File

@ -4794,8 +4794,8 @@ bool llvm::isGuaranteedNotToBeUndefOrPoison(const Value *V,
isa<ConstantPointerNull>(C) || isa<Function>(C))
return true;
if (C->getType()->isVectorTy())
return !C->containsUndefElement() && !C->containsConstantExpression();
if (C->getType()->isVectorTy() && !isa<ConstantExpr>(C))
return !C->containsConstantExpression() && !C->containsUndefElement();
}
// Strip cast operations from a pointer value.

23
llvm/test/Transforms/GVN/constexpr-vector-constainsundef-crash.ll Normal file
View File

@ -0,0 +1,23 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -gvn -S %s | FileCheck %s
; Reduced test case from
; https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=24278
; Make sure we do not crash when dealing with a vector constant expression.
define <4 x i64*> @test(i64* %ptr) {
; CHECK-LABEL: @test(
; CHECK-NEXT: entry:
; CHECK-NEXT: ret <4 x i64*> getelementptr (i64, i64* null, <4 x i64> <i64 0, i64 0, i64 0, i64 -128>)
;
entry:
%B9 = sdiv i16 -32768, 256
%L3 = load i64, i64* %ptr, align 4
%B3 = sub i16 0, %B9
%0 = insertelement <4 x i16> undef, i16 %B3, i32 3
%1 = sub <4 x i16> zeroinitializer, %0
%2 = sext <4 x i16> %1 to <4 x i32>
%3 = getelementptr inbounds i64, i64* null, <4 x i32> %2
%I6 = insertelement <4 x i64*> %3, i64* undef, i64 %L3
ret <4 x i64*> %I6
}