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Revert "[clang] Add early exit when checking for const init of arrays." 

This reverts commit 48bb5f4cbe.

Several breakages, including ARM (fixed later, but not sufficient) and
MSan (to be diagnosed later).

Differential Revision: https://reviews.llvm.org/D113599
This commit is contained in:
Adam Czachorowski 2021-11-10 20:46:38 +01:00
parent 9ee5cec688
commit 6d09aaecdf
2 changed files with 13 additions and 51 deletions
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45
clang/lib/AST/ExprConstant.cpp
View File

@ -10596,55 +10596,28 @@ bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
bool HadZeroInit = Value->hasValue();
if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) {
unsigned FinalSize = CAT->getSize().getZExtValue();
unsigned N = CAT->getSize().getZExtValue();
// Preserve the array filler if we had prior zero-initialization.
APValue Filler =
HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller()
: APValue();
*Value = APValue(APValue::UninitArray(), 0, FinalSize);
if (FinalSize == 0)
return true;
LValue ArrayElt = Subobject;
ArrayElt.addArray(Info, E, CAT);
// We do the whole initialization in two passes, first for just one element,
// then for the whole array. It's possible we may find out we can't do const
// init in the first pass, in which case we avoid allocating a potentially
// large array. We don't do more passes because expanding array requires
// copying the data, which is wasteful.
for (const unsigned N : {1u, FinalSize}) {
unsigned OldElts = Value->getArrayInitializedElts();
if (OldElts == N)
break;
// Expand the array to appropriate size.
APValue NewValue(APValue::UninitArray(), N, FinalSize);
for (unsigned I = 0; I < OldElts; ++I)
NewValue.getArrayInitializedElt(I).swap(
Value->getArrayInitializedElt(I));
Value->swap(NewValue);
*Value = APValue(APValue::UninitArray(), N, N);
if (HadZeroInit)
for (unsigned I = OldElts; I < N; ++I)
for (unsigned I = 0; I != N; ++I)
Value->getArrayInitializedElt(I) = Filler;
// Initialize the elements.
for (unsigned I = OldElts; I < N; ++I) {
if (!VisitCXXConstructExpr(E, ArrayElt,
&Value->getArrayInitializedElt(I),
LValue ArrayElt = Subobject;
ArrayElt.addArray(Info, E, CAT);
for (unsigned I = 0; I != N; ++I)
if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I),
CAT->getElementType()) ||
!HandleLValueArrayAdjustment(Info, E, ArrayElt,
CAT->getElementType(), 1))
!HandleLValueArrayAdjustment(Info, E, ArrayElt, CAT->getElementType(),
1))
return false;
// When checking for const initilization any diagnostic is considered
// an error.
if (Info.EvalStatus.Diag && !Info.EvalStatus.Diag->empty() &&
!Info.keepEvaluatingAfterFailure())
return false;
}
}
return true;
}

11
clang/test/SemaCXX/PR51712-large-array-constexpr-check-oom.cpp
View File

@ -1,11 +0,0 @@
// REQUIRES: shell
// UNSUPPORTED: win32
// RUN: ulimit -v 1048576
// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -triple=x86_64 %s
// expected-no-diagnostics
// This used to require too much memory and crash with OOM.
struct {
int a, b, c, d;
} arr[1<<30];