adamcz updated this revision to Diff 385102.
adamcz marked an inline comment as done.
adamcz added a comment.
review comments
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D113120/new/
https://reviews.llvm.org/D113120
Files:
clang/lib/AST/ExprConstant.cpp
clang/test/SemaCXX/PR51712-large-array-constexpr-check-oom.cpp
Index: clang/test/SemaCXX/PR51712-large-array-constexpr-check-oom.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/PR51712-large-array-constexpr-check-oom.cpp
@@ -0,0 +1,11 @@
+// REQUIRES: shell
+// UNSUPPORTED: win32
+// RUN: ulimit -v 1048576
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
+// expected-no-diagnostics
+
+// This used to require too much memory and crash with OOM.
+struct {
+ int a, b, c, d;
+} arr[1<<30];
+
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -10596,28 +10596,55 @@
bool HadZeroInit = Value->hasValue();
if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) {
- unsigned N = CAT->getSize().getZExtValue();
+ unsigned FinalSize = 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(), N, N);
-
- if (HadZeroInit)
- for (unsigned I = 0; I != N; ++I)
- Value->getArrayInitializedElt(I) = Filler;
+ *Value = APValue(APValue::UninitArray(), 0, FinalSize);
+ if (FinalSize == 0)
+ return true;
- // Initialize the elements.
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))
- return false;
+ // 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);
+
+ if (HadZeroInit)
+ for (unsigned I = OldElts; I < N; ++I)
+ Value->getArrayInitializedElt(I) = Filler;
+
+ // Initialize the elements.
+ for (unsigned I = OldElts; I < N; ++I) {
+ if (!VisitCXXConstructExpr(E, ArrayElt,
+ &Value->getArrayInitializedElt(I),
+ CAT->getElementType()) ||
+ !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;
}
Index: clang/test/SemaCXX/PR51712-large-array-constexpr-check-oom.cpp
===================================================================
--- /dev/null
+++ clang/test/SemaCXX/PR51712-large-array-constexpr-check-oom.cpp
@@ -0,0 +1,11 @@
+// REQUIRES: shell
+// UNSUPPORTED: win32
+// RUN: ulimit -v 1048576
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify %s
+// expected-no-diagnostics
+
+// This used to require too much memory and crash with OOM.
+struct {
+ int a, b, c, d;
+} arr[1<<30];
+
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -10596,28 +10596,55 @@
bool HadZeroInit = Value->hasValue();
if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) {
- unsigned N = CAT->getSize().getZExtValue();
+ unsigned FinalSize = 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(), N, N);
-
- if (HadZeroInit)
- for (unsigned I = 0; I != N; ++I)
- Value->getArrayInitializedElt(I) = Filler;
+ *Value = APValue(APValue::UninitArray(), 0, FinalSize);
+ if (FinalSize == 0)
+ return true;
- // Initialize the elements.
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))
- return false;
+ // 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);
+
+ if (HadZeroInit)
+ for (unsigned I = OldElts; I < N; ++I)
+ Value->getArrayInitializedElt(I) = Filler;
+
+ // Initialize the elements.
+ for (unsigned I = OldElts; I < N; ++I) {
+ if (!VisitCXXConstructExpr(E, ArrayElt,
+ &Value->getArrayInitializedElt(I),
+ CAT->getElementType()) ||
+ !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;
}
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