[clang] 52c8f0b - [clang] Add -fcheck-new support
Fangrui Song via cfe-commits
cfe-commits at lists.llvm.org
Fri Jun 23 22:45:22 PDT 2023
Author: Pedro Falcato
Date: 2023-06-23T22:45:17-07:00
New Revision: 52c8f0bb20eb9e7b1b54ffdddf6da77b53caeb3a
URL: https://github.com/llvm/llvm-project/commit/52c8f0bb20eb9e7b1b54ffdddf6da77b53caeb3a
DIFF: https://github.com/llvm/llvm-project/commit/52c8f0bb20eb9e7b1b54ffdddf6da77b53caeb3a.diff
LOG: [clang] Add -fcheck-new support
Add -fcheck-new and -fno-check-new, from GCC, which make the compiler
not assume pointers returned from operator new are non-null.
Fixes #16931.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D125272
Added:
clang/test/CodeGenCXX/fcheck-new.cpp
Modified:
clang/include/clang/Basic/LangOptions.def
clang/include/clang/Basic/LangOptions.h
clang/include/clang/Driver/Options.td
clang/lib/AST/ExprCXX.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Sema/SemaDecl.cpp
clang/lib/Sema/SemaExprCXX.cpp
clang/test/Driver/clang_f_opts.c
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index d4ee06b66d9a5..1cb9b27c7e9eb 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -466,6 +466,8 @@ LANGOPT(IncrementalExtensions, 1, 0, " True if we want to process statements"
"avoid tearing the Lexer and etc. down). Controlled by "
"-fincremental-extensions.")
+BENIGN_LANGOPT(CheckNew, 1, 0, "Do not assume C++ operator new may not return NULL")
+
#undef LANGOPT
#undef COMPATIBLE_LANGOPT
#undef BENIGN_LANGOPT
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
index 1c98e28231b57..3ef68ca8af668 100644
--- a/clang/include/clang/Basic/LangOptions.h
+++ b/clang/include/clang/Basic/LangOptions.h
@@ -487,6 +487,10 @@ class LangOptions : public LangOptionsBase {
/// forward slash (/) elsewhere.
bool UseTargetPathSeparator = false;
+ // Indicates whether we should keep all nullptr checks for pointers
+ // received as a result of a standard operator new (-fcheck-new)
+ bool CheckNew = false;
+
LangOptions();
/// Set language defaults for the given input language and
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index b90d6763d6f3c..bb3d487886eb7 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5101,7 +5101,11 @@ def falign_jumps_EQ : Joined<["-"], "falign-jumps=">, Group<clang_ignored_gcc_op
// ignore it for now to avoid breaking builds that use it.
def fdiagnostics_show_location_EQ : Joined<["-"], "fdiagnostics-show-location=">, Group<clang_ignored_f_Group>;
-defm fcheck_new : BooleanFFlag<"check-new">, Group<clang_ignored_f_Group>;
+defm check_new : BoolOption<"f", "check-new",
+ LangOpts<"CheckNew">, DefaultFalse,
+ PosFlag<SetTrue, [], "Do not assume C++ operator new may not return NULL">,
+ NegFlag<SetFalse>, BothFlags<[CC1Option]>>;
+
defm caller_saves : BooleanFFlag<"caller-saves">, Group<clang_ignored_gcc_optimization_f_Group>;
defm reorder_blocks : BooleanFFlag<"reorder-blocks">, Group<clang_ignored_gcc_optimization_f_Group>;
defm branch_count_reg : BooleanFFlag<"branch-count-reg">, Group<clang_ignored_gcc_optimization_f_Group>;
diff --git a/clang/lib/AST/ExprCXX.cpp b/clang/lib/AST/ExprCXX.cpp
index 09e64b8c82c8e..8c061b0ad9316 100644
--- a/clang/lib/AST/ExprCXX.cpp
+++ b/clang/lib/AST/ExprCXX.cpp
@@ -276,6 +276,8 @@ CXXNewExpr *CXXNewExpr::CreateEmpty(const ASTContext &Ctx, bool IsArray,
}
bool CXXNewExpr::shouldNullCheckAllocation() const {
+ if (getOperatorNew()->getLangOpts().CheckNew)
+ return true;
return !getOperatorNew()->hasAttr<ReturnsNonNullAttr>() &&
getOperatorNew()
->getType()
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 883544b9e37ec..de22ea4455fa7 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -6157,6 +6157,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
Triple.hasDefaultEmulatedTLS()))
CmdArgs.push_back("-femulated-tls");
+ Args.addOptInFlag(CmdArgs, options::OPT_fcheck_new,
+ options::OPT_fno_check_new);
+
if (Arg *A = Args.getLastArg(options::OPT_fzero_call_used_regs_EQ)) {
// FIXME: There's no reason for this to be restricted to X86. The backend
// code needs to be changed to include the appropriate function calls
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 698f57f0245b0..d72d4e097879f 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -16146,7 +16146,11 @@ void Sema::AddKnownFunctionAttributesForReplaceableGlobalAllocationFunction(
// indicates failure by returning a null pointer value. Any other allocation
// function never returns a null pointer value and indicates failure only by
// throwing an exception [...]
- if (!IsNothrow && !FD->hasAttr<ReturnsNonNullAttr>())
+ //
+ // However, -fcheck-new invalidates this possible assumption, so don't add
+ // NonNull when that is enabled.
+ if (!IsNothrow && !FD->hasAttr<ReturnsNonNullAttr>() &&
+ !getLangOpts().CheckNew)
FD->addAttr(ReturnsNonNullAttr::CreateImplicit(Context, FD->getLocation()));
// C++2a [basic.stc.dynamic.allocation]p2:
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index f2ff924bc7dea..817fd2d2d7d3f 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -3157,7 +3157,8 @@ void Sema::DeclareGlobalAllocationFunction(DeclarationName Name,
// Global allocation functions should always be visible.
Alloc->setVisibleDespiteOwningModule();
- if (HasBadAllocExceptionSpec && getLangOpts().NewInfallible)
+ if (HasBadAllocExceptionSpec && getLangOpts().NewInfallible &&
+ !getLangOpts().CheckNew)
Alloc->addAttr(
ReturnsNonNullAttr::CreateImplicit(Context, Alloc->getLocation()));
diff --git a/clang/test/CodeGenCXX/fcheck-new.cpp b/clang/test/CodeGenCXX/fcheck-new.cpp
new file mode 100644
index 0000000000000..d5800cc73bb9a
--- /dev/null
+++ b/clang/test/CodeGenCXX/fcheck-new.cpp
@@ -0,0 +1,30 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
+// RUN: %clang_cc1 -fcheck-new -triple x86_64-linux-gnu -disable-O0-optnone \
+// RUN: -emit-llvm -o - %s | FileCheck %s
+
+struct A { A(); };
+
+// CHECK-LABEL: @_Z5test0v(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[CALL:%.*]] = call noalias noundef ptr @_Znwm(i64 noundef 1) #[[ATTR3:[0-9]+]]
+// CHECK-NEXT: [[NEW_ISNULL:%.*]] = icmp eq ptr [[CALL]], null
+// CHECK-NEXT: br i1 [[NEW_ISNULL]], label [[NEW_CONT:%.*]], label [[NEW_NOTNULL:%.*]]
+// CHECK: new.notnull:
+// CHECK-NEXT: call void @_ZN1AC1Ev(ptr noundef nonnull align 1 dereferenceable(1) [[CALL]])
+// CHECK-NEXT: br label [[NEW_CONT]]
+// CHECK: new.cont:
+// CHECK-NEXT: [[TMP0:%.*]] = phi ptr [ [[CALL]], [[NEW_NOTNULL]] ], [ null, [[ENTRY:%.*]] ]
+// CHECK-NEXT: ret ptr [[TMP0]]
+//
+A *test0() {
+ return new A();
+}
+
+// CHECK-LABEL: @_Z5test1v(
+// CHECK-NEXT: entry:
+// CHECK-NEXT: [[CALL:%.*]] = call noalias noundef ptr @_Znwm(i64 noundef 4) #[[ATTR3]]
+// CHECK-NEXT: ret ptr [[CALL]]
+//
+int *test1() {
+ return new int;
+}
diff --git a/clang/test/Driver/clang_f_opts.c b/clang/test/Driver/clang_f_opts.c
index 8060e52d5e8fd..65ba66fa325f5 100644
--- a/clang/test/Driver/clang_f_opts.c
+++ b/clang/test/Driver/clang_f_opts.c
@@ -302,7 +302,6 @@
// RUN: -fno-reorder-blocks -freorder-blocks \
// RUN: -fno-schedule-insns2 -fschedule-insns2 \
// RUN: -fno-stack-check \
-// RUN: -fno-check-new -fcheck-new \
// RUN: -ffriend-injection \
// RUN: -fno-implement-inlines -fimplement-inlines \
// RUN: -fstack-check \
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