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Disable -fmerge-all-constants as default. 

Summary:
"-fmerge-all-constants" is a non-conforming optimization and should not
be the default. It is also causing miscompiles when building Linux
Kernel (https://lkml.org/lkml/2018/3/20/872).

Fixes PR18538.

Reviewers: rjmccall, rsmith, chandlerc

Reviewed By: rsmith, chandlerc

Subscribers: srhines, cfe-commits

Differential Revision: https://reviews.llvm.org/D45289

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@329300 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Manoj Gupta 2018-04-05 15:29:52 +00:00
parent 47f00f8474
commit abb490ec96
11 changed files with 28 additions and 19 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/clang/Driver/Options.td
View File

@ -1133,7 +1133,8 @@ def fthinlto_index_EQ : Joined<["-"], "fthinlto-index=">,
HelpText<"Perform ThinLTO importing using provided function summary index">;
def fmacro_backtrace_limit_EQ : Joined<["-"], "fmacro-backtrace-limit=">,
Group<f_Group>, Flags<[DriverOption, CoreOption]>;
def fmerge_all_constants : Flag<["-"], "fmerge-all-constants">, Group<f_Group>;
def fmerge_all_constants : Flag<["-"], "fmerge-all-constants">, Group<f_Group>,
Flags<[CC1Option]>, HelpText<"Allow merging of constants">;
def fmessage_length_EQ : Joined<["-"], "fmessage-length=">, Group<f_Group>;
def fms_extensions : Flag<["-"], "fms-extensions">, Group<f_Group>, Flags<[CC1Option, CoreOption]>,
HelpText<"Accept some non-standard constructs supported by the Microsoft compiler">;
@ -1282,7 +1283,7 @@ def fveclib : Joined<["-"], "fveclib=">, Group<f_Group>, Flags<[CC1Option]>,
def fno_lax_vector_conversions : Flag<["-"], "fno-lax-vector-conversions">, Group<f_Group>,
HelpText<"Disallow implicit conversions between vectors with a different number of elements or different element types">, Flags<[CC1Option]>;
def fno_merge_all_constants : Flag<["-"], "fno-merge-all-constants">, Group<f_Group>,
Flags<[CC1Option]>, HelpText<"Disallow merging of constants">;
HelpText<"Disallow merging of constants">;
def fno_modules : Flag <["-"], "fno-modules">, Group<f_Group>,
Flags<[DriverOption]>;
def fno_implicit_module_maps : Flag <["-"], "fno-implicit-module-maps">, Group<f_Group>,

3
lib/AST/ExprConstant.cpp
View File

@ -8596,9 +8596,6 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
(LHSValue.Base && isZeroSized(RHSValue)))
return Error(E);
// Pointers with different bases cannot represent the same object.
// (Note that clang defaults to -fmerge-all-constants, which can
// lead to inconsistent results for comparisons involving the address
// of a constant; this generally doesn't matter in practice.)
return Success(E->getOpcode() == BO_NE, E);
}

6
lib/Driver/ToolChains/Clang.cpp
View File

@ -3361,9 +3361,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
Args.AddLastArg(CmdArgs, options::OPT_fveclib);
if (!Args.hasFlag(options::OPT_fmerge_all_constants,
options::OPT_fno_merge_all_constants))
CmdArgs.push_back("-fno-merge-all-constants");
if (Args.hasFlag(options::OPT_fmerge_all_constants,
options::OPT_fno_merge_all_constants, false))
CmdArgs.push_back("-fmerge-all-constants");
// LLVM Code Generator Options.

2
lib/Frontend/CompilerInvocation.cpp
View File

@ -605,7 +605,7 @@ static bool ParseCodeGenArgs(CodeGenOptions &Opts, ArgList &Args, InputKind IK,
Args.hasFlag(OPT_ffine_grained_bitfield_accesses,
OPT_fno_fine_grained_bitfield_accesses, false);
Opts.DwarfDebugFlags = Args.getLastArgValue(OPT_dwarf_debug_flags);
Opts.MergeAllConstants = !Args.hasArg(OPT_fno_merge_all_constants);
Opts.MergeAllConstants = Args.hasArg(OPT_fmerge_all_constants);
Opts.NoCommon = Args.hasArg(OPT_fno_common);
Opts.NoImplicitFloat = Args.hasArg(OPT_no_implicit_float);
Opts.OptimizeSize = getOptimizationLevelSize(Args);

11
test/CodeGen/array-init.c
View File

@ -1,8 +1,11 @@
// RUN: %clang_cc1 %s -O0 -triple x86_64-unknown-linux-gnu -emit-llvm -o - | FileCheck %s
// RUN: %clang_cc1 %s -O0 -triple x86_64-unknown-linux-gnu -emit-llvm -o - | FileCheck -check-prefix=CHECK-NO-MERGE-CONSTANTS %s
// RUN: %clang_cc1 %s -O0 -triple x86_64-unknown-linux-gnu -fmerge-all-constants -emit-llvm -o - | FileCheck -check-prefix=CHECK-MERGE-CONSTANTS %s
// CHECK: @{{.*}}.a1 = internal constant [5 x i32] [i32 0, i32 1, i32 2, i32 0, i32 0]
// CHECK: @{{.*}}.a2 = internal constant [5 x i32] zeroinitializer
// CHECK: @{{.*}}.a3 = internal constant [5 x i32] zeroinitializer
// CHECK-NO-MERGE-CONSTANTS: @{{.*}}.a1 = private unnamed_addr constant [5 x i32] [i32 0, i32 1, i32 2, i32 0, i32 0]
// CHECK-MERGE-CONSTANTS: @{{.*}}.a1 = internal constant [5 x i32] [i32 0, i32 1, i32 2, i32 0, i32 0]
// CHECK-MERGE-CONSTANTS: @{{.*}}.a2 = internal constant [5 x i32] zeroinitializer
// CHECK-MERGE-CONSTANTS: @{{.*}}.a3 = internal constant [5 x i32] zeroinitializer
void testConstArrayInits(void)
{

2
test/CodeGen/decl.c
View File

@ -1,4 +1,4 @@
// RUN: %clang_cc1 -w -emit-llvm < %s | FileCheck %s
// RUN: %clang_cc1 -w -fmerge-all-constants -emit-llvm < %s | FileCheck %s
// CHECK: @test1.x = internal constant [12 x i32] [i32 1
// CHECK: @test2.x = private unnamed_addr constant [13 x i32] [i32 1,

2
test/CodeGenCXX/const-init-cxx11.cpp
View File

@ -1,4 +1,4 @@
// RUN: %clang_cc1 -w -triple x86_64-elf-gnu -emit-llvm -o - %s -std=c++11 | FileCheck %s
// RUN: %clang_cc1 -w -fmerge-all-constants -triple x86_64-elf-gnu -emit-llvm -o - %s -std=c++11 | FileCheck %s
// FIXME: The padding in all these objects should be zero-initialized.
namespace StructUnion {

2
test/CodeGenCXX/cxx0x-initializer-references.cpp
View File

@ -1,4 +1,4 @@
// RUN: %clang_cc1 -std=c++11 -S -triple armv7-none-eabi -emit-llvm -o - %s | FileCheck %s
// RUN: %clang_cc1 -std=c++11 -S -triple armv7-none-eabi -fmerge-all-constants -emit-llvm -o - %s | FileCheck %s
namespace reference {
struct A {

4
test/CodeGenCXX/cxx0x-initializer-stdinitializerlist.cpp
View File

@ -1,5 +1,5 @@
// RUN: %clang_cc1 -std=c++11 -triple x86_64-none-linux-gnu -emit-llvm -o - %s | FileCheck -check-prefixes=X86,CHECK %s
// RUN: %clang_cc1 -std=c++11 -triple amdgcn-amd-amdhsa -DNO_TLS -emit-llvm -o - %s | FileCheck -check-prefixes=AMDGCN,CHECK %s
// RUN: %clang_cc1 -std=c++11 -triple x86_64-none-linux-gnu -fmerge-all-constants -emit-llvm -o - %s | FileCheck -check-prefixes=X86,CHECK %s
// RUN: %clang_cc1 -std=c++11 -triple amdgcn-amd-amdhsa -DNO_TLS -fmerge-all-constants -emit-llvm -o - %s | FileCheck -check-prefixes=AMDGCN,CHECK %s
namespace std {
typedef decltype(sizeof(int)) size_t;

2
test/CodeGenObjCXX/arc-cxx11-init-list.mm
View File

@ -1,4 +1,4 @@
// RUN: %clang_cc1 -triple armv7-ios5.0 -std=c++11 -fobjc-arc -Os -emit-llvm -o - %s | FileCheck %s
// RUN: %clang_cc1 -triple armv7-ios5.0 -std=c++11 -fmerge-all-constants -fobjc-arc -Os -emit-llvm -o - %s | FileCheck %s
// CHECK: @[[STR0:.*]] = private unnamed_addr constant [5 x i8] c"str0\00", section "__TEXT,__cstring,cstring_literals"
// CHECK: @[[UNNAMED_CFSTRING0:.*]] = private global %struct.__NSConstantString_tag { i32* getelementptr inbounds ([0 x i32], [0 x i32]* @__CFConstantStringClassReference, i32 0, i32 0), i32 1992, i8* getelementptr inbounds ([5 x i8], [5 x i8]* @[[STR0]], i32 0, i32 0), i32 4 }, section "__DATA,__cfstring"

8
test/Driver/clang_f_opts.c
View File

@ -276,6 +276,7 @@
// RUN: -fno-inline-small-functions -finline-small-functions \
// RUN: -fno-fat-lto-objects -ffat-lto-objects \
// RUN: -fno-merge-constants -fmerge-constants \
// RUN: -fno-merge-all-constants -fmerge-all-constants \
// RUN: -fno-caller-saves -fcaller-saves \
// RUN: -fno-reorder-blocks -freorder-blocks \
// RUN: -fno-schedule-insns2 -fschedule-insns2 \
@ -522,3 +523,10 @@
// RUN: %clang -### -S -fno-discard-value-names %s 2>&1 | FileCheck -check-prefix=CHECK-NO-DISCARD-NAMES %s
// CHECK-DISCARD-NAMES: "-discard-value-names"
// CHECK-NO-DISCARD-NAMES-NOT: "-discard-value-names"
//
// RUN: %clang -### -S -fmerge-all-constants %s 2>&1 | FileCheck -check-prefix=CHECK-MERGE-ALL-CONSTANTS %s
// RUN: %clang -### -S -fno-merge-all-constants %s 2>&1 | FileCheck -check-prefix=CHECK-NO-MERGE-ALL-CONSTANTS %s
// RUN: %clang -### -S -fmerge-all-constants -fno-merge-all-constants %s 2>&1 | FileCheck -check-prefix=CHECK-NO-MERGE-ALL-CONSTANTS %s
// RUN: %clang -### -S -fno-merge-all-constants -fmerge-all-constants %s 2>&1 | FileCheck -check-prefix=CHECK-MERGE-ALL-CONSTANTS %s
// CHECK-NO-MERGE-ALL-CONSTANTS-NOT: "-fmerge-all-constants"
// CHECK-MERGE-ALL-CONSTANTS: "-fmerge-all-constants"