[IR] Make stack protector symbol dso_local according to -f[no-]direct-access-external-data

[MaskRay]

Summary

There are two motivations.

-fno-pic -fstack-protector -mstack-protector-guard=global created
__stack_chk_guard is referenced directly on all ELF OSes except FreeBSD.
This patch allows referencing the symbol indirectly with
-fno-direct-access-external-data.

Some Linux kernel folks want
-fno-pic -fstack-protector -mstack-protector-guard-reg=gs -mstack-protector-guard-symbol=__stack_chk_guard
created __stack_chk_guard to be referenced directly, avoiding
R_X86_64_REX_GOTPCRELX (even if the relocation may be optimized out by the linker).
https://github.com/llvm/llvm-project/issues/60116
Why they need this isn't so clear to me.

---

Add module flag "direct-access-external-data" and set the dso_local property of
the stack protector symbol. The module flag can benefit other LLVMCodeGen
synthesized symbols that are not represented in LLVM IR.

Nowadays, with -fno-pic being uncommon, ideally we should set
"direct-access-external-data" when it is true. However, doing so would require
~90 clang/test tests to be updated, which are too much.

As a compromise, we set "direct-access-external-data" only when it's different
from the implied default value.

[nickdesaulniers]

This also resolves https://github.com/llvm/llvm-project/issues/62482; was that intentional? If so, consider adding a link to https://github.com/llvm/llvm-project/issues/62482 to this commit description (or closing https://github.com/llvm/llvm-project/issues/62482 as a duplicate of https://github.com/llvm/llvm-project/issues/60116 if that makes more sense).

llvm/lib/IR/Module.cpp

675–684

I think the presubmit bot failed due to clang-format changes to code introduced in this hunk.

[MaskRay]

In D150841#4362676, @nickdesaulniers wrote:

This also resolves https://github.com/llvm/llvm-project/issues/62482; was that intentional? If so, consider adding a link to https://github.com/llvm/llvm-project/issues/62482 to this commit description (or closing https://github.com/llvm/llvm-project/issues/62482 as a duplicate of https://github.com/llvm/llvm-project/issues/60116 if that makes more sense).

Thanks for the review!

I think https://github.com/llvm/llvm-project/issues/62482 and https://github.com/llvm/llvm-project/issues/60116 are about the same thing and I've closed the former as a duplicate of the latter.

[MaskRay]

fix clang-format lint

clang/lib/CodeGen/CodeGenModule.cpp

if (getCodeGenOpts().CodeModel.size() > 0) {
     if (CM != ~0u) {
       llvm::CodeModel::Model codeModel = static_cast<llvm::CodeModel::Model>(CM);
       getModule().setCodeModel(codeModel);
     }
   }
 
   if (CodeGenOpts.NoPLT)
     getModule().setRtLibUseGOT();
+  if (getTriple().isOSBinFormatELF() &&
+      CodeGenOpts.DirectAccessExternalData !=
+          getModule().getDirectAccessExternalData()) {
+    getModule().setDirectAccessExternalData(
+        CodeGenOpts.DirectAccessExternalData);
+  }
   if (CodeGenOpts.UnwindTables)
     getModule().setUwtable(llvm::UWTableKind(CodeGenOpts.UnwindTables));
 
   switch (CodeGenOpts.getFramePointer()) {
   case CodeGenOptions::FramePointerKind::None:
     // 0 ("none") is the default.
     break;
   case CodeGenOptions::FramePointerKind::NonLeaf:

clang/test/CodeGen/dso-local-executable.c

 // STATIC-NEXT: @weak_bar = extern_weak dso_local global i32
 // STATIC-NEXT: @bar = external dso_local global i32
 // STATIC-NEXT: @local_thread_var = dso_local thread_local global i32 42
 // STATIC-NEXT: @thread_var = external thread_local global i32
 // STATIC-DAG: declare dso_local void @foo()
 // STATIC-DAG: define dso_local ptr @zed()
 // STATIC-DAG: declare dso_local void @import_func()
 
+// STATIC-NOT: !"direct-access-external-data"
+
 /// If -fno-direct-access-external-data is set, drop dso_local from global variable
 /// declarations.
 // RUN: %clang_cc1 -triple x86_64 -emit-llvm %s -mrelocation-model static -fno-direct-access-external-data -o - | FileCheck --check-prefix=STATIC-INDIRECT %s
 // STATIC-INDIRECT:      @baz = dso_local global i32 42
 // STATIC-INDIRECT-NEXT: @import_var = external global i32
 // STATIC-INDIRECT-NEXT: @weak_bar = extern_weak global i32
 // STATIC-INDIRECT-NEXT: @bar = external global i32
 // STATIC-INDIRECT-NEXT: @local_thread_var = dso_local thread_local global i32 42
 // STATIC-INDIRECT-NEXT: @thread_var = external thread_local global i32
 // STATIC-INDIRECT-DAG:  declare void @import_func()
 // STATIC-INDIRECT-DAG:  define dso_local ptr @zed()
 // STATIC-INDIRECT-DAG:  declare void @foo()
 
+// STATIC-INDIRECT:      ![[#]] = !{i32 7, !"direct-access-external-data", i32 0}
+
 // RUN: %clang_cc1 -triple x86_64 -emit-llvm -pic-level 1 -pic-is-pie %s -o - | FileCheck --check-prefix=PIE %s
 // PIE:      @baz = dso_local global i32 42
 // PIE-NEXT: @import_var = external global i32
 // PIE-NEXT: @weak_bar = extern_weak global i32
 // PIE-NEXT: @bar = external global i32
 // PIE-NEXT: @local_thread_var = dso_local thread_local global i32 42
 // PIE-NEXT: @thread_var = external thread_local global i32
 // PIE-DAG: declare void @foo()
 // PIE-DAG: define dso_local ptr @zed()
 // PIE-DAG: declare void @import_func()
 
+// PIE-NOT:  !"direct-access-external-data"
+
 // RUN: %clang_cc1 -triple x86_64 -emit-llvm -pic-level 1 -pic-is-pie -fdirect-access-external-data %s -o - | FileCheck --check-prefix=PIE-DIRECT %s
 // PIE-DIRECT:      @baz = dso_local global i32 42
 // PIE-DIRECT-NEXT: @import_var = external dso_local global i32
 // PIE-DIRECT-NEXT: @weak_bar = extern_weak global i32
 // PIE-DIRECT-NEXT: @bar = external dso_local global i32
 // PIE-DIRECT-NEXT: @local_thread_var = dso_local thread_local global i32 42
 // PIE-DIRECT-NEXT: @thread_var = external thread_local global i32
 // PIE-DIRECT-DAG: declare void @foo()
 // PIE-DIRECT-DAG: define dso_local ptr @zed()
 // PIE-DIRECT-DAG: declare void @import_func()
 
+// PIE-DIRECT:      ![[#]] = !{i32 7, !"direct-access-external-data", i32 1}
+
 // RUN: %clang_cc1 -triple x86_64 -emit-llvm -mrelocation-model static -fno-plt %s -o - | FileCheck --check-prefix=NOPLT %s
 // NOPLT:      @baz = dso_local global i32 42
 // NOPLT-NEXT: @import_var = external dso_local global i32
 // NOPLT-NEXT: @weak_bar = extern_weak dso_local global i32
 // NOPLT-NEXT: @bar = external dso_local global i32
 // NOPLT-NEXT: @local_thread_var = dso_local thread_local global i32 42
 // NOPLT-NEXT: @thread_var = external thread_local global i32
 // NOPLT-DAG: declare void @foo()

llvm/include/llvm/IR/Module.h

/// @}
   void setSemanticInterposition(bool);
 
   /// Returns true if PLT should be avoided for RTLib calls.
   bool getRtLibUseGOT() const;
 
   /// Set that PLT should be avoid for RTLib calls.
   void setRtLibUseGOT();
 
+  /// Get/set whether referencing global variables can use direct access
+  /// relocations on ELF targets.
+  bool getDirectAccessExternalData() const;
+  void setDirectAccessExternalData(bool Value);
+
   /// Get/set whether synthesized functions should get the uwtable attribute.
   UWTableKind getUwtable() const;
   void setUwtable(UWTableKind Kind);
 
   /// Get/set whether synthesized functions should get the "frame-pointer"
   /// attribute.
   FramePointerKind getFramePointer() const;
   void setFramePointer(FramePointerKind Kind);

llvm/lib/CodeGen/TargetLoweringBase.cpp

 // TODO: add LOAD_STACK_GUARD support.
 void TargetLoweringBase::insertSSPDeclarations(Module &M) const {
   if (!M.getNamedValue("__stack_chk_guard")) {
     auto *GV = new GlobalVariable(M, Type::getInt8PtrTy(M.getContext()), false,
                                   GlobalVariable::ExternalLinkage, nullptr,
                                   "__stack_chk_guard");
 
     // FreeBSD has "__stack_chk_guard" defined externally on libc.so
-    if (TM.getRelocationModel() == Reloc::Static &&
+    if (M.getDirectAccessExternalData() &&
         !TM.getTargetTriple().isWindowsGNUEnvironment() &&
         !TM.getTargetTriple().isOSFreeBSD())
       GV->setDSOLocal(true);
   }
 }
 
 // Currently only support "standard" __stack_chk_guard.
 // TODO: add LOAD_STACK_GUARD support.

llvm/lib/IR/Module.cpp

bool Module::getRtLibUseGOT() const {
   auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("RtLibUseGOT"));
   return Val && (cast<ConstantInt>(Val->getValue())->getZExtValue() > 0);
 }
 
 void Module::setRtLibUseGOT() {
   addModuleFlag(ModFlagBehavior::Max, "RtLibUseGOT", 1);
 }
 
+bool Module::getDirectAccessExternalData() const {
+  auto *Val = cast_or_null<ConstantAsMetadata>(
+      getModuleFlag("direct-access-external-data"));
+  if (Val)
+    return cast<ConstantInt>(Val->getValue())->getZExtValue() > 0;
+  return getPICLevel() == PICLevel::NotPIC;
+}
+
+void Module::setDirectAccessExternalData(bool Value) {
+  addModuleFlag(ModFlagBehavior::Max, "direct-access-external-data", Value);
+}
+
 UWTableKind Module::getUwtable() const {
   if (auto *Val = cast_or_null<ConstantAsMetadata>(getModuleFlag("uwtable")))
     return UWTableKind(cast<ConstantInt>(Val->getValue())->getZExtValue());
   return UWTableKind::None;
 }
 
 void Module::setUwtable(UWTableKind Kind) {
   addModuleFlag(ModFlagBehavior::Max, "uwtable", uint32_t(Kind));

llvm/lib/Target/X86/X86ISelLowering.cpp

if (Subtarget.isTargetFuchsia()) {
       if (!GuardSymb.empty()) {
         GlobalVariable *GV = M->getGlobalVariable(GuardSymb);
         if (!GV) {
           Type *Ty = Subtarget.is64Bit() ? Type::getInt64Ty(M->getContext())
                                          : Type::getInt32Ty(M->getContext());
           GV = new GlobalVariable(*M, Ty, false, GlobalValue::ExternalLinkage,
                                   nullptr, GuardSymb, nullptr,
                                   GlobalValue::NotThreadLocal, AddressSpace);
+          GV->setDSOLocal(M->getDirectAccessExternalData());
         }
         return GV;
       }
 
       return SegmentOffset(IRB, Offset, AddressSpace);
     }
   }
   return TargetLowering::getIRStackGuard(IRB);

llvm/test/CodeGen/AArch64/arm64_32.ll

; CHECK: b _bzero
   %size.64 = lshr i64 %in, 32
   %size = trunc i64 %size.64 to i32
   %ptr = inttoptr i32 %ptr.i32 to ptr
   tail call void @llvm.memset.p0.i32(ptr align 4 %ptr, i8 0, i32 %size, i1 false)
   ret void
 }
 
 declare void @llvm.memset.p0.i32(ptr nocapture writeonly, i8, i32, i1)
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"PIC Level", i32 2}

llvm/test/CodeGen/AArch64/stack-guard-sve.ll

entry:
   %vec = alloca <vscale x 4 x float>, align 16
   %gep = getelementptr <vscale x 4 x float>, <vscale x 4 x float>* %vec, i64 0, i64 %n
   store float 0.0, float* %gep, align 4
   ret void
 }
 
 attributes #0 = { ssp "frame-pointer"="non-leaf" }
 attributes #1 = { sspstrong "frame-pointer"="non-leaf" }
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"direct-access-external-data", i32 1}

llvm/test/CodeGen/AArch64/stack-guard-vaarg.ll

 declare void @llvm.va_start(ptr)
 declare void @baz(ptr, ptr)
 declare void @llvm.memcpy.p0.p0.i64(ptr nocapture, ptr nocapture readonly, i64, i32, i1)
 declare void @bar(ptr)
 declare void @llvm.va_end(ptr)
 declare void @llvm.lifetime.end(i64, ptr nocapture)
 
 attributes #0 = { noinline nounwind optnone ssp }
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"direct-access-external-data", i32 1}

llvm/test/CodeGen/AArch64/stack_guard_remat.ll

-; RUN: llc < %s -mtriple=arm64-apple-ios -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=DARWIN
-; RUN: llc < %s -mtriple=arm64-apple-ios -relocation-model=static -no-integrated-as | FileCheck %s -check-prefix=DARWIN
-; RUN: llc < %s -mtriple=aarch64-linux-gnu -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=PIC-LINUX
-; RUN: llc < %s -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=large -no-integrated-as | FileCheck %s -check-prefix=STATIC-LARGE
-; RUN: llc < %s -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=small -no-integrated-as | FileCheck %s -check-prefix=STATIC-SMALL
-
-; RUN: llc < %s -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=arm64-apple-ios -relocation-model=pic -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=DARWIN,FALLBACK
-; RUN: llc < %s -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=arm64-apple-ios -relocation-model=static -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=DARWIN,FALLBACK
-; RUN: llc < %s -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=aarch64-linux-gnu -relocation-model=pic -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=PIC-LINUX,FALLBACK
-; RUN: llc < %s -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=large -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=STATIC-LARGE,FALLBACK
-; RUN: llc < %s -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=small -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=STATIC-SMALL,FALLBACK
+; RUN: rm -rf %t && split-file %s %t && cd %t
+; RUN: cat a.ll pic.ll > b.ll
+; RUN: llc < b.ll -mtriple=arm64-apple-ios -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=DARWIN
+; RUN: llc < b.ll -mtriple=arm64-apple-ios -relocation-model=static -no-integrated-as | FileCheck %s -check-prefix=DARWIN
+; RUN: llc < b.ll -mtriple=aarch64-linux-gnu -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=PIC-LINUX
+; RUN: llc < a.ll -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=large -no-integrated-as | FileCheck %s -check-prefix=STATIC-LARGE
+; RUN: llc < a.ll -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=small -no-integrated-as | FileCheck %s -check-prefix=STATIC-SMALL
+
+; RUN: llc < b.ll -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=arm64-apple-ios -relocation-model=pic -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=DARWIN,FALLBACK
+; RUN: llc < b.ll -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=arm64-apple-ios -relocation-model=static -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=DARWIN,FALLBACK
+; RUN: llc < b.ll -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=aarch64-linux-gnu -relocation-model=pic -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=PIC-LINUX,FALLBACK
+; RUN: llc < a.ll -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=large -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=STATIC-LARGE,FALLBACK
+; RUN: llc < a.ll -global-isel -global-isel-abort=2 -pass-remarks-missed=gisel* -mtriple=aarch64-linux-gnu -relocation-model=static -code-model=small -no-integrated-as 2>&1 | FileCheck %s -check-prefixes=STATIC-SMALL,FALLBACK
 
 ; DARWIN: foo2
 ; DARWIN: adrp [[R0:x[0-9]+]], ___stack_chk_guard@GOTPAGE
 ; DARWIN: ldr [[R1:x[0-9]+]], [[[R0]], ___stack_chk_guard@GOTPAGEOFF]
 ; DARWIN: ldr {{x[0-9]+}}, [[[R1]]]
 
 ; PIC-LINUX: foo2
 ; PIC-LINUX: adrp [[R0:x[0-9]+]], :got:__stack_chk_guard
 ; PIC-LINUX: ldr [[R1:x[0-9]+]], [[[R0]], :got_lo12:__stack_chk_guard]
 ; PIC-LINUX: ldr {{x[0-9]+}}, [[[R1]]]
 
 ; STATIC-LARGE: foo2
 ; STATIC-LARGE: movz [[R0:x[0-9]+]], #:abs_g0_nc:__stack_chk_guard
 ; STATIC-LARGE: movk [[R0]], #:abs_g1_nc:__stack_chk_guard
 ; STATIC-LARGE: movk [[R0]], #:abs_g2_nc:__stack_chk_guard
 ; STATIC-LARGE: movk [[R0]], #:abs_g3:__stack_chk_guard
 ; STATIC-LARGE: ldr {{x[0-9]+}}, [[[R0]]]
 
 ; STATIC-SMALL: foo2
 ; STATIC-SMALL: adrp [[R0:x[0-9]+]], __stack_chk_guard
 ; STATIC-SMALL: ldr {{x[0-9]+}}, [[[R0]], :lo12:__stack_chk_guard]
 
 ; FALLBACK-NOT: remark:{{.*}}llvm.lifetime.end
 ; FALLBACK-NOT: remark:{{.*}}llvm.lifetime.start
+;--- a.ll
 define i32 @test_stack_guard_remat() #0 {
 entry:
   %a1 = alloca [256 x i32], align 4
   call void @llvm.lifetime.start.p0(i64 1024, ptr %a1)
   call void @foo3(ptr %a1)
   call void asm sideeffect "foo2", "~{w0},~{w1},~{w2},~{w3},~{w4},~{w5},~{w6},~{w7},~{w8},~{w9},~{w10},~{w11},~{w12},~{w13},~{w14},~{w15},~{w16},~{w17},~{w18},~{w19},~{w20},~{w21},~{w22},~{w23},~{w24},~{w25},~{w26},~{w27},~{w28},~{w29},~{w30}"()
   call void @llvm.lifetime.end.p0(i64 1024, ptr %a1)
   ret i32 0
 }
 
 ; Function Attrs: nounwind
 declare void @llvm.lifetime.start.p0(i64, ptr nocapture)
 
 declare void @foo3(ptr)
 
 ; Function Attrs: nounwind
 declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
 
 attributes #0 = { nounwind sspstrong "less-precise-fpmad"="false" "frame-pointer"="all" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+;--- pic.ll
+!llvm.module.flags = !{!0}
+!0 = !{i32 8, !"PIC Level", i32 2}

llvm/test/CodeGen/ARM/expand-pseudos.ll

define void @_ZN2v88internal4wasm16LiftoffAssembler13emit_i32_addiENS0_8RegisterES3_i(ptr %0, [1 x i32] %1, [1 x i32] %2, i32 %3) #0 {
   %9 = getelementptr %"class.v8::internal::Operand", ptr %5
   %10 = getelementptr %"class.v8::internal::Operand", ptr %5, i32 0, i32 4, i32 0
   store i32 %3, ptr %10, align 4
   call void @_ZN2v88internal9Assembler3addENS0_8RegisterES2_RKNS0_7OperandENS0_4SBitENS0_9ConditionE(ptr %0, [1 x i32] %1, [1 x i32] %2, ptr %5, i32 0, i32 2)
   ret void
 }
 
 attributes #0 = { ssp }
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"PIC Level", i32 2}

llvm/test/CodeGen/ARM/stack-guard-rwpi.ll

 define dso_local i32 @foo(i32 %t) nounwind sspstrong {
 entry:
   %vla = alloca i32, i32 %t
   %call = call i32 @baz(ptr %vla)
   ret i32 %call
 }
 
 declare dso_local i32 @baz(ptr)
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"PIC Level", i32 2}

llvm/test/CodeGen/ARM/stack_guard_remat.ll

 declare void @llvm.lifetime.start.p0(i64, ptr nocapture)
 
 declare void @foo3(ptr)
 
 ; Function Attrs: nounwind
 declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
 
 attributes #0 = { nounwind ssp "less-precise-fpmad"="false" "frame-pointer"="all" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"PIC Level", i32 2}

llvm/test/CodeGen/Inputs/stack-guard-reassign.ll

entry:
   ret i32 %conv
 }
 
 declare i8* @strcpy(i8*, i8*)
 
 declare i32 @puts(i8*)
 
 attributes #0 = { noinline nounwind optnone ssp }
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"direct-access-external-data", i32 1}

llvm/test/CodeGen/PowerPC/stack-guard-oob.ll

define i32 @multi_dimensional_array() #0 {
   %var = alloca %struct.multi_dimensional, align 4
   %gep2 = getelementptr inbounds [10 x [10 x i32]], ptr %var, i32 0, i32 10
   %gep3 = getelementptr inbounds [10 x i32], ptr %gep2, i32 0, i32 5
   %ret = load i32, ptr %gep3, align 4
   ret i32 %ret
 }
 
 attributes #0 = { sspstrong }
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"direct-access-external-data", i32 1}

llvm/test/CodeGen/Thumb/stack_guard_remat.ll

 declare void @llvm.lifetime.start.p0(i64, ptr nocapture)
 
 declare void @foo3(ptr)
 
 ; Function Attrs: nounwind
 declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
 
 attributes #0 = { nounwind ssp "less-precise-fpmad"="false" "frame-pointer"="all" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"PIC Level", i32 2}

llvm/test/CodeGen/Thumb2/stack_guard_remat.ll

 declare void @llvm.lifetime.start.p0(i64, ptr nocapture)
 
 declare void @foo3(ptr)
 
 ; Function Attrs: nounwind
 declare void @llvm.lifetime.end.p0(i64, ptr nocapture)
 
 attributes #0 = { nounwind ssp "less-precise-fpmad"="false" "frame-pointer"="all" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"PIC Level", i32 2}

llvm/test/CodeGen/X86/2009-04-14-IllegalRegs.ll

entry:
   br label %return
 
 return:   ; preds = %entry
   %retval1 = load i32, ptr %retval    ; <i32> [#uses=1]
   ret i32 %retval1
 }
 
 declare i32 @f(ptr byval(%struct.X) align 4, ptr byval(%struct.X) align 4) nounwind ssp
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"PIC Level", i32 2}

llvm/test/CodeGen/X86/2010-09-17-SideEffectsInChain.ll

entry:
   %c = getelementptr inbounds [64 x i8], ptr %a, i64 0, i32 30
   %d = load i8, ptr %a, align 8
   %e = load i8, ptr %c, align 8
   call void @llvm.memcpy.p0.p0.i64(ptr align 8 %a, ptr align 8 %in, i64 64, i1 false) nounwind
   store i8 %d, ptr %a, align 8
   store i8 %e, ptr %c, align 8
   ret i32 0
 }
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 7, !"direct-access-external-data", i32 1}

llvm/test/CodeGen/X86/stack-protector-3.ll

 ; RUN: split-file %s %t
 ; RUN: cat %t/main.ll %t/a.ll > %t/a2.ll
 ; RUN: cat %t/main.ll %t/b.ll > %t/b2.ll
 ; RUN: cat %t/main.ll %t/c.ll > %t/c2.ll
 ; RUN: cat %t/main.ll %t/d.ll > %t/d2.ll
 ; RUN: cat %t/main.ll %t/e.ll > %t/e2.ll
 ; RUN: cat %t/main.ll %t/f.ll > %t/f2.ll
 ; RUN: cat %t/main.ll %t/g.ll > %t/g2.ll
 ; RUN: cat %t/main.ll %t/h.ll > %t/h2.ll
-; RUN: cat %t/existedGV.ll %t/main.ll %t/h.ll > %t/i2.ll
+; RUN: cat %t/existedGV.ll %t/main.ll %t/h.ll > %t/h3.ll
+; RUN: cat %t/main.ll %t/i.ll > %t/i2.ll
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/a2.ll | FileCheck --check-prefix=CHECK-TLS-FS-40 %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/b2.ll | FileCheck --check-prefix=CHECK-TLS-FS-40 %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/c2.ll | FileCheck --check-prefix=CHECK-GLOBAL %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/d2.ll | FileCheck --check-prefix=CHECK-TLS-FS-40 %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/e2.ll | FileCheck --check-prefix=CHECK-GS %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/f2.ll | FileCheck --check-prefix=CHECK-OFFSET %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/g2.ll | FileCheck --check-prefix=CHECK-NEGATIVE-OFFSET %s
 ; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/h2.ll | FileCheck --check-prefix=CHECK-SYM %s
-; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/i2.ll | FileCheck --check-prefix=CHECK-SYMGV %s
+; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/h3.ll | FileCheck --check-prefix=CHECK-SYMGV %s
+; RUN: llc -mtriple=x86_64-pc-linux-gnu -o - < %t/i2.ll | FileCheck --check-prefix=CHECK-SYM2 %s
 
 ; CHECK-TLS-FS-40:       movq    %fs:40, %rax
 ; CHECK-TLS-FS-40:       movq    %fs:40, %rax
 ; CHECK-TLS-FS-40-NEXT:  cmpq    16(%rsp), %rax
 ; CHECK-TLS-FS-40-NEXT:  jne     .LBB0_2
 ; CHECK-TLS-FS-40:       .LBB0_2:
 ; CHECK-TLS-FS-40-NEXT:  .cfi_def_cfa_offset 32
 ; CHECK-TLS-FS-40-NEXT:  callq   __stack_chk_fail

 ; CHECK-SYM:         movq    __woof@GOTPCREL(%rip), %rax
 ; CHECK-SYM-NEXT:    movq    %fs:(%rax), %rcx
 ; CHECK-SYM-NEXT:    movq    %rcx, 16(%rsp)
 ; CHECK-SYM:         movq    %fs:(%rax), %rax
 ; CHECK-SYM-NEXT:    cmpq    16(%rsp), %rax
 ; CHECK-SYM-NEXT:    jne     .LBB0_2
 ; CHECK-SYM:         .LBB0_2:
 ; CHECK-SYM-NEXT:    .cfi_def_cfa_offset 32
-; CHECK-SYM-NEXT:    callq   __stack_chk_fai
+; CHECK-SYM-NEXT:    callq   __stack_chk_fail
 
 ; CHECK-SYMGV:       movq    __woof(%rip), %rax
 ; CHECK-SYMGV-NEXT:  movq    %rax, 16(%rsp)
 ; CHECK-SYMGV:       cmpq    16(%rsp), %rax
 ; CHECK-SYMGV-NEXT:  jne     .LBB0_2
 ; CHECK-SYMGV:       .LBB0_2:
 ; CHECK-SYMGV-NEXT:  .cfi_def_cfa_offset 32
 ; CHECK-SYMGV-NEXT:  callq   __stack_chk_fail
 
+; CHECK-SYM2:         movq    %fs:__woof(%rip), %rax
+; CHECK-SYM2-NEXT:    movq    %rax, 16(%rsp)
+; CHECK-SYM2:         movq    %fs:__woof(%rip), %rax
+; CHECK-SYM2-NEXT:    cmpq    16(%rsp), %rax
+; CHECK-SYM2-NEXT:    jne     .LBB0_2
+; CHECK-SYM2:         .LBB0_2:
+; CHECK-SYM2-NEXT:    .cfi_def_cfa_offset 32
+; CHECK-SYM2-NEXT:    callq   __stack_chk_fai
+
 ; ModuleID = 't.c'
 ;--- existedGV.ll
 
 @__woof = dso_local local_unnamed_addr global ptr null, align 8
 
 ;--- main.ll
 
 @.str = private unnamed_addr constant [14 x i8] c"stackoverflow\00", align 1

 attributes #1 = { argmemonly nounwind willreturn }
 attributes #2 = { nounwind }
 
 ;--- a.ll
 ;--- b.ll
 !llvm.module.flags = !{!1}
 !1 = !{i32 2, !"stack-protector-guard", !"tls"}
 ;--- c.ll
-!llvm.module.flags = !{!1}
+!llvm.module.flags = !{!0,!1}
+!0 = !{i32 7, !"direct-access-external-data", i32 1}
 !1 = !{i32 2, !"stack-protector-guard", !"global"}
 ;--- d.ll
 !llvm.module.flags = !{!1}
 !1 = !{i32 2, !"stack-protector-guard-reg", !"fs"}
 ;--- e.ll
 !llvm.module.flags = !{!1}
 !1 = !{i32 2, !"stack-protector-guard-reg", !"gs"}
 ;--- f.ll
 !llvm.module.flags = !{!1}
 !1 = !{i32 2, !"stack-protector-guard-offset", i32 20}
 ;--- g.ll
 !llvm.module.flags = !{!1}
 !1 = !{i32 2, !"stack-protector-guard-offset", i32 -20}
 ;--- h.ll
-!llvm.module.flags = !{!1}
+!llvm.module.flags = !{!0,!1}
+!0 = !{i32 7, !"direct-access-external-data", i32 0}
+!1 = !{i32 2, !"stack-protector-guard-symbol", !"__woof"}
+;--- i.ll
+!llvm.module.flags = !{!0,!1}
+!0 = !{i32 7, !"direct-access-external-data", i32 1}
 !1 = !{i32 2, !"stack-protector-guard-symbol", !"__woof"}