https://github.com/wolfy1961 created https://github.com/llvm/llvm-project/pull/65512:
As described in issue [#64999](https://github.com/llvm/llvm-project/issues/64999), commit [e018cbf7208](https://github.com/llvm/llvm-project/commit/e018cbf7208b3d34f18997ddee84c66cee32fb1b) caused the symbol __stack_chk_guard to not become dso_local when PIC is enabled in a module. However, during LTO we can force a static relocation model, which overrides the PIC level. In this case __stack_chk_guard should become dso_local. For this purpose we're adding a boolean to the interface of getDirectAccessExternalData() to indicate the relocation model. Fixes https://github.com/llvm/llvm-project/issues/64999 >From 6a176368c90183fc1744b73632746636fe46da42 Mon Sep 17 00:00:00 2001 From: wpieb <wolfgang.p...@sony.com> Date: Tue, 5 Sep 2023 10:43:23 -0700 Subject: [PATCH] [LTO] A static relocation model can override the PIC level wrt treating external address as directly accessible. Fixes https://github.com/llvm/llvm-project/issues/64999 --- clang/lib/CodeGen/CodeGenModule.cpp | 5 +-- llvm/include/llvm/IR/Module.h | 2 +- llvm/lib/CodeGen/TargetLoweringBase.cpp | 3 +- llvm/lib/IR/Module.cpp | 4 +-- llvm/lib/Target/X86/X86ISelLoweringCall.cpp | 3 +- llvm/test/LTO/ARM/ssp-static-reloc.ll | 38 +++++++++++++++++++++ 6 files changed, 48 insertions(+), 7 deletions(-) create mode 100644 llvm/test/LTO/ARM/ssp-static-reloc.ll diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index 95f185f5824d8c..f0a10f5d294270 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -1127,7 +1127,8 @@ void CodeGenModule::Release() { if (LangOpts.HLSL) getHLSLRuntime().finishCodeGen(); - if (uint32_t PLevel = Context.getLangOpts().PICLevel) { + uint32_t PLevel = Context.getLangOpts().PICLevel; + if (PLevel) { assert(PLevel < 3 && "Invalid PIC Level"); getModule().setPICLevel(static_cast<llvm::PICLevel::Level>(PLevel)); if (Context.getLangOpts().PIE) @@ -1152,7 +1153,7 @@ void CodeGenModule::Release() { getModule().setRtLibUseGOT(); if (getTriple().isOSBinFormatELF() && CodeGenOpts.DirectAccessExternalData != - getModule().getDirectAccessExternalData()) { + getModule().getDirectAccessExternalData(PLevel == 0)) { getModule().setDirectAccessExternalData( CodeGenOpts.DirectAccessExternalData); } diff --git a/llvm/include/llvm/IR/Module.h b/llvm/include/llvm/IR/Module.h index 670a40b28eabbe..bf2c41bb9c3e44 100644 --- a/llvm/include/llvm/IR/Module.h +++ b/llvm/include/llvm/IR/Module.h @@ -947,7 +947,7 @@ class LLVM_EXTERNAL_VISIBILITY Module { /// Get/set whether referencing global variables can use direct access /// relocations on ELF targets. - bool getDirectAccessExternalData() const; + bool getDirectAccessExternalData(bool IsStaticRelocModel) const; void setDirectAccessExternalData(bool Value); /// Get/set whether synthesized functions should get the uwtable attribute. diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp index 3e4bff5ddce126..e1f439fd32dad1 100644 --- a/llvm/lib/CodeGen/TargetLoweringBase.cpp +++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp @@ -2016,7 +2016,8 @@ void TargetLoweringBase::insertSSPDeclarations(Module &M) const { "__stack_chk_guard"); // FreeBSD has "__stack_chk_guard" defined externally on libc.so - if (M.getDirectAccessExternalData() && + if (M.getDirectAccessExternalData(TM.getRelocationModel() == + Reloc::Static) && !TM.getTargetTriple().isWindowsGNUEnvironment() && !TM.getTargetTriple().isOSFreeBSD() && !TM.getTargetTriple().isOSDarwin()) diff --git a/llvm/lib/IR/Module.cpp b/llvm/lib/IR/Module.cpp index 73354a8f36d215..8186f256007c48 100644 --- a/llvm/lib/IR/Module.cpp +++ b/llvm/lib/IR/Module.cpp @@ -672,12 +672,12 @@ void Module::setRtLibUseGOT() { addModuleFlag(ModFlagBehavior::Max, "RtLibUseGOT", 1); } -bool Module::getDirectAccessExternalData() const { +bool Module::getDirectAccessExternalData(bool IsStaticRelocModel) 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; + return getPICLevel() == PICLevel::NotPIC || IsStaticRelocModel; } void Module::setDirectAccessExternalData(bool Value) { diff --git a/llvm/lib/Target/X86/X86ISelLoweringCall.cpp b/llvm/lib/Target/X86/X86ISelLoweringCall.cpp index 754d2042105e57..9eeb9bf682b1f4 100644 --- a/llvm/lib/Target/X86/X86ISelLoweringCall.cpp +++ b/llvm/lib/Target/X86/X86ISelLoweringCall.cpp @@ -606,7 +606,8 @@ Value *X86TargetLowering::getIRStackGuard(IRBuilderBase &IRB) const { nullptr, GuardSymb, nullptr, GlobalValue::NotThreadLocal, AddressSpace); if (!Subtarget.isTargetDarwin()) - GV->setDSOLocal(M->getDirectAccessExternalData()); + GV->setDSOLocal(M->getDirectAccessExternalData( + getTargetMachine().getRelocationModel() == Reloc::Static)); } return GV; } diff --git a/llvm/test/LTO/ARM/ssp-static-reloc.ll b/llvm/test/LTO/ARM/ssp-static-reloc.ll new file mode 100644 index 00000000000000..3c8688d8e7b1c6 --- /dev/null +++ b/llvm/test/LTO/ARM/ssp-static-reloc.ll @@ -0,0 +1,38 @@ +; Check that we do not generate an extra indirection accessing the stack guard +; variable, when the relocation model is static. +; +; RUN: llvm-as < %s > %t.bc +; RUN: llvm-lto -O0 -relocation-model=static -o %t.o %t.bc +; RUN: llvm-objdump -d -r %t.o | FileCheck %s + +target triple = "armv4t-unknown-unknown" + +define arm_aapcscc i8 @foo() #0 { +entry: + %arr = alloca [200 x i8], align 1 + call void @llvm.memset.p0.i32(ptr align 1 %arr, i8 0, i32 200, i1 false) + %arrayidx = getelementptr inbounds [200 x i8], ptr %arr, i32 0, i8 5 + %0 = load i8, ptr %arrayidx, align 1 + ret i8 %0 +} + +; CHECK: <foo>: +; CHECK: [[#%x,CURPC:]]:{{.*}} ldr r[[REG1:[0-9]+]], [pc, #0x[[#%x,OFFSET:]]] +; CHECK-NEXT: ldr r[[REG2:[0-9]+]], [r[[REG1]]] +; CHECK-NEXT: str r[[REG2]], +; CHECK: [[#CURPC + OFFSET + 8]]:{{.*}}.word +; CHECK-NEXT: R_ARM_ABS32 __stack_chk_guard + +declare void @llvm.memset.p0.i32(ptr nocapture writeonly, i8, i32, i1 immarg) + +define arm_aapcscc i32 @main() { +entry: + %call = call arm_aapcscc i8 @foo() + %conv = zext i8 %call to i32 + ret i32 %conv +} + +attributes #0 = { noinline nounwind optnone sspstrong } + +!llvm.module.flags = !{!0} +!0 = !{i32 8, !"PIC Level", i32 2} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
