Index: include/clang/Driver/Options.td =================================================================== --- include/clang/Driver/Options.td +++ include/clang/Driver/Options.td @@ -2057,6 +2057,14 @@ def mno_embedded_data : Flag<["-"], "mno-embedded-data">, Group, HelpText<"Do not place constants in the .rodata section instead of the " ".sdata if they meet the -G threshold (MIPS)">; +def muninit_const_in_rodata : Flag<["-"], "muninit-const-in-rodata">, + Group, Flags<[DriverOption,CC1Option]>, HelpText<"Place " + "uninitialized constants in the read-only data section instead of" + " the common section (MIPS)">; +def mno_uninit_const_in_rodata : Flag<["-"], "mno-uninit-const-in-rodata">, + Group, HelpText<"Do not Place uninitialized constants in the " + "read-only data section instead of the common" + " section (MIPS)">; def mnan_EQ : Joined<["-"], "mnan=">, Group; def mabicalls : Flag<["-"], "mabicalls">, Group, HelpText<"Enable SVR4-style position-independent code (Mips only)">; Index: include/clang/Frontend/CodeGenOptions.def =================================================================== --- include/clang/Frontend/CodeGenOptions.def +++ include/clang/Frontend/CodeGenOptions.def @@ -101,6 +101,8 @@ CODEGENOPT(MergeFunctions , 1, 0) ///< Set when -fmerge-functions is enabled. CODEGENOPT(MSVolatile , 1, 0) ///< Set when /volatile:ms is enabled. CODEGENOPT(NoCommon , 1, 0) ///< Set when -fno-common or C++ is enabled. +CODEGENOPT(UInitCstDataInROData, 1, 0) ///< Set when -mgpopt & -membedded-data + ///< & -muinit-const-in-rodata is set CODEGENOPT(NoDwarfDirectoryAsm , 1, 0) ///< Set when -fno-dwarf-directory-asm is ///< enabled. CODEGENOPT(NoExecStack , 1, 0) ///< Set when -Wa,--noexecstack is enabled. Index: lib/CodeGen/TargetInfo.cpp =================================================================== --- lib/CodeGen/TargetInfo.cpp +++ lib/CodeGen/TargetInfo.cpp @@ -6659,6 +6659,20 @@ void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &CGM, ForDefinition_t IsForDefinition) const override { + + if (const VarDecl *VD = dyn_cast_or_null(D)) { + if (CGM.getCodeGenOpts().UInitCstDataInROData && + VD->getType().isConstQualified() && !VD->hasInit()) { + llvm::GlobalVariable *GVar = dyn_cast_or_null(GV); + if (GVar && !GVar->hasSection()) { + GVar->setLinkage(llvm::GlobalValue::ExternalLinkage); + GVar->setSection("rodata"); + } + } + + return; + } + const FunctionDecl *FD = dyn_cast_or_null(D); if (!FD) return; llvm::Function *Fn = cast(GV); Index: lib/Driver/ToolChains/Clang.cpp =================================================================== --- lib/Driver/ToolChains/Clang.cpp +++ lib/Driver/ToolChains/Clang.cpp @@ -1515,6 +1515,14 @@ CmdArgs.push_back("-membedded-data=0"); } EmbeddedData->claim(); + + if (Arg *A = Args.getLastArg(options::OPT_muninit_const_in_rodata, + options::OPT_mno_uninit_const_in_rodata)) { + if (A->getOption().matches(options::OPT_muninit_const_in_rodata)) { + CmdArgs.push_back("-muninit-const-in-rodata"); + A->claim(); + } + } } } else if ((!ABICalls || (!NoABICalls && ABICalls)) && WantGPOpt) Index: lib/Frontend/CompilerInvocation.cpp =================================================================== --- lib/Frontend/CompilerInvocation.cpp +++ lib/Frontend/CompilerInvocation.cpp @@ -949,6 +949,8 @@ Opts.Backchain = Args.hasArg(OPT_mbackchain); + Opts.UInitCstDataInROData = Args.hasArg(OPT_muninit_const_in_rodata); + Opts.EmitCheckPathComponentsToStrip = getLastArgIntValue( Args, OPT_fsanitize_undefined_strip_path_components_EQ, 0, Diags); Index: test/CodeGen/mips-uninit-const-in-ro.c =================================================================== --- /dev/null +++ test/CodeGen/mips-uninit-const-in-ro.c @@ -0,0 +1,10 @@ +// RUN: %clang_cc1 -triple mips-mti--elf -emit-llvm -mrelocation-model static \ +// RUN: -target-feature +noabicalls -mllvm -mgpopt -mllvm \ +// RUN: -membedded-data=1 -muninit-const-in-rodata -o - %s | \ +// RUN: FileCheck %s + +// Test that -muninit-const-in-rodata places constant uninitialized structures +// in the .rodata section rather than the commeon section. + +// CHECK: @a = global [8 x i32] zeroinitializer, section "rodata", align 4 +const int a[8];