From 88934e85f81abdc4fb5202325252be3bcab5ebf0 Mon Sep 17 00:00:00 2001 From: Daniel Dunbar Date: Wed, 5 Oct 2011 21:04:55 +0000 Subject: [PATCH] Driver & AST: Implement support for -fpack-struct and -fpack-struct= command line options. - , PR9631 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@141211 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/clang/Basic/LangOptions.def | 2 ++ include/clang/Driver/CC1Options.td | 2 ++ include/clang/Driver/Options.td | 3 +++ lib/AST/RecordLayoutBuilder.cpp | 5 +++++ lib/Driver/Tools.cpp | 12 ++++++++++++ lib/Frontend/CompilerInvocation.cpp | 1 + test/Sema/fpack-struct.c | 9 +++++++++ 7 files changed, 34 insertions(+) create mode 100644 test/Sema/fpack-struct.c diff --git a/include/clang/Basic/LangOptions.def b/include/clang/Basic/LangOptions.def index 9ff9dbacce..03882f8cdb 100644 --- a/include/clang/Basic/LangOptions.def +++ b/include/clang/Basic/LangOptions.def @@ -94,6 +94,8 @@ BENIGN_LANGOPT(HeinousExtensions , 1, 0, "Extensions that we really don't like a LANGOPT(Optimize , 1, 0, "__OPTIMIZE__ predefined macro") LANGOPT(OptimizeSize , 1, 0, "__OPTIMIZE_SIZE__ predefined macro") LANGOPT(Static , 1, 0, "__STATIC__ predefined macro (as opposed to __DYNAMIC__)") +VALUE_LANGOPT(PackStruct , 32, 0, + "default struct packing maximum alignment") VALUE_LANGOPT(PICLevel , 2, 0, "__PIC__ level") LANGOPT(GNUInline , 1, 0, "GNU inline semantics") LANGOPT(NoInline , 1, 0, "__NO_INLINE__ predefined macro") diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td index 00fc815fd2..ffe1eafd61 100644 --- a/include/clang/Driver/CC1Options.td +++ b/include/clang/Driver/CC1Options.td @@ -541,6 +541,8 @@ def pic_level : Separate<"-pic-level">, HelpText<"Value for __PIC__">; def pthread : Flag<"-pthread">, HelpText<"Support POSIX threads in generated code">; +def fpack_struct : Separate<"-fpack-struct">, + HelpText<"Specify the default maximum struct packing alignment">; def fpascal_strings : Flag<"-fpascal-strings">, HelpText<"Recognize and construct Pascal-style string literals">; def fno_rtti : Flag<"-fno-rtti">, diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td index 3f48b96d75..a0520f0bea 100644 --- a/include/clang/Driver/Options.td +++ b/include/clang/Driver/Options.td @@ -440,6 +440,9 @@ def force__cpusubtype__ALL : Flag<"-force_cpusubtype_ALL">; def force__flat__namespace : Flag<"-force_flat_namespace">; def force__load : Separate<"-force_load">; def foutput_class_dir_EQ : Joined<"-foutput-class-dir=">, Group; +def fpack_struct : Flag<"-fpack-struct">, Group; +def fno_pack_struct : Flag<"-fno-pack-struct">, Group; +def fpack_struct_EQ : Joined<"-fpack-struct=">, Group; def fpascal_strings : Flag<"-fpascal-strings">, Group; def fpch_preprocess : Flag<"-fpch-preprocess">, Group; def fpic : Flag<"-fpic">, Group; diff --git a/lib/AST/RecordLayoutBuilder.cpp b/lib/AST/RecordLayoutBuilder.cpp index 97355dc04e..8e71588768 100644 --- a/lib/AST/RecordLayoutBuilder.cpp +++ b/lib/AST/RecordLayoutBuilder.cpp @@ -1211,6 +1211,11 @@ void RecordLayoutBuilder::InitializeLayout(const Decl *D) { IsMsStruct = D->hasAttr(); + // Honor the default struct packing maximum alignment flag. + if (unsigned DefaultMaxFieldAlignment = Context.getLangOptions().PackStruct) { + MaxFieldAlignment = CharUnits::fromQuantity(DefaultMaxFieldAlignment); + } + // mac68k alignment supersedes maximum field alignment and attribute aligned, // and forces all structures to have 2-byte alignment. The IBM docs on it // allude to additional (more complicated) semantics, especially with regard diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp index e193c0f505..1dcb8bc91d 100644 --- a/lib/Driver/Tools.cpp +++ b/lib/Driver/Tools.cpp @@ -2062,11 +2062,23 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA, false)) CmdArgs.push_back("-fpascal-strings"); + // Honor -fpack-struct= and -fpack-struct, if given. Note that + // -fno-pack-struct doesn't apply to -fpack-struct=. + if (Arg *A = Args.getLastArg(options::OPT_fpack_struct_EQ)) { + CmdArgs.push_back("-fpack-struct"); + CmdArgs.push_back(A->getValue(Args)); + } else if (Args.hasFlag(options::OPT_fpack_struct, + options::OPT_fno_pack_struct, false)) { + CmdArgs.push_back("-fpack-struct"); + CmdArgs.push_back("1"); + } + if (Args.hasArg(options::OPT_mkernel) || Args.hasArg(options::OPT_fapple_kext)) { if (!Args.hasArg(options::OPT_fcommon)) CmdArgs.push_back("-fno-common"); } + // -fcommon is default, only pass non-default. else if (!Args.hasFlag(options::OPT_fcommon, options::OPT_fno_common)) CmdArgs.push_back("-fno-common"); diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp index 5252ebadac..4fb3ee62f0 100644 --- a/lib/Frontend/CompilerInvocation.cpp +++ b/lib/Frontend/CompilerInvocation.cpp @@ -1728,6 +1728,7 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK, Args.hasArg(OPT_fobjc_default_synthesize_properties); Opts.CatchUndefined = Args.hasArg(OPT_fcatch_undefined_behavior); Opts.EmitAllDecls = Args.hasArg(OPT_femit_all_decls); + Opts.PackStruct = Args.getLastArgIntValue(OPT_fpack_struct, 0, Diags); Opts.PICLevel = Args.getLastArgIntValue(OPT_pic_level, 0, Diags); Opts.Static = Args.hasArg(OPT_static_define); Opts.DumpRecordLayouts = Args.hasArg(OPT_fdump_record_layouts); diff --git a/test/Sema/fpack-struct.c b/test/Sema/fpack-struct.c new file mode 100644 index 0000000000..37c8444ae9 --- /dev/null +++ b/test/Sema/fpack-struct.c @@ -0,0 +1,9 @@ +// RUN: %clang_cc1 -DEXPECTED_STRUCT_SIZE=5 -fpack-struct 1 %s +// RUN: %clang_cc1 -DEXPECTED_STRUCT_SIZE=6 -fpack-struct 2 %s + +struct s0 { + int x; + char c; +}; + +int t0[sizeof(struct s0) == EXPECTED_STRUCT_SIZE ?: -1]; -- 2.40.0