Implement -fshort-enums (rdar://8490496).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@116020 91177308-0d34-0410-b5e6-96231b3b80d8

10 files changed, 31 insertions, 7 deletions

diff --git a/include/clang/Basic/DiagnosticFrontendKinds.td b/include/clang/Basic/DiagnosticFrontendKinds.td
index a5f6ac4a58..727d8f6d8a 100644
--- a/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -243,6 +243,9 @@ def warn_pch_char_signed : Error<
 def warn_pch_short_wchar : Error<
     "-fshort-wchar was %select{disabled|enabled}0 in the PCH file but "
     "is currently %select{disabled|enabled}1">;
+def warn_pch_short_enums : Error<
+    "-fshort-enums was %select{disabled|enabled}0 in the PCH file but "
+    "is currently %select{disabled|enabled}1">;
 
 def err_not_a_pch_file : Error<
     "'%0' does not appear to be a precompiled header file">, DefaultFatal;
diff --git a/include/clang/Basic/LangOptions.h b/include/clang/Basic/LangOptions.h
index fec984fae8..e10d776015 100644
--- a/include/clang/Basic/LangOptions.h
+++ b/include/clang/Basic/LangOptions.h
@@ -89,6 +89,9 @@ public:
   unsigned CharIsSigned      : 1; // Whether char is a signed or unsigned type
   unsigned ShortWChar        : 1; // Force wchar_t to be unsigned short int.
 
+  unsigned ShortEnums        : 1; // The enum type will be equivalent to the
+                                  // smallest integer type with enough room.
+
   unsigned OpenCL            : 1; // OpenCL C99 language extensions.
   
   unsigned AssumeSaneOperatorNew : 1; // Whether to add __attribute__((malloc))
@@ -182,6 +185,7 @@ public:
 
     CharIsSigned = 1;
     ShortWChar = 0;
+    ShortEnums = 0;
     CatchUndefined = 0;
     DumpRecordLayouts = 0;
     DumpVTableLayouts = 0;
diff --git a/include/clang/Driver/CC1Options.td b/include/clang/Driver/CC1Options.td
index 363ea7bb54..e6463b07c1 100644
--- a/include/clang/Driver/CC1Options.td
+++ b/include/clang/Driver/CC1Options.td
@@ -478,6 +478,8 @@ def fno_validate_pch : Flag<"-fno-validate-pch">,
   HelpText<"Disable validation of precompiled headers">;
 def fshort_wchar : Flag<"-fshort-wchar">,
   HelpText<"Force wchar_t to be a short unsigned int">;
+def fshort_enums : Flag<"-fshort-enums">,
+  HelpText<"Allocate to an enum type only as many bytes as it needs for the declared range of possible values">;
 def static_define : Flag<"-static-define">,
   HelpText<"Should __STATIC__ be defined">;
 def stack_protector : Separate<"-stack-protector">,
diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index fed03f755a..c39a79dfa1 100644
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -333,6 +333,7 @@ def fno_objc_legacy_dispatch : Flag<"-fno-objc-legacy-dispatch">, Group<f_Group>
 def fno_omit_frame_pointer : Flag<"-fno-omit-frame-pointer">, Group<f_Group>;
 def fno_pascal_strings : Flag<"-fno-pascal-strings">, Group<f_Group>;
 def fno_rtti : Flag<"-fno-rtti">, Group<f_Group>;
+def fno_short_enums : Flag<"-fno-short-enums">, Group<f_Group>;
 def fno_show_column : Flag<"-fno-show-column">, Group<f_Group>;
 def fno_show_source_location : Flag<"-fno-show-source-location">, Group<f_Group>;
 def fno_spell_checking : Flag<"-fno-spell-checking">, Group<f_Group>;
@@ -376,7 +377,7 @@ def framework : Separate<"-framework">, Flags<[LinkerInput]>;
 def frandom_seed_EQ : Joined<"-frandom-seed=">, Group<clang_ignored_f_Group>;
 def frtti : Flag<"-frtti">, Group<f_Group>;
 def fsched_interblock : Flag<"-fsched-interblock">, Group<clang_ignored_f_Group>;
-def fshort_enums : Flag<"-fshort-enums">, Group<clang_ignored_f_Group>;
+def fshort_enums : Flag<"-fshort-enums">, Group<f_Group>;
 def freorder_blocks : Flag<"-freorder-blocks">, Group<clang_ignored_f_Group>;
 def fshort_wchar : Flag<"-fshort-wchar">, Group<f_Group>;
 def fshow_overloads_EQ : Joined<"-fshow-overloads=">, Group<f_Group>;
diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index c3c224e9db..a98609dda4 100644
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -1002,8 +1002,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   if (!Args.hasArg(options::OPT_fallow_unsupported)) {
     Arg *Unsupported;
     if ((Unsupported = Args.getLastArg(options::OPT_MG)) ||
-        (Unsupported = Args.getLastArg(options::OPT_iframework)) ||
-        (Unsupported = Args.getLastArg(options::OPT_fshort_enums)))
+        (Unsupported = Args.getLastArg(options::OPT_iframework)))
       D.Diag(clang::diag::err_drv_clang_unsupported)
         << Unsupported->getOption().getName();
 
@@ -1258,6 +1257,12 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
       !Args.hasFlag(options::OPT_frtti, options::OPT_fno_rtti))
     CmdArgs.push_back("-fno-rtti");
 
+  // -fshort-enums=0 is default.
+  // FIXME: Are there targers where -fshort-enums is on by default ?
+  if (Args.hasFlag(options::OPT_fshort_enums,
+                   options::OPT_fno_short_enums, false))
+    CmdArgs.push_back("-fshort-enums");
+
   // -fsigned-char is default.
   if (!Args.hasFlag(options::OPT_fsigned_char, options::OPT_funsigned_char,
                     isSignedCharDefault(getToolChain().getTriple())))
diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 132d7d0f8e..927c6a441f 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -1352,6 +1352,7 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.Blocks = Args.hasArg(OPT_fblocks);
   Opts.CharIsSigned = !Args.hasArg(OPT_fno_signed_char);
   Opts.ShortWChar = Args.hasArg(OPT_fshort_wchar);
+  Opts.ShortEnums = Args.hasArg(OPT_fshort_enums);
   Opts.Freestanding = Args.hasArg(OPT_ffreestanding);
   Opts.NoBuiltin = Args.hasArg(OPT_fno_builtin) || Opts.Freestanding;
   Opts.AssumeSaneOperatorNew = !Args.hasArg(OPT_fno_assume_sane_operator_new);
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index d0411c035a..6cb2bcf512 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -7083,6 +7083,10 @@ void Sema::ActOnEnumBody(SourceLocation EnumLoc, SourceLocation LBraceLoc,
   QualType BestPromotionType;
 
   bool Packed = Enum->getAttr<PackedAttr>() ? true : false;
+  // -fshort-enums is the equivalent to specifying the packed attribute on all
+  // enum definitions.
+  if (LangOpts.ShortEnums)
+    Packed = true;
 
   if (NumNegativeBits) {
     // If there is a negative value, figure out the smallest integer type (of
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 33c032dcaa..9ee818367b 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -118,6 +118,7 @@ PCHValidator::ReadLanguageOptions(const LangOptions &LangOpts) {
   PARSE_LANGOPT_IMPORTANT(AccessControl, diag::warn_pch_access_control);
   PARSE_LANGOPT_IMPORTANT(CharIsSigned, diag::warn_pch_char_signed);
   PARSE_LANGOPT_IMPORTANT(ShortWChar, diag::warn_pch_short_wchar);
+  PARSE_LANGOPT_IMPORTANT(ShortEnums, diag::warn_pch_short_enums);
   if ((PPLangOpts.getGCMode() != 0) != (LangOpts.getGCMode() != 0)) {
     Reader.Diag(diag::warn_pch_gc_mode)
       << LangOpts.getGCMode() << PPLangOpts.getGCMode();
diff --git a/test/Driver/clang_f_opts.c b/test/Driver/clang_f_opts.c
index 50bce3b274..8e6b0fe850 100644
--- a/test/Driver/clang_f_opts.c
+++ b/test/Driver/clang_f_opts.c
@@ -1,6 +1,5 @@
 // RUN: %clang -### -S -fasm -fblocks -fbuiltin -fno-math-errno -fcommon -fpascal-strings -fno-blocks -fno-builtin -fmath-errno -fno-common -fno-pascal-strings -fblocks -fbuiltin -fmath-errno -fcommon -fpascal-strings %s 2>&1 | FileCheck -check-prefix=CHECK-OPTIONS1 %s
-// RUN: %clang -### -S -fasm -fblocks -fbuiltin -fno-math-errno -fcommon -fpascal-strings -fno-asm -fno-blocks -fno-builtin -fmath-errno -fno-common -fno-pascal-strings -fno-show-source-location -fshort-wchar %s 2>&1 | FileCheck -check-prefix=CHECK-OPTIONS2 %s
-// RUN: %clang -### -fshort-enums %s 2>&1 | FileCheck -check-prefix=CHECK-SHORT-ENUMS %s
+// RUN: %clang -### -S -fasm -fblocks -fbuiltin -fno-math-errno -fcommon -fpascal-strings -fno-asm -fno-blocks -fno-builtin -fmath-errno -fno-common -fno-pascal-strings -fno-show-source-location -fshort-enums -fshort-wchar %s 2>&1 | FileCheck -check-prefix=CHECK-OPTIONS2 %s
 
 // CHECK-OPTIONS1: -fgnu-keywords
 // CHECK-OPTIONS1: -fblocks
@@ -9,8 +8,7 @@
 // CHECK_OPTIONS2: -fno-gnu-keywords
 // CHECK-OPTIONS2: -fmath-errno
 // CHECK-OPTIONS2: -fno-builtin
+// CHECK-OPTIONS2: -fshort-enums
 // CHECK-OPTIONS2: -fshort-wchar
 // CHECK-OPTIONS2: -fno-common
 // CHECK-OPTIONS2: -fno-show-source-location
-
-// CHECK-SHORT-ENUMS: compiler does not support '-fshort-enums'
diff --git a/test/Sema/short-enums.c b/test/Sema/short-enums.c
new file mode 100644
index 0000000000..6605c4e8fc
--- /dev/null
+++ b/test/Sema/short-enums.c
@@ -0,0 +1,5 @@
+// RUN: not %clang_cc1 -fsyntax-only %s -verify
+// RUN: %clang_cc1 -fshort-enums -fsyntax-only %s -verify
+
+enum x { A };
+int t0[sizeof(enum x) == 1 ? 1 : -1];