Add -f[no-]strict-overflow to the Clang driver. Use it to set the

default for -fwrapv if that flag isn't specified explicitly. We always
prefer an explict setting of -fwrapv when present. Also adds support for
-fno-wrapv to allow disabling -fwrapv even when -fno-strict-overflow is
passed.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@128353 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index f5e92022c37a61f57faf3bdb5cf21243684b9c24..6cd5645cdff1ff1b7be2693bfd7be687197215c2 100644 (file)
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -355,12 +355,14 @@ def fno_show_source_location : Flag<"-fno-show-source-location">, Group<f_Group>
 def fno_spell_checking : Flag<"-fno-spell-checking">, Group<f_Group>;
 def fno_stack_protector : Flag<"-fno-stack-protector">, Group<f_Group>;
 def fno_strict_aliasing : Flag<"-fno-strict-aliasing">, Group<f_Group>;
+def fno_strict_overflow : Flag<"-fno-strict-overflow">, Group<f_Group>;
 def fno_threadsafe_statics : Flag<"-fno-threadsafe-statics">, Group<f_Group>;
 def fno_use_cxa_atexit : Flag<"-fno-use-cxa-atexit">, Group<f_Group>;
 def fno_unit_at_a_time : Flag<"-fno-unit-at-a-time">, Group<f_Group>;
 def fno_unwind_tables : Flag<"-fno-unwind-tables">, Group<f_Group>;
 def fno_verbose_asm : Flag<"-fno-verbose-asm">, Group<f_Group>;
 def fno_working_directory : Flag<"-fno-working-directory">, Group<f_Group>;
+def fno_wrapv : Flag<"-fno-wrapv">, Group<f_Group>;
 def fno_zero_initialized_in_bss : Flag<"-fno-zero-initialized-in-bss">, Group<f_Group>;
 def fobjc_atdefs : Flag<"-fobjc-atdefs">, Group<clang_ignored_f_Group>;
 def fobjc_call_cxx_cdtors : Flag<"-fobjc-call-cxx-cdtors">, Group<clang_ignored_f_Group>;
@@ -408,6 +410,7 @@ def fsigned_char : Flag<"-fsigned-char">, Group<f_Group>;
 def fstack_protector_all : Flag<"-fstack-protector-all">, Group<f_Group>;
 def fstack_protector : Flag<"-fstack-protector">, Group<f_Group>;
 def fstrict_aliasing : Flag<"-fstrict-aliasing">, Group<f_Group>;
+def fstrict_overflow : Flag<"-fstrict-overflow">, Group<f_Group>;
 def fsyntax_only : Flag<"-fsyntax-only">, Flags<[DriverOption]>;
 def ftabstop_EQ : Joined<"-ftabstop=">, Group<f_Group>;
 def ferror_limit_EQ : Joined<"-ferror-limit=">, Group<f_Group>;

diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index beaeade836cec340a79b335e1265d2d3ebb84043..81585c85674daf1f70780bf496b1d0e50acde99a 100644 (file)
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -1448,7 +1448,17 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back(A->getValue(Args));
   }
 
-  Args.AddLastArg(CmdArgs, options::OPT_fwrapv);
+  // -fno-strict-overflow implies -fwrapv if it isn't disabled, but
+  // -fstrict-overflow won't turn off an explicitly enabled -fwrapv.
+  if (Arg *A = Args.getLastArg(options::OPT_fwrapv,
+                               options::OPT_fno_wrapv)) {
+    if (A->getOption().matches(options::OPT_fwrapv))
+      CmdArgs.push_back("-fwrapv");
+  } else if (Arg *A = Args.getLastArg(options::OPT_fstrict_overflow,
+                                      options::OPT_fno_strict_overflow)) {
+    if (A->getOption().matches(options::OPT_fno_strict_overflow))
+      CmdArgs.push_back("-fwrapv");
+  }
   Args.AddLastArg(CmdArgs, options::OPT_fwritable_strings);
   Args.AddLastArg(CmdArgs, options::OPT_funroll_loops);