Implement support for -fwrapv, rdar://7221421

As part of this, pull together trapv handling into the same enum.

This also add support for NSW multiplies.

This also makes PCH disagreement on overflow behavior silent, since it
really doesn't matter except for warnings and codegen (no macros get 
defined etc).



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@106956 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 18 insertions, 17 deletions

diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index e7a75a619d..76770ae36c 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -549,8 +549,11 @@ static void LangOptsToArgs(const LangOptions &Opts,
     Res.push_back("-femit-all-decls");
   if (Opts.MathErrno)
     Res.push_back("-fmath-errno");
-  if (Opts.OverflowChecking)
-    Res.push_back("-ftrapv");
+  switch (Opts.getSignedOverflowBehavior()) {
+  case LangOptions::SOB_Undefined: break;
+  case LangOptions::SOB_Defined:   Res.push_back("-fwrapv"); break;
+  case LangOptions::SOB_Trapping:  Res.push_back("-ftrapv"); break;
+  }
   if (Opts.HeinousExtensions)
     Res.push_back("-fheinous-gnu-extensions");
   // Optimize is implicit.
@@ -1257,8 +1260,11 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
 
   if (Args.hasArg(OPT_fvisibility_inlines_hidden))
     Opts.InlineVisibilityHidden = 1;
-    
-  Opts.OverflowChecking = Args.hasArg(OPT_ftrapv);
+  
+  if (Args.hasArg(OPT_ftrapv))
+    Opts.setSignedOverflowBehavior(LangOptions::SOB_Trapping); 
+  else if (Args.hasArg(OPT_fwrapv))
+    Opts.setSignedOverflowBehavior(LangOptions::SOB_Defined); 
 
   // Mimicing gcc's behavior, trigraphs are only enabled if -trigraphs
   // is specified, or -std is set to a conforming mode.
diff --git a/lib/Frontend/PCHReader.cpp b/lib/Frontend/PCHReader.cpp
index 5bd3c0481a..c220e269c2 100644
--- a/lib/Frontend/PCHReader.cpp
+++ b/lib/Frontend/PCHReader.cpp
@@ -93,7 +93,7 @@ PCHValidator::ReadLanguageOptions(const LangOptions &LangOpts) {
   PARSE_LANGOPT_IMPORTANT(Blocks, diag::warn_pch_blocks);
   PARSE_LANGOPT_BENIGN(EmitAllDecls);
   PARSE_LANGOPT_IMPORTANT(MathErrno, diag::warn_pch_math_errno);
-  PARSE_LANGOPT_IMPORTANT(OverflowChecking, diag::warn_pch_overflow_checking);
+  PARSE_LANGOPT_BENIGN(getSignedOverflowBehavior());
   PARSE_LANGOPT_IMPORTANT(HeinousExtensions,
                           diag::warn_pch_heinous_extensions);
   // FIXME: Most of the options below are benign if the macro wasn't
@@ -1915,7 +1915,8 @@ bool PCHReader::ParseLanguageOptions(
     PARSE_LANGOPT(Blocks);
     PARSE_LANGOPT(EmitAllDecls);
     PARSE_LANGOPT(MathErrno);
-    PARSE_LANGOPT(OverflowChecking);
+    LangOpts.setSignedOverflowBehavior((LangOptions::SignedOverflowBehaviorTy)
+                                       Record[Idx++]);
     PARSE_LANGOPT(HeinousExtensions);
     PARSE_LANGOPT(Optimize);
     PARSE_LANGOPT(OptimizeSize);
@@ -1926,13 +1927,10 @@ bool PCHReader::ParseLanguageOptions(
     PARSE_LANGOPT(AccessControl);
     PARSE_LANGOPT(CharIsSigned);
     PARSE_LANGOPT(ShortWChar);
-    LangOpts.setGCMode((LangOptions::GCMode)Record[Idx]);
-    ++Idx;
-    LangOpts.setVisibilityMode((LangOptions::VisibilityMode)Record[Idx]);
-    ++Idx;
+    LangOpts.setGCMode((LangOptions::GCMode)Record[Idx++]);
+    LangOpts.setVisibilityMode((LangOptions::VisibilityMode)Record[Idx++]);
     LangOpts.setStackProtectorMode((LangOptions::StackProtectorMode)
-                                   Record[Idx]);
-    ++Idx;
+                                   Record[Idx++]);
     PARSE_LANGOPT(InstantiationDepth);
     PARSE_LANGOPT(OpenCL);
     PARSE_LANGOPT(CatchUndefined);
diff --git a/lib/Frontend/PCHWriter.cpp b/lib/Frontend/PCHWriter.cpp
index 3c42d474dc..efed0f0a6c 100644
--- a/lib/Frontend/PCHWriter.cpp
+++ b/lib/Frontend/PCHWriter.cpp
@@ -833,11 +833,8 @@ void PCHWriter::WriteLanguageOptions(const LangOptions &LangOpts) {
   Record.push_back(LangOpts.MathErrno); // Math functions must respect errno
                                   // (modulo the platform support).
 
-  Record.push_back(LangOpts.OverflowChecking); // Extension to call a handler function when
-                                  // signed integer arithmetic overflows.
-
-  Record.push_back(LangOpts.HeinousExtensions); // Extensions that we really don't like and
-                                  // may be ripped out at any time.
+  Record.push_back(LangOpts.getSignedOverflowBehavior());
+  Record.push_back(LangOpts.HeinousExtensions);
 
   Record.push_back(LangOpts.Optimize); // Whether __OPTIMIZE__ should be defined.
   Record.push_back(LangOpts.OptimizeSize); // Whether __OPTIMIZE_SIZE__ should be