Using an invalid -O falls back on -O3 instead of an error

Summary:
Currently with clang:
$ clang -O20 foo.c
error: invalid value '20' in '-O20'

With the patch:
$ clang -O20 foo.c
warning: optimization level '-O20' is unsupported; using '-O3' instead.
1 warning generated.

This matches the gcc behavior (with a warning added)

Pass all tests:
Testing: 0 .. 10.. 20.. 30.. 40.. 50.. 60.. 70.. 80.. 90..
Testing Time: 94.14s
  Expected Passes    : 6721
  Expected Failures  : 20
  Unsupported Tests  : 17

(which was not the case of http://llvm-reviews.chandlerc.com/D2125)

Reviewers: chandlerc, rafael, rengolin, hfinkel

Reviewed By: rengolin

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2152

llvm-svn: 194817

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index ceef90f171c..f43694de1cb 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -2760,7 +2760,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   // preprocessed inputs and configure concludes that -fPIC is not supported.
   Args.ClaimAllArgs(options::OPT_D);
 
-  // Manually translate -O4 to -O3; let clang reject others.
+  // Manually translate -O4 to -O3; let clang fall back on -O3 for others
   if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
     if (A->getOption().matches(options::OPT_O4)) {
       CmdArgs.push_back("-O3");