r182203 - Fix a logic bug in the handling of -fmath-errno in the driver. We would

[Chandler Carruth]

Author: chandlerc
Date: Sat May 18 15:47:36 2013
New Revision: 182203

URL: http://llvm.org/viewvc/llvm-project?rev=182203&view=rev
Log:
Fix a logic bug in the handling of -fmath-errno in the driver. We would
imply -fno-math-errno if the user passed -fno-fast-math OR -ffast-math,
regardless of in which order and regardless of the tool chain default.

I've fixed this to follow the logic:

1) If the last dominating flag is -fno-math-errno, -ffast-math, or
   -Ofast, then do not use math-errno.
2) If the last dominating flag is an explicit -fmath-errno, do use
   math-errno.
3) Otherwise, use the toolchain default.

This, for example, allows the flag sequence
'-ffast-math ... -fno-fast-math' with no mention of '-fmath-errno' or
'-fno-math-errno' to preserve the toolchain default. Most notably, this
should prevent users trying to disable fast-math optimizations on Darwin
and BSD platforms from simultaneously enabling (pointless) -fmath-errno.

I've enhanced the tests (after more reorganization) to cover this and
other weird permutations of flags and targets.

Modified:
    cfe/trunk/lib/Driver/Tools.cpp
    cfe/trunk/test/Driver/fast-math.c

Modified: cfe/trunk/lib/Driver/Tools.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Driver/Tools.cpp?rev=182203&r1=182202&r2=182203&view=diff
==============================================================================
--- cfe/trunk/lib/Driver/Tools.cpp (original)
+++ cfe/trunk/lib/Driver/Tools.cpp Sat May 18 15:47:36 2013
@@ -2208,8 +2208,17 @@ void Clang::ConstructJob(Compilation &C,
   if (Arg *A = Args.getLastArg(options::OPT_ffast_math, FastMathAliasOption,
                                options::OPT_fno_fast_math,
                                options::OPT_fmath_errno,
-                               options::OPT_fno_math_errno))
-    MathErrno = A->getOption().getID() == options::OPT_fmath_errno;
+                               options::OPT_fno_math_errno)) {
+    // Turning on -ffast_math (with either flag) removes the need for MathErrno.
+    // However, turning *off* -ffast_math merely restores the toolchain default
+    // (which may be false).
+    if (A->getOption().getID() == options::OPT_fno_math_errno ||
+        A->getOption().getID() == options::OPT_ffast_math ||
+        A->getOption().getID() == options::OPT_Ofast)
+      MathErrno = false;
+    else if (A->getOption().getID() == options::OPT_fmath_errno)
+      MathErrno = true;
+  }
   if (MathErrno)
     CmdArgs.push_back("-fmath-errno");
 

Modified: cfe/trunk/test/Driver/fast-math.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Driver/fast-math.c?rev=182203&r1=182202&r2=182203&view=diff
==============================================================================
--- cfe/trunk/test/Driver/fast-math.c (original)
+++ cfe/trunk/test/Driver/fast-math.c Sat May 18 15:47:36 2013
@@ -39,17 +39,17 @@
 //
 // RUN: %clang -### -fmath-errno -c %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-MATH-ERRNO %s
-// RUN: %clang -### -target x86_64-unknown-linux -c %s 2>&1 \
-// RUN:   | FileCheck --check-prefix=CHECK-MATH-ERRNO %s
-// RUN: %clang -### -fmath-errno -fno-fast-math -c %s 2>&1 \
-// RUN:   | FileCheck --check-prefix=CHECK-MATH-ERRNO %s
-// RUN: %clang -### -fno-fast-math -fmath-errno -c %s 2>&1 \
-// RUN:   | FileCheck --check-prefix=CHECK-MATH-ERRNO %s
 // CHECK-MATH-ERRNO: "-cc1"
 // CHECK-MATH-ERRNO: "-fmath-errno"
 //
 // RUN: %clang -### -fmath-errno -fno-math-errno -c %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
+// CHECK-NO-MATH-ERRNO: "-cc1"
+// CHECK-NO-MATH-ERRNO-NOT: "-fmath-errno"
+//
+// Target defaults for -fmath-errno (reusing the above checks).
+// RUN: %clang -### -target i686-unknown-linux -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MATH-ERRNO %s
 // RUN: %clang -### -target i686-apple-darwin -c %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
 // RUN: %clang -### -target x86_64-unknown-freebsd -c %s 2>&1 \
@@ -60,8 +60,26 @@
 // RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
 // RUN: %clang -### -target x86_64-unknown-dragonfly -c %s 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
-// CHECK-NO-MATH-ERRNO: "-cc1"
-// CHECK-NO-MATH-ERRNO-NOT: "-fmath-errno"
+//
+// Check that -ffast-math disables -fmath-errno, and -fno-fast-math merely
+// preserves the target default. Also check various flag set operations between
+// the two flags. (Resuses above checks.)
+// RUN: %clang -### -ffast-math -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
+// RUN: %clang -### -fmath-errno -ffast-math -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
+// RUN: %clang -### -ffast-math -fmath-errno -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MATH-ERRNO %s
+// RUN: %clang -### -target i686-unknown-linux -fno-fast-math -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MATH-ERRNO %s
+// RUN: %clang -### -target i686-unknown-linux -fno-math-errno -fno-fast-math -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MATH-ERRNO %s
+// RUN: %clang -### -target i686-apple-darwin -fno-fast-math -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
+// RUN: %clang -### -target i686-apple-darwin -fno-math-errno -fno-fast-math -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
+// RUN: %clang -### -fno-fast-math -fno-math-errno -c %s 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-NO-MATH-ERRNO %s
 //
 // RUN: %clang -### -fno-math-errno -fassociative-math -freciprocal-math \
 // RUN:     -fno-signed-zeros -fno-trapping-math -c %s 2>&1 \