Support -fno-omit-frame-pointer with -pg.

[srhines]

Summary

Previously, any instance of -fomit-frame-pointer would make it such that
-pg was an invalid flag combination. If -fno-omit-frame-pointer is
passed later on the command line (such that it actually takes effect),
-pg should be allowed.

[srhines]

This was discovered in the Android build system (which passes -fomit-frame-pointer by default for ARM configurations. This leads to the inability to specify -pg, since there is no way to override the mere presence of -fomit-frame-pointer.

[srhines]

http://b/32510864 was the internal bug request, so I am noting it here for future reference, but I think that the patch itself is pretty self-explanatory (rather than filing a distinct upstream bug about this issue).

[manojgupta]

What is the call generated with -pg for AMR32, gnu_mcount_nc or _mount? gnu_mcount_nc with "-pg" is known to be broken ( https://bugs.llvm.org/show_bug.cgi?id=33845)

[srhines]

In D51713#1232414, @manojgupta wrote:

What is the call generated with -pg for AMR32, gnu_mcount_nc or _mount? gnu_mcount_nc with "-pg" is known to be broken ( https://bugs.llvm.org/show_bug.cgi?id=33845)

I CCed myself on that issue as we are trying to do a better job of supporting code coverage, but I don't think this bug is relevant for this patch.

Unless there are any additional reviews, I will likely submit this patch in a few hours.

[manojgupta]

In D51713#1232497, @srhines wrote:

In D51713#1232414, @manojgupta wrote:

What is the call generated with -pg for AMR32, gnu_mcount_nc or _mount? gnu_mcount_nc with "-pg" is known to be broken ( https://bugs.llvm.org/show_bug.cgi?id=33845)

I CCed myself on that issue as we are trying to do a better job of supporting code coverage, but I don't think this bug is relevant for this patch.

Unless there are any additional reviews, I will likely submit this patch in a few hours.

Yes, Submitting this patch is totally fine, I just wanted to warn you about the potential issue you may run into with "-pg" and ARM32.

cfe/trunk/lib/Driver/ToolChains/Clang.cpp

if (Args.hasArg(options::OPT__SLASH_fallback) &&
     // fails, so that the main compilation's fallback to cl.exe runs.
     C.addCommand(llvm::make_unique<ForceSuccessCommand>(JA, *this, Exec,
                                                         CmdArgs, Inputs));
   } else {
     C.addCommand(llvm::make_unique<Command>(JA, *this, Exec, CmdArgs, Inputs));
   }
 
   if (Arg *A = Args.getLastArg(options::OPT_pg))
-    if (Args.hasArg(options::OPT_fomit_frame_pointer))
+    if (Args.hasFlag(options::OPT_fomit_frame_pointer,
+                     options::OPT_fno_omit_frame_pointer, /*default=*/false))
       D.Diag(diag::err_drv_argument_not_allowed_with) << "-fomit-frame-pointer"
                                                       << A->getAsString(Args);
 
   // Claim some arguments which clang supports automatically.
 
   // -fpch-preprocess is used with gcc to add a special marker in the output to
   // include the PCH file. Clang's PTH solution is completely transparent, so we
   // do not need to deal with it at all.

cfe/trunk/test/Driver/clang_f_opts.c

 // CHECK-MERGE-ALL-CONSTANTS: "-fmerge-all-constants"
 
 // RUN: %clang -### -S -fdelete-null-pointer-checks %s 2>&1 | FileCheck -check-prefix=CHECK-NULL-POINTER-CHECKS %s
 // RUN: %clang -### -S -fno-delete-null-pointer-checks %s 2>&1 | FileCheck -check-prefix=CHECK-NO-NULL-POINTER-CHECKS %s
 // RUN: %clang -### -S -fdelete-null-pointer-checks -fno-delete-null-pointer-checks %s 2>&1 | FileCheck -check-prefix=CHECK-NO-NULL-POINTER-CHECKS %s
 // RUN: %clang -### -S -fno-delete-null-pointer-checks -fdelete-null-pointer-checks %s 2>&1 | FileCheck -check-prefix=CHECK-NULL-POINTER-CHECKS %s
 // CHECK-NO-NULL-POINTER-CHECKS: "-fno-delete-null-pointer-checks"
 // CHECK-NULL-POINTER-CHECKS-NOT: "-fno-delete-null-pointer-checks"
+
+// RUN: %clang -### -S -fomit-frame-pointer -pg %s 2>&1 | FileCheck -check-prefix=CHECK-NO-MIX-OMIT-FP-PG %s
+// RUN: %clang -### -S -fomit-frame-pointer -fno-omit-frame-pointer -pg %s 2>&1 | FileCheck -check-prefix=CHECK-MIX-NO-OMIT-FP-PG %s
+// CHECK-NO-MIX-OMIT-FP-PG: '-fomit-frame-pointer' not allowed with '-pg'
+// CHECK-MIX-NO-OMIT-FP-PG-NOT: '-fomit-frame-pointer' not allowed with '-pg'