Re: [PATCH ARM v2] PR69770 -mlong-calls does not affect calls to __gnu_mcount_nc generated by -pg

[Kugan <kugan dot vivekanandarajah at linaro dot org>]

On 25/03/16 08:02, Charles Baylis wrote:
> When compiling with -mlong-calls and -pg, calls to the __gnu_mcount_nc
> function are not generated as long calls.
> 
> This is the sequel to this patch
>     https://gcc.gnu.org/ml/gcc-patches/2016-02/msg00881.html
> 
> This patch fixes the following problems with the previous patch.
> . Nested functions now work (thanks to Richard E for spotting this)
> . Thumb-1 now works
> 
> This patch works by adding new patterns (one for ARM/Thumb-2 and one
> for Thumb-1) which are placed in the prologue as a placeholder for
> some RTL which describes the address. This is either a SYMBOL_REF for
> targets with MOVW/MOVT, or a literal pool reference for other targets.
> The implementation of ARM_FUNCTION_PROFILER is changed to search for
> this insn so that the the address of the __gnu_mcount_nc function can
> be loaded using an appropriate sequence for the target.
> 
> I also tried generating the profiling call sequence directly in the
> prologue, but this requires some unpleasant hacks to prevent spurious
> register pushes from ASM_OUTPUT_REG_PUSH.
> 
> Tested with no new regressions on arm-unknown-linux-gnueabihf on QEMU.
> The generated code sequences have been inspected for normal and nested
> functions on ARM v6, ARM v7, Thumb-1, and Thumb-2 targets.
> 
> This does not fix a regression, so I don't expect to apply it for
> GCC6, is it OK for when stage 1 re-opens.
> 

Hi Charles,

+static void
+arm_emit_long_call_profile_insn ()
+{
+  rtx sym_ref = gen_rtx_SYMBOL_REF (Pmode, "__gnu_mcount_nc");
+  /* if movt/movw are not available, use a constant pool */
+  if (!arm_arch_thumb2)

Should this be !TARGET_USE_MOVT?

Thanks,
Kugan