Commit 21f2b7c1 authored May 30, 2020 by Ian Rogers Committed by Arnaldo Carvalho de Melo Jun 01, 2020

tools compiler.h: Add attribute to disable tail calls



Tail call optimizations can remove stack frames that are used in
unwinding tests. Add an attribute that can be used to disable the tail
call optimization. Tested  on clang and GCC.

Committer notes:

Old versions of clang don't like that __attribute__((optimize)), so add
an ifdef to make it go away.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: clang-built-linux@googlegroups.com
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Monnet <quentin@isovalent.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lore.kernel.org/lkml/20200530082015.39162-2-irogers@google.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 9300acc6

tools/include/linux/compiler-gcc.h

+12 −0

Original line number	Diff line number	Diff line
		@@ -27,6 +27,18 @@
		#define __pure __attribute__((pure))
		#endif
		#define noinline __attribute__((noinline))
		#ifdef __has_attribute
		#if __has_attribute(disable_tail_calls)
		#define __no_tail_call __attribute__((disable_tail_calls))
		#endif
		#endif
		#ifndef __no_tail_call
		#if GCC_VERSION > 40201
		#define __no_tail_call __attribute__((optimize("no-optimize-sibling-calls")))
		#else
		#define __no_tail_call
		#endif
		#endif
		#ifndef __packed
		#define __packed __attribute__((packed))
		#endif

tools/include/linux/compiler.h

+3 −0

Original line number	Diff line number	Diff line
		@@ -47,6 +47,9 @@
		#ifndef noinline
		#define noinline
		#endif
		#ifndef __no_tail_call
		#define __no_tail_call
		#endif

		/* Are two types/vars the same type (ignoring qualifiers)? */
		#ifndef __same_type

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