tools: Rename __fallthrough to fallthrough

Rename the fallthrough attribute to better align with the kernel
version.  Copy the definition from include/linux/compiler_attributes.h
including the #else clause.  Adding the #else clause allows the tools
compiler.h header to drop the check for a definition entirely and keeps
both definitions together.

Change any __fallthrough statements to fallthrough anywhere it was used
within perf.

This allows other tools to use the same key word as the kernel.

Committer notes:

Did some missing conversions to:

  builtin-list.c

Also included gtk.h before the 'fallthrough' definition in:

  tools/perf/ui/gtk/hists.c
  tools/perf/ui/gtk/helpline.c
  tools/perf/ui/gtk/browser.c

As it is the arg name for a macro in glib.h:

  /var/home/acme/git/perf-tools-next/tools/include/linux/compiler-gcc.h:16:55: error: missing binary operator before token "("
     16 | # define fallthrough                    __attribute__((__fallthrough__))
        |                                                       ^
  /usr/include/glib-2.0/glib/gmacros.h:637:28: note: in expansion of macro ‘fallthrough’
    637 | #if g_macro__has_attribute(fallthrough)

Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tom Rix <trix@redhat.com>
Cc: linux-sparse@vger.kernel.org <linux-sparse@vger.kernel.org>
Cc: llvm@lists.linux.dev <llvm@lists.linux.dev>
Link: https://lore.kernel.org/r/20221125154947.2163498-1-Liam.Howlett@oracle.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/include/linux/compiler-gcc.h

@@ -12,8 +12,10 @@
 		     + __GNUC_PATCHLEVEL__)
 #endif
 
-#if GCC_VERSION >= 70000 && !defined(__CHECKER__)
-# define __fallthrough __attribute__ ((fallthrough))
+#if __has_attribute(__fallthrough__)
+# define fallthrough                    __attribute__((__fallthrough__))
+#else
+# define fallthrough                    do {} while (0)  /* fallthrough */
 #endif
 
 #if __has_attribute(__error__)

tools/include/linux/compiler.h

@@ -186,10 +186,6 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
 })
 
 
-#ifndef __fallthrough
-# define __fallthrough
-#endif
-
 /* Indirect macros required for expanded argument pasting, eg. __LINE__. */
 #define ___PASTE(a, b) a##b
 #define __PASTE(a, b) ___PASTE(a, b)

tools/perf/builtin-list.c

@@ -278,10 +278,10 @@ static void fix_escape_printf(struct strbuf *buf, const char *fmt, ...)
 						strbuf_addstr(buf, "\\n");
 						break;
 					case '\\':
-						__fallthrough;
+						fallthrough;
 					case '\"':
 						strbuf_addch(buf, '\\');
-						__fallthrough;
+						fallthrough;
 					default:
 						strbuf_addch(buf, s[s_pos]);
 						break;

tools/perf/builtin-probe.c

@@ -715,7 +715,7 @@ __cmd_probe(int argc, const char **argv)
 			pr_err("  Error: --bootconfig doesn't support uprobes.\n");
 			return -EINVAL;
 		}
-		__fallthrough;
+		fallthrough;
 	case 'a':
 
 		/* Ensure the last given target is used */

tools/perf/builtin-stat.c

@@ -549,7 +549,7 @@ static void process_evlist(struct evlist *evlist, unsigned int interval)
 	if (evlist__ctlfd_process(evlist, &cmd) > 0) {
 		switch (cmd) {
 		case EVLIST_CTL_CMD_ENABLE:
-			__fallthrough;
+			fallthrough;
 		case EVLIST_CTL_CMD_DISABLE:
 			if (interval)
 				process_interval();

tools/perf/builtin-top.c

@@ -709,7 +709,7 @@ static void *display_thread(void *arg)
 		case -1:
 			if (errno == EINTR)
 				continue;
-			__fallthrough;
+			fallthrough;
 		default:
 			c = getc(stdin);
 			tcsetattr(0, TCSAFLUSH, &save);

tools/perf/ui/gtk/browser.c

@@ -1,9 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
+#include "gtk.h"
 #include "../evsel.h"
 #include "../sort.h"
 #include "../hist.h"
 #include "../helpline.h"
-#include "gtk.h"
 
 #include <signal.h>
 

tools/perf/ui/gtk/helpline.c

@@ -1,9 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
+#include "gtk.h"
 #include <stdio.h>
 #include <string.h>
 #include <linux/kernel.h>
 
-#include "gtk.h"
 #include "../ui.h"
 #include "../helpline.h"
 

tools/perf/ui/gtk/hists.c

@@ -1,12 +1,12 @@
 // SPDX-License-Identifier: GPL-2.0
+#include "gtk.h"
 #include "../evlist.h"
 #include "../callchain.h"
 #include "../evsel.h"
 #include "../sort.h"
 #include "../hist.h"
 #include "../helpline.h"
 #include "../string2.h"
-#include "gtk.h"
 #include <signal.h>
 #include <stdlib.h>
 #include <linux/string.h>

tools/perf/util/callchain.c

@@ -724,7 +724,7 @@ static enum match_result match_chain(struct callchain_cursor_node *node,
 		if (match != MATCH_ERROR)
 			break;
 		/* otherwise fall-back to symbol-based comparison below */
-		__fallthrough;
+		fallthrough;
 	case CCKEY_FUNCTION:
 		if (node->ms.sym && cnode->ms.sym) {
 			/*
@@ -745,7 +745,7 @@ static enum match_result match_chain(struct callchain_cursor_node *node,
 			}
 		}
 		/* otherwise fall-back to IP-based comparison below */
-		__fallthrough;
+		fallthrough;
 	case CCKEY_ADDRESS:
 	default:
 		match = match_chain_dso_addresses(cnode->ms.map, cnode->ip, node->ms.map, node->ip);

tools/perf/util/intel-pt-decoder/intel-pt-decoder.c

@@ -3546,7 +3546,7 @@ static int intel_pt_walk_psb(struct intel_pt_decoder *decoder)
 		switch (decoder->packet.type) {
 		case INTEL_PT_TIP_PGD:
 			decoder->continuous_period = false;
-			__fallthrough;
+			fallthrough;
 		case INTEL_PT_TIP_PGE:
 		case INTEL_PT_TIP:
 		case INTEL_PT_PTWRITE:
@@ -3616,7 +3616,7 @@ static int intel_pt_walk_psb(struct intel_pt_decoder *decoder)
 			decoder->pge = false;
 			decoder->continuous_period = false;
 			intel_pt_clear_tx_flags(decoder);
-			__fallthrough;
+			fallthrough;
 
 		case INTEL_PT_TNT:
 			decoder->have_tma = false;
@@ -3980,7 +3980,7 @@ const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder)
 			decoder->have_last_ip = false;
 			decoder->last_ip = 0;
 			decoder->ip = 0;
-			__fallthrough;
+			fallthrough;
 		case INTEL_PT_STATE_ERR_RESYNC:
 			err = intel_pt_sync_ip(decoder);
 			break;

tools/perf/util/intel-pt-decoder/intel-pt-pkt-decoder.c

@@ -730,7 +730,7 @@ int intel_pt_pkt_desc(const struct intel_pt_pkt *packet, char *buf,
 	case INTEL_PT_FUP:
 		if (!(packet->count))
 			return snprintf(buf, buf_len, "%s no ip", name);
-		__fallthrough;
+		fallthrough;
 	case INTEL_PT_CYC:
 	case INTEL_PT_VMCS:
 	case INTEL_PT_MTC:

tools/perf/util/ordered-events.c

@@ -284,7 +284,7 @@ static int __ordered_events__flush(struct ordered_events *oe, enum oe_flush how,
 	switch (how) {
 	case OE_FLUSH__FINAL:
 		show_progress = true;
-		__fallthrough;
+		fallthrough;
 	case OE_FLUSH__TOP:
 		oe->next_flush = ULLONG_MAX;
 		break;

tools/perf/util/strfilter.c

@@ -274,7 +274,7 @@ static int strfilter_node__sprint(struct strfilter_node *node, char *buf)
 		len = strfilter_node__sprint_pt(node->l, buf);
 		if (len < 0)
 			return len;
-		__fallthrough;
+		fallthrough;
 	case '!':
 		if (buf) {
 			*(buf + len++) = *node->p;

tools/perf/util/string.c

@@ -35,7 +35,7 @@ s64 perf_atoll(const char *str)
 			if (*p)
 				goto out_err;
 
-			__fallthrough;
+			fallthrough;
 		case '\0':
 			return length;
 		default: