[igt-dev] [PATCH i-g-t] lib: Make libunwind optional again

[Daniel Vetter]

Apparently it's really not great to require it for a bunch of
platforms. Requested by Sean and Eric.

v2: Use combo option (Petri).

v3: Fix the right option (Petri)

v4: try a bit harder ...

Cc: Petri Latvala <petri.latvala at intel.com>
Reviewed-by: Eric Anholt <eric at anholt.net> (v1)
Cc: Sean Paul <sean at poorly.run>
Cc: Eric Anholt <eric at anholt.net>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
 lib/meson.build                 |  7 ++++-
 lib/stubs/libunwind/libunwind.h | 46 +++++++++++++++++++++++++++++++++
 meson.build                     | 13 +++++++++-
 meson_options.txt               |  6 +++++
 4 files changed, 70 insertions(+), 2 deletions(-)
 create mode 100644 lib/stubs/libunwind/libunwind.h

diff --git a/lib/meson.build b/lib/meson.build
index 7e2c9b7a98e0..8961ca494af8 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -59,7 +59,6 @@ lib_deps = [
 	libkmod,
 	libprocps,
 	libudev,
-	libunwind,
 	libdw,
 	pciaccess,
 	pthreads,
@@ -76,6 +75,12 @@ else
 	inc = [ inc, include_directories('stubs/drm') ]
 endif
 
+if libunwind.found()
+	lib_deps += libunwind
+else
+	inc = [ inc, include_directories('stubs/libunwind') ]
+endif
+
 if valgrind.found()
 	lib_deps += valgrind
 endif
diff --git a/lib/stubs/libunwind/libunwind.h b/lib/stubs/libunwind/libunwind.h
new file mode 100644
index 000000000000..ce5f30df6ce1
--- /dev/null
+++ b/lib/stubs/libunwind/libunwind.h
@@ -0,0 +1,46 @@
+/*
+ * Copyright © 2018 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Daniel Vetter <daniel.vetter at ffwll.ch>
+ */
+
+/* dummy libunwind header with stubs, only the minimal amount we need to get by */
+
+
+typedef int unw_cursor_t;
+typedef int unw_context_t;
+typedef int unw_word_t;
+
+#define UNW_REG_IP 0
+
+static inline void unw_getcontext(unw_context_t *uc) {}
+static inline void unw_init_local(unw_cursor_t *cursor, unw_context_t *uc) {}
+static inline int unw_step(unw_cursor_t *cursor) { return 0; }
+static inline int unw_get_reg (unw_cursor_t *cursor, int i, unw_word_t * word)
+{
+	return 0;
+}
+static inline int unw_get_proc_name (unw_cursor_t *cursor, char *c, size_t s, unw_word_t *word)
+{
+	return 0;
+}
diff --git a/meson.build b/meson.build
index eff35585f619..861d7f88a3e1 100644
--- a/meson.build
+++ b/meson.build
@@ -50,6 +50,7 @@ build_chamelium = get_option('build_chamelium')
 build_docs = get_option('build_docs')
 build_tests = get_option('build_tests')
 with_libdrm = get_option('with_libdrm')
+with_libunwind = get_option('with_libunwind')
 build_runner = get_option('build_runner')
 
 _build_overlay = build_overlay != 'false'
@@ -102,7 +103,17 @@ build_info += 'With libdrm: ' + ','.join(libdrm_info)
 pciaccess = dependency('pciaccess', version : '>=0.10')
 libkmod = dependency('libkmod')
 libprocps = dependency('libprocps', required : true)
-libunwind = dependency('libunwind', required : true)
+
+libunwind = null_dep
+libunwindinfo = 'No'
+if with_libunwind == 'auto' or with_libunwind == 'true'
+	libunwind = dependency('libunwind', required : with_libunwind == 'true')
+	if libunwind.found()
+		libunwindinfo = 'Yes'
+	endif
+endif
+build_info += 'With libunwind: ' + libunwindinfo
+
 libdw = dependency('libdw', required : true)
 ssl = dependency('openssl', required : true)
 pixman = dependency('pixman-1', required : true)
diff --git a/meson_options.txt b/meson_options.txt
index 89a3731c19ee..0cd3b350d994 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -52,6 +52,12 @@ option('with_libdrm',
        choices : ['', 'auto', 'intel', 'nouveau', 'amdgpu'],
        description : 'libdrm libraries to be used')
 
+option('with_libunwind',
+       type : 'combo',
+       value : 'auto',
+       choices : ['auto', 'true', 'false'],
+       description : 'Use libunwind')
+
 option('build_runner',
        type : 'combo',
        value : 'auto',
-- 
2.19.1