gst1-plugins-base: re-enable the NEON audio resampler on 32-bit ARM

The NEON audio resampler has been compiled out of every 32-bit ARM build
since 1.28. Its inline asm advances pointers with add.w, a Thumb-2 only
mnemonic that gas rejects in ARM (A32) state, which is how OpenWrt builds
ARM. The same add.w sits in the meson probe that gates HAVE_ARM_NEON, so
the probe fails first and hides the broken asm behind the generic C path.

Backport the upstream fix, which selects the operand form per ISA and
drops add.w from the probe. Thumb-2 code generation is unchanged.

Signed-off-by: Alexandru Ardelean <redacted>

diff --git a/multimedia/gst1-plugins-base/patches/100-audio-resampler-neon-a32-syntax.patch b/multimedia/gst1-plugins-base/patches/100-audio-resampler-neon-a32-syntax.patch
new file mode 100644 (file)
index 0000000..bb3f3ce
--- /dev/null
+++ b/multimedia/gst1-plugins-base/patches/100-audio-resampler-neon-a32-syntax.patch
@@ -0,0 +1,144 @@
+From af3ad8dc31da3072bd6b9ce3e44cd20e6253c50d Mon Sep 17 00:00:00 2001
+From: "L. E. Segovia" <amy@centricular.com>
+Date: Tue, 15 Sep 2026 17:50:56 -0300
+Subject: [PATCH] audio-resampler-neon: handle Thumb1-only builds correctly
+
+Fixes #5280
+
+Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/12490>
+
+Upstream-Status: Backport [https://gitlab.freedesktop.org/gstreamer/gstreamer/-/commit/af3ad8dc31da3072bd6b9ce3e44cd20e6253c50d]
+Cherry-picked to the 1.28 branch as 4f4fec2de8b8 (!12501), so this patch
+can be dropped at 1.28.8.
+
+Signed-off-by: Alexandru Ardelean <alex@shruggie.ro>
+---
+ .../gst-libs/gst/audio/audio-resampler-neon.h | 48 ++++++++++++-------
+ meson.build      |  3 +-
+ 2 files changed, 31 insertions(+), 20 deletions(-)
+
+--- a/gst-libs/gst/audio/audio-resampler-neon.h
++++ b/gst-libs/gst/audio/audio-resampler-neon.h
+@@ -20,6 +20,18 @@
+ #include <gst/gstcpuid.h>
+ #include <stdint.h>
+ 
++#if defined(__thumb2__)
++/* Thumb-2: request the wide encoding explicitly. */
++#define ADD_W(x, y) "add.w " #x ", " #x ", %[" #y "]\n"
++#elif defined(__thumb__)
++/* Thumb-1 has no 3-operand ADD for high registers and no wide encodings. */
++#define ADD_W(x, y) "add " #x ", %[" #y "]\n"
++#else
++/* ARM (A32) has a single 32-bit ADD encoding and rejects the .w width
++ * suffix as invalid syntax, so emit a plain 3-operand ADD. */
++#define ADD_W(x, y) "add " #x ", " #x ", %[" #y "]\n"
++#endif
++
+ static inline void
+ inner_product_gint16_full_1_neon (gint16 * o, const gint16 * a,
+     const gint16 * b, gint len, const gint16 * icoeff, gint bstride)
+@@ -133,11 +145,11 @@ inner_product_gint16_cubic_1_neon (gint1
+                   "1:"
+                   "      mov r8, %[b]\n"
+                   "      vld1.16 {d16, d17}, [%[b]]!\n"
+-                  "      add.w r8, r8, %[bstride]\n"
++                  ADD_W(r8, bstride)
+                   "      vld1.16 {d18, d19}, [r8]\n"
+-                  "      add.w r8, r8, %[bstride]\n"
++                  ADD_W(r8, bstride)
+                   "      vld1.16 {d20, d21}, [r8]\n"
+-                  "      add.w r8, r8, %[bstride]\n"
++                  ADD_W(r8, bstride)
+                   "      vld1.16 {d22, d23}, [r8]\n"
+                   "      vld1.16 {d24, d25}, [%[a]]!\n"
+                   "      subs %[len], %[len], #8\n"
+@@ -214,11 +226,11 @@ interpolate_gint16_cubic_neon (gpointer
+                   "1:"
+                   "      mov r8, %[a]\n"
+                   "      vld1.16 {d16, d17}, [%[a]]!\n"
+-                  "      add.w r8, r8, %[astride]\n"
++                  ADD_W(r8, astride)
+                   "      vld1.16 {d18, d19}, [r8]\n"
+-                  "      add.w r8, r8, %[astride]\n"
++                  ADD_W(r8, astride)
+                   "      vld1.16 {d20, d21}, [r8]\n"
+-                  "      add.w r8, r8, %[astride]\n"
++                  ADD_W(r8, astride)
+                   "      vld1.16 {d22, d23}, [r8]\n"
+                   "      subs %[len], %[len], #8\n"
+                   "      vmull.s16 q0, d16, d24\n"
+@@ -340,11 +352,11 @@ inner_product_gint32_cubic_1_neon (gint3
+                   "1:"
+                   "      mov r8, %[b]\n"
+                   "      vld1.32 {d16, d17}, [%[b]]!\n"
+-                  "      add.w r8, r8, %[bstride]\n"
++                  ADD_W(r8, bstride)
+                   "      vld1.32 {d18, d19}, [r8]\n"
+-                  "      add.w r8, r8, %[bstride]\n"
++                  ADD_W(r8, bstride)
+                   "      vld1.32 {d20, d21}, [r8]\n"
+-                  "      add.w r8, r8, %[bstride]\n"
++                  ADD_W(r8, bstride)
+                   "      vld1.32 {d22, d23}, [r8]\n"
+                   "      vld1.32 {d24, d25}, [%[a]]!\n"
+                   "      subs %[len], %[len], #4\n"
+@@ -426,11 +438,11 @@ interpolate_gint32_cubic_neon (gpointer
+                   "1:"
+                   "      mov r8, %[a]\n"
+                   "      vld1.32 {d16, d17}, [%[a]]!\n"
+-                  "      add.w r8, r8, %[astride]\n"
++                  ADD_W(r8, astride)
+                   "      vld1.32 {d18, d19}, [r8]\n"
+-                  "      add.w r8, r8, %[astride]\n"
++                  ADD_W(r8, astride)
+                   "      vld1.32 {d20, d21}, [r8]\n"
+-                  "      add.w r8, r8, %[astride]\n"
++                  ADD_W(r8, astride)
+                   "      vld1.32 {d22, d23}, [r8]\n"
+                   "      subs %[len], %[len], #4\n"
+                   "      vmull.s32 q0, d16, d24\n"
+@@ -545,11 +557,11 @@ inner_product_gfloat_cubic_1_neon (gfloa
+                   "1:"
+                   "      mov r8, %[b]\n"
+                   "      vld1.32 {q8}, [%[b]]!\n"
+-                  "      add.w r8, r8, %[bstride]\n"
++                  ADD_W(r8, bstride)
+                   "      vld1.32 {q9}, [r8]\n"
+-                  "      add.w r8, r8, %[bstride]\n"
++                  ADD_W(r8, bstride)
+                   "      vld1.32 {q10}, [r8]\n"
+-                  "      add.w r8, r8, %[bstride]\n"
++                  ADD_W(r8, bstride)
+                   "      vld1.32 {q11}, [r8]\n"
+                   "      vld1.32 {q12}, [%[a]]!\n"
+                   "      subs %[len], %[len], #4\n"
+@@ -623,11 +635,11 @@ interpolate_gfloat_cubic_neon (gpointer
+                   "1:"
+                   "      mov r8, %[a]\n"
+                   "      vld1.32 {q8}, [%[a]]!\n"
+-                  "      add.w r8, r8, %[astride]\n"
++                  ADD_W(r8, astride)
+                   "      vld1.32 {q9}, [r8]\n"
+-                  "      add.w r8, r8, %[astride]\n"
++                  ADD_W(r8, astride)
+                   "      vld1.32 {q10}, [r8]\n"
+-                  "      add.w r8, r8, %[astride]\n"
++                  ADD_W(r8, astride)
+                   "      vld1.32 {q11}, [r8]\n"
+                   "      subs %[len], %[len], #4\n"
+                   "      vmul.f32 q0, q8, q12\n"
+--- a/meson.build
++++ b/meson.build
+@@ -457,10 +457,9 @@ if host_machine.cpu_family() == 'arm'
+ #include <arm_neon.h>
+ int32x4_t testfunc(int16_t *a, int16_t *b) {
+   asm volatile ("vmull.s16 q0, d0, d0" : : : "q0");
+-  asm volatile ("add.w r1, r0, r0" : : : "r0", "r1");
+   return vmull_s16(vld1_s16(a), vld1_s16(b));
+ }
+-''', name : 'NEON with 32-bit wide Thumb support')
++''', name : 'NEON support')
+     core_conf.set('HAVE_ARM_NEON', true)
+   endif
+ endif