Add experimental ggml-hexagon backend for the Hexagon NPU (#16547)

* model: add support for extra bufs for all devices

* hexagon: add experimental ggml-hexagon backend for the Hexagon NPU

This commit introduces a new experimental backend `ggml-hexagon` with support for the Hexagon NPU.

Highlights:
- Supports Hexagon versions: v73, v75, v79, and v81
- Targets Android devices based on Snapdragon SoCs: Gen3, 8-Elite, and 8-Elite Gen5
- Supports Q4_0, Q8_0, MXFP4, and FP32 data types
- Implements core LLM ops: MUL_MAT/MUL_MAT_ID, ADD/SUB/MUL/ADD_ID, RMS_NORM, ROPE, GLU/SWIGLU, SOFTMAX

**Note:** This backend is experimental and may exhibit instability or limited performance across supported devices.
It is intended for early testing and feedback from llama.cpp/ggml developer and user community.

Co-Authored-By: Rajdeep Ganguly <rganguly@qti.qualcomm.com>
Co-Authored-By: Todor Boinovski <todorb@qti.qualcomm.com>

* hexagon: fix format checker errors

* hexagon: update readme and cmake presets

* ci: add android-ndk-build jobs that build plain ARM64 and Snapdragon versions

* hexagon: add simple graph optimizer for stacking MUL_MAT ops with the same input

* hexagon: move ADB helper scripts into scripts/snapdragon/adb

* hexagon: replace all f/printfs with GGML_LOG_...

* readme: add hexagon to the list supported backends

* hexagon: stack malmuts with quantized inputs only

* hexagon: add TODO for fixing issues in hexagon_graph_optimize

* hexagon: update to hex-sdk 6.4.0 and add scripts for running on QDC

* scripts: fix lint errors

* scripts: update qdc pytest script to make linter happy

* hexagon: add reduce sum in fp32

* hexagon: reduce number of vector stores in matmul output

* hexagon: remove the need for vdelta in reduce-multiply-x8

* hexagon: consistent use of reduce_sum_fp32 for row_sums

* hexagon: some more matmul optimizations and comments

Optimize cases where tensor dims are not multiple of 1024 (e.g in Qwen models).
We've handled those cases already but at a higher overhead.

* hexagon: update cmake presets

* hexagon: add OPMASK support for run-bench.sh wrapper

* hexagon: update to use GGML_BACKEND_API

* hexagon: remove unused logic for setting tensor flags for the views

* hexagon: add asserts to set/get_tensor to make sure we handle complete tensors

Same asserts as the CPU backend.

* hexagon: use cpy_tensor slow path for non-host buffers

* hexagon: error checks in the buffer allocator

* cmake: move include(extProj) under ggml-hexagon

* hexagon: don't forget to delete the backend on free

* hexagon: set/get_tensor size assert apply only to quantized tensors

* hexagon: reintroduce HEX_VERBOSE wrapper for GGML_LOG_DEBUG for now

GGML_LOG_DEBUG is always enabled for test-backend-ops and the output gets in the way.
Ideally we need a bit more finer log levels.

* docs: typos in hexagon developer docs (libggm-...)

* hexagon: overhaul error handling in the session/device allocation

this should handle all failure paths in the session allocation.

* hexagon: update cmake presets to enable fp16 vectors

* hexagon: remove unused time_usec function

* hexagon: don't forget to release buffer contexts

* hexagon: fixed indents in hvx-utils (missed clang-format auto-format failure)

* hexagon: remove custom can_repeat function and use ggml_can_repeat

---------

Co-authored-by: Rajdeep Ganguly <rganguly@qti.qualcomm.com>
Co-authored-by: Todor Boinovski <todorb@qti.qualcomm.com>

scripts/snapdragon/adb/llama-cli.farf

@@ -0,0 +1 @@
+0xffff

scripts/snapdragon/adb/run-bench.sh

@@ -0,0 +1,39 @@
+#!/bin/sh
+#
+
+# Basedir on device
+basedir=/data/local/tmp/llama.cpp
+
+branch=.
+[ "$B" != "" ] && branch=$B
+
+adbserial=
+[ "$S" != "" ] && adbserial="-s $S"
+
+model="Llama-3.2-3B-Instruct-Q4_0.gguf"
+[ "$M" != "" ] && model="$M"
+
+device="HTP0"
+[ "$D" != "" ] && device="$D"
+
+verbose=""
+[ "$V" != "" ] && verbose="$V"
+
+opmask=
+[ "$OPMASK" != "" ] && opmask="GGML_HEXAGON_OPMASK=$OPMASK"
+
+nhvx=
+[ "$NHVX" != "" ] && nhvx="GGML_HEXAGON_NHVX=$NHVX"
+
+ndev=
+[ "$NDEV" != "" ] && ndev="GGML_HEXAGON_NDEV=$NDEV"
+
+set -x
+
+adb $adbserial shell " \
+  cd $basedir;         \
+  LD_LIBRARY_PATH=$basedir/$branch/lib   \
+  ADSP_LIBRARY_PATH=$basedir/$branch/lib \
+    $ndev $nhvx $opmask ./$branch/bin/llama-bench --device $device --mmap 0 -m $basedir/../gguf/$model \
+        -t 4 --batch-size 128 -ngl 99 $@ \
+"

scripts/snapdragon/adb/run-cli.sh

@@ -0,0 +1,52 @@
+#!/bin/sh
+#
+
+# Basedir on device
+basedir=/data/local/tmp/llama.cpp
+
+cli_opts=
+
+branch=.
+[ "$B" != "" ] && branch=$B
+
+adbserial=
+[ "$S" != "" ] && adbserial="-s $S"
+
+model="Llama-3.2-3B-Instruct-Q4_0.gguf"
+[ "$M" != "" ] && model="$M"
+
+device="HTP0"
+[ "$D" != "" ] && device="$D"
+
+verbose=
+[ "$V" != "" ] && verbose="GGML_HEXAGON_VERBOSE=$V"
+
+experimental=
+[ "$E" != "" ] && experimental="GGML_HEXAGON_EXPERIMENTAL=$E"
+
+sched=
+[ "$SCHED" != "" ] && sched="GGML_SCHED_DEBUG=2" cli_opts="$cli_opts -v"
+
+profile=
+[ "$PROF" != "" ] && profile="GGML_HEXAGON_PROFILE=$PROF GGML_HEXAGON_OPSYNC=1"
+
+opmask=
+[ "$OPMASK" != "" ] && opmask="GGML_HEXAGON_OPMASK=$OPMASK"
+
+nhvx=
+[ "$NHVX" != "" ] && nhvx="GGML_HEXAGON_NHVX=$NHVX"
+
+ndev=
+[ "$NDEV" != "" ] && ndev="GGML_HEXAGON_NDEV=$NDEV"
+
+set -x
+
+adb $adbserial shell " \
+  cd $basedir; ulimit -c unlimited;        \
+    LD_LIBRARY_PATH=$basedir/$branch/lib   \
+    ADSP_LIBRARY_PATH=$basedir/$branch/lib \
+    $verbose $experimental $sched $opmask $profile $nhvx $ndev           \
+      ./$branch/bin/llama-cli --no-mmap -m $basedir/../gguf/$model       \
+         -t 4 --ctx-size 8192 --batch-size 128 -ctk q8_0 -ctv q8_0 -fa on \
+         -ngl 99 --device $device $cli_opts $@ \
+"

scripts/snapdragon/adb/run-tool.sh

@@ -0,0 +1,51 @@
+#!/bin/sh
+#
+
+# Basedir on device
+basedir=/data/local/tmp/llama.cpp
+
+cli_opts=
+
+branch=.
+[ "$B" != "" ] && branch=$B
+
+adbserial=
+[ "$S" != "" ] && adbserial="-s $S"
+
+device="HTP0"
+[ "$D" != "" ] && device="$D"
+
+verbose=
+[ "$V" != "" ] && verbose="GGML_HEXAGON_VERBOSE=$V"
+
+experimental=
+[ "$E" != "" ] && experimental="GGML_HEXAGON_EXPERIMENTAL=$V"
+
+sched=
+[ "$SCHED" != "" ] && sched="GGML_SCHED_DEBUG=2" cli_opts="$cli_opts -v"
+
+profile=
+[ "$PROF" != "" ] && profile="GGML_HEXAGON_PROFILE=$PROF GGML_HEXAGON_OPSYNC=1"
+
+opmask=
+[ "$OPMASK" != "" ] && opmask="GGML_HEXAGON_OPMASK=$OPMASK"
+
+nhvx=
+[ "$NHVX" != "" ] && nhvx="GGML_HEXAGON_NHVX=$NHVX"
+
+ndev=
+[ "$NDEV" != "" ] && ndev="GGML_HEXAGON_NDEV=$NDEV"
+
+hb=
+[ "$HB" != "" ] && hb="GGML_HEXAGON_HOSTBUF=$HB"
+
+set -x
+
+tool=$1; shift
+
+adb $adbserial shell " \
+  cd $basedir; ulimit -c unlimited;        \
+    LD_LIBRARY_PATH=$basedir/$branch/lib   \
+    ADSP_LIBRARY_PATH=$basedir/$branch/lib \
+    $verbose $experimental $sched $opmask $profile $nhvx $ndev $hb ./$branch/bin/$tool $@ \
+"