Merge pull request 'mesa-panvk-bifrost r7: fix XFB store channel-extract for packed varyings (iter19)' (#96) from claude-noether/marfrit-packages:mesa-panvk-bifrost-r7 into main

Reviewed-on: #96

arch/mesa-panvk-bifrost/0007-panvk-bifrost-xfb-component-base-fix.patch

@@ -0,0 +1,103 @@
+From: marfrit-packages noether <claude-noether@reauktion.de>
+Subject: [PATCH] panvk-bifrost: fix XFB store channel-extract for packed varyings
+
+iter19 — fixes a reliable SIGSEGV during vkCreateGraphicsPipeline on any
+shader that uses XFB-bound varyings declared with non-zero `layout
+(component=N)` qualifiers. Surfaced by
+dEQP-VK.transform_feedback.simple.holes_vert; backtrace lands 11 frames
+into libvulkan_panfrost.so called from `vkt::TransformFeedback::
+TransformFeedbackHolesInstance::iterate`.
+
+Root cause: `lower_xfb_output_iter17` (and upstream `lower_xfb_output`,
+which carries a `// TODO` on the same assertion) computes the source-
+channel mask as `mask << channel_idx`, where `channel_idx` is the
+varying-location component (0..3) but `src` only contains channels for
+the source-side range starting at `nir_intrinsic_component(intr)`. For
+`flat out float vegeta` declared with `component=2`, NIR emits
+`store_output src=<vec1>, component=2`, and the lowering computes
+`mask << 2` against a single-component src — out-of-range; the
+resulting malformed nir_def then segfaults inside downstream NIR
+constant-folding (`nir_constant_expressions.c::evaluate_*`).
+
+The assertion `assert(nir_intrinsic_component(intr) == 0)` was inherited
+from upstream `pan_nir_lower_xfb.c` as a documented `// TODO`; release
+builds (-DNDEBUG) elide it. The fix translates `channel_idx` to the
+source-channel space by subtracting `nir_intrinsic_component(intr)`
+before shifting the mask, and replaces the elided asserts with explicit
+release-mode guards (the patch closes the same release-mode-elision
+class as the original bug).
+
+Verified on PineTab2 (Mali-G52 r1 MC1, PAN_ARCH 7) against vulkan-cts
+1.3.10.0:
+  - holes_vert / holes_extra_draw_vert no longer SIGSEGV (now Fail on
+    color-check; that is a separate iter20 finding — the rasterized
+    varying gets removed alongside the XFB-bound one).
+  - basic_*: 36/36 Pass. depth_clip_*: 1 Pass + 4 NotSupported.
+    lines_or_triangles*: 16 NotSupported. 0 Fail across the full set.
+  - holes_geom / holes_extra_draw_geom remain NotSupported
+    (geometryShader not on G52) — unchanged.
+
+Caveat: max_output_components_64/_128/_256 were never reached on the
+r5 sweep (watchdog killed transform_feedback after the holes_vert
+crash). With this fix in place, those tests now run and surface
+*their own pre-existing* coredumps — confirmed on shipped r6 baseline
+too. They are NOT regressions from this patch; they are latent crashes
+unmasked by it. iter20+ territory.
+
+Phase 5 (2nd-model) review: APPROVE WITH CHANGES (non-blocking).
+Changes applied: release-mode defensive guards on both preconditions
+plus a dispatcher-side comment clarifying the i*2+j semantics.
+
+Cross-refs:
+  - iter19/phase{0,1,2,3}_holes_vert*.md in panvk-bifrost repo
+
+---
+ src/panfrost/vulkan/panvk_vX_xfb_lower.c | 24 +++++++++++++++++++++---
+ 1 file changed, 21 insertions(+), 3 deletions(-)
+
+diff --git a/src/panfrost/vulkan/panvk_vX_xfb_lower.c b/src/panfrost/vulkan/panvk_vX_xfb_lower.c
+@@ -339,7 +339,20 @@
+                         unsigned buffer, unsigned offset_words)
+ {
+    assert(buffer < MAX_XFB_BUFFERS);
+-   assert(nir_intrinsic_component(intr) == 0);
++
++   /* iter19: nir_intrinsic_component(intr) is the source-channel base —
++    * for a packed varying like `layout (location=0, component=2) flat out
++    * float vegeta`, NIR emits store_output with component=2 and a single-
++    * component src. The XFB iteration index `channel_idx` (0..3) is the
++    * varying-location component, not the source channel. Translate by
++    * subtracting the base before shifting the mask. Fixes the long-
++    * standing `assert(nir_intrinsic_component(intr) == 0) // TODO` in
++    * upstream pan_nir_lower_xfb that surfaces on holes_vert. */
++   const unsigned base_comp = nir_intrinsic_component(intr);
++   /* Defensive against release-build elision: this is precisely the
++    * bug class the patch is fixing, so don't re-introduce it. */
++   if (channel_idx < base_comp)
++      return;
+ 
+    uint16_t stride = b->shader->info.xfb_stride[buffer] * 4;
+    assert(stride != 0);
+@@ -357,7 +370,11 @@
+ 
+    nir_def *src = intr->src[0].ssa;
+    nir_component_mask_t mask = nir_component_mask(num_components);
+-   nir_def *value = nir_channels(b, src, mask << channel_idx);
++   const unsigned src_channel = channel_idx - base_comp;
++   /* Same defensive class as the channel_idx >= base_comp guard above. */
++   if (src_channel + num_components > src->num_components)
++      return;
++   nir_def *value = nir_channels(b, src, mask << src_channel);
+ 
+    /* Topology dispatch ladder. LIST first (fast path). */
+    nir_push_if(b, nir_ieq_imm(b, topology, PANVK_XFB_TOPO_LIST));
+@@ -465,6 +482,9 @@
+       for (unsigned j = 0; j < 2; ++j) {
+          if (!xfb.out[j].num_components)
+             continue;
++         /* `i*2+j` is the varying-location component (0..3) — io_xfb covers
++          * slots 0..1, io_xfb2 covers 2..3. The leaf translates this into
++          * a source-channel index by subtracting nir_intrinsic_component(intr). */
+          lower_xfb_output_iter17(b, intr, i * 2 + j, xfb.out[j].num_components,
+                                  xfb.out[j].buffer, xfb.out[j].offset);
+          progress = true;

arch/mesa-panvk-bifrost/PKGBUILD

@@ -30,7 +30,7 @@
 
 pkgname=mesa-panvk-bifrost
 _mesaver=26.0.6
-pkgver=26.0.6.r6
+pkgver=26.0.6.r7
 pkgrel=1
 pkgdesc="Patched Mesa libvulkan_panfrost.so exposing Bifrost-gen Mali to Vulkan apps (panvk-bifrost campaign)"
 arch=('aarch64')
@@ -83,6 +83,7 @@ source=(
     "0004-panvk-bifrost-xfb-primitive-decomposition.patch"
     "0005-panvk-bifrost-fragment-stores-atomics.patch"
     "0006-panvk-bifrost-legacy-dithering.patch"
+    "0007-panvk-bifrost-xfb-component-base-fix.patch"
     "brave-vulkan"
     "icd.json"
 )
@@ -96,6 +97,7 @@ sha256sums=(
     'SKIP'
     'SKIP'
     'SKIP'
+    'SKIP'
 )
 
 prepare() {
@@ -152,6 +154,16 @@ prepare() {
     # extension as Mali-G52-architecture supported.
     patch -p1 < "${srcdir}/0006-panvk-bifrost-legacy-dithering.patch"
 
+    # r7 (2026-05-25): XFB store channel-extract fix for packed varyings.
+    # Eliminates a reliable SIGSEGV in vkCreateGraphicsPipeline whenever
+    # an XFB-bound vertex output is declared with non-zero
+    # `layout (component=N)`. Surfaced by dEQP-VK.transform_feedback.
+    # simple.holes_vert (now Fails on color-check rather than crashing;
+    # the color-check residual is a separate iter20 finding).
+    # Phase-doc context: ~/src/panvk-bifrost/iter19/phase{0,1,2,3}_*.md.
+    # Phase 5 reviewed; release-mode-elision defensive guards applied.
+    patch -p1 < "${srcdir}/0007-panvk-bifrost-xfb-component-base-fix.patch"
+
     # Sanity-check the patches landed.
     grep -q "KHR_robustness2 = true," src/panfrost/vulkan/panvk_vX_physical_device.c
     grep -q "EXT_robustness2 = true," src/panfrost/vulkan/panvk_vX_physical_device.c
@@ -171,6 +183,9 @@ prepare() {
     grep -q "xfb_topology" src/panfrost/vulkan/panvk_shader.h
     grep -q "panvk_xfb_topology" src/panfrost/vulkan/panvk_shader.h
     test -f src/panfrost/vulkan/panvk_vX_xfb_lower.c
+    # r7 sanity: XFB channel-base correction landed
+    grep -q "iter19: nir_intrinsic_component(intr) is the source-channel base" src/panfrost/vulkan/panvk_vX_xfb_lower.c
+    grep -q "mask << src_channel" src/panfrost/vulkan/panvk_vX_xfb_lower.c
 }
 
 build() {