From 9017d37e84771f921a63676dd8b955df9ef20f29 Mon Sep 17 00:00:00 2001
From: Ian Romanick <ian.d.romanick@intel.com>
Date: Fri, 23 Jan 2026 10:07:27 -0800
Subject: [PATCH] nir: Use STACK_ARRAY instead of NIR_VLA

The number of fields comes from the shader, so it could be a value large
enough that using alloca would be problematic.

Fixes: c11833ab24d ("nir,spirv: Rework function calls")
Reviewed-by: Caio Oliveira <caio.oliveira@intel.com>
Reviewed-by: Ryan Neph <ryanneph@google.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/39866>
---
 src/compiler/nir/nir_functions.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Index: mesa-21.2.4/src/compiler/nir/nir_inline_functions.c
===================================================================
--- mesa-21.2.4.orig/src/compiler/nir/nir_inline_functions.c
+++ mesa-21.2.4/src/compiler/nir/nir_inline_functions.c
@@ -24,7 +24,24 @@
 #include "nir.h"
 #include "nir_builder.h"
 #include "nir_control_flow.h"
-#include "nir_vla.h"
+
+#include <stdlib.h>
+
+#define STACK_ARRAY_SIZE 8
+
+/* Sometimes gcc may claim -Wmaybe-uninitialized for the stack array in some
+ * places it can't verify that when size is 0 nobody down the call chain reads
+ * the array. Please don't try to fix it by zero-initializing the array here
+ * since it's used in a lot of different places. An "if (size == 0) return;"
+ * may work for you.
+ */
+#define STACK_ARRAY(type, name, size) \
+   type _stack_##name[STACK_ARRAY_SIZE]; \
+   type *const name = \
+     ((size) <= STACK_ARRAY_SIZE ? _stack_##name : (type *)malloc((size) * sizeof(type)))
+
+#define STACK_ARRAY_FINISH(name) \
+   if (name != _stack_##name) free(name)
 
 void nir_inline_function_impl(struct nir_builder *b,
                               const nir_function_impl *impl,
@@ -146,13 +163,14 @@ inline_functions_block(nir_block *block,
        * to an SSA value first.
        */
       const unsigned num_params = call->num_params;
-      NIR_VLA(nir_ssa_def *, params, num_params);
+      STACK_ARRAY(nir_ssa_def *, params, num_params);
       for (unsigned i = 0; i < num_params; i++) {
          params[i] = nir_ssa_for_src(b, call->params[i],
                                      call->callee->params[i].num_components);
       }
 
       nir_inline_function_impl(b, call->callee->impl, params, NULL);
+      STACK_ARRAY_FINISH(params);
    }
 
    return progress;