intel/fs: Stop stack allocating large arrays

Normally, we haven't worried too much about stack sizes as Linux tends
to be fairly friendly towards large stacks.  However, when running DXVK
apps under wine, we're suddenly subject to Windows' more stringent stack
limitations and can run out of space more easily.  In particular, some
of the shaders in Elite Dangerous: Horizons have quite a few registers
and the arrays in split_virtual_grfs are large enough to blow a 1 MiB
stack leading to crashes during shader compilation.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=108662
Reviewed-by: Lionel Landwerlin <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>
Reviewed-by: Matt Turner <[email protected]>
Cc: [email protected]

1 files changed, 12 insertions, 6 deletions

diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
index a9273ebef2d..25e4dd9971c 100644
--- a/src/intel/compiler/brw_fs.cpp
+++ b/src/intel/compiler/brw_fs.cpp
@@ -1890,8 +1890,8 @@ fs_visitor::split_virtual_grfs()
     * destination), we mark the used slots as inseparable.  Then we go
     * through and split the registers into the smallest pieces we can.
     */
-   bool split_points[reg_count];
-   memset(split_points, 0, sizeof(split_points));
+   bool *split_points = new bool[reg_count];
+   memset(split_points, 0, reg_count * sizeof(*split_points));
 
    /* Mark all used registers as fully splittable */
    foreach_block_and_inst(block, fs_inst, inst, cfg) {
@@ -1925,8 +1925,8 @@ fs_visitor::split_virtual_grfs()
       }
    }
 
-   int new_virtual_grf[reg_count];
-   int new_reg_offset[reg_count];
+   int *new_virtual_grf = new int[reg_count];
+   int *new_reg_offset = new int[reg_count];
 
    int reg = 0;
    for (int i = 0; i < num_vars; i++) {
@@ -1982,6 +1982,10 @@ fs_visitor::split_virtual_grfs()
       }
    }
    invalidate_live_intervals();
+
+   delete[] split_points;
+   delete[] new_virtual_grf;
+   delete[] new_reg_offset;
 }
 
 /**
@@ -1997,8 +2001,8 @@ bool
 fs_visitor::compact_virtual_grfs()
 {
    bool progress = false;
-   int remap_table[this->alloc.count];
-   memset(remap_table, -1, sizeof(remap_table));
+   int *remap_table = new int[this->alloc.count];
+   memset(remap_table, -1, this->alloc.count * sizeof(int));
 
    /* Mark which virtual GRFs are used. */
    foreach_block_and_inst(block, const fs_inst, inst, cfg) {
@@ -2054,6 +2058,8 @@ fs_visitor::compact_virtual_grfs()
       }
    }
 
+   delete[] remap_table;
+
    return progress;
 }