radeonsi: add a workaround for a compute VGPR-usage LLVM bug

v2: use abort(), describe which LLVM version is affected

Cc: 12.0 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c
index c7ecb7e6553e4adf2fa9a6e42b29b803bbfb7b56..64fbd74cb443295d9cec38b5112e20535ba6708d 100644 (file)
--- a/src/gallium/drivers/radeonsi/si_shader.c
+++ b/src/gallium/drivers/radeonsi/si_shader.c
@@ -6697,6 +6697,41 @@ int si_compile_tgsi_shader(struct si_screen *sscreen,
 
        radeon_llvm_dispose(&ctx.radeon_bld);
 
+       /* Validate SGPR and VGPR usage for compute to detect compiler bugs.
+        * LLVM 3.9svn has this bug.
+        */
+       if (sel->type == PIPE_SHADER_COMPUTE) {
+               unsigned *props = sel->info.properties;
+               unsigned wave_size = 64;
+               unsigned max_vgprs = 256;
+               unsigned max_sgprs = sscreen->b.chip_class >= VI ? 800 : 512;
+               unsigned max_sgprs_per_wave = 128;
+               unsigned min_waves_per_cu =
+                       DIV_ROUND_UP(props[TGSI_PROPERTY_CS_FIXED_BLOCK_WIDTH] *
+                                    props[TGSI_PROPERTY_CS_FIXED_BLOCK_HEIGHT] *
+                                    props[TGSI_PROPERTY_CS_FIXED_BLOCK_DEPTH],
+                                    wave_size);
+               unsigned min_waves_per_simd = DIV_ROUND_UP(min_waves_per_cu, 4);
+
+               max_vgprs = max_vgprs / min_waves_per_simd;
+               max_sgprs = MIN2(max_sgprs / min_waves_per_simd, max_sgprs_per_wave);
+
+               if (shader->config.num_sgprs > max_sgprs ||
+                   shader->config.num_vgprs > max_vgprs) {
+                       fprintf(stderr, "LLVM failed to compile a shader correctly: "
+                               "SGPR:VGPR usage is %u:%u, but the hw limit is %u:%u\n",
+                               shader->config.num_sgprs, shader->config.num_vgprs,
+                               max_sgprs, max_vgprs);
+
+                       /* Just terminate the process, because dependent
+                        * shaders can hang due to bad input data, but use
+                        * the env var to allow shader-db to work.
+                        */
+                       if (!debug_get_bool_option("SI_PASS_BAD_SHADERS", false))
+                               abort();
+               }
+       }
+
        /* Add the scratch offset to input SGPRs. */
        if (shader->config.scratch_bytes_per_wave)
                shader->info.num_input_sgprs += 1; /* scratch byte offset */