glsl: add driconf to zero-init unintialized vars

Some games are sloppy.. perhaps because it is defined behavior for DX or
perhaps because nv blob driver defaults things to zero.

So add driconf param to force uninitialized variables to default to zero.

This issue was observed with rust, from steam store.  But has surfaced
elsewhere in the past.

Signed-off-by: Rob Clark <[email protected]>
Reviewed-by: Kenneth Graunke <[email protected]>

11 files changed, 34 insertions, 1 deletions

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index 0cfce6893ee..8ddc084cab7 100644
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -4697,6 +4697,14 @@ ast_declarator_list::hir(exec_list *instructions,
       apply_layout_qualifier_to_variable(&this->type->qualifier, var, state,
                                          &loc);
 
+      if ((var->data.mode == ir_var_auto || var->data.mode == ir_var_temporary)
+          && (var->type->is_numeric() || var->type->is_boolean())
+          && state->zero_init) {
+         const ir_constant_data data = {0};
+         var->data.has_initializer = true;
+         var->constant_initializer = new(var) ir_constant(var->type, &data);
+      }
+
       if (this->type->qualifier.flags.q.invariant) {
          if (!is_varying_var(var, state->stage)) {
             _mesa_glsl_error(&loc, state,
diff --git a/src/compiler/glsl/glsl_parser_extras.cpp b/src/compiler/glsl/glsl_parser_extras.cpp
index fab64bbb87b..96014247e5d 100644
--- a/src/compiler/glsl/glsl_parser_extras.cpp
+++ b/src/compiler/glsl/glsl_parser_extras.cpp
@@ -74,6 +74,7 @@ _mesa_glsl_parse_state::_mesa_glsl_parse_state(struct gl_context *_ctx,
    /* Set default language version and extensions */
    this->language_version = 110;
    this->forced_language_version = ctx->Const.ForceGLSLVersion;
+   this->zero_init = ctx->Const.GLSLZeroInit;
    this->es_shader = false;
    this->ARB_texture_rectangle_enable = true;
 
diff --git a/src/compiler/glsl/glsl_parser_extras.h b/src/compiler/glsl/glsl_parser_extras.h
index 8c43292d8aa..669b3d1b201 100644
--- a/src/compiler/glsl/glsl_parser_extras.h
+++ b/src/compiler/glsl/glsl_parser_extras.h
@@ -306,6 +306,7 @@ struct _mesa_glsl_parse_state {
    bool es_shader;
    unsigned language_version;
    unsigned forced_language_version;
+   bool zero_init;
    gl_shader_stage stage;
 
    /**
diff --git a/src/gallium/include/state_tracker/st_api.h b/src/gallium/include/state_tracker/st_api.h
index 41daa47986c..21d5177aa2f 100644
--- a/src/gallium/include/state_tracker/st_api.h
+++ b/src/gallium/include/state_tracker/st_api.h
@@ -242,6 +242,7 @@ struct st_config_options
    unsigned force_glsl_version;
    boolean force_s3tc_enable;
    boolean allow_glsl_extension_directive_midshader;
+   boolean glsl_zero_init;
 };
 
 /**
diff --git a/src/gallium/state_trackers/dri/dri_screen.c b/src/gallium/state_trackers/dri/dri_screen.c
index 2ac55c88926..b16585a38cc 100644
--- a/src/gallium/state_trackers/dri/dri_screen.c
+++ b/src/gallium/state_trackers/dri/dri_screen.c
@@ -74,6 +74,7 @@ const __DRIconfigOptionsExtension gallium_config_options = {
 
       DRI_CONF_SECTION_MISCELLANEOUS
          DRI_CONF_ALWAYS_HAVE_DEPTH_BUFFER("false")
+         DRI_CONF_GLSL_ZERO_INIT("false")
       DRI_CONF_SECTION_END
    DRI_CONF_END
 };
@@ -98,6 +99,7 @@ dri_fill_st_options(struct st_config_options *options,
       driQueryOptionb(optionCache, "force_s3tc_enable");
    options->allow_glsl_extension_directive_midshader =
       driQueryOptionb(optionCache, "allow_glsl_extension_directive_midshader");
+   options->glsl_zero_init = driQueryOptionb(optionCache, "glsl_zero_init");
 }
 
 static const __DRIconfig **
diff --git a/src/mesa/drivers/dri/common/drirc b/src/mesa/drivers/dri/common/drirc
index 3912d8b8c7e..af84ee82e8a 100644
--- a/src/mesa/drivers/dri/common/drirc
+++ b/src/mesa/drivers/dri/common/drirc
@@ -96,5 +96,9 @@ TODO: document the other workarounds.
         <application name="Warsow (64-bit)" executable="warsow.x86_64">
             <option name="allow_glsl_extension_directive_midshader" value="true" />
         </application>
+
+        <application name="Rust" executable="rust">
+            <option name="glsl_zero_init" value="true"/>
+        </application>
     </device>
 </driconf>
diff --git a/src/mesa/drivers/dri/common/xmlpool/t_options.h b/src/mesa/drivers/dri/common/xmlpool/t_options.h
index 4b298a46112..341c3763dee 100644
--- a/src/mesa/drivers/dri/common/xmlpool/t_options.h
+++ b/src/mesa/drivers/dri/common/xmlpool/t_options.h
@@ -337,7 +337,10 @@ DRI_CONF_OPT_BEGIN_B(always_have_depth_buffer, def) \
         DRI_CONF_DESC(en,gettext("Create all visuals with a depth buffer")) \
 DRI_CONF_OPT_END
 
-
+#define DRI_CONF_GLSL_ZERO_INIT(def) \
+DRI_CONF_OPT_BEGIN_B(glsl_zero_init, def) \
+        DRI_CONF_DESC(en,gettext("Force uninitialized variables to default to zero")) \
+DRI_CONF_OPT_END
 
 /**
  * \brief Initialization configuration options
diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 5e3c9d169b3..3f0c2e3b483 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -827,6 +827,8 @@ brw_process_driconf_options(struct brw_context *brw)
    ctx->Const.AllowGLSLExtensionDirectiveMidShader =
       driQueryOptionb(options, "allow_glsl_extension_directive_midshader");
 
+   ctx->Const.GLSLZeroInit = driQueryOptionb(options, "glsl_zero_init");
+
    brw->dual_color_blend_by_location =
       driQueryOptionb(options, "dual_color_blend_by_location");
 }
diff --git a/src/mesa/drivers/dri/i965/intel_screen.c b/src/mesa/drivers/dri/i965/intel_screen.c
index 1c71e09e7ad..432ab7bdb63 100644
--- a/src/mesa/drivers/dri/i965/intel_screen.c
+++ b/src/mesa/drivers/dri/i965/intel_screen.c
@@ -88,6 +88,10 @@ DRI_CONF_BEGIN
 	 DRI_CONF_DESC(en, "Perform code generation at shader link time.")
       DRI_CONF_OPT_END
    DRI_CONF_SECTION_END
+
+   DRI_CONF_SECTION_MISCELLANEOUS
+      DRI_CONF_GLSL_ZERO_INIT("false")
+   DRI_CONF_SECTION_END
 DRI_CONF_END
 };
 
diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
index cab315df23d..29e47debfc2 100644
--- a/src/mesa/main/mtypes.h
+++ b/src/mesa/main/mtypes.h
@@ -3536,6 +3536,11 @@ struct gl_constants
    GLboolean AllowGLSLExtensionDirectiveMidShader;
 
    /**
+    * Force uninitialized variables to default to zero.
+    */
+   GLboolean GLSLZeroInit;
+
+   /**
     * Does the driver support real 32-bit integers?  (Otherwise, integers are
     * simulated via floats.)
     */
diff --git a/src/mesa/state_tracker/st_extensions.c b/src/mesa/state_tracker/st_extensions.c
index c5ecd5a2dd7..3d27ca3a905 100644
--- a/src/mesa/state_tracker/st_extensions.c
+++ b/src/mesa/state_tracker/st_extensions.c
@@ -925,6 +925,8 @@ void st_init_extensions(struct pipe_screen *screen,
       extensions->EXT_texture_integer = GL_FALSE;
    }
 
+   consts->GLSLZeroInit = options->glsl_zero_init;
+
    consts->UniformBooleanTrue = consts->NativeIntegers ? ~0U : fui(1.0f);
 
    /* Below are the cases which cannot be moved into tables easily. */