r300: Print warning when stubbing derivatives

Fixes: e1c640c3a43d741719864b35cbf855aa82be0611
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/14669>

diff --git a/src/gallium/drivers/r300/compiler/radeon_program_alu.c b/src/gallium/drivers/r300/compiler/radeon_program_alu.c
index 47fdd78..7ea348d 100644 (file)
--- a/src/gallium/drivers/r300/compiler/radeon_program_alu.c
+++ b/src/gallium/drivers/r300/compiler/radeon_program_alu.c
@@ -38,6 +38,7 @@
 #include "radeon_compiler.h"
 #include "radeon_compiler_util.h"
 
+#include "util/log.h"
 
 static struct rc_instruction *emit1(
        struct radeon_compiler * c, struct rc_instruction * after,
@@ -1100,6 +1101,10 @@ int radeonStubDeriv(struct radeon_compiler* c,
        inst->U.I.Opcode = RC_OPCODE_MOV;
        inst->U.I.SrcReg[0].Swizzle = RC_SWIZZLE_0000;
 
+       mesa_logw_once("r300: WARNING: Shader is trying to use derivatives, "
+                                       "but the hardware doesn't support it. "
+                                       "Expect possible misrendering (it's not a bug, do not report it).");
+
        return 1;
 }