i965: Store floating point mode choice in brw_stage_prog_data.

We use IEEE mode for GLSL programs, but need to use ALT mode for ARB
programs so that 0^0 == 1.  The choice is based entirely on the shader
source language.

Previously, our code to determine which mode we wanted was duplicated
in 8 different places (VS and FS for Gen4-5, Gen6, Gen7, and Gen8).
The ctx->_Shader->CurrentProgram[stage] == NULL check was confusing
as well - we use CurrentProgram (non-derived state), but _Shader
(derived state).  It also relies on knowing that ARB programs don't
use gl_shader_program structures today.  The compiler already makes
this assumption in a few places, but I'd rather keep that assumption
out of the state upload code.

With this patch, we select the mode at compile time, and store that
choice in prog_data.  The state upload code simply uses that decision.

This eliminates a BRW_NEW_*_PROGRAM dependency in the state upload code.

Signed-off-by: Kenneth Graunke <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>
Reviewed-by: Matt Turner <[email protected]>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_vs.c b/src/mesa/drivers/dri/i965/brw_vs.c
index 2f628e59e8e..970d86cc698 100644
--- a/src/mesa/drivers/dri/i965/brw_vs.c
+++ b/src/mesa/drivers/dri/i965/brw_vs.c
@@ -209,6 +209,10 @@ do_vs_prog(struct brw_context *brw,
    memcpy(&c.key, key, sizeof(*key));
    memset(&prog_data, 0, sizeof(prog_data));
 
+   /* Use ALT floating point mode for ARB programs so that 0^0 == 1. */
+   if (!prog)
+      stage_prog_data->use_alt_mode = true;
+
    mem_ctx = ralloc_context(NULL);
 
    c.vp = vp;