[Mesa-dev] [PATCH 22/25] i965/fs: Fix constant combining for instructions that cannot accept source mods.

[Francisco Jerez]

This is the case for SNB math instructions so we need to be careful
and insert the literal value of the immediate into the table (rather
than its absolute value) if the instruction is unable to invert the
sign of the constant on the fly.
---
 src/mesa/drivers/dri/i965/brw_fs_combine_constants.cpp | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_combine_constants.cpp b/src/mesa/drivers/dri/i965/brw_fs_combine_constants.cpp
index d7a1456..5bd5343 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_combine_constants.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_combine_constants.cpp
@@ -147,8 +147,6 @@ struct table {
 static struct imm *
 find_imm(struct table *table, float val)
 {
-   assert(signbit(val) == 0);
-
    for (int i = 0; i < table->len; i++) {
       if (table->imm[i].val == val) {
          return &table->imm[i];
@@ -220,7 +218,8 @@ fs_visitor::opt_combine_constants()
              inst->src[i].type != BRW_REGISTER_TYPE_F)
             continue;
 
-         float val = fabsf(inst->src[i].f);
+         float val = !inst->can_do_source_mods(devinfo) ? inst->src[i].f :
+                     fabs(inst->src[i].f);
          struct imm *imm = find_imm(&table, val);
 
          if (imm) {
@@ -301,7 +300,7 @@ fs_visitor::opt_combine_constants()
          reg->stride = 0;
          reg->negate = signbit(reg->f) != signbit(table.imm[i].val);
          assert((isnan(reg->f) && isnan(table.imm[i].val)) ||
-                fabsf(reg->f) == table.imm[i].val);
+                fabsf(reg->f) == fabs(table.imm[i].val));
       }
    }
 
-- 
2.7.3