i965/fs: Fix constant combining for instructions that cannot accept source mods.

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.

Cc: "12.0" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

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 d7a1456bce027514f1ba96b275b009c68858b355..5bd5343b8b4436adf8a20569d92c0466387c4d4b 100644 (file)
--- 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));
       }
    }