i965/fs/generator: refactor rounding mode helper in preparation for float controls

v2:
- Fix bug in defining BRW_CR0_FP_MODE_MASK.

v3:
- Update comment (Caio).

v4:
- Split the patch into the helper (this one) and the new
  opcode (Caio).

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>

3 files changed, 32 insertions, 35 deletions

diff --git a/src/intel/compiler/brw_eu.h b/src/intel/compiler/brw_eu.h
index cb23c9ff51a..306c24a4e4f 100644
--- a/src/intel/compiler/brw_eu.h
+++ b/src/intel/compiler/brw_eu.h
@@ -1145,8 +1145,8 @@ brw_broadcast(struct brw_codegen *p,
               struct brw_reg idx);
 
 void
-brw_rounding_mode(struct brw_codegen *p,
-                  enum brw_rnd_mode mode);
+brw_float_controls_mode(struct brw_codegen *p,
+                        unsigned mode, unsigned mask);
 
 /***********************************************************************
  * brw_eu_util.c:
diff --git a/src/intel/compiler/brw_eu_emit.c b/src/intel/compiler/brw_eu_emit.c
index c26a22fdb2e..28254024bbc 100644
--- a/src/intel/compiler/brw_eu_emit.c
+++ b/src/intel/compiler/brw_eu_emit.c
@@ -3476,37 +3476,27 @@ brw_WAIT(struct brw_codegen *p)
    brw_inst_set_mask_control(devinfo, insn, BRW_MASK_DISABLE);
 }
 
-/**
- * Changes the floating point rounding mode updating the control register
- * field defined at cr0.0[5-6] bits. This function supports the changes to
- * RTNE (00), RU (01), RD (10) and RTZ (11) rounding using bitwise operations.
- * Only RTNE and RTZ rounding are enabled at nir.
- */
 void
-brw_rounding_mode(struct brw_codegen *p,
-                  enum brw_rnd_mode mode)
-{
-   const unsigned bits = mode << BRW_CR0_RND_MODE_SHIFT;
-
-   if (bits != BRW_CR0_RND_MODE_MASK) {
-      brw_inst *inst = brw_AND(p, brw_cr0_reg(0), brw_cr0_reg(0),
-                               brw_imm_ud(~BRW_CR0_RND_MODE_MASK));
-      brw_inst_set_exec_size(p->devinfo, inst, BRW_EXECUTE_1);
-
-      /* From the Skylake PRM, Volume 7, page 760:
-       *  "Implementation Restriction on Register Access: When the control
-       *   register is used as an explicit source and/or destination, hardware
-       *   does not ensure execution pipeline coherency. Software must set the
-       *   thread control field to ‘switch’ for an instruction that uses
-       *   control register as an explicit operand."
-       */
-      brw_inst_set_thread_control(p->devinfo, inst, BRW_THREAD_SWITCH);
-    }
-
-   if (bits) {
-      brw_inst *inst = brw_OR(p, brw_cr0_reg(0), brw_cr0_reg(0),
-                              brw_imm_ud(bits));
-      brw_inst_set_exec_size(p->devinfo, inst, BRW_EXECUTE_1);
-      brw_inst_set_thread_control(p->devinfo, inst, BRW_THREAD_SWITCH);
+brw_float_controls_mode(struct brw_codegen *p,
+                        unsigned mode, unsigned mask)
+{
+   brw_inst *inst = brw_AND(p, brw_cr0_reg(0), brw_cr0_reg(0),
+                            brw_imm_ud(~mask));
+   brw_inst_set_exec_size(p->devinfo, inst, BRW_EXECUTE_1);
+
+   /* From the Skylake PRM, Volume 7, page 760:
+    *  "Implementation Restriction on Register Access: When the control
+    *   register is used as an explicit source and/or destination, hardware
+    *   does not ensure execution pipeline coherency. Software must set the
+    *   thread control field to ‘switch’ for an instruction that uses
+    *   control register as an explicit operand."
+    */
+   brw_inst_set_thread_control(p->devinfo, inst, BRW_THREAD_SWITCH);
+
+   if (mode) {
+      brw_inst *inst_or = brw_OR(p, brw_cr0_reg(0), brw_cr0_reg(0),
+                                 brw_imm_ud(mode));
+      brw_inst_set_exec_size(p->devinfo, inst_or, BRW_EXECUTE_1);
+      brw_inst_set_thread_control(p->devinfo, inst_or, BRW_THREAD_SWITCH);
    }
 }
diff --git a/src/intel/compiler/brw_fs_generator.cpp b/src/intel/compiler/brw_fs_generator.cpp
index b6e6925ac9e..48ac635bf90 100644
--- a/src/intel/compiler/brw_fs_generator.cpp
+++ b/src/intel/compiler/brw_fs_generator.cpp
@@ -2218,9 +2218,16 @@ fs_generator::generate_code(const cfg_t *cfg, int dispatch_width,
          brw_DIM(p, dst, retype(src[0], BRW_REGISTER_TYPE_F));
          break;
 
-      case SHADER_OPCODE_RND_MODE:
+      case SHADER_OPCODE_RND_MODE: {
          assert(src[0].file == BRW_IMMEDIATE_VALUE);
-         brw_rounding_mode(p, (brw_rnd_mode) src[0].d);
+         /*
+          * Changes the floating point rounding mode updating the control
+          * register field defined at cr0.0[5-6] bits.
+          */
+         enum brw_rnd_mode mode =
+            (enum brw_rnd_mode) (src[0].d << BRW_CR0_RND_MODE_SHIFT);
+         brw_float_controls_mode(p, mode, BRW_CR0_RND_MODE_MASK);
+      }
          break;
 
       default: