Mesa (master): i965: Expand uniform args to gen6 math to full registers to get hstride == 1.

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 720ed3c906b0f6d5822fe9fa442294c9828e1560
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=720ed3c906b0f6d5822fe9fa442294c9828e1560

Author: Eric Anholt <eric at anholt.net>
Date:   Mon Oct 11 13:42:11 2010 -0700

i965: Expand uniform args to gen6 math to full registers to get hstride == 1.

This is a hw requirement in math args.  This also is inefficient, as
we're calculating the same result 8 times, but then we've been doing
that on pre-gen6 as well.  If we're doing math on uniforms, though,
we'd probably be better served by having some sort of mechanism for
precalculating those results into another uniform value to use.

Fixes 7 piglit math tests.

---

 src/mesa/drivers/dri/i965/brw_fs.cpp |   25 +++++++++++++++++++++++++
 1 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 0353bb5..35ec79e 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -530,6 +530,18 @@ fs_visitor::emit_math(fs_opcodes opcode, fs_reg dst, fs_reg src)
       assert(!"not reached: bad math opcode");
       return NULL;
    }
+
+   /* Can't do hstride == 0 args to gen6 math, so expand it out.  We
+    * might be able to do better by doing execsize = 1 math and then
+    * expanding that result out, but we would need to be careful with
+    * masking.
+    */
+   if (intel->gen >= 6 && src.file == UNIFORM) {
+      fs_reg expanded = fs_reg(this, glsl_type::float_type);
+      emit(fs_inst(BRW_OPCODE_MOV, expanded, src));
+      src = expanded;
+   }
+
    fs_inst *inst = emit(fs_inst(opcode, dst, src));
 
    if (intel->gen < 6) {
@@ -549,6 +561,19 @@ fs_visitor::emit_math(fs_opcodes opcode, fs_reg dst, fs_reg src0, fs_reg src1)
    assert(opcode == FS_OPCODE_POW);
 
    if (intel->gen >= 6) {
+      /* Can't do hstride == 0 args to gen6 math, so expand it out. */
+      if (src0.file == UNIFORM) {
+	 fs_reg expanded = fs_reg(this, glsl_type::float_type);
+	 emit(fs_inst(BRW_OPCODE_MOV, expanded, src0));
+	 src0 = expanded;
+      }
+
+      if (src1.file == UNIFORM) {
+	 fs_reg expanded = fs_reg(this, glsl_type::float_type);
+	 emit(fs_inst(BRW_OPCODE_MOV, expanded, src1));
+	 src1 = expanded;
+      }
+
       inst = emit(fs_inst(opcode, dst, src0, src1));
    } else {
       emit(fs_inst(BRW_OPCODE_MOV, fs_reg(MRF, base_mrf + 1), src1));