Mesa (master): i965: Fix the new implementation of ir_unop_sign to match brw_wm_emit.c

[Eric Anholt]

Module: Mesa
Branch: master
Commit: 4ff25c2106fb981334bdc1b032fcf37d8753ba62
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=4ff25c2106fb981334bdc1b032fcf37d8753ba62

Author: Eric Anholt <eric at anholt.net>
Date:   Sat Aug 28 22:42:01 2010 -0700

i965: Fix the new implementation of ir_unop_sign to match brw_wm_emit.c

Like the comparison operations, this suffered from CMP only setting
the low bit.  Doing the AND instructions would be the same instruction
count as the more obvious conditional moves, so do cond moves.

Fixes glsl-fs-sign and 6 other cases, like trig functions that use
sign() internally.

---

 src/mesa/drivers/dri/i965/brw_fs.cpp |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 233fee4..0d29c86 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -655,14 +655,17 @@ fs_visitor::visit(ir_expression *ir)
    case ir_unop_sign:
       temp = fs_reg(this, ir->type);
 
-      inst = emit(fs_inst(BRW_OPCODE_CMP, this->result, op[0], fs_reg(0.0f)));
+      emit(fs_inst(BRW_OPCODE_MOV, this->result, fs_reg(0.0f)));
+
+      inst = emit(fs_inst(BRW_OPCODE_CMP, reg_null, op[0], fs_reg(0.0f)));
       inst->conditional_mod = BRW_CONDITIONAL_G;
+      inst = emit(fs_inst(BRW_OPCODE_MOV, this->result, fs_reg(1.0f)));
+      inst->predicated = true;
 
-      inst = emit(fs_inst(BRW_OPCODE_CMP, temp, op[0], fs_reg(0.0f)));
+      inst = emit(fs_inst(BRW_OPCODE_CMP, reg_null, op[0], fs_reg(0.0f)));
       inst->conditional_mod = BRW_CONDITIONAL_L;
-
-      temp.negate = true;
-      emit(fs_inst(BRW_OPCODE_ADD, this->result, this->result, temp));
+      inst = emit(fs_inst(BRW_OPCODE_MOV, this->result, fs_reg(-1.0f)));
+      inst->predicated = true;
 
       break;
    case ir_unop_rcp: