From 44d68fd06ff8b53fc70a9a07c897dda9b3457ef8 Mon Sep 17 00:00:00 2001
From: Eric Anholt <eric@anholt.net>
Date: Sat, 27 Mar 2010 13:01:51 -0700
Subject: [PATCH] Add sqrt() builtin as an IR operation.

Following a discussion in #dri-devel, I think this makes more sense
than implementing it as RSQ RCP CMP as Mesa did.  The i965 has a
hardware sqrt that should work, and AMD is suppposed to be able to
implement it as RSQ RCP with an alternate floating point mode so that
the 0.0 case is handled like we want.
---
 builtin_function.cpp | 10 +++++++++-
 ir.h                 |  1 +
 ir_print_visitor.cpp |  1 +
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/builtin_function.cpp b/builtin_function.cpp
index ec1b54a..9d231e8 100644
--- a/builtin_function.cpp
+++ b/builtin_function.cpp
@@ -85,6 +85,14 @@ generate_rsq(exec_list *instructions,
 }
 
 static void
+generate_sqrt(exec_list *instructions,
+	       ir_variable **declarations,
+	       const glsl_type *type)
+{
+   generate_unop(instructions, declarations, type, ir_unop_sqrt);
+}
+
+static void
 generate_abs(exec_list *instructions,
 	     ir_variable **declarations,
 	     const glsl_type *type)
@@ -227,7 +235,7 @@ generate_110_functions(glsl_symbol_table *symtab, exec_list *instructions)
    make_gentype_function(symtab, instructions, "log", 1, generate_log);
    /* FINISHME: exp2() */
    /* FINISHME: log2() */
-   /* FINISHME: sqrt() */
+   make_gentype_function(symtab, instructions, "sqrt", 1, generate_sqrt);
    make_gentype_function(symtab, instructions, "inversesqrt", 1, generate_rsq);
    make_gentype_function(symtab, instructions, "abs", 1, generate_abs);
    /* FINISHME: sign() */
diff --git a/ir.h b/ir.h
index bad5111..4590528 100644
--- a/ir.h
+++ b/ir.h
@@ -225,6 +225,7 @@ enum ir_expression_operation {
    ir_unop_abs,
    ir_unop_rcp,
    ir_unop_rsq,
+   ir_unop_sqrt,
    ir_unop_exp,
    ir_unop_log,
    ir_unop_f2i,      /**< Float-to-integer conversion. */
diff --git a/ir_print_visitor.cpp b/ir_print_visitor.cpp
index ecfdb49..8b2080f 100644
--- a/ir_print_visitor.cpp
+++ b/ir_print_visitor.cpp
@@ -93,6 +93,7 @@ void ir_print_visitor::visit(ir_expression *ir)
       "abs",
       "rcp",
       "rsq",
+      "sqrt",
       "exp",
       "log",
       "f2i",
-- 
2.7.4