glsl/ir_builder: Add a generic constructor for unary expressions.

I needed to compute logs and square roots in a patch I was working on,
and wanted to use the convenient interface.  We already have a similar
constructor for binops; adding one for unops seems reasonable.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Eric Anholt <eric@anholt.net>

src/glsl/ir_builder.cpp

@@ -142,6 +142,14 @@ swizzle_xyzw(operand a)
    return swizzle(a, SWIZZLE_XYZW, 4);
 }
 
+ir_expression *
+expr(ir_expression_operation op, operand a)
+{
+   void *mem_ctx = ralloc_parent(a.val);
+
+   return new(mem_ctx) ir_expression(op, a.val);
+}
+
 ir_expression *
 expr(ir_expression_operation op, operand a, operand b)
 {

src/glsl/ir_builder.h

@@ -83,6 +83,7 @@ public:
 ir_assignment *assign(deref lhs, operand rhs);
 ir_assignment *assign(deref lhs, operand rhs, int writemask);
 
+ir_expression *expr(ir_expression_operation op, operand a);
 ir_expression *expr(ir_expression_operation op, operand a, operand b);
 ir_expression *add(operand a, operand b);
 ir_expression *sub(operand a, operand b);