ir_to_mesa: Fix binop_sqrt for multi-channel and negative source channels.

Fixes glsl-fs-sqrt-branch.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/mesa/shader/ir_to_mesa.cpp b/src/mesa/shader/ir_to_mesa.cpp
index 9cf78391484..d371e35f9cf 100644
--- a/src/mesa/shader/ir_to_mesa.cpp
+++ b/src/mesa/shader/ir_to_mesa.cpp
@@ -706,7 +706,10 @@ ir_to_mesa_visitor::visit(ir_expression *ir)
       break;
    case ir_unop_sqrt:
       ir_to_mesa_emit_scalar_op1(ir, OPCODE_RSQ, result_dst, op[0]);
-      ir_to_mesa_emit_op1(ir, OPCODE_RCP, result_dst, result_src);
+      ir_to_mesa_emit_scalar_op1(ir, OPCODE_RCP, result_dst, result_src);
+      /* For incoming channels < 0, set the result to 0. */
+      ir_to_mesa_emit_op3(ir, OPCODE_CMP, result_dst,
+			  op[0], src_reg_for_float(0.0), result_src);
       break;
    case ir_unop_rsq:
       ir_to_mesa_emit_scalar_op1(ir, OPCODE_RSQ, result_dst, op[0]);