From: Matt Turner Date: Wed, 18 Sep 2013 01:02:05 +0000 (-0700) Subject: glsl: Implement usubBorrow() built-in for ARB_gpu_shader5. X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=6f9428eb68bb0f7592f4384455fc7aab23940d92;p=mesa.git glsl: Implement usubBorrow() built-in for ARB_gpu_shader5. i965 implements this with a single (multiple destination) instruction, SUBB. Emitting SUBB directly from usubBorrow() would be ideal, but our optimization passes don't know how to copy with expressions with side-effects. Radeon has an SUBB_UINT instruction that only generates the borrow bit. I've chosen to go this route and implement usubBorrow() by doing the subtraction and the borrow operations separately. Reviewed-by: Kenneth Graunke Reviewed-by: Ian Romanick --- diff --git a/src/glsl/builtin_functions.cpp b/src/glsl/builtin_functions.cpp index 9465ee3e785..5b1b9c3b7c1 100644 --- a/src/glsl/builtin_functions.cpp +++ b/src/glsl/builtin_functions.cpp @@ -532,6 +532,7 @@ private: B2(ldexp) B2(frexp) B1(uaddCarry) + B1(usubBorrow) #undef B0 #undef B1 #undef B2 @@ -1954,6 +1955,12 @@ builtin_builder::create_builtins() _uaddCarry(glsl_type::uvec3_type), _uaddCarry(glsl_type::uvec4_type), NULL); + add_function("usubBorrow", + _usubBorrow(glsl_type::uint_type), + _usubBorrow(glsl_type::uvec2_type), + _usubBorrow(glsl_type::uvec3_type), + _usubBorrow(glsl_type::uvec4_type), + NULL); #undef F #undef FI #undef FIU @@ -3741,6 +3748,20 @@ builtin_builder::_uaddCarry(const glsl_type *type) return sig; } + +ir_function_signature * +builtin_builder::_usubBorrow(const glsl_type *type) +{ + ir_variable *x = in_var(type, "x"); + ir_variable *y = in_var(type, "y"); + ir_variable *borrow = out_var(type, "borrow"); + MAKE_SIG(type, gpu_shader5, 3, x, y, borrow); + + body.emit(assign(borrow, ir_builder::borrow(x, y))); + body.emit(ret(sub(x, y))); + + return sig; +} /** @} */ /******************************************************************************/