From eb47d0efd39d73d4388389d6c0ebe458160f79fa Mon Sep 17 00:00:00 2001 From: Matt Turner Date: Wed, 4 Feb 2015 18:08:30 -0800 Subject: [PATCH] i965: Optimize multiplication by -1 into a negated MOV. instructions in affected programs: 968 -> 942 (-2.69%) helped: 4 Reviewed-by: Ian Romanick --- src/mesa/drivers/dri/i965/brw_fs.cpp | 9 +++++++++ src/mesa/drivers/dri/i965/brw_vec4.cpp | 5 +++++ 2 files changed, 14 insertions(+) diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp index c7c6accebf6..0f1300c1cc6 100644 --- a/src/mesa/drivers/dri/i965/brw_fs.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp @@ -2325,6 +2325,15 @@ fs_visitor::opt_algebraic() break; } + /* a * -1.0 = -a */ + if (inst->src[1].is_negative_one()) { + inst->opcode = BRW_OPCODE_MOV; + inst->src[0].negate = !inst->src[0].negate; + inst->src[1] = reg_undef; + progress = true; + break; + } + /* a * 0.0 = 0.0 */ if (inst->src[1].is_zero()) { inst->opcode = BRW_OPCODE_MOV; diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp index fda8552d841..58828c3f320 100644 --- a/src/mesa/drivers/dri/i965/brw_vec4.cpp +++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp @@ -725,6 +725,11 @@ vec4_visitor::opt_algebraic() inst->opcode = BRW_OPCODE_MOV; inst->src[1] = src_reg(); progress = true; + } else if (inst->src[1].is_negative_one()) { + inst->opcode = BRW_OPCODE_MOV; + inst->src[0].negate = !inst->src[0].negate; + inst->src[1] = src_reg(); + progress = true; } break; case BRW_OPCODE_CMP: -- 2.30.2