<div dir="ltr"> <div class="gmail_extra"> <div class="gmail_quote">On Mon, Jan 19, 2015 at 3:31 PM, Matt Turner <<a href="mailto:mattst88@gmail.com" target="_blank">mattst88@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">For some reason, we occasionally write the flag register with a <a href="http://MOV.NZ" target="_blank">MOV.NZ</a> instruction: add(8) g25<1>F -g6<0,1,0>F g15<8,8,1>F cmp.l.f0(8) g26<1>D g25<8,8,1>F 0F mov.nz.f0(8) null g26<8,8,1>D A <a href="http://MOV.NZ" target="_blank">MOV.NZ</a> instruction on the result of a CMP is like comparing for equality with true in C. It's useless. Removing it allows us to generate: add.l.f0(8) null -g6<0,1,0>F g15<8,8,1>F total instructions in shared programs: 5955701 -> 5951657 (-0.07%) instructions in affected programs: 302910 -> 298866 (-1.34%) GAINED: 1 LOST: 0 --- .../drivers/dri/i965/brw_fs_cmod_propagation.cpp | 23 ++++++++++++++-- .../drivers/dri/i965/test_fs_cmod_propagation.cpp | 32 ++++++++++++++++++++++ 2 files changed, 52 insertions(+), 3 deletions(-) diff --git a/src/mesa/drivers/dri/i965/brw_fs_cmod_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_cmod_propagation.cpp index b521350..dd89512 100644 --- a/src/mesa/drivers/dri/i965/brw_fs_cmod_propagation.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs_cmod_propagation.cpp @@ -57,12 +57,20 @@ opt_cmod_propagation_local(fs_visitor *v, bblock_t *block) foreach_inst_in_block_reverse_safe(fs_inst, inst, block) { ip--; - if (inst->opcode != BRW_OPCODE_CMP || + if ((inst->opcode != BRW_OPCODE_CMP && + inst->opcode != BRW_OPCODE_MOV) || inst->predicate != BRW_PREDICATE_NONE || !inst->dst.is_null() || inst->src[0].file != GRF || - inst->src[0].abs || - !inst->src[1].is_zero()) + inst->src[0].abs) + continue; + + if (inst->opcode == BRW_OPCODE_CMP && !inst->src[1].is_zero()) + continue; + + if (inst->opcode == BRW_OPCODE_MOV && + (inst->conditional_mod != BRW_CONDITIONAL_NZ || + inst->src[0].negate)) </blockquote><div> </div><div>I think negate is ok here. I'm not 100% sure on the symantics of <a href="http://move.nz">move.nz</a>, but if it's a "!= 0" then negation shouldn't matter. If it only considers the bottom bit then negation shouldn't matter there either. </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> continue; bool read_flag = false; @@ -72,6 +80,15 @@ opt_cmod_propagation_local(fs_visitor *v, bblock_t *block) scan_inst->dst.reg == inst->src[0].reg && scan_inst->dst.reg_offset == inst->src[0].reg_offset && !scan_inst->is_partial_write()) { + if (inst->opcode == BRW_OPCODE_MOV) { + if (!scan_inst->writes_flag()) + break; + + inst->remove(block); + progress = true; + break; + } + enum brw_conditional_mod cond = inst->src[0].negate ? brw_invert_cmod(inst->conditional_mod) : inst->conditional_mod; diff --git a/src/mesa/drivers/dri/i965/test_fs_cmod_propagation.cpp b/src/mesa/drivers/dri/i965/test_fs_cmod_propagation.cpp index 15f685e..9541597 100644 --- a/src/mesa/drivers/dri/i965/test_fs_cmod_propagation.cpp +++ b/src/mesa/drivers/dri/i965/test_fs_cmod_propagation.cpp @@ -343,3 +343,35 @@ TEST_F(cmod_propagation_test, negate) EXPECT_EQ(BRW_OPCODE_ADD, instruction(block0, 0)->opcode); EXPECT_EQ(BRW_CONDITIONAL_L, instruction(block0, 0)->conditional_mod); } + +TEST_F(cmod_propagation_test, movnz) +{ + fs_reg dest(v, glsl_type::float_type); + fs_reg src0(v, glsl_type::float_type); + fs_reg src1(v, glsl_type::float_type); + v->emit(BRW_OPCODE_CMP, dest, src0, src1) + ->conditional_mod = BRW_CONDITIONAL_GE; + v->emit(BRW_OPCODE_MOV, v->reg_null_f, dest) + ->conditional_mod = BRW_CONDITIONAL_NZ; + + /* = Before = + * + * 0: cmp.ge.f0(8) dest src0 src1 + * 1: mov.nz.f0(8) null dest + * + * = After = + * 0: cmp.ge.f0(8) dest src0 src1 + */ + + v->calculate_cfg(); + bblock_t *block0 = v->cfg->blocks[0]; + + EXPECT_EQ(0, block0->start_ip); + EXPECT_EQ(1, block0->end_ip); + + EXPECT_TRUE(cmod_propagation(v)); + EXPECT_EQ(0, block0->start_ip); + EXPECT_EQ(0, block0->end_ip); + EXPECT_EQ(BRW_OPCODE_CMP, instruction(block0, 0)->opcode); + EXPECT_EQ(BRW_CONDITIONAL_GE, instruction(block0, 0)->conditional_mod); +} -- 2.0.4 _______________________________________________ mesa-dev mailing list <a href="mailto:mesa-dev@lists.freedesktop.org">mesa-dev@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/mesa-dev" target="_blank">http://lists.freedesktop.org/mailman/listinfo/mesa-dev</a> </blockquote></div> </div></div>