From 40ae302a3c41d1aa839eb24c429888932f6fee53 Mon Sep 17 00:00:00 2001 From: Matt Turner Date: Tue, 30 Dec 2014 17:19:41 -0800 Subject: [PATCH] i965/fs: Add support for removing MOV.NZ instructions. For some reason, we occasionally write the flag register with a MOV.NZ 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 MOV.NZ 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 Reviewed-by: Kenneth Graunke --- .../dri/i965/brw_fs_cmod_propagation.cpp | 23 +++++++++++-- .../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 8a03315bc4c..ec9f812ea11 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)) continue; bool read_flag = false; @@ -73,6 +81,15 @@ opt_cmod_propagation_local(fs_visitor *v, bblock_t *block) scan_inst->dst.reg_offset != inst->src[0].reg_offset) break; + 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_swap_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 fefe515a216..fbe4fd90f86 100644 --- a/src/mesa/drivers/dri/i965/test_fs_cmod_propagation.cpp +++ b/src/mesa/drivers/dri/i965/test_fs_cmod_propagation.cpp @@ -383,3 +383,35 @@ TEST_F(cmod_propagation_test, negate) EXPECT_EQ(BRW_OPCODE_ADD, instruction(block0, 0)->opcode); EXPECT_EQ(BRW_CONDITIONAL_LE, instruction(block0, 0)->conditional_mod); } + +TEST_F(cmod_propagation_test, movnz) +{ + fs_reg dest = v->vgrf(glsl_type::float_type); + fs_reg src0 = v->vgrf(glsl_type::float_type); + fs_reg src1 = v->vgrf(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); +} -- 2.30.2