Hexagon (target/hexagon) Enable more short-circuit packets (scalar core)
Look for read-after-write instead of overlap of reads and writes Here is an example with overalp but no read-after-write: 0x000200fc: 0x38103876 { R0 = add(R0,R1); R6 = add(R6,R7) } BEFORE: ---- 00000000000200fc mov_i32 loc2,$0x0 mov_i32 loc2,r0 add_i32 loc3,loc2,r1 mov_i32 loc2,loc3 mov_i32 loc4,$0x0 mov_i32 loc4,r6 add_i32 loc5,loc4,r7 mov_i32 loc4,loc5 mov_i32 r0,loc2 mov_i32 r6,loc4 AFTER: ---- 00000000000200fc add_i32 loc2,r0,r1 mov_i32 r0,loc2 add_i32 loc3,r6,r7 mov_i32 r6,loc3 We can also short-circuit packets with .new values by reading from the real destination instead of the temporary. 0x00020100: 0x78005ff3 { R19 = #0xff 0x00020104: 0x2002e204 if (cmp.eq(N19.new,R2)) jump:t PC+8 } BEFORE: ---- 0000000000020100 mov_i32 pc,$0x20108 mov_i32 loc8,$0x0 mov_i32 loc8,$0xff setcond_i32 loc10,loc8,r2,eq mov_i32 loc6,loc10 mov_i32 r19,loc8 add_i32 pkt_cnt,pkt_cnt,$0x2 add_i32 insn_cnt,insn_cnt,$0x4 brcond_i32 loc6,$0x0,eq,$L1 goto_tb $0x0 mov_i32 pc,$0x20108 exit_tb $0x7fbb54000040 set_label $L1 goto_tb $0x1 exit_tb $0x7fbb54000041 set_label $L0 exit_tb $0x7fbb54000043 AFTER: ---- 0000000000020100 mov_i32 pc,$0x20108 mov_i32 r19,$0xff setcond_i32 loc7,r19,r2,eq mov_i32 loc4,loc7 add_i32 pkt_cnt,pkt_cnt,$0x2 add_i32 insn_cnt,insn_cnt,$0x4 brcond_i32 loc4,$0x0,eq,$L1 goto_tb $0x0 mov_i32 pc,$0x20108 exit_tb $0x7f9764000040 set_label $L1 goto_tb $0x1 exit_tb $0x7f9764000041 set_label $L0 exit_tb $0x7f9764000043 Signed-off-by: Taylor Simpson <ltaylorsimpson@gmail.com> Reviewed-by: Brian Cain <bcain@quicinc.com> Message-Id: <20240201103340.119081-3-ltaylorsimpson@gmail.com> Signed-off-by: Brian Cain <bcain@quicinc.com>
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@ -1,5 +1,5 @@
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/*
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* Copyright(c) 2019-2023 Qualcomm Innovation Center, Inc. All Rights Reserved.
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* Copyright(c) 2019-2024 Qualcomm Innovation Center, Inc. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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@ -396,20 +396,8 @@ static bool need_commit(DisasContext *ctx)
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}
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}
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/* Check for overlap between register reads and writes */
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for (int i = 0; i < ctx->reg_log_idx; i++) {
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int rnum = ctx->reg_log[i];
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if (test_bit(rnum, ctx->regs_read)) {
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return true;
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}
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}
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/* Check for overlap between predicate reads and writes */
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for (int i = 0; i < ctx->preg_log_idx; i++) {
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int pnum = ctx->preg_log[i];
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if (test_bit(pnum, ctx->pregs_read)) {
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return true;
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}
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if (ctx->read_after_write) {
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return true;
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}
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/* Check for overlap between HVX reads and writes */
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@ -468,6 +456,7 @@ static void analyze_packet(DisasContext *ctx)
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{
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Packet *pkt = ctx->pkt;
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ctx->has_hvx_helper = false;
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ctx->read_after_write = false;
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for (int i = 0; i < pkt->num_insns; i++) {
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Insn *insn = &pkt->insn[i];
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ctx->insn = insn;
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@ -492,11 +481,9 @@ static void gen_start_packet(DisasContext *ctx)
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ctx->next_PC = next_PC;
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ctx->reg_log_idx = 0;
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bitmap_zero(ctx->regs_written, TOTAL_PER_THREAD_REGS);
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bitmap_zero(ctx->regs_read, TOTAL_PER_THREAD_REGS);
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bitmap_zero(ctx->predicated_regs, TOTAL_PER_THREAD_REGS);
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ctx->preg_log_idx = 0;
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bitmap_zero(ctx->pregs_written, NUM_PREGS);
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bitmap_zero(ctx->pregs_read, NUM_PREGS);
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ctx->future_vregs_idx = 0;
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ctx->tmp_vregs_idx = 0;
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ctx->vreg_log_idx = 0;
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@ -38,12 +38,10 @@ typedef struct DisasContext {
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int reg_log[REG_WRITES_MAX];
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int reg_log_idx;
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DECLARE_BITMAP(regs_written, TOTAL_PER_THREAD_REGS);
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DECLARE_BITMAP(regs_read, TOTAL_PER_THREAD_REGS);
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DECLARE_BITMAP(predicated_regs, TOTAL_PER_THREAD_REGS);
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int preg_log[PRED_WRITES_MAX];
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int preg_log_idx;
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DECLARE_BITMAP(pregs_written, NUM_PREGS);
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DECLARE_BITMAP(pregs_read, NUM_PREGS);
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uint8_t store_width[STORES_MAX];
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bool s1_store_processed;
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int future_vregs_idx;
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@ -68,6 +66,7 @@ typedef struct DisasContext {
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bool is_tight_loop;
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bool short_circuit;
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bool has_hvx_helper;
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bool read_after_write;
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TCGv new_value[TOTAL_PER_THREAD_REGS];
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TCGv new_pred_value[NUM_PREGS];
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TCGv pred_written;
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@ -88,13 +87,14 @@ static inline void ctx_log_pred_write(DisasContext *ctx, int pnum)
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static inline void ctx_log_pred_read(DisasContext *ctx, int pnum)
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{
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set_bit(pnum, ctx->pregs_read);
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if (test_bit(pnum, ctx->pregs_written)) {
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ctx->read_after_write = true;
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}
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}
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static inline void ctx_log_pred_read_new(DisasContext *ctx, int pnum)
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{
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g_assert(test_bit(pnum, ctx->pregs_written));
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set_bit(pnum, ctx->pregs_read);
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}
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static inline void ctx_log_reg_write(DisasContext *ctx, int rnum,
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@ -125,13 +125,14 @@ static inline void ctx_log_reg_write_pair(DisasContext *ctx, int rnum,
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static inline void ctx_log_reg_read(DisasContext *ctx, int rnum)
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{
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set_bit(rnum, ctx->regs_read);
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if (test_bit(rnum, ctx->regs_written)) {
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ctx->read_after_write = true;
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}
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}
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static inline void ctx_log_reg_read_new(DisasContext *ctx, int rnum)
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{
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g_assert(test_bit(rnum, ctx->regs_written));
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set_bit(rnum, ctx->regs_read);
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}
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static inline void ctx_log_reg_read_pair(DisasContext *ctx, int rnum)
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