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Hexagon (target/hexagon) Short-circuit packet HVX writes

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In certain cases, we can avoid the overhead of writing to future_VRegs
and write directly to VRegs.  We consider HVX reads/writes when computing
ctx->need_commit.  Then, we can early-exit from gen_commit_hvx.

Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230427230012.3800327-14-tsimpson@quicinc.com>
This commit is contained in:
Taylor Simpson 2023-04-27 16:00:04 -07:00
parent 455e169d7c
commit b85529854e
2 changed files with 50 additions and 2 deletions
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6
target/hexagon/genptr.c
View File

@ -1104,7 +1104,11 @@ static void gen_log_vreg_write_pair(DisasContext *ctx, intptr_t srcoff, int num,
static intptr_t get_result_qreg(DisasContext *ctx, int qnum)
{
return offsetof(CPUHexagonState, future_QRegs[qnum]);
if (ctx->need_commit) {
return offsetof(CPUHexagonState, future_QRegs[qnum]);
} else {
return offsetof(CPUHexagonState, QRegs[qnum]);
}
}
static void gen_vreg_load(DisasContext *ctx, intptr_t dstoff, TCGv src,

46
target/hexagon/translate.c
View File

@ -70,6 +70,10 @@ intptr_t ctx_future_vreg_off(DisasContext *ctx, int regnum,
{
intptr_t offset;
if (!ctx->need_commit) {
return offsetof(CPUHexagonState, VRegs[regnum]);
}
/* See if it is already allocated */
for (int i = 0; i < ctx->future_vregs_idx; i++) {
if (ctx->future_vregs_num[i] == regnum) {
@ -374,7 +378,7 @@ static bool need_commit(DisasContext *ctx)
return true;
}
if (pkt->num_insns == 1) {
if (pkt->num_insns == 1 && !pkt->pkt_has_hvx) {
return false;
}
@ -394,6 +398,40 @@ static bool need_commit(DisasContext *ctx)
}
}
/* Check for overlap between HVX reads and writes */
for (int i = 0; i < ctx->vreg_log_idx; i++) {
int vnum = ctx->vreg_log[i];
if (test_bit(vnum, ctx->vregs_read)) {
return true;
}
}
if (!bitmap_empty(ctx->vregs_updated_tmp, NUM_VREGS)) {
int i = find_first_bit(ctx->vregs_updated_tmp, NUM_VREGS);
while (i < NUM_VREGS) {
if (test_bit(i, ctx->vregs_read)) {
return true;
}
i = find_next_bit(ctx->vregs_updated_tmp, NUM_VREGS, i + 1);
}
}
if (!bitmap_empty(ctx->vregs_select, NUM_VREGS)) {
int i = find_first_bit(ctx->vregs_select, NUM_VREGS);
while (i < NUM_VREGS) {
if (test_bit(i, ctx->vregs_read)) {
return true;
}
i = find_next_bit(ctx->vregs_select, NUM_VREGS, i + 1);
}
}
/* Check for overlap between HVX predicate reads and writes */
for (int i = 0; i < ctx->qreg_log_idx; i++) {
int qnum = ctx->qreg_log[i];
if (test_bit(qnum, ctx->qregs_read)) {
return true;
}
}
return false;
}
@ -790,6 +828,12 @@ static void gen_commit_hvx(DisasContext *ctx)
{
int i;
/* Early exit if not needed */
if (!ctx->need_commit) {
g_assert(!pkt_has_hvx_store(ctx->pkt));
return;
}
/*
* for (i = 0; i < ctx->vreg_log_idx; i++) {
* int rnum = ctx->vreg_log[i];