97 lines
3.0 KiB
Diff
97 lines
3.0 KiB
Diff
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From 2aa7d268e2ce37025d68a3f428001f6f779f56e8 Mon Sep 17 00:00:00 2001
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From: Guy Harris <gharris@sonic.net>
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Date: Thu, 21 May 2020 23:36:09 -0700
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Subject: [PATCH 876/977] optimize: fix some of those changes.
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For loops with predecrements that we eliminated because we don't want to
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rely on the loop index going negative if it's zero before the
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predecrement - the index is now unsigned, so it'll *never go negative -
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we revert to a similar loop, but with the test checking whether the
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index is 0 and decrementing it as the first action in the loop body.
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(Yeah, it means that, on machines with condition codes, you don't get to
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use the condition code setting of the decrement "for free"; we'll let
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the compiler and the processor figure out how to do that efficiently.)
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---
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optimize.c | 35 ++++++++++++++++-------------------
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1 file changed, 16 insertions(+), 19 deletions(-)
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diff --git a/optimize.c b/optimize.c
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index bea8cdc..07fc0f3 100644
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--- a/optimize.c
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+++ b/optimize.c
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@@ -427,20 +427,18 @@ find_dom(opt_state_t *opt_state, struct block *root)
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*/
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x = opt_state->all_dom_sets;
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/*
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- * These are both guaranteed to be > 0, so the product is
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- * guaranteed to be > 0.
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- *
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- * XXX - but what if it overflows?
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+ * XXX - what if the multiplication overflows?
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*/
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i = opt_state->n_blocks * opt_state->nodewords;
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- do
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+ while (i != 0) {
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+ --i;
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*x++ = 0xFFFFFFFFU;
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- while (--i != 0);
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+ }
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/* Root starts off empty. */
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- i = opt_state->nodewords;
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- do
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+ for (i = opt_state->nodewords; i != 0;) {
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+ --i;
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root->dom[i] = 0;
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- while (--i != 0);
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+ }
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/* root->level is the highest level no found. */
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for (level = root->level; level >= 0; --level) {
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@@ -478,15 +476,12 @@ find_edom(opt_state_t *opt_state, struct block *root)
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x = opt_state->all_edge_sets;
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/*
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- * These are both guaranteed to be > 0, so the product is
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- * guaranteed to be > 0.
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- *
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- * XXX - but what if it overflows?
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+ * XXX - what if the multiplication overflows?
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*/
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- i = opt_state->n_edges * opt_state->edgewords;
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- do
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+ for (i = opt_state->n_edges * opt_state->edgewords; i != 0; ) {
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+ --i;
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x[i] = 0xFFFFFFFFU;
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- while (--i != 0);
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+ }
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/* root->level is the highest level no found. */
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memset(root->et.edom, 0, opt_state->edgewords * sizeof(*(uset)0));
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@@ -2138,17 +2133,19 @@ link_inedge(struct edge *parent, struct block *child)
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static void
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find_inedges(opt_state_t *opt_state, struct block *root)
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{
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+ u_int i;
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+ int level;
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struct block *b;
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- for (u_int i = 0; i < opt_state->n_blocks; ++i)
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+ for (i = 0; i < opt_state->n_blocks; ++i)
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opt_state->blocks[i]->in_edges = 0;
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/*
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* Traverse the graph, adding each edge to the predecessor
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* list of its successors. Skip the leaves (i.e. level 0).
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*/
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- for (int i = root->level; i > 0; --i) {
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- for (b = opt_state->levels[i]; b != 0; b = b->link) {
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+ for (level = root->level; level > 0; --level) {
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+ for (b = opt_state->levels[level]; b != 0; b = b->link) {
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link_inedge(&b->et, JT(b));
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link_inedge(&b->ef, JF(b));
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}
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--
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1.8.3.1
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