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add tracking of control flow information

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Vern Paxson 2024-08-05 17:59:50 +01:00 • committed by Arne Welzel
parent e94764982d
commit a1185ee6bb
6 changed files with 144 additions and 24 deletions
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75
src/script_opt/ZAM/AM-Opt.cc
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@ -962,16 +962,75 @@ void ZAMCompiler::KillInst(zeek_uint_t i) {
}
}
if ( num_labels == 0 )
// No labels to propagate.
return;
ZInstI* succ = nullptr;
for ( auto j = i + 1; j < insts1.size(); ++j ) {
auto succ = insts1[j];
if ( succ->live ) {
succ->num_labels += num_labels;
break;
if ( num_labels > 0 ) {
for ( auto j = i + 1; j < insts1.size(); ++j ) {
if ( insts1[j]->live ) {
succ = insts1[j];
break;
}
}
if ( succ )
succ->num_labels += num_labels;
}
// Look into propagating control flow info.
if ( inst->aux && ! inst->aux->cft.empty() ) {
auto& cft = inst->aux->cft;
if ( cft.count(CFT_ELSE) > 0 ) {
// Push forward unless this was the end of the block.
if ( cft.count(CFT_BLOCK_END) == 0 ) {
ASSERT(succ);
AddCFT(succ, CFT_ELSE);
}
else
// But if it *was* the end of the block, remove that block.
--cft[CFT_BLOCK_END];
}
if ( cft.count(CFT_BREAK) > 0 ) {
// ### Factor this with the following
// Propagate breaks backwards.
int j = i;
while ( --j >= 0 )
if ( insts1[j]->live )
break;
ASSERT(j >= 0);
// Make sure the CFT entry is created.
AddCFT(insts1[j], CFT_BREAK);
auto be_cnt = cft[CFT_BREAK];
--be_cnt; // we already did one above
insts1[j]->aux->cft[CFT_BREAK] += be_cnt;
}
if ( cft.count(CFT_BLOCK_END) > 0 ) {
// Propagate block-ends backwards.
int j = i;
while ( --j >= 0 )
if ( insts1[j]->live )
break;
ASSERT(j >= 0);
// Make sure the CFT entry is created.
AddCFT(insts1[j], CFT_BLOCK_END);
auto be_cnt = cft[CFT_BLOCK_END];
--be_cnt; // we already did one above
insts1[j]->aux->cft[CFT_BLOCK_END] += be_cnt;
}
// If's can be killed because their bodies become empty,
// break's because they just lead to their following instruction,
// and next's if they become dead code.
// However, loop's and next's should not be killed.
ASSERT(cft.count(CFT_LOOP) == 0);
ASSERT(cft.count(CFT_LOOP_COND) == 0);
}
}