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[pruned-liveness] Change PrunedLiveBlocks so that it can propagate multiple bits of liveness rather than just one.

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This is useful for making a form of PrunedLiveness that is sensitive to address
fields. I wired up the current PrunedLiveness to just use PrunedLiveBlocks with
num bits set to 1.
This commit is contained in:
Michael Gottesman
2022-08-19 15:16:22 -07:00
parent 0f1a132251
commit 04144d8214
2 changed files with 43 additions and 29 deletions
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22
lib/SIL/Utils/PrunedLiveness.cpp
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@@ -19,10 +19,11 @@ using namespace swift;
/// Mark blocks live during a reverse CFG traversal from one specific block
/// containing a user.
void PrunedLiveBlocks::computeUseBlockLiveness(SILBasicBlock *userBB) {
// If we are visiting this block, then it is not already LiveOut. Mark it
void PrunedLiveBlocks::computeUseBlockLiveness(SILBasicBlock *userBB,
unsigned bitNo) {
// If, we are visiting this block, then it is not already LiveOut. Mark it
// LiveWithin to indicate a liveness boundary within the block.
markBlockLive(userBB, LiveWithin);
markBlockLive(userBB, LiveWithin, bitNo);
SmallVector<SILBasicBlock *, 8> predBBWorklist({userBB});
while (!predBBWorklist.empty()) {
@@ -33,12 +34,12 @@ void PrunedLiveBlocks::computeUseBlockLiveness(SILBasicBlock *userBB) {
// Traversal terminates at any previously visited block, including the
// blocks initialized as definition blocks.
for (auto *predBB : bb->getPredecessorBlocks()) {
switch (getBlockLiveness(predBB)) {
switch (getBlockLiveness(predBB, bitNo)) {
case Dead:
predBBWorklist.push_back(predBB);
LLVM_FALLTHROUGH;
case LiveWithin:
markBlockLive(predBB, LiveOut);
markBlockLive(predBB, LiveOut, bitNo);
break;
case LiveOut:
break;
@@ -52,11 +53,12 @@ void PrunedLiveBlocks::computeUseBlockLiveness(SILBasicBlock *userBB) {
/// Return the updated liveness of the \p use block (LiveOut or LiveWithin).
///
/// Terminators are not live out of the block.
PrunedLiveBlocks::IsLive PrunedLiveBlocks::updateForUse(SILInstruction *user) {
PrunedLiveBlocks::IsLive PrunedLiveBlocks::updateForUse(SILInstruction *user,
unsigned bitNo) {
SWIFT_ASSERT_ONLY(seenUse = true);
auto *bb = user->getParent();
switch (getBlockLiveness(bb)) {
switch (getBlockLiveness(bb, bitNo)) {
case LiveOut:
return LiveOut;
case LiveWithin:
@@ -64,8 +66,8 @@ PrunedLiveBlocks::IsLive PrunedLiveBlocks::updateForUse(SILInstruction *user) {
case Dead: {
// This use block has not yet been marked live. Mark it and its predecessor
// blocks live.
computeUseBlockLiveness(bb);
return getBlockLiveness(bb);
computeUseBlockLiveness(bb, bitNo);
return getBlockLiveness(bb, bitNo);
}
}
llvm_unreachable("covered switch");
@@ -76,7 +78,7 @@ PrunedLiveBlocks::IsLive PrunedLiveBlocks::updateForUse(SILInstruction *user) {
//===----------------------------------------------------------------------===//
void PrunedLiveness::updateForUse(SILInstruction *user, bool lifetimeEnding) {
auto useBlockLive = liveBlocks.updateForUse(user);
auto useBlockLive = liveBlocks.updateForUse(user, 0);
// Record all uses of blocks on the liveness boundary. For blocks marked
// LiveWithin, the boundary is considered to be the last use in the block.
//