[Beignet] [PATCH] GBE: Optimize extraLiveOut register info.
Zhigang Gong
zhigang.gong at gmail.com
Mon Jun 6 03:18:33 UTC 2016
This patch LGTM, thx.
On Thu, Jun 2, 2016 at 10:21 AM, Ruiling Song <ruiling.song at intel.com>
wrote:
> extraLiveout anlysis is used to detect registers defined in loop and
> used out-of the loop. Previous logic may also include registers defined
> BEFORE loop and live-through loop as extraLiveout, which is not accurate.
> As the extraLiveout registers will be forced as non-uniform, which may
> waste some register space. Excluding registers that are defined before loop
> while used out-of loop will make such registers get correct
> uniform/non-uniform
> information. This would benefit some gemm cl kernel.
>
> also fix a small issue: do intersection when the exit-block has more
> than one predecessors.
>
> Signed-off-by: Ruiling Song <ruiling.song at intel.com>
> ---
> backend/src/ir/function.cpp | 4 ++--
> backend/src/ir/function.hpp | 7 ++++---
> backend/src/ir/liveness.cpp | 25 +++++++++++++++++++++---
> backend/src/llvm/llvm_gen_backend.cpp | 36
> ++++++-----------------------------
> 4 files changed, 34 insertions(+), 38 deletions(-)
>
> diff --git a/backend/src/ir/function.cpp b/backend/src/ir/function.cpp
> index 3b7891b..4112f06 100644
> --- a/backend/src/ir/function.cpp
> +++ b/backend/src/ir/function.cpp
> @@ -62,8 +62,8 @@ namespace ir {
> return unit.getPointerFamily();
> }
>
> - void Function::addLoop(const vector<LabelIndex> &bbs, const
> vector<std::pair<LabelIndex, LabelIndex>> &exits) {
> - loops.push_back(GBE_NEW(Loop, bbs, exits));
> + void Function::addLoop(LabelIndex preheader, const vector<LabelIndex>
> &bbs, const vector<std::pair<LabelIndex, LabelIndex>> &exits) {
> + loops.push_back(GBE_NEW(Loop, preheader, bbs, exits));
> }
>
> void Function::checkEmptyLabels(void) {
> diff --git a/backend/src/ir/function.hpp b/backend/src/ir/function.hpp
> index 5785bee..6a90767 100644
> --- a/backend/src/ir/function.hpp
> +++ b/backend/src/ir/function.hpp
> @@ -273,8 +273,9 @@ namespace ir {
> struct Loop : public NonCopyable
> {
> public:
> - Loop(const vector<LabelIndex> &in, const vector<std::pair<LabelIndex,
> LabelIndex>> &exit) :
> - bbs(in), exits(exit) {}
> + Loop(LabelIndex pre, const vector<LabelIndex> &in, const
> vector<std::pair<LabelIndex, LabelIndex>> &exit) :
> + preheader(pre), bbs(in), exits(exit) {}
> + LabelIndex preheader;
> vector<LabelIndex> bbs;
> vector<std::pair<LabelIndex, LabelIndex>> exits;
> GBE_STRUCT(Loop);
> @@ -522,7 +523,7 @@ namespace ir {
> /*! Push stack size. */
> INLINE void pushStackSize(uint32_t step) { this->stackSize += step; }
> /*! add the loop info for later liveness analysis */
> - void addLoop(const vector<LabelIndex> &bbs, const
> vector<std::pair<LabelIndex, LabelIndex>> &exits);
> + void addLoop(LabelIndex preheader, const vector<LabelIndex> &bbs,
> const vector<std::pair<LabelIndex, LabelIndex>> &exits);
> INLINE const vector<Loop * > &getLoops() { return loops; }
> vector<BasicBlock *> &getBlocks() { return blocks; }
> /*! Get surface starting address register from bti */
> diff --git a/backend/src/ir/liveness.cpp b/backend/src/ir/liveness.cpp
> index d48f067..4a89a73 100644
> --- a/backend/src/ir/liveness.cpp
> +++ b/backend/src/ir/liveness.cpp
> @@ -217,19 +217,38 @@ namespace ir {
> if(loops.size() == 0) return;
>
> for (auto l : loops) {
> + const BasicBlock &preheader = fn.getBlock(l->preheader);
> + BlockInfo *preheaderInfo = liveness[&preheader];
> for (auto x : l->exits) {
> const BasicBlock &a = fn.getBlock(x.first);
> const BasicBlock &b = fn.getBlock(x.second);
> BlockInfo * exiting = liveness[&a];
> BlockInfo * exit = liveness[&b];
> std::vector<Register> toExtend;
> + std::vector<Register> toExtendCand;
>
> - if(b.getPredecessorSet().size() > 1) {
> + if(b.getPredecessorSet().size() <= 1) {
> + // the exits only have one predecessor
> for (auto p : exit->upwardUsed)
> - toExtend.push_back(p);
> + toExtendCand.push_back(p);
> } else {
> - std::set_intersection(exiting->liveOut.begin(),
> exiting->liveOut.end(), exit->upwardUsed.begin(), exit->upwardUsed.end(),
> std::back_inserter(toExtend));
> + // the exits have more than one predecessors
> + std::set_intersection(exiting->liveOut.begin(),
> + exiting->liveOut.end(),
> + exit->upwardUsed.begin(),
> + exit->upwardUsed.end(),
> + std::back_inserter(toExtendCand));
> }
> + // toExtendCand may contain some virtual register defined before
> loop,
> + // which need to be excluded. Because what we need is registers
> defined
> + // in the loop. Such kind of registers must be in live-out of the
> loop's
> + // preheader. So we do the subtraction here.
> + std::set_difference(toExtendCand.begin(),
> + toExtendCand.end(),
> + preheaderInfo->liveOut.begin(),
> + preheaderInfo->liveOut.end(),
> + std::back_inserter(toExtend));
> +
> if (toExtend.size() == 0) continue;
> for(auto r : toExtend)
> extentRegs.insert(r);
> diff --git a/backend/src/llvm/llvm_gen_backend.cpp
> b/backend/src/llvm/llvm_gen_backend.cpp
> index acad1b2..0b44f24 100644
> --- a/backend/src/llvm/llvm_gen_backend.cpp
> +++ b/backend/src/llvm/llvm_gen_backend.cpp
> @@ -2737,35 +2737,6 @@ namespace gbe
> std::vector<std::pair<Loop*, int>> lp;
>
> findAllLoops(LI, lp);
> -#if GBE_DEBUG
> - // check two loops' interference
> - for(unsigned int i = 0; i < lp.size(); i++) {
> - SmallVector<Loop::Edge, 8> exitBBs;
> - lp[i].first->getExitEdges(exitBBs);
> -
> - const std::vector<BasicBlock*> &inBBs = lp[i].first->getBlocks();
> - std::vector<ir::LabelIndex> bbs1;
> - for(auto x : inBBs) {
> - bbs1.push_back(labelMap[x]);
> - }
> - std::sort(bbs1.begin(), bbs1.end());
> - for(unsigned int j = i+1; j < lp.size(); j++) {
> - if(! lp[i].first->contains(lp[j].first)) {
> - const std::vector<BasicBlock*> &inBBs2 =
> lp[j].first->getBlocks();
> - std::vector<ir::LabelIndex> bbs2;
> - std::vector<ir::LabelIndex> bbs3;
> -
> - for(auto x : inBBs2) {
> - bbs2.push_back(labelMap[x]);
> - }
> -
> - std::sort(bbs2.begin(), bbs2.end());
> - std::set_intersection(bbs1.begin(), bbs1.end(), bbs2.begin(),
> bbs2.end(), std::back_inserter(bbs3));
> - GBE_ASSERT(bbs3.size() < 1);
> - }
> - }
> - }
> -#endif
>
> for (auto loop : lp) {
> loopBBs.clear();
> @@ -2776,6 +2747,11 @@ namespace gbe
> GBE_ASSERT(labelMap.find(b) != labelMap.end());
> loopBBs.push_back(labelMap[b]);
> }
> + BasicBlock *preheader = loop.first->getLoopPreheader();
> + ir::LabelIndex preheaderBB(0);
> + if (preheader) {
> + preheaderBB = labelMap[preheader];
> + }
>
> SmallVector<Loop::Edge, 8> exitBBs;
> loop.first->getExitEdges(exitBBs);
> @@ -2784,7 +2760,7 @@ namespace gbe
> GBE_ASSERT(labelMap.find(b.second) != labelMap.end());
> loopExits.push_back(std::make_pair(labelMap[b.first],
> labelMap[b.second]));
> }
> - fn.addLoop(loopBBs, loopExits);
> + fn.addLoop(preheaderBB, loopBBs, loopExits);
> }
> }
>
> --
> 2.4.1
>
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