[Beignet] [PATCH V2 3/3] add local copy propagation optimization for each basic block
Guo Yejun
yejun.guo at intel.com
Thu Sep 10 17:50:49 PDT 2015
It is done at selection ir level, it removes MOV instructions
and helps to reduce the register pressure.
For instructions like:
MOV(8) %42<2>:UB : %53<32,8,4>:UB
ADD(8) %43<2>:B : %40<16,8,2>:B -%42<16,8,2>:B
can be optimized as:
ADD(8) %43<2>:UB : %56<32,8,4>:UB -%53<32,8,4>:UB
Signed-off-by: Guo Yejun <yejun.guo at intel.com>
---
backend/src/backend/gen_insn_selection.cpp | 4 +
backend/src/backend/gen_insn_selection.hpp | 2 +
.../src/backend/gen_insn_selection_optimize.cpp | 201 ++++++++++++++++++++-
3 files changed, 202 insertions(+), 5 deletions(-)
diff --git a/backend/src/backend/gen_insn_selection.cpp b/backend/src/backend/gen_insn_selection.cpp
index 28c7ed2..038b839 100644
--- a/backend/src/backend/gen_insn_selection.cpp
+++ b/backend/src/backend/gen_insn_selection.cpp
@@ -2062,6 +2062,10 @@ namespace gbe
///////////////////////////////////////////////////////////////////////////
// Code selection public implementation
///////////////////////////////////////////////////////////////////////////
+ const GenContext& Selection::getCtx()
+ {
+ return this->opaque->ctx;
+ }
Selection::Selection(GenContext &ctx) {
this->blockList = NULL;
diff --git a/backend/src/backend/gen_insn_selection.hpp b/backend/src/backend/gen_insn_selection.hpp
index 86542b0..275eb9c 100644
--- a/backend/src/backend/gen_insn_selection.hpp
+++ b/backend/src/backend/gen_insn_selection.hpp
@@ -271,6 +271,8 @@ namespace gbe
void optimize(void);
uint32_t opt_features;
+ const GenContext &getCtx();
+
/*! Use custom allocators */
GBE_CLASS(Selection);
};
diff --git a/backend/src/backend/gen_insn_selection_optimize.cpp b/backend/src/backend/gen_insn_selection_optimize.cpp
index c82fbe5..1c2f559 100644
--- a/backend/src/backend/gen_insn_selection_optimize.cpp
+++ b/backend/src/backend/gen_insn_selection_optimize.cpp
@@ -12,38 +12,229 @@
namespace gbe
{
+ //helper functions
+ static uint32_t CalculateElements(const GenRegister& reg, uint32_t execWidth)
+ {
+ uint32_t elements = 0;
+ uint32_t elementSize = typeSize(reg.type);
+ uint32_t width = GenRegister::width_size(reg);
+ assert(execWidth >= width);
+ uint32_t height = execWidth / width;
+ uint32_t vstride = GenRegister::vstride_size(reg);
+ uint32_t hstride = GenRegister::hstride_size(reg);
+ uint32_t base = reg.subnr;
+ for (uint32_t i = 0; i < height; ++i) {
+ uint32_t offsetInByte = base;
+ for (uint32_t j = 0; j < width; ++j) {
+ uint32_t offsetInType = offsetInByte / elementSize;
+ elements |= (1 << offsetInType);
+ offsetInByte += hstride * elementSize;
+ }
+ offsetInByte += vstride * elementSize;
+ }
+ return elements;
+ }
class SelOptimizer
{
public:
- SelOptimizer(uint32_t features) : features(features) {}
+ SelOptimizer(const GenContext& ctx, uint32_t features) : ctx(ctx), features(features) {}
virtual void run() = 0;
virtual ~SelOptimizer() {}
protected:
+ const GenContext &ctx; //in case that we need it
uint32_t features;
};
class SelBasicBlockOptimizer : public SelOptimizer
{
public:
- SelBasicBlockOptimizer(uint32_t features, SelectionBlock &bb) : SelOptimizer(features), bb(bb) {}
+ SelBasicBlockOptimizer(const GenContext& ctx,
+ const ir::Liveness::LiveOut& liveout,
+ uint32_t features,
+ SelectionBlock &bb) :
+ SelOptimizer(ctx, features), bb(bb), liveout(liveout), optimized(false)
+ {
+ }
~SelBasicBlockOptimizer() {}
virtual void run();
private:
+ // local copy propagation
+ class ReplaceInfo
+ {
+ public:
+ ReplaceInfo(SelectionInstruction& insn,
+ const GenRegister& intermedia,
+ const GenRegister& replacement,
+ uint32_t execWidth) :
+ insn(insn), intermedia(intermedia), replacement(replacement)
+ {
+ assert(insn.opcode == SEL_OP_MOV);
+ assert(&(insn.src(0)) == &replacement);
+ assert(&(insn.dst(0)) == &intermedia);
+ this->elements = CalculateElements(intermedia, execWidth);
+ replacementChanged = false;
+ }
+ ~ReplaceInfo()
+ {
+ this->toBeReplacements.clear();
+ }
+
+ SelectionInstruction& insn;
+ const GenRegister& intermedia;
+ uint32_t elements;
+ const GenRegister& replacement;
+ set<GenRegister*> toBeReplacements;
+ bool replacementChanged;
+ GBE_CLASS(ReplaceInfo);
+ };
+ set<ReplaceInfo*> replaceInfos;
+ void doLocalCopyPropagation();
+ void addToReplaceInfos(SelectionInstruction& insn);
+ void changeInsideReplaceInfos(const SelectionInstruction& insn, GenRegister& var);
+ void removeFromReplaceInfos(const GenRegister& var);
+ void doReplacement(ReplaceInfo* info);
+ void cleanReplaceInfos();
+ static void propagateRegister(GenRegister& dst, const GenRegister& src);
+
SelectionBlock &bb;
- static const size_t MaxTries = 1; //the times for optimization
+ const ir::Liveness::LiveOut& liveout;
+ bool optimized;
+ static const size_t MaxTries = 1; //the max times of optimization try
};
+ void SelBasicBlockOptimizer::propagateRegister(GenRegister& dst, const GenRegister& src)
+ {
+ dst.type = src.type;
+ dst.file = src.file;
+ dst.physical = src.physical;
+ dst.subphysical = src.subphysical;
+ dst.value.reg = src.value.reg;
+ dst.vstride = src.vstride;
+ dst.width = src.width;
+ dst.hstride = src.hstride;
+ dst.quarter = src.quarter;
+ dst.nr = src.nr;
+ dst.subnr = src.subnr;
+ dst.address_mode = src.address_mode;
+ dst.a0_subnr = src.a0_subnr;
+ dst.addr_imm = src.addr_imm;
+
+ dst.negation = dst.negation ^ src.negation;
+ dst.absolute = dst.absolute | src.absolute;
+ }
+
+ void SelBasicBlockOptimizer::doReplacement(ReplaceInfo* info)
+ {
+ for (GenRegister* reg : info->toBeReplacements) {
+ propagateRegister(*reg, info->replacement);
+ }
+ bb.insnList.erase(&(info->insn));
+ }
+
+ void SelBasicBlockOptimizer::cleanReplaceInfos()
+ {
+ for (ReplaceInfo* info : replaceInfos) {
+ doReplacement(info);
+ delete info;
+ }
+ replaceInfos.clear();
+ }
+
+ void SelBasicBlockOptimizer::removeFromReplaceInfos(const GenRegister& var)
+ {
+ for (set<ReplaceInfo*>::iterator pos = replaceInfos.begin(); pos != replaceInfos.end(); ) {
+ ReplaceInfo* info = *pos;
+ if (info->intermedia.reg() == var.reg()) {
+ if (info->intermedia.quarter == var.quarter && info->intermedia.subnr == var.subnr)
+ doReplacement(info);
+ replaceInfos.erase(pos++);
+ delete info;
+ }
+ else if (info->replacement.reg() == var.reg()) {
+ info->replacementChanged = true;
+ ++pos;
+ }
+ else
+ ++pos;
+ }
+ }
+
+ void SelBasicBlockOptimizer::addToReplaceInfos(SelectionInstruction& insn)
+ {
+ assert(insn.opcode == SEL_OP_MOV);
+ const GenRegister& src = insn.src(0);
+ const GenRegister& dst = insn.dst(0);
+ if (src.type != dst.type || src.file != dst.file)
+ return;
+
+ if (liveout.find(dst.reg()) != liveout.end())
+ return;
+
+ ReplaceInfo* info = new ReplaceInfo(insn, dst, src, insn.state.execWidth);
+ replaceInfos.insert(info);
+ }
+
+ void SelBasicBlockOptimizer::changeInsideReplaceInfos(const SelectionInstruction& insn, GenRegister& var)
+ {
+ for (ReplaceInfo* info : replaceInfos) {
+ if (info->intermedia.reg() == var.reg()) {
+ bool replaceable = false;
+ if (insn.opcode != SEL_OP_BSWAP && !insn.isWrite()) {
+ if (!info->replacementChanged && info->intermedia.type == var.type && info->intermedia.quarter == var.quarter && info->intermedia.subnr == var.subnr) {
+ uint32_t elements = CalculateElements(var, insn.state.execWidth);
+ if (info->elements == elements) {
+ info->toBeReplacements.insert(&var);
+ replaceable = true;
+ }
+ }
+ }
+
+ //if we found the same register, but could not be replaced for some reason,
+ //that means we could not remove MOV instruction, and so no replacement,
+ //so we'll remove the info for this case.
+ if (!replaceable) {
+ replaceInfos.erase(info);
+ delete info;
+ }
+ break;
+ }
+ }
+ }
+
+ void SelBasicBlockOptimizer::doLocalCopyPropagation()
+ {
+ for (SelectionInstruction &insn : bb.insnList) {
+ for (uint8_t i = 0; i < insn.srcNum; ++i)
+ changeInsideReplaceInfos(insn, insn.src(i));
+
+ for (uint8_t i = 0; i < insn.dstNum; ++i)
+ removeFromReplaceInfos(insn.dst(i));
+
+ if (insn.opcode == SEL_OP_MOV)
+ addToReplaceInfos(insn);
+ }
+ cleanReplaceInfos();
+ }
+
void SelBasicBlockOptimizer::run()
{
+ for (size_t i = 0; i < MaxTries; ++i) {
+ optimized = false;
+ doLocalCopyPropagation();
+ //doOtherLocalOptimization();
+
+ if (!optimized)
+ break; //break since no optimization found at this round
+ }
}
class SelGlobalOptimizer : public SelOptimizer
{
public:
- SelGlobalOptimizer(uint32_t features) : SelOptimizer(features) {}
+ SelGlobalOptimizer(const GenContext& ctx, uint32_t features) : SelOptimizer(ctx, features) {}
~SelGlobalOptimizer() {}
virtual void run();
};
@@ -57,7 +248,7 @@ namespace gbe
{
//do basic block level optimization
for (SelectionBlock &block : *blockList) {
- SelBasicBlockOptimizer bbopt(opt_features, block);
+ SelBasicBlockOptimizer bbopt(getCtx(), getCtx().getLiveOut(block.bb), opt_features, block);
bbopt.run();
}
--
1.9.1
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