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Merged
AndyAyersMS merged 1 commit into from
Feb 3, 2023
Merged

JIT: remove cheap preds #81562

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38 changes: 1 addition & 37 deletions src/coreclr/jit/block.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -554,35 +554,6 @@ unsigned BasicBlock::dspPreds()
return count;
}

/*****************************************************************************
*
* Display the bbCheapPreds basic block list (the block predecessors).
* Returns the number of characters printed.
*/

unsigned BasicBlock::dspCheapPreds()
{
unsigned count = 0;
for (BasicBlockList* pred = bbCheapPreds; pred != nullptr; pred = pred->next)
{
if (count != 0)
{
printf(",");
count += 1;
}
printf(FMT_BB, pred->block->bbNum);
count += 4;

// Account for %02u only handling 2 digits, but we can display more than that.
unsigned digits = CountDigits(pred->block->bbNum);
if (digits > 2)
{
count += digits - 2;
}
}
return count;
}

//------------------------------------------------------------------------
// dspSuccs: Display the basic block successors.
//
Expand Down Expand Up @@ -731,14 +702,7 @@ void BasicBlock::dspBlockHeader(Compiler* compiler,
if (showPreds)
{
printf(", preds={");
if (compiler->fgCheapPredsValid)
{
dspCheapPreds();
}
else
{
dspPreds();
}
dspPreds();
printf("} succs={");
dspSuccs(compiler);
printf("}");
Expand Down
18 changes: 5 additions & 13 deletions src/coreclr/jit/block.h
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Expand Up @@ -665,7 +665,6 @@ struct BasicBlock : private LIR::Range

#ifdef DEBUG
void dspFlags(); // Print the flags
unsigned dspCheapPreds(); // Print the predecessors (bbCheapPreds)
unsigned dspPreds(); // Print the predecessors (bbPreds)
void dspSuccs(Compiler* compiler); // Print the successors. The 'compiler' argument determines whether EH
// regions are printed: see NumSucc() for details.
Expand Down Expand Up @@ -1052,16 +1051,11 @@ struct BasicBlock : private LIR::Range
unsigned short bbFPinVars; // number of inner enregistered FP vars
};

// Basic block predecessor lists. Early in compilation, some phases might need to compute "cheap" predecessor
// lists. These are stored in bbCheapPreds, computed by fgComputeCheapPreds(). If bbCheapPreds is valid,
// 'fgCheapPredsValid' will be 'true'. Later, the "full" predecessor lists are created by fgComputePreds(), stored
// Basic block predecessor lists. Predecessor lists are created by fgLinkBasicBlocks(), stored
// in 'bbPreds', and then maintained throughout compilation. 'fgComputePredsDone' will be 'true' after the
// full predecessor lists are created. See the comment at fgComputeCheapPreds() to see how those differ from
// the "full" variant.
union {
BasicBlockList* bbCheapPreds; // ptr to list of cheap predecessors (used before normal preds are computed)
flowList* bbPreds; // ptr to list of predecessors
};
// predecessor lists are created.
//
flowList* bbPreds; // ptr to list of predecessors

// PredEdges: convenience method for enabling range-based `for` iteration over predecessor edges, e.g.:
// for (flowList* const edge : block->PredEdges()) ...
Expand Down Expand Up @@ -1774,9 +1768,7 @@ inline BBArrayIterator BasicBlock::BBSuccList::end() const
// by Compiler::fgReorderBlocks()
//
// We have a simpler struct, BasicBlockList, which is simply a singly-linked
// list of blocks. This is used for various purposes, but one is as a "cheap"
// predecessor list, computed by fgComputeCheapPreds(), and stored as a list
// on BasicBlock pointed to by bbCheapPreds.
// list of blocks.

struct BasicBlockList
{
Expand Down
14 changes: 0 additions & 14 deletions src/coreclr/jit/compiler.cpp
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Expand Up @@ -8860,7 +8860,6 @@ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
* cVarDsc, dVarDsc : Display a local variable given a LclVarDsc* (call lvaDumpEntry()).
* cVars, dVars : Display the local variable table (call lvaTableDump()).
* cVarsFinal, dVarsFinal : Display the local variable table (call lvaTableDump(FINAL_FRAME_LAYOUT)).
* cBlockCheapPreds, dBlockCheapPreds : Display a block's cheap predecessors (call block->dspCheapPreds()).
* cBlockPreds, dBlockPreds : Display a block's predecessors (call block->dspPreds()).
* cBlockSuccs, dBlockSuccs : Display a block's successors (call block->dspSuccs(compiler)).
* cReach, dReach : Display all block reachability (call fgDispReach()).
Expand Down Expand Up @@ -8962,14 +8961,6 @@ void cVarsFinal(Compiler* comp)
comp->lvaTableDump(Compiler::FINAL_FRAME_LAYOUT);
}

void cBlockCheapPreds(Compiler* comp, BasicBlock* block)
{
static unsigned sequenceNumber = 0; // separate calls with a number to indicate this function has been called
printf("===================================================================== *BlockCheapPreds %u\n",
sequenceNumber++);
block->dspCheapPreds();
}

void cBlockPreds(Compiler* comp, BasicBlock* block)
{
static unsigned sequenceNumber = 0; // separate calls with a number to indicate this function has been called
Expand Down Expand Up @@ -9115,11 +9106,6 @@ void dBlockPreds(BasicBlock* block)
cBlockPreds(JitTls::GetCompiler(), block);
}

void dBlockCheapPreds(BasicBlock* block)
{
cBlockCheapPreds(JitTls::GetCompiler(), block);
}

void dBlockSuccs(BasicBlock* block)
{
cBlockSuccs(JitTls::GetCompiler(), block);
Expand Down
17 changes: 0 additions & 17 deletions src/coreclr/jit/compiler.h
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Expand Up @@ -4513,7 +4513,6 @@ class Compiler

bool fgModified; // True if the flow graph has been modified recently
bool fgComputePredsDone; // Have we computed the bbPreds list
bool fgCheapPredsValid; // Is the bbCheapPreds list valid?
bool fgDomsComputed; // Have we computed the dominator sets?
bool fgReturnBlocksComputed; // Have we computed the return blocks list?
bool fgOptimizedFinally; // Did we optimize any try-finallys?
Expand Down Expand Up @@ -5223,22 +5222,6 @@ class Compiler
//
void fgUpdateChangedFlowGraph(FlowGraphUpdates updates);

public:
// Compute the predecessors of the blocks in the control flow graph.
void fgComputePreds();

// Remove all predecessor information.
void fgRemovePreds();

// Compute the cheap flow graph predecessors lists. This is used in some early phases
// before the full predecessors lists are computed.
void fgComputeCheapPreds();

private:
void fgAddCheapPred(BasicBlock* block, BasicBlock* blockPred);

void fgRemoveCheapPred(BasicBlock* block, BasicBlock* blockPred);

public:
enum GCPollType
{
Expand Down
4 changes: 0 additions & 4 deletions src/coreclr/jit/fgbasic.cpp
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Expand Up @@ -23,9 +23,6 @@ void Compiler::fgInit()
/* We haven't yet computed the bbPreds lists */
fgComputePredsDone = false;

/* We haven't yet computed the bbCheapPreds lists */
fgCheapPredsValid = false;

/* We haven't yet computed the edge weight */
fgEdgeWeightsComputed = false;
fgHaveValidEdgeWeights = false;
Expand Down Expand Up @@ -641,7 +638,6 @@ void Compiler::fgReplacePred(BasicBlock* block, BasicBlock* oldPred, BasicBlock*
noway_assert(block != nullptr);
noway_assert(oldPred != nullptr);
noway_assert(newPred != nullptr);
assert(!fgCheapPredsValid);

bool modified = false;

Expand Down
23 changes: 3 additions & 20 deletions src/coreclr/jit/fgdiagnostic.cpp
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Expand Up @@ -1871,15 +1871,7 @@ void Compiler::fgTableDispBasicBlock(BasicBlock* block, int ibcColWidth /* = 0 *
// Display block predecessor list
//

unsigned charCnt;
if (fgCheapPredsValid)
{
charCnt = block->dspCheapPreds();
}
else
{
charCnt = block->dspPreds();
}
unsigned charCnt = block->dspPreds();

if (charCnt < 19)
{
Expand Down Expand Up @@ -2283,7 +2275,6 @@ void Compiler::fgDispBasicBlocks(BasicBlock* firstBlock, BasicBlock* lastBlock,
maxBlockNumWidth, "----");
printf("BBnum %*sBBid ref try hnd %s weight %*s%s lp [IL range] [jump]%*s [EH region] [flags]\n",
padWidth, "",
fgCheapPredsValid ? "cheap preds" :
(fgComputePredsDone ? "preds "
: " "),
((ibcColWidth > 0) ? ibcColWidth - 3 : 0), "", // Subtract 3 for the width of "IBC", printed next.
Expand Down Expand Up @@ -2504,11 +2495,6 @@ class BBPredsChecker
// the number of incoming edges for the block.
unsigned BBPredsChecker::CheckBBPreds(BasicBlock* block, unsigned curTraversalStamp)
{
if (comp->fgCheapPredsValid)
{
return 0;
}

if (!comp->fgComputePredsDone)
{
assert(block->bbPreds == nullptr);
Expand Down Expand Up @@ -2857,11 +2843,8 @@ void Compiler::fgDebugCheckBBlist(bool checkBBNum /* = false */, bool checkBBRef

if (block->bbCatchTyp == BBCT_FILTER)
{
if (!fgCheapPredsValid) // Don't check cheap preds
{
// A filter has no predecessors
assert(block->bbPreds == nullptr);
}
// A filter has no predecessors
assert(block->bbPreds == nullptr);
}

#if defined(FEATURE_EH_FUNCLETS)
Expand Down
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