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Merged
kunalspathak merged 4 commits into from
Jul 8, 2021
Merged

Loop alignment: Handle blocks added in loop as part of split edges of LSRA #55047

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2565e4d
Handle blocks added in loop as part of split edges of LSRA
kunalspathak Jul 1, 2021
5d777fa
Retain LOOP_ALIGN flag of loops whose start are same
kunalspathak Jul 2, 2021
aae9dcd
jit format
kunalspathak Jul 2, 2021
cd2004c
review feedback
kunalspathak Jul 8, 2021
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jit format
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@kunalspathak
kunalspathak committed Jul 2, 2021
commit aae9dcd1921c85dd533c444cea2eb404420700d5
31 changes: 16 additions & 15 deletions src/coreclr/jit/emit.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1023,9 +1023,9 @@ void emitter::emitBegFN(bool hasFramePtr
emitIGbuffSize = 0;

#if FEATURE_LOOP_ALIGN
emitLastAlignedIgNum = 0;
emitLastLoopStart = 0;
emitLastLoopEnd = 0;
emitLastAlignedIgNum = 0;
emitLastLoopStart = 0;
emitLastLoopEnd = 0;
#endif

/* Record stack frame info (the temp size is just an estimate) */
Expand Down Expand Up @@ -4822,17 +4822,17 @@ unsigned emitter::getLoopSize(insGroup* igLoopHeader, unsigned maxLoopSize DEBUG
// Notes:
// Despite we align only inner most loop, we might see intersected loops because of control flow
// re-arrangement like adding a split edge in LSRA.
//
//
// If there is an intersection of current loop with last loop that is already marked as align,
// then *do not align* one of the loop that completely encloses the other one. Or if they both intersect,
// then *do not align* either of them because since the flow is complicated enough that aligning one of them
// will not improve the performance.
//
void emitter::emitSetLoopBackEdge(BasicBlock* loopTopBlock)
{
insGroup* dstIG = (insGroup*)loopTopBlock->bbEmitCookie;
bool noAlignCurrentLoop = false;
bool noAlignLastLoop = false;
insGroup* dstIG = (insGroup*)loopTopBlock->bbEmitCookie;
bool noAlignCurrentLoop = false;
bool noAlignLastLoop = false;

// With (dstIG != nullptr), ensure that only back edges are tracked.
// If there is forward jump, dstIG is not yet generated.
Expand Down Expand Up @@ -4867,17 +4867,16 @@ void emitter::emitSetLoopBackEdge(BasicBlock* loopTopBlock)
// |-----.
//
}
// else if current loop completely encloses last loop,
// then current loop should not be aligned.
else if ((currLoopStart < emitLastLoopStart) && (emitLastLoopEnd < currLoopEnd))
{
// if current loop completely encloses last loop,
// then current loop should not be aligned.
noAlignCurrentLoop = true;
}

// else if last loop completely encloses current loop,
// then last loop should not be aligned.
else if ((emitLastLoopStart < currLoopStart) && (currLoopEnd < emitLastLoopEnd))
{
// if last loop completely encloses current loop,
// then last loop should not be aligned.
noAlignLastLoop = true;
}
else
Expand All @@ -4889,7 +4888,7 @@ void emitter::emitSetLoopBackEdge(BasicBlock* loopTopBlock)

if (noAlignLastLoop || noAlignCurrentLoop)
{
instrDescAlign* alignInstr = emitAlignList;
instrDescAlign* alignInstr = emitAlignList;
bool markedLastLoop = !noAlignLastLoop;
bool markedCurrLoop = !noAlignCurrentLoop;
while ((alignInstr != nullptr))
Expand All @@ -4900,7 +4899,8 @@ void emitter::emitSetLoopBackEdge(BasicBlock* loopTopBlock)
assert(!markedCurrLoop);
alignInstr->idaIG->igFlags &= ~IGF_LOOP_ALIGN;
markedCurrLoop = true;
JITDUMP("** Skip alignment for current loop IG%02u ~ IG%02u because it encloses an aligned loop IG%02u ~ IG%02u.\n",
JITDUMP("** Skip alignment for current loop IG%02u ~ IG%02u because it encloses an aligned loop "
"IG%02u ~ IG%02u.\n",
currLoopStart, currLoopEnd, emitLastLoopStart, emitLastLoopEnd);
}

Expand All @@ -4912,7 +4912,8 @@ void emitter::emitSetLoopBackEdge(BasicBlock* loopTopBlock)
assert(alignInstr->idaIG->isLoopAlign());
alignInstr->idaIG->igFlags &= ~IGF_LOOP_ALIGN;
markedLastLoop = true;
JITDUMP("** Skip alignment for aligned loop IG%02u ~ IG%02u because it encloses the current loop IG%02u ~ IG%02u.\n",
JITDUMP("** Skip alignment for aligned loop IG%02u ~ IG%02u because it encloses the current loop "
"IG%02u ~ IG%02u.\n",
emitLastLoopStart, emitLastLoopEnd, currLoopStart, currLoopEnd);
}

Expand Down
12 changes: 6 additions & 6 deletions src/coreclr/jit/emit.h
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Expand Up @@ -1762,12 +1762,12 @@ class emitter
void emitJumpDistBind(); // Bind all the local jumps in method

#if FEATURE_LOOP_ALIGN
instrDescAlign* emitCurIGAlignList; // list of align instructions in current IG
unsigned emitLastLoopStart; // Start IG of last inner loop
unsigned emitLastLoopEnd; // End IG of last inner loop
unsigned emitLastAlignedIgNum; // last IG that has align instruction
instrDescAlign* emitAlignList; // list of local align instructions in method
instrDescAlign* emitAlignLast; // last align instruction in method
instrDescAlign* emitCurIGAlignList; // list of align instructions in current IG
unsigned emitLastLoopStart; // Start IG of last inner loop
unsigned emitLastLoopEnd; // End IG of last inner loop
unsigned emitLastAlignedIgNum; // last IG that has align instruction
instrDescAlign* emitAlignList; // list of local align instructions in method
instrDescAlign* emitAlignLast; // last align instruction in method
unsigned getLoopSize(insGroup* igLoopHeader,
unsigned maxLoopSize DEBUG_ARG(bool isAlignAdjusted)); // Get the smallest loop size
void emitLoopAlignment();
Expand Down