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Fix loop cloning for OSR #67067

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merged 1 commit into from
Mar 24, 2022
Merged

Fix loop cloning for OSR #67067

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5 changes: 3 additions & 2 deletions src/coreclr/jit/loopcloning.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1904,13 +1904,14 @@ void Compiler::optCloneLoop(unsigned loopInd, LoopCloneContext* context)
// so that "h" already falls through to "e" (e == t).
// It might look like this code is unreachable, since "h" must be a BBJ_ALWAYS, but
// later we will change "h" to a BBJ_COND along with a set of loop conditions.
// TODO: it still might be unreachable, since cloning currently is restricted to "do-while" loop forms.
// Cloning is currently restricted to "do-while" loop forms, where this case won't occur.
// However, it can occur in OSR methods.
BasicBlock* h2 = nullptr;
if (h->bbNext != loop.lpEntry)
{
assert(h->bbJumpKind == BBJ_ALWAYS);
JITDUMP("Create branch to entry of optimized loop\n");
BasicBlock* h2 = fgNewBBafter(BBJ_ALWAYS, h, /*extendRegion*/ true);
h2 = fgNewBBafter(BBJ_ALWAYS, h, /*extendRegion*/ true);
JITDUMP("Adding " FMT_BB " after " FMT_BB "\n", h2->bbNum, h->bbNum);
h2->bbWeight = h2->isRunRarely() ? BB_ZERO_WEIGHT : ambientWeight;

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15 changes: 13 additions & 2 deletions src/coreclr/jit/optimizer.cpp
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Expand Up @@ -3023,12 +3023,23 @@ bool Compiler::optLoopContains(unsigned l1, unsigned l2) const
}
}

//-----------------------------------------------------------------------------
// optUpdateLoopHead: Replace the `head` block of a loop in the loop table.
// Considers all child loops that might share the same head (recursively).
//
// Arguments:
// loopInd -- loop num of loop
// from -- current loop head block
// to -- replacement loop head block
//
void Compiler::optUpdateLoopHead(unsigned loopInd, BasicBlock* from, BasicBlock* to)
{
assert(optLoopTable[loopInd].lpHead == from);
JITDUMP("Replace " FMT_LP " head " FMT_BB " with " FMT_BB "\n", loopInd, from->bbNum, to->bbNum);
optLoopTable[loopInd].lpHead = to;
for (unsigned char childLoop = optLoopTable[loopInd].lpChild; childLoop != BasicBlock::NOT_IN_LOOP;
childLoop = optLoopTable[childLoop].lpSibling)
for (unsigned char childLoop = optLoopTable[loopInd].lpChild; //
childLoop != BasicBlock::NOT_IN_LOOP; //
childLoop = optLoopTable[childLoop].lpSibling)
{
if (optLoopTable[childLoop].lpHead == from)
{
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