Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

JIT: Recompute test block weights after loop inversion #112197

Merged
merged 1 commit into from
Feb 6, 2025
Merged

JIT: Recompute test block weights after loop inversion #112197

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
35 changes: 14 additions & 21 deletions src/coreclr/jit/optimizer.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2240,13 +2240,6 @@ bool Compiler::optInvertWhileLoop(BasicBlock* block)
//
bNewCond->inheritWeight(block);

const weight_t totalWeight = bTest->bbWeight;

if (haveProfileWeights)
{
bTest->decreaseBBProfileWeight(block->bbWeight);
}

// Move all predecessor edges that look like loop entry edges to point to the new cloned condition
// block, not the existing condition block. The idea is that if we only move `block` to point to
// `bNewCond`, but leave other `bTest` predecessors still pointing to `bTest`, when we eventually
Expand Down Expand Up @@ -2281,14 +2274,6 @@ bool Compiler::optInvertWhileLoop(BasicBlock* block)
case BBJ_SWITCH:
case BBJ_EHFINALLYRET:
fgReplaceJumpTarget(predBlock, bTest, bNewCond);

// Redirect profile weight, too
if (haveProfileWeights)
{
const weight_t edgeWeight = predEdge->getLikelyWeight();
bNewCond->increaseBBProfileWeight(edgeWeight);
bTest->decreaseBBProfileWeight(edgeWeight);
}
break;

case BBJ_EHCATCHRET:
Expand All @@ -2302,13 +2287,21 @@ bool Compiler::optInvertWhileLoop(BasicBlock* block)
}
}

const weight_t loopWeight = bTest->bbWeight;
const weight_t nonLoopWeight = bNewCond->bbWeight;
if (haveProfileWeights && !fgProfileWeightsConsistent(totalWeight, loopWeight + nonLoopWeight))
if (haveProfileWeights)
{
JITDUMP("Redirecting flow from " FMT_BB " to " FMT_BB " introduced inconsistency. Data %s inconsistent.\n",
bTest->bbNum, bNewCond->bbNum, fgPgoConsistent ? "is now" : "was already");
fgPgoConsistent = false;
// The above change should have moved some flow out of 'bTest', and into 'bNewCond'.
// Check that no extraneous flow was lost or gained in the process.
//
const weight_t totalWeight = bTest->bbWeight;
bTest->setBBProfileWeight(bTest->computeIncomingWeight());
bNewCond->setBBProfileWeight(bNewCond->computeIncomingWeight());

if (!fgProfileWeightsConsistent(totalWeight, bTest->bbWeight + bNewCond->bbWeight))
{
JITDUMP("Redirecting flow from " FMT_BB " to " FMT_BB " introduced inconsistency. Data %s inconsistent.\n",
bTest->bbNum, bNewCond->bbNum, fgPgoConsistent ? "is now" : "was already");
fgPgoConsistent = false;
}
}

#ifdef DEBUG
Expand Down
Loading