Skip to content

Drt layer preference sorting #10585

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

Draft
openroad-ci wants to merge 5 commits into
base: master
Choose a base branch
from
+31 −2
Draft

Drt layer preference sorting #10585

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
5 commits
Select commit Hold shift + click to select a range
e95e3a7
drt: access point sorting is done on the preffered direction of the i…
bnmfw May 27, 2026
2ef455b
Merge remote-tracking branch 'origin/master' into drt_layer_preferenc…
bnmfw May 27, 2026
07e0a51
Merge remote-tracking branch 'origin/master' into drt_layer_preferenc…
bnmfw Jun 1, 2026
8921ce2
drt: pin_acc_idx guard
bnmfw Jun 3, 2026
f09ba7d
Merge remote-tracking branch 'origin/master' into drt_layer_preferenc…
bnmfw Jun 3, 2026
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
1 change: 1 addition & 0 deletions src/drt/src/pa/FlexPA.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -721,6 +721,7 @@ class FlexPA
*
* @param unique_inst unique inst
*/
bool instPrefersHorizontal(frInst* unique_inst);
void prepPatternInst(frInst* unique_inst);

/**
Expand Down
32 changes: 30 additions & 2 deletions src/drt/src/pa/FlexPA_acc_pattern.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -82,14 +82,42 @@ void FlexPA::addToInstsSet(frInst* inst)
insts_set_.insert(inst);
}

bool FlexPA::instPrefersHorizontal(frInst* unique_inst)
{
const int pin_access_idx = unique_inst->getPinAccessIdx();
// Positive if most access points are on Horizontal layers, Negative if on
// Vertical Layers
if (pin_access_idx < 0) {
return true;
}
int layer_direction_bias = 0;
const auto tech = getDesign()->getTech();
for (auto& inst_term : unique_inst->getInstTerms()) {
if (isSkipInstTerm(inst_term.get())) {
continue;
}
for (auto& pin : inst_term->getTerm()->getPins()) {
for (auto& ap : pin->getPinAccess(pin_access_idx)->getAccessPoints()) {
if (tech->getLayer(ap->getLayerNum())->isHorizontal()) {
layer_direction_bias++;
} else {
layer_direction_bias--;
}
}
}
}
return layer_direction_bias >= 0;
}
Comment on lines +85 to +110

@gemini-code-assist gemini-code-assist Bot Jun 2, 2026

Copy link
Copy Markdown
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

high

To prevent potential crashes or undefined behavior, add defensive checks to ensure pin_access_idx is valid (non-negative) and that the retrieved pin_access pointer is not null before dereferencing it. Since pin_access_idx defaults to -1 when uninitialized, accessing it directly can lead to out-of-bounds memory access or null pointer dereferences.

bool FlexPA::instPrefersHorizontal(frInst* unique_inst)
{
  const int pin_access_idx = unique_inst->getPinAccessIdx();
  if (pin_access_idx < 0) {
    return true;
  }
  // Positive if most access points are on Horizontal layers, Negative if on
  // Vertical Layers
  int layer_direction_bias = 0;
  const auto tech = getDesign()->getTech();
  for (auto& inst_term : unique_inst->getInstTerms()) {
    if (isSkipInstTerm(inst_term.get())) {
      continue;
    }
    for (auto& pin : inst_term->getTerm()->getPins()) {
      auto pin_access = pin->getPinAccess(pin_access_idx);
      if (!pin_access) {
        continue;
      }
      for (auto& ap : pin_access->getAccessPoints()) {
        if (tech->getLayer(ap->getLayerNum())->isHorizontal()) {
          layer_direction_bias++;
        } else {
          layer_direction_bias--;
        }
      }
    }
  }
  return layer_direction_bias >= 0;
}


void FlexPA::prepPatternInst(frInst* unique_inst)
{
int num_valid_pattern = prepPatternInstHelper(unique_inst, true);
const bool prefer_x = !instPrefersHorizontal(unique_inst);
int num_valid_pattern = prepPatternInstHelper(unique_inst, prefer_x);

if (num_valid_pattern > 0) {
return;
}
num_valid_pattern = prepPatternInstHelper(unique_inst, false);
num_valid_pattern = prepPatternInstHelper(unique_inst, !prefer_x);

if (num_valid_pattern == 0) {
logger_->warn(DRT,
Expand Down
Loading