Merge pull request #10655 from oharboe/rsz-deterministic-buffer-sizes

rsz: tie-break buffer size sort for deterministic output

Author: maliberty

src/rsz/src/Rebuffer.cc

@@ -1500,7 +1500,12 @@ void Rebuffer::init()
   }
 
   std::ranges::sort(buffer_sizes_, [=](BufferSize a, BufferSize b) {
-    return bufferCin(a.cell) < bufferCin(b.cell);
+    const float cin_a = bufferCin(a.cell);
+    const float cin_b = bufferCin(b.cell);
+    if (cin_a != cin_b) {
+      return cin_a < cin_b;
+    }
+    return a.cell->id() < b.cell->id();
   });
 
   buffer_sizes_index_.clear();

src/rsz/src/RepairDesign.cc

@@ -647,7 +647,12 @@ void RepairDesign::findBufferSizes()
                    resizer_->buffer_fast_sizes_.end()};
   std::ranges::sort(buffer_sizes_,
                     [=](sta::LibertyCell* a, sta::LibertyCell* b) {
-                      return bufferCin(a) < bufferCin(b);
+                      const float cin_a = bufferCin(a);
+                      const float cin_b = bufferCin(b);
+                      if (cin_a != cin_b) {
+                        return cin_a < cin_b;
+                      }
+                      return a->id() < b->id();
                     });
 }