Use the last 7 bits to represent the discriminator to fit it in 1 byte ULEB128 (NFC).
From experiments, discriminator is rarely greater than 127. Here we enforce it to be no greater than 127 so that it will always fit in 1 byte.
llvm-svn: 286245
diff --git a/llvm/lib/Transforms/Utils/AddDiscriminators.cpp b/llvm/lib/Transforms/Utils/AddDiscriminators.cpp
index 66781ca..2e95926 100644
--- a/llvm/lib/Transforms/Utils/AddDiscriminators.cpp
+++ b/llvm/lib/Transforms/Utils/AddDiscriminators.cpp
@@ -188,12 +188,13 @@
continue;
// If we could insert more than one block with the same line+file, a
// discriminator is needed to distinguish both instructions.
- unsigned Discriminator = R.second ? ++LDM[L] : LDM[L];
+ // Only the lowest 7 bits are used to represent a discriminator to fit
+ // it in 1 byte ULEB128 representation.
+ unsigned Discriminator = (R.second ? ++LDM[L] : LDM[L]) & 0x7f;
I.setDebugLoc(DIL->cloneWithDiscriminator(Discriminator));
DEBUG(dbgs() << DIL->getFilename() << ":" << DIL->getLine() << ":"
- << DIL->getColumn() << ":"
- << Discriminator << " "
- << I << "\n");
+ << DIL->getColumn() << ":" << Discriminator << " " << I
+ << "\n");
Changed = true;
}
}
@@ -215,7 +216,8 @@
Location L =
std::make_pair(CurrentDIL->getFilename(), CurrentDIL->getLine());
if (!CallLocations.insert(L).second) {
- Current->setDebugLoc(CurrentDIL->cloneWithDiscriminator(++LDM[L]));
+ Current->setDebugLoc(
+ CurrentDIL->cloneWithDiscriminator((++LDM[L]) & 0x7f));
Changed = true;
}
}