release/19.x: [RemoveDIs] Simplify spliceDebugInfo, fixing splice-to-end edge case (#105670) #106690
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@SLTozer What do you think about merging this PR to the release branch? |
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@llvm/pr-subscribers-llvm-ir Author: None (llvmbot) ChangesBackport f581553 Requested by: @OCHyams Full diff: https://github.com/llvm/llvm-project/pull/106690.diff 2 Files Affected:
diff --git a/llvm/lib/IR/BasicBlock.cpp b/llvm/lib/IR/BasicBlock.cpp
index bf19934da047c4..0a9498f051cb59 100644
--- a/llvm/lib/IR/BasicBlock.cpp
+++ b/llvm/lib/IR/BasicBlock.cpp
@@ -961,9 +961,13 @@ void BasicBlock::spliceDebugInfoImpl(BasicBlock::iterator Dest, BasicBlock *Src,
// Detach the marker at Dest -- this lets us move the "====" DbgRecords
// around.
DbgMarker *DestMarker = nullptr;
- if (Dest != end()) {
- if ((DestMarker = getMarker(Dest)))
+ if ((DestMarker = getMarker(Dest))) {
+ if (Dest == end()) {
+ assert(DestMarker == getTrailingDbgRecords());
+ deleteTrailingDbgRecords();
+ } else {
DestMarker->removeFromParent();
+ }
}
// If we're moving the tail range of DbgRecords (":::"), absorb them into the
@@ -1005,22 +1009,14 @@ void BasicBlock::spliceDebugInfoImpl(BasicBlock::iterator Dest, BasicBlock *Src,
} else {
// Insert them right at the start of the range we moved, ahead of First
// and the "++++" DbgRecords.
+ // This also covers the rare circumstance where we insert at end(), and we
+ // did not generate the iterator with begin() / getFirstInsertionPt(),
+ // meaning any trailing debug-info at the end of the block would
+ // "normally" have been pushed in front of "First". We move it there now.
DbgMarker *FirstMarker = createMarker(First);
FirstMarker->absorbDebugValues(*DestMarker, true);
}
DestMarker->eraseFromParent();
- } else if (Dest == end() && !InsertAtHead) {
- // In the rare circumstance where we insert at end(), and we did not
- // generate the iterator with begin() / getFirstInsertionPt(), it means
- // any trailing debug-info at the end of the block would "normally" have
- // been pushed in front of "First". Move it there now.
- DbgMarker *TrailingDbgRecords = getTrailingDbgRecords();
- if (TrailingDbgRecords) {
- DbgMarker *FirstMarker = createMarker(First);
- FirstMarker->absorbDebugValues(*TrailingDbgRecords, true);
- TrailingDbgRecords->eraseFromParent();
- deleteTrailingDbgRecords();
- }
}
}
diff --git a/llvm/unittests/IR/BasicBlockDbgInfoTest.cpp b/llvm/unittests/IR/BasicBlockDbgInfoTest.cpp
index 91a0745a0cc76e..835780e63aaf4f 100644
--- a/llvm/unittests/IR/BasicBlockDbgInfoTest.cpp
+++ b/llvm/unittests/IR/BasicBlockDbgInfoTest.cpp
@@ -141,11 +141,11 @@ TEST(BasicBlockDbgInfoTest, SplitBasicBlockBefore) {
Function *F = M->getFunction("func");
BasicBlock &BB = F->getEntryBlock();
- auto I = std::prev(BB.end(), 2);
+ auto I = std::prev(BB.end(), 2); // store i32 2, ptr %1.
BB.splitBasicBlockBefore(I, "before");
BasicBlock &BBBefore = F->getEntryBlock();
- auto I2 = std::prev(BBBefore.end(), 2);
+ auto I2 = std::prev(BBBefore.end()); // br label %1 (new).
ASSERT_TRUE(I2->hasDbgRecords());
}
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SLTozer
approved these changes
Aug 30, 2024
…lvm#105670) Not quite NFC, fixes splitBasicBlockBefore case when we split before an instruction with debug records (but without the headBit set, i.e., we are splitting before the instruction but after the debug records that come before it). splitBasicBlockBefore splices the instructions before the split point into a new block. Prior to this patch, the debug records would get shifted up to the front of the spliced instructions (as seen in the modified unittest - I believe the unittest was checking erroneous behaviour). We instead want to leave those debug records at the end of the spliced instructions. The functionality of the deleted `else if` branch is covered by the remaining `if` now that `DestMarker` is set to the trailing marker if `Dest` is `end()`. Previously the "===" markers were sometimes detached, now we always detach them and always reattach them. Note: `deleteTrailingDbgRecords` only "unlinks" the tailing marker from the block, it doesn't delete anything. The trailing marker is still cleaned up properly inside the final `if` body with `DestMarker->eraseFromParent();`. Part 1 of 2 needed for llvm#105571 (cherry picked from commit f581553)
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@OCHyams (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR. |
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Backport f581553
Requested by: @OCHyams