[Mlir-commits] [mlir] 765208b - [mlir] Make remove-dead-values remove block and successorOperands before delete ops (#166766)
llvmlistbot at llvm.org
llvmlistbot at llvm.org
Wed Nov 19 21:55:13 PST 2025
Author: lonely eagle
Date: 2025-11-20T13:55:09+08:00
New Revision: 765208b3131ce26dc5845babe86457e204f97c02
URL: https://github.com/llvm/llvm-project/commit/765208b3131ce26dc5845babe86457e204f97c02
DIFF: https://github.com/llvm/llvm-project/commit/765208b3131ce26dc5845babe86457e204f97c02.diff
LOG: [mlir] Make remove-dead-values remove block and successorOperands before delete ops (#166766)
Reland https://github.com/llvm/llvm-project/pull/165725, fix the Failed
test by removing successor operands before delete operations. Following
the deletion of cond.branch, its successor operands will subsequently be
removed.
Added:
Modified:
mlir/lib/Transforms/RemoveDeadValues.cpp
mlir/test/Transforms/remove-dead-values.mlir
Removed:
################################################################################
diff --git a/mlir/lib/Transforms/RemoveDeadValues.cpp b/mlir/lib/Transforms/RemoveDeadValues.cpp
index 41f3f9d76a3b1..989c614ef6617 100644
--- a/mlir/lib/Transforms/RemoveDeadValues.cpp
+++ b/mlir/lib/Transforms/RemoveDeadValues.cpp
@@ -742,7 +742,49 @@ static void processBranchOp(BranchOpInterface branchOp, RunLivenessAnalysis &la,
static void cleanUpDeadVals(RDVFinalCleanupList &list) {
LDBG() << "Starting cleanup of dead values...";
- // 1. Operations
+ // 1. Blocks, We must remove the block arguments and successor operands before
+ // deleting the operation, as they may reside in the region operation.
+ LDBG() << "Cleaning up " << list.blocks.size() << " block argument lists";
+ for (auto &b : list.blocks) {
+ // blocks that are accessed via multiple codepaths processed once
+ if (b.b->getNumArguments() != b.nonLiveArgs.size())
+ continue;
+ LDBG() << "Erasing " << b.nonLiveArgs.count()
+ << " non-live arguments from block: " << b.b;
+ // it iterates backwards because erase invalidates all successor indexes
+ for (int i = b.nonLiveArgs.size() - 1; i >= 0; --i) {
+ if (!b.nonLiveArgs[i])
+ continue;
+ LDBG() << " Erasing block argument " << i << ": " << b.b->getArgument(i);
+ b.b->getArgument(i).dropAllUses();
+ b.b->eraseArgument(i);
+ }
+ }
+
+ // 2. Successor Operands
+ LDBG() << "Cleaning up " << list.successorOperands.size()
+ << " successor operand lists";
+ for (auto &op : list.successorOperands) {
+ SuccessorOperands successorOperands =
+ op.branch.getSuccessorOperands(op.successorIndex);
+ // blocks that are accessed via multiple codepaths processed once
+ if (successorOperands.size() != op.nonLiveOperands.size())
+ continue;
+ LDBG() << "Erasing " << op.nonLiveOperands.count()
+ << " non-live successor operands from successor "
+ << op.successorIndex << " of branch: "
+ << OpWithFlags(op.branch, OpPrintingFlags().skipRegions());
+ // it iterates backwards because erase invalidates all successor indexes
+ for (int i = successorOperands.size() - 1; i >= 0; --i) {
+ if (!op.nonLiveOperands[i])
+ continue;
+ LDBG() << " Erasing successor operand " << i << ": "
+ << successorOperands[i];
+ successorOperands.erase(i);
+ }
+ }
+
+ // 3. Operations
LDBG() << "Cleaning up " << list.operations.size() << " operations";
for (auto &op : list.operations) {
LDBG() << "Erasing operation: "
@@ -751,14 +793,14 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
op->erase();
}
- // 2. Values
+ // 4. Values
LDBG() << "Cleaning up " << list.values.size() << " values";
for (auto &v : list.values) {
LDBG() << "Dropping all uses of value: " << v;
v.dropAllUses();
}
- // 3. Functions
+ // 5. Functions
LDBG() << "Cleaning up " << list.functions.size() << " functions";
// Record which function arguments were erased so we can shrink call-site
// argument segments for CallOpInterface operations (e.g. ops using
@@ -780,7 +822,7 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
(void)f.funcOp.eraseResults(f.nonLiveRets);
}
- // 4. Operands
+ // 6. Operands
LDBG() << "Cleaning up " << list.operands.size() << " operand lists";
for (OperationToCleanup &o : list.operands) {
// Handle call-specific cleanup only when we have a cached callee reference.
@@ -822,7 +864,7 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
}
}
- // 5. Results
+ // 7. Results
LDBG() << "Cleaning up " << list.results.size() << " result lists";
for (auto &r : list.results) {
LDBG() << "Erasing " << r.nonLive.count()
@@ -830,48 +872,6 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
<< OpWithFlags(r.op, OpPrintingFlags().skipRegions());
dropUsesAndEraseResults(r.op, r.nonLive);
}
-
- // 6. Blocks
- LDBG() << "Cleaning up " << list.blocks.size() << " block argument lists";
- for (auto &b : list.blocks) {
- // blocks that are accessed via multiple codepaths processed once
- if (b.b->getNumArguments() != b.nonLiveArgs.size())
- continue;
- LDBG() << "Erasing " << b.nonLiveArgs.count()
- << " non-live arguments from block: " << b.b;
- // it iterates backwards because erase invalidates all successor indexes
- for (int i = b.nonLiveArgs.size() - 1; i >= 0; --i) {
- if (!b.nonLiveArgs[i])
- continue;
- LDBG() << " Erasing block argument " << i << ": " << b.b->getArgument(i);
- b.b->getArgument(i).dropAllUses();
- b.b->eraseArgument(i);
- }
- }
-
- // 7. Successor Operands
- LDBG() << "Cleaning up " << list.successorOperands.size()
- << " successor operand lists";
- for (auto &op : list.successorOperands) {
- SuccessorOperands successorOperands =
- op.branch.getSuccessorOperands(op.successorIndex);
- // blocks that are accessed via multiple codepaths processed once
- if (successorOperands.size() != op.nonLiveOperands.size())
- continue;
- LDBG() << "Erasing " << op.nonLiveOperands.count()
- << " non-live successor operands from successor "
- << op.successorIndex << " of branch: "
- << OpWithFlags(op.branch, OpPrintingFlags().skipRegions());
- // it iterates backwards because erase invalidates all successor indexes
- for (int i = successorOperands.size() - 1; i >= 0; --i) {
- if (!op.nonLiveOperands[i])
- continue;
- LDBG() << " Erasing successor operand " << i << ": "
- << successorOperands[i];
- successorOperands.erase(i);
- }
- }
-
LDBG() << "Finished cleanup of dead values";
}
diff --git a/mlir/test/Transforms/remove-dead-values.mlir b/mlir/test/Transforms/remove-dead-values.mlir
index e7304505c809e..4bae85dcf4f7d 100644
--- a/mlir/test/Transforms/remove-dead-values.mlir
+++ b/mlir/test/Transforms/remove-dead-values.mlir
@@ -674,3 +674,16 @@ func.func @dead_value_loop_ivs_no_result(%lb: index, %ub: index, %step: index, %
}
return
}
+
+// -----
+
+// CHECK-LABEL: func @op_block_have_dead_arg
+func.func @op_block_have_dead_arg(%arg0: index, %arg1: index, %arg2: i1) {
+ scf.execute_region {
+ cf.cond_br %arg2, ^bb1(%arg0 : index), ^bb1(%arg1 : index)
+ ^bb1(%0: index):
+ scf.yield
+ }
+ // CHECK-NEXT: return
+ return
+}
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