[Mlir-commits] [mlir] [mlir] Make remove-dead-values remove block and successorOperands before delete ops (PR #166766)
lonely eagle
llvmlistbot at llvm.org
Thu Nov 6 04:48:29 PST 2025
https://github.com/linuxlonelyeagle created https://github.com/llvm/llvm-project/pull/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.
>From ca81fd7142de5f8ec70f9a1bf773492eda3ccfb9 Mon Sep 17 00:00:00 2001
From: linuxlonelyeagle <2020382038 at qq.com>
Date: Thu, 30 Oct 2025 14:29:51 +0000
Subject: [PATCH 1/3] Make-remove-dead-values-remove-block-first
---
mlir/lib/Transforms/RemoveDeadValues.cpp | 46 ++++++++++----------
mlir/test/Transforms/remove-dead-values.mlir | 15 +++++++
2 files changed, 38 insertions(+), 23 deletions(-)
diff --git a/mlir/lib/Transforms/RemoveDeadValues.cpp b/mlir/lib/Transforms/RemoveDeadValues.cpp
index 41f3f9d76a3b1..979b3965e4ba9 100644
--- a/mlir/lib/Transforms/RemoveDeadValues.cpp
+++ b/mlir/lib/Transforms/RemoveDeadValues.cpp
@@ -742,7 +742,25 @@ static void processBranchOp(BranchOpInterface branchOp, RunLivenessAnalysis &la,
static void cleanUpDeadVals(RDVFinalCleanupList &list) {
LDBG() << "Starting cleanup of dead values...";
- // 1. Operations
+ // 1. 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);
+ }
+ }
+
+ // 2. Operations
LDBG() << "Cleaning up " << list.operations.size() << " operations";
for (auto &op : list.operations) {
LDBG() << "Erasing operation: "
@@ -751,14 +769,14 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
op->erase();
}
- // 2. Values
+ // 3. Values
LDBG() << "Cleaning up " << list.values.size() << " values";
for (auto &v : list.values) {
LDBG() << "Dropping all uses of value: " << v;
v.dropAllUses();
}
- // 3. Functions
+ // 4. 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 +798,7 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
(void)f.funcOp.eraseResults(f.nonLiveRets);
}
- // 4. Operands
+ // 5. 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 +840,7 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
}
}
- // 5. Results
+ // 6. Results
LDBG() << "Cleaning up " << list.results.size() << " result lists";
for (auto &r : list.results) {
LDBG() << "Erasing " << r.nonLive.count()
@@ -831,24 +849,6 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
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";
diff --git a/mlir/test/Transforms/remove-dead-values.mlir b/mlir/test/Transforms/remove-dead-values.mlir
index e7304505c809e..8f56c656aa859 100644
--- a/mlir/test/Transforms/remove-dead-values.mlir
+++ b/mlir/test/Transforms/remove-dead-values.mlir
@@ -674,3 +674,18 @@ 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: i64, %arg1: i64, %arg2: i64, %arg3: i1) {
+ omp.wsloop {
+ omp.loop_nest (%arg4) : i64 = (%arg0) to (%arg1) step (%arg2) {
+ cf.cond_br %arg3, ^bb1(%arg0 : i64), ^bb1(%arg1 : i64)
+ ^bb1(%0: i64):
+ omp.yield
+ }
+ }
+// CHECK-NEXT: return
+ return
+}
>From dd2592520eed27eb9d12b20e236e8a6d75e7c115 Mon Sep 17 00:00:00 2001
From: linuxlonelyeagle <2020382038 at qq.com>
Date: Thu, 6 Nov 2025 07:27:15 +0000
Subject: [PATCH 2/3] update test.
---
mlir/test/Transforms/remove-dead-values.mlir | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/mlir/test/Transforms/remove-dead-values.mlir b/mlir/test/Transforms/remove-dead-values.mlir
index 8f56c656aa859..8b5ccdcf204dd 100644
--- a/mlir/test/Transforms/remove-dead-values.mlir
+++ b/mlir/test/Transforms/remove-dead-values.mlir
@@ -678,12 +678,12 @@ func.func @dead_value_loop_ivs_no_result(%lb: index, %ub: index, %step: index, %
// -----
// CHECK-LABEL: func @op_block_have_dead_arg
-func.func @op_block_have_dead_arg(%arg0: i64, %arg1: i64, %arg2: i64, %arg3: i1) {
- omp.wsloop {
- omp.loop_nest (%arg4) : i64 = (%arg0) to (%arg1) step (%arg2) {
- cf.cond_br %arg3, ^bb1(%arg0 : i64), ^bb1(%arg1 : i64)
- ^bb1(%0: i64):
- omp.yield
+func.func @op_block_have_dead_arg(%arg0: index, %arg1: index, %arg2: index, %arg3: i1) {
+ scf.for %iv = %arg0 to %arg1 step %arg2 {
+ scf.execute_region {
+ cf.cond_br %arg3, ^bb1(%arg0 : index), ^bb1(%arg1 : index)
+ ^bb1(%0: index):
+ scf.yield
}
}
// CHECK-NEXT: return
>From 06d74505bbb16df3638cf9f55cfab37c3aa0fafd Mon Sep 17 00:00:00 2001
From: linuxlonelyeagle <2020382038 at qq.com>
Date: Thu, 6 Nov 2025 12:41:28 +0000
Subject: [PATCH 3/3] move delete delete SuccessorOperands before delete op.
---
mlir/lib/Transforms/RemoveDeadValues.cpp | 57 ++++++++++++------------
1 file changed, 28 insertions(+), 29 deletions(-)
diff --git a/mlir/lib/Transforms/RemoveDeadValues.cpp b/mlir/lib/Transforms/RemoveDeadValues.cpp
index 979b3965e4ba9..872ec9738f26d 100644
--- a/mlir/lib/Transforms/RemoveDeadValues.cpp
+++ b/mlir/lib/Transforms/RemoveDeadValues.cpp
@@ -760,7 +760,30 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
}
}
- // 2. Operations
+ // 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: "
@@ -769,14 +792,14 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
op->erase();
}
- // 3. Values
+ // 4. Values
LDBG() << "Cleaning up " << list.values.size() << " values";
for (auto &v : list.values) {
LDBG() << "Dropping all uses of value: " << v;
v.dropAllUses();
}
- // 4. 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
@@ -798,7 +821,7 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
(void)f.funcOp.eraseResults(f.nonLiveRets);
}
- // 5. 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.
@@ -840,7 +863,7 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
}
}
- // 6. Results
+ // 7. Results
LDBG() << "Cleaning up " << list.results.size() << " result lists";
for (auto &r : list.results) {
LDBG() << "Erasing " << r.nonLive.count()
@@ -848,30 +871,6 @@ static void cleanUpDeadVals(RDVFinalCleanupList &list) {
<< OpWithFlags(r.op, OpPrintingFlags().skipRegions());
dropUsesAndEraseResults(r.op, r.nonLive);
}
-
- // 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";
}
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