Fix Bug in RemoveDeadValues Pass #148437
Open
Fix Bug in RemoveDeadValues Pass #148437
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
Thank you for submitting a Pull Request (PR) to the LLVM Project! This PR will be automatically labeled and the relevant teams will be notified. If you wish to, you can add reviewers by using the "Reviewers" section on this page. If this is not working for you, it is probably because you do not have write permissions for the repository. In which case you can instead tag reviewers by name in a comment by using If you have received no comments on your PR for a week, you can request a review by "ping"ing the PR by adding a comment “Ping”. The common courtesy "ping" rate is once a week. Please remember that you are asking for valuable time from other developers. If you have further questions, they may be answered by the LLVM GitHub User Guide. You can also ask questions in a comment on this PR, on the LLVM Discord or on the forums. |
|
@llvm/pr-subscribers-mlir-core Author: None (ronigoldman22) ChangesThis patch fixes a bug in the RemoveDeadValues pass where unused function arguments were not removed from the function signature in an edge case where the function returns void. Full diff: https://github.com/llvm/llvm-project/pull/148437.diff 2 Files Affected:
diff --git a/mlir/lib/Transforms/RemoveDeadValues.cpp b/mlir/lib/Transforms/RemoveDeadValues.cpp
index 608bdcb948176..ddd5f2ba1a7b7 100644
--- a/mlir/lib/Transforms/RemoveDeadValues.cpp
+++ b/mlir/lib/Transforms/RemoveDeadValues.cpp
@@ -345,8 +345,6 @@ static void processFuncOp(FunctionOpInterface funcOp, Operation *module,
// since it forwards only to non-live value(s) (%1#1).
Operation *lastReturnOp = funcOp.back().getTerminator();
size_t numReturns = lastReturnOp->getNumOperands();
- if (numReturns == 0)
- return;
BitVector nonLiveRets(numReturns, true);
for (SymbolTable::SymbolUse use : uses) {
Operation *callOp = use.getUser();
@@ -368,6 +366,8 @@ static void processFuncOp(FunctionOpInterface funcOp, Operation *module,
cl.functions.push_back({funcOp, nonLiveArgs, nonLiveRets});
// Do (5) and (6).
+ if (numReturns == 0)
+ return;
for (SymbolTable::SymbolUse use : uses) {
Operation *callOp = use.getUser();
assert(isa<CallOpInterface>(callOp) && "expected a call-like user");
diff --git a/mlir/test/Transforms/remove-dead-values.mlir b/mlir/test/Transforms/remove-dead-values.mlir
index 3af95db3c0e24..dcaeefc3f2a6f 100644
--- a/mlir/test/Transforms/remove-dead-values.mlir
+++ b/mlir/test/Transforms/remove-dead-values.mlir
@@ -548,3 +548,43 @@ func.func @test_atomic_yield(%I: memref<10xf32>, %idx : index) {
func.return
}
+// CHECK-LABEL: module @return_void_with_unused_argument {
+// CHECK-LABEL: func.func private @noop() {
+// CHECK-NEXT: return
+// CHECK-NEXT: }
+// CHECK-LABEL: func.func private @fn_return_void_with_unused_argument(%arg0: memref<1x1xsi8, 1>, %arg1: memref<1x1xsi16, 1>) {
+// CHECK-NEXT: %alloc = memref.alloc() {alignment = 8 : i64} : memref<1x73xsi8, 3>
+// CHECK-NEXT: %alloc_0 = memref.alloc() {alignment = 8 : i64} : memref<1x1xsi16, 3>
+// CHECK-NEXT: %alloc_1 = memref.alloc() {alignment = 8 : i64} : memref<1x1xsi8, 3>
+// CHECK-NEXT: memref.copy %arg0, %alloc_1 : memref<1x1xsi8, 1> to memref<1x1xsi8, 3>
+// CHECK-NEXT: memref.copy %arg1, %alloc_0 : memref<1x1xsi16, 1> to memref<1x1xsi16, 3>
+// CHECK-NEXT: call @noop() : () -> ()
+// CHECK-NEXT: return
+// CHECK-NEXT: }
+// CHECK-LABEL: func.func @main(%arg0: memref<1x73xsi8, 1>, %arg1: memref<1x1xsi8, 1>, %arg2: memref<1x1xsi16, 1>) -> memref<1x73xsi8, 1> {
+// CHECK-NEXT: %alloc = memref.alloc() : memref<1x73xsi8, 1>
+// CHECK-NEXT: call @fn_return_void_with_unused_argument(%arg1, %arg2) : (memref<1x1xsi8, 1>, memref<1x1xsi16, 1>) -> ()
+// CHECK-NEXT: return %alloc : memref<1x73xsi8, 1>
+// CHECK-NEXT: }
+// CHECK-NEXT:}
+module @return_void_with_unused_argument {
+ func.func private @noop(%arg0: memref<1x1xsi8, 3>, %arg1: memref<1x1xsi16, 3>, %arg2: memref<1x73xsi8, 1>) {
+ return
+ }
+ func.func private @fn_return_void_with_unused_argument(%arg0: memref<1x73xsi8, 1> , %arg1: memref<1x1xsi8, 1> , %arg2: memref<1x1xsi16, 1> , %arg3: memref<1x73xsi8, 1>) {
+ %alloc = memref.alloc() {alignment = 8 : i64} : memref<1x73xsi8, 3>
+ %alloc_0 = memref.alloc() {alignment = 8 : i64} : memref<1x1xsi16, 3>
+ %alloc_1 = memref.alloc() {alignment = 8 : i64} : memref<1x1xsi8, 3>
+ memref.copy %arg1, %alloc_1 : memref<1x1xsi8, 1> to memref<1x1xsi8, 3>
+ memref.copy %arg2, %alloc_0 : memref<1x1xsi16, 1> to memref<1x1xsi16, 3>
+ call @noop(%alloc_1, %alloc_0, %arg0) :
+ (memref<1x1xsi8, 3>, memref<1x1xsi16, 3>, memref<1x73xsi8, 1>) -> ()
+ return
+ }
+ func.func @main(%arg0: memref<1x73xsi8, 1> , %arg1: memref<1x1xsi8, 1> , %arg2: memref<1x1xsi16, 1>) -> (memref<1x73xsi8, 1> ) {
+ %alloc = memref.alloc() : memref<1x73xsi8, 1>
+ call @fn_return_void_with_unused_argument(%arg0, %arg1, %arg2, %alloc) : (memref<1x73xsi8, 1>, memref<1x1xsi8, 1>, memref<1x1xsi16, 1>, memref<1x73xsi8, 1>) -> ()
+ return %alloc : memref<1x73xsi8, 1>
+ }
+}
+
|
|
@llvm/pr-subscribers-mlir Author: None (ronigoldman22) ChangesThis patch fixes a bug in the RemoveDeadValues pass where unused function arguments were not removed from the function signature in an edge case where the function returns void. Full diff: https://github.com/llvm/llvm-project/pull/148437.diff 2 Files Affected:
diff --git a/mlir/lib/Transforms/RemoveDeadValues.cpp b/mlir/lib/Transforms/RemoveDeadValues.cpp
index 608bdcb948176..ddd5f2ba1a7b7 100644
--- a/mlir/lib/Transforms/RemoveDeadValues.cpp
+++ b/mlir/lib/Transforms/RemoveDeadValues.cpp
@@ -345,8 +345,6 @@ static void processFuncOp(FunctionOpInterface funcOp, Operation *module,
// since it forwards only to non-live value(s) (%1#1).
Operation *lastReturnOp = funcOp.back().getTerminator();
size_t numReturns = lastReturnOp->getNumOperands();
- if (numReturns == 0)
- return;
BitVector nonLiveRets(numReturns, true);
for (SymbolTable::SymbolUse use : uses) {
Operation *callOp = use.getUser();
@@ -368,6 +366,8 @@ static void processFuncOp(FunctionOpInterface funcOp, Operation *module,
cl.functions.push_back({funcOp, nonLiveArgs, nonLiveRets});
// Do (5) and (6).
+ if (numReturns == 0)
+ return;
for (SymbolTable::SymbolUse use : uses) {
Operation *callOp = use.getUser();
assert(isa<CallOpInterface>(callOp) && "expected a call-like user");
diff --git a/mlir/test/Transforms/remove-dead-values.mlir b/mlir/test/Transforms/remove-dead-values.mlir
index 3af95db3c0e24..dcaeefc3f2a6f 100644
--- a/mlir/test/Transforms/remove-dead-values.mlir
+++ b/mlir/test/Transforms/remove-dead-values.mlir
@@ -548,3 +548,43 @@ func.func @test_atomic_yield(%I: memref<10xf32>, %idx : index) {
func.return
}
+// CHECK-LABEL: module @return_void_with_unused_argument {
+// CHECK-LABEL: func.func private @noop() {
+// CHECK-NEXT: return
+// CHECK-NEXT: }
+// CHECK-LABEL: func.func private @fn_return_void_with_unused_argument(%arg0: memref<1x1xsi8, 1>, %arg1: memref<1x1xsi16, 1>) {
+// CHECK-NEXT: %alloc = memref.alloc() {alignment = 8 : i64} : memref<1x73xsi8, 3>
+// CHECK-NEXT: %alloc_0 = memref.alloc() {alignment = 8 : i64} : memref<1x1xsi16, 3>
+// CHECK-NEXT: %alloc_1 = memref.alloc() {alignment = 8 : i64} : memref<1x1xsi8, 3>
+// CHECK-NEXT: memref.copy %arg0, %alloc_1 : memref<1x1xsi8, 1> to memref<1x1xsi8, 3>
+// CHECK-NEXT: memref.copy %arg1, %alloc_0 : memref<1x1xsi16, 1> to memref<1x1xsi16, 3>
+// CHECK-NEXT: call @noop() : () -> ()
+// CHECK-NEXT: return
+// CHECK-NEXT: }
+// CHECK-LABEL: func.func @main(%arg0: memref<1x73xsi8, 1>, %arg1: memref<1x1xsi8, 1>, %arg2: memref<1x1xsi16, 1>) -> memref<1x73xsi8, 1> {
+// CHECK-NEXT: %alloc = memref.alloc() : memref<1x73xsi8, 1>
+// CHECK-NEXT: call @fn_return_void_with_unused_argument(%arg1, %arg2) : (memref<1x1xsi8, 1>, memref<1x1xsi16, 1>) -> ()
+// CHECK-NEXT: return %alloc : memref<1x73xsi8, 1>
+// CHECK-NEXT: }
+// CHECK-NEXT:}
+module @return_void_with_unused_argument {
+ func.func private @noop(%arg0: memref<1x1xsi8, 3>, %arg1: memref<1x1xsi16, 3>, %arg2: memref<1x73xsi8, 1>) {
+ return
+ }
+ func.func private @fn_return_void_with_unused_argument(%arg0: memref<1x73xsi8, 1> , %arg1: memref<1x1xsi8, 1> , %arg2: memref<1x1xsi16, 1> , %arg3: memref<1x73xsi8, 1>) {
+ %alloc = memref.alloc() {alignment = 8 : i64} : memref<1x73xsi8, 3>
+ %alloc_0 = memref.alloc() {alignment = 8 : i64} : memref<1x1xsi16, 3>
+ %alloc_1 = memref.alloc() {alignment = 8 : i64} : memref<1x1xsi8, 3>
+ memref.copy %arg1, %alloc_1 : memref<1x1xsi8, 1> to memref<1x1xsi8, 3>
+ memref.copy %arg2, %alloc_0 : memref<1x1xsi16, 1> to memref<1x1xsi16, 3>
+ call @noop(%alloc_1, %alloc_0, %arg0) :
+ (memref<1x1xsi8, 3>, memref<1x1xsi16, 3>, memref<1x73xsi8, 1>) -> ()
+ return
+ }
+ func.func @main(%arg0: memref<1x73xsi8, 1> , %arg1: memref<1x1xsi8, 1> , %arg2: memref<1x1xsi16, 1>) -> (memref<1x73xsi8, 1> ) {
+ %alloc = memref.alloc() : memref<1x73xsi8, 1>
+ call @fn_return_void_with_unused_argument(%arg0, %arg1, %arg2, %alloc) : (memref<1x73xsi8, 1>, memref<1x1xsi8, 1>, memref<1x1xsi16, 1>, memref<1x73xsi8, 1>) -> ()
+ return %alloc : memref<1x73xsi8, 1>
+ }
+}
+
|
ftynse
requested changes
Jul 13, 2025
There was a problem hiding this comment.
Thanks for your patch, please make the test minimal and only checking the output relevant to the behavior being changed. In particular, never pattern-match specific SSA value names. See https://mlir.llvm.org/getting_started/TestingGuide/#contributor-guidelines.
ronigoldman22
force-pushed
the
fix-remove-dead-values-bug
branch
from
8dc188b to
6ee6862
Compare
joker-eph
approved these changes
Jul 14, 2025
ronigoldman22
force-pushed
the
fix-remove-dead-values-bug
branch
from
6ee6862 to
e116811
Compare
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This patch fixes a bug in the RemoveDeadValues pass where unused function arguments were not removed from the function signature in an edge case where the function returns void.
A corresponding test was added to the MLIR LIT test suite to cover this case.