[Mlir-commits] [mlir] 253f4bf - [mlir][LLVM] drop `llvm.intr.dbg.value` when promoting in `SROA` or `mem2reg`

[Markus Böck]

Author: Markus Böck
Date: 2023-07-04T17:15:23+02:00
New Revision: 253f4bfa87f30c6c4def3801fc1bce7b130a8795

URL: https://github.com/llvm/llvm-project/commit/253f4bfa87f30c6c4def3801fc1bce7b130a8795
DIFF: https://github.com/llvm/llvm-project/commit/253f4bfa87f30c6c4def3801fc1bce7b130a8795.diff

LOG: [mlir][LLVM] drop `llvm.intr.dbg.value` when promoting in `SROA` or `mem2reg`

This has previously been done for `llvm.intr.dbg.declare`, which is a common occurrence when the debug info points to the variable through the pointer, but may also occur when the `alloca` itself is a local variable in debug info.

Not doing so prevents `SROA` and `mem2reg` from promoting e.g. an `alloca`. We simply drop the value completetly, since there is no meaninful debug info that can be constructed instead as the pointer value is removed.

Differential Revision: https://reviews.llvm.org/D154451

Added: 
    

Modified: 
    mlir/include/mlir/Dialect/LLVMIR/LLVMIntrinsicOps.td
    mlir/lib/Dialect/LLVMIR/IR/LLVMMemorySlot.cpp
    mlir/test/Dialect/LLVMIR/mem2reg-dbginfo.mlir

Removed: 
    


################################################################################
diff  --git a/mlir/include/mlir/Dialect/LLVMIR/LLVMIntrinsicOps.td b/mlir/include/mlir/Dialect/LLVMIR/LLVMIntrinsicOps.td
index e8065daaf5da98..66edaab2ad5d47 100644
--- a/mlir/include/mlir/Dialect/LLVMIR/LLVMIntrinsicOps.td
+++ b/mlir/include/mlir/Dialect/LLVMIR/LLVMIntrinsicOps.td
@@ -571,7 +571,8 @@ def LLVM_DbgDeclareOp : LLVM_DbgIntrOp<"dbg.declare", "addr",
   let arguments = (ins LLVM_AnyPointer:$addr, LLVM_DILocalVariableAttr:$varInfo);
 }
 
-def LLVM_DbgValueOp : LLVM_DbgIntrOp<"dbg.value", "value"> {
+def LLVM_DbgValueOp : LLVM_DbgIntrOp<"dbg.value", "value",
+    [DeclareOpInterfaceMethods<PromotableOpInterface>]> {
   let summary = "Describes how the value relates to a source language variable.";
   let arguments = (ins LLVM_Type:$value, LLVM_DILocalVariableAttr:$varInfo);
 }

diff  --git a/mlir/lib/Dialect/LLVMIR/IR/LLVMMemorySlot.cpp b/mlir/lib/Dialect/LLVMIR/IR/LLVMMemorySlot.cpp
index 8248a1e08a25ce..241bfdb732dc42 100644
--- a/mlir/lib/Dialect/LLVMIR/IR/LLVMMemorySlot.cpp
+++ b/mlir/lib/Dialect/LLVMIR/IR/LLVMMemorySlot.cpp
@@ -260,6 +260,17 @@ DeletionKind LLVM::DbgDeclareOp::removeBlockingUses(
   return DeletionKind::Delete;
 }
 
+bool LLVM::DbgValueOp::canUsesBeRemoved(
+    const SmallPtrSetImpl<OpOperand *> &blockingUses,
+    SmallVectorImpl<OpOperand *> &newBlockingUses) {
+  return true;
+}
+
+DeletionKind LLVM::DbgValueOp::removeBlockingUses(
+    const SmallPtrSetImpl<OpOperand *> &blockingUses, RewriterBase &rewriter) {
+  return DeletionKind::Delete;
+}
+
 //===----------------------------------------------------------------------===//
 // Interfaces for GEPOp
 //===----------------------------------------------------------------------===//

diff  --git a/mlir/test/Dialect/LLVMIR/mem2reg-dbginfo.mlir b/mlir/test/Dialect/LLVMIR/mem2reg-dbginfo.mlir
index 0c1908ec8fdce2..b01fb55653612b 100644
--- a/mlir/test/Dialect/LLVMIR/mem2reg-dbginfo.mlir
+++ b/mlir/test/Dialect/LLVMIR/mem2reg-dbginfo.mlir
@@ -77,11 +77,13 @@ llvm.func @double_block_argument_value(%arg0: i64, %arg1: i1) -> i64 {
 
 // CHECK-LABEL: llvm.func @always_drop_promoted_declare
 // CHECK-NOT: = llvm.alloca
-// CHECK-NOT: llvm.intr.dbg.
+// CHECK-NOT: llvm.intr.dbg.declare
+// CHECK-NOT: llvm.intr.dbg.value
 llvm.func @always_drop_promoted_declare() {
   %0 = llvm.mlir.constant(1 : i32) : i32
   %1 = llvm.alloca %0 x i64 {alignment = 8 : i64} : (i32) -> !llvm.ptr
   llvm.intr.dbg.declare #di_local_variable = %1 : !llvm.ptr
+  llvm.intr.dbg.value #di_local_variable = %1 : !llvm.ptr
   llvm.return
 }