[Mlir-commits] [mlir] 432745f - [MLIR][LLVMIR] Preserve byval alignment in memcpy after inlining (#185433)

[llvmlistbot at llvm.org]

Author: Berke Ates
Date: 2026-03-10T07:55:44+01:00
New Revision: 432745f24d06e46e24cfdaeeed2eb2274e2d4cc9

URL: https://github.com/llvm/llvm-project/commit/432745f24d06e46e24cfdaeeed2eb2274e2d4cc9
DIFF: https://github.com/llvm/llvm-project/commit/432745f24d06e46e24cfdaeeed2eb2274e2d4cc9.diff

LOG: [MLIR][LLVMIR] Preserve byval alignment in memcpy after inlining (#185433)

This PR adds alignment attributes to the generated memcpy intrinsics
after inlining functions with byval arguments.

Added: 
    

Modified: 
    mlir/lib/Dialect/LLVMIR/Transforms/InlinerInterfaceImpl.cpp
    mlir/test/Dialect/LLVMIR/inlining.mlir

Removed: 
    


################################################################################
diff  --git a/mlir/lib/Dialect/LLVMIR/Transforms/InlinerInterfaceImpl.cpp b/mlir/lib/Dialect/LLVMIR/Transforms/InlinerInterfaceImpl.cpp
index b61138ad4678b..680fafcc099f2 100644
--- a/mlir/lib/Dialect/LLVMIR/Transforms/InlinerInterfaceImpl.cpp
+++ b/mlir/lib/Dialect/LLVMIR/Transforms/InlinerInterfaceImpl.cpp
@@ -623,8 +623,18 @@ static Value handleByValArgumentInit(OpBuilder &builder, Location loc,
   Value copySize =
       LLVM::ConstantOp::create(builder, loc, builder.getI64Type(),
                                builder.getI64IntegerAttr(elementTypeSize));
+  // Preserve the alignment of the destination (alloca) in the memcpy's
+  // arg_attrs.
+  NamedAttribute dstAlignAttr =
+      builder.getNamedAttr(LLVM::LLVMDialect::getAlignAttrName(),
+                           builder.getI64IntegerAttr(targetAlignment));
+  ArrayAttr argAttrs =
+      builder.getArrayAttr({builder.getDictionaryAttr({dstAlignAttr})});
   LLVM::MemcpyOp::create(builder, loc, allocaOp, argument, copySize,
-                         /*isVolatile=*/false);
+                         /*isVolatile=*/false,
+                         /*access_groups=*/nullptr, /*alias_scopes=*/nullptr,
+                         /*noalias_scopes=*/nullptr, /*tbaa=*/nullptr, argAttrs,
+                         /*res_attrs=*/nullptr);
   return allocaOp;
 }
 

diff  --git a/mlir/test/Dialect/LLVMIR/inlining.mlir b/mlir/test/Dialect/LLVMIR/inlining.mlir
index cc3600af431ea..85cae992f01de 100644
--- a/mlir/test/Dialect/LLVMIR/inlining.mlir
+++ b/mlir/test/Dialect/LLVMIR/inlining.mlir
@@ -570,6 +570,26 @@ llvm.func @test_byval_global() {
 
 // -----
 
+// Check that alignment information is preserved in the memcpy when inlining
+// byval arguments.
+
+llvm.func @byval_aligned_arg(%ptr : !llvm.ptr { llvm.byval = i32, llvm.align = 16 }) {
+  llvm.return
+}
+
+// CHECK-LABEL: llvm.func @test_byval_memcpy_alignment
+// CHECK-SAME: %[[PTR:[a-zA-Z0-9_]+]]: !llvm.ptr
+llvm.func @test_byval_memcpy_alignment(%ptr : !llvm.ptr) {
+  // Verify the memcpy carries the alignment info from the byval attribute.
+  // CHECK: %[[ALLOCA:.+]] = llvm.alloca
+  // CHECK: "llvm.intr.memcpy"(%[[ALLOCA]], %[[PTR]]
+  // CHECK-SAME: {llvm.align = 16 : i64}
+  llvm.call @byval_aligned_arg(%ptr) : (!llvm.ptr) -> ()
+  llvm.return
+}
+
+// -----
+
 // Check that inlining does not hoist byval allocas out of automatic allocation
 // scopes, such as parallel forall regions. Each parallel iteration must have
 // its own private copy of the byval argument.