[MLIR] Model llvm.inline_asm side_effects (#91507)

Allow more cleanups on inline_asm ops modeling side effects based on the
side_effect attributed.

Author: ThomasRaoux

mlir/include/mlir/Dialect/LLVMIR/LLVMOps.td

@@ -1795,7 +1795,7 @@ def LLVM_FenceOp : LLVM_Op<"fence">, LLVM_MemOpPatterns {
   let hasVerifier = 1;
 }
 
-def LLVM_InlineAsmOp : LLVM_Op<"inline_asm", []> {
+def LLVM_InlineAsmOp : LLVM_Op<"inline_asm", [DeclareOpInterfaceMethods<MemoryEffectsOpInterface>]> {
   let description = [{
     The InlineAsmOp mirrors the underlying LLVM semantics with a notable
     exception: the embedded `asm_string` is not allowed to define or reference

mlir/lib/Dialect/LLVMIR/IR/LLVMDialect.cpp

@@ -3034,6 +3034,19 @@ LogicalResult LinkerOptionsOp::verify() {
   return success();
 }
 
+//===----------------------------------------------------------------------===//
+// InlineAsmOp
+//===----------------------------------------------------------------------===//
+
+void InlineAsmOp::getEffects(
+    SmallVectorImpl<SideEffects::EffectInstance<MemoryEffects::Effect>>
+        &effects) {
+  if (getHasSideEffects()) {
+    effects.emplace_back(MemoryEffects::Write::get());
+    effects.emplace_back(MemoryEffects::Read::get());
+  }
+}
+
 //===----------------------------------------------------------------------===//
 // LLVMDialect initialization, type parsing, and registration.
 //===----------------------------------------------------------------------===//

mlir/test/Dialect/LLVMIR/canonicalize.mlir

@@ -248,3 +248,14 @@ llvm.func @volatile_load(%x : !llvm.ptr) {
   %3 = llvm.load %x  atomic unordered { alignment = 1 } : !llvm.ptr -> i8
   llvm.return
 }
+
+// -----
+
+// CHECK-LABEL: func @inline_asm_side_effects
+llvm.func @inline_asm_side_effects(%x : i32) {
+  // CHECK-NOT: llvm.inline_asm "pure inline asm"
+  llvm.inline_asm "pure inline asm", "r" %x : (i32) -> ()
+  // CHECK: llvm.inline_asm has_side_effects "inline asm with side effects"
+  llvm.inline_asm has_side_effects "inline asm with side effects", "r" %x : (i32) -> ()
+  llvm.return
+}