[MLIR][LLVM] Allow inlining llvm.intr.assume.

[definelicht]

Summary

This operation is not marked pure because it needs to survive DCE, but
is otherwise safe to inline.

[Dinistro]

LGTM!

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

if (auto iface = dyn_cast<LLVM::AccessGroupOpInterface>(op)) {
       if (iface.getAccessGroupsOrNull()) {
         LLVM_DEBUG(llvm::dbgs()
                    << "Cannot inline: unhandled access group metadata\n");
         return false;
       }
     }
     // clang-format off
     if (isa<LLVM::AllocaOp,
+            LLVM::AssumeOp,
             LLVM::AtomicRMWOp,
             LLVM::AtomicCmpXchgOp,
             LLVM::CallOp,
             LLVM::DbgDeclareOp,
             LLVM::DbgValueOp,
             LLVM::FenceOp,
             LLVM::InlineAsmOp,
             LLVM::LifetimeEndOp,

mlir/test/Dialect/LLVMIR/inlining.mlir

 // RUN: mlir-opt %s -inline -split-input-file | FileCheck %s
 
 #file = #llvm.di_file<"foo.mlir" in "/foo/">
 #variable = #llvm.di_local_variable<scope = #file>
 #variableAddr = #llvm.di_local_variable<scope = #file>
 
 func.func @inner_func_inlinable(%ptr : !llvm.ptr) -> i32 {
   %0 = llvm.mlir.constant(42 : i32) : i32
   %stack = llvm.intr.stacksave : !llvm.ptr
   llvm.store %0, %ptr { alignment = 8 } : i32, !llvm.ptr
   %1 = llvm.load %ptr { alignment = 8 } : !llvm.ptr -> i32
   llvm.intr.dbg.value #variable = %0 : i32
   llvm.intr.dbg.declare #variableAddr = %ptr : !llvm.ptr
   %byte = llvm.mlir.constant(43 : i8) : i8
-  %volatile = llvm.mlir.constant(1 : i1) : i1
-  "llvm.intr.memset"(%ptr, %byte, %0, %volatile) : (!llvm.ptr, i8, i32, i1) -> ()
-  "llvm.intr.memmove"(%ptr, %ptr, %0, %volatile) : (!llvm.ptr, !llvm.ptr, i32, i1) -> ()
-  "llvm.intr.memcpy"(%ptr, %ptr, %0, %volatile) : (!llvm.ptr, !llvm.ptr, i32, i1) -> ()
+  %true = llvm.mlir.constant(1 : i1) : i1
+  "llvm.intr.memset"(%ptr, %byte, %0, %true) : (!llvm.ptr, i8, i32, i1) -> ()
+  "llvm.intr.memmove"(%ptr, %ptr, %0, %true) : (!llvm.ptr, !llvm.ptr, i32, i1) -> ()
+  "llvm.intr.memcpy"(%ptr, %ptr, %0, %true) : (!llvm.ptr, !llvm.ptr, i32, i1) -> ()
+  "llvm.intr.assume"(%true) : (i1) -> ()
   llvm.fence release
   %2 = llvm.atomicrmw add %ptr, %0 monotonic : !llvm.ptr, i32
   %3 = llvm.cmpxchg %ptr, %0, %1 acq_rel monotonic : !llvm.ptr, i32
   llvm.inline_asm has_side_effects "foo", "bar" : () -> ()
-  llvm.cond_br %volatile, ^bb1, ^bb2
+  llvm.cond_br %true, ^bb1, ^bb2
 ^bb1:
   llvm.unreachable
 ^bb2:
   llvm.intr.stackrestore %stack : !llvm.ptr
   return %1 : i32
 }
 
 // CHECK-LABEL: func.func @test_inline(
 // CHECK-SAME: %[[PTR:[a-zA-Z0-9_]+]]
 // CHECK: %[[CST:.*]] = llvm.mlir.constant(42
 // CHECK: %[[STACK:.+]] = llvm.intr.stacksave
 // CHECK: llvm.store %[[CST]], %[[PTR]]
 // CHECK: %[[RES:.+]] = llvm.load %[[PTR]]
 // CHECK: llvm.intr.dbg.value #{{.+}} = %[[CST]]
 // CHECK: llvm.intr.dbg.declare #{{.+}} = %[[PTR]]
 // CHECK: "llvm.intr.memset"(%[[PTR]]
 // CHECK: "llvm.intr.memmove"(%[[PTR]], %[[PTR]]
 // CHECK: "llvm.intr.memcpy"(%[[PTR]], %[[PTR]]
+// CHECK: "llvm.intr.assume"
 // CHECK: llvm.fence release
 // CHECK: llvm.atomicrmw add %[[PTR]], %[[CST]] monotonic
 // CHECK: llvm.cmpxchg %[[PTR]], %[[CST]], %[[RES]] acq_rel monotonic
 // CHECK: llvm.inline_asm has_side_effects "foo", "bar"
 // CHECK: llvm.unreachable
 // CHECK: llvm.intr.stackrestore %[[STACK]]
 func.func @test_inline(%ptr : !llvm.ptr) -> i32 {
   %0 = call @inner_func_inlinable(%ptr) : (!llvm.ptr) -> i32