[MLIR][LLVMIR] Import: fix llvm.call attribute inheritance (#130221)

`inst->getFnAttr(Kind)` fallbacks to check if the parent has an
attribute, which breaks roundtriping the LLVM IR. This change actually
checks only in the call attribute list (no fallback to parent queries).

It's possible to argue that this small optimization isn't harmful, but
seems too early if it's breaking roundtrip behavior.

Author: bcardosolopes

mlir/lib/Target/LLVMIR/ModuleImport.cpp

@@ -2263,10 +2263,15 @@ LogicalResult ModuleImport::convertInvokeAttributes(llvm::InvokeInst *inst,
 LogicalResult ModuleImport::convertCallAttributes(llvm::CallInst *inst,
                                                   CallOp op) {
   setFastmathFlagsAttr(inst, op.getOperation());
+  // Query the attributes directly instead of using `inst->getFnAttr(Kind)`, the
+  // latter does additional lookup to the parent and inherits, changing the
+  // semantics too early.
+  llvm::AttributeList callAttrs = inst->getAttributes();
+
   op.setTailCallKind(convertTailCallKindFromLLVM(inst->getTailCallKind()));
-  op.setConvergent(inst->isConvergent());
-  op.setNoUnwind(inst->doesNotThrow());
-  op.setWillReturn(inst->hasFnAttr(llvm::Attribute::WillReturn));
+  op.setConvergent(callAttrs.getFnAttr(llvm::Attribute::Convergent).isValid());
+  op.setNoUnwind(callAttrs.getFnAttr(llvm::Attribute::NoUnwind).isValid());
+  op.setWillReturn(callAttrs.getFnAttr(llvm::Attribute::WillReturn).isValid());
 
   llvm::MemoryEffects memEffects = inst->getMemoryEffects();
   ModRefInfo othermem = convertModRefInfoFromLLVM(

mlir/test/Target/LLVMIR/Import/call-argument-attributes.ll

@@ -1,4 +1,4 @@
-; RUN: mlir-translate -import-llvm %s | FileCheck %s
+; RUN: mlir-translate -import-llvm -split-input-file %s | FileCheck %s
 
 ; CHECK-LABEL: llvm.func @somefunc(i32, !llvm.ptr)
 declare void @somefunc(i32, ptr)
@@ -20,3 +20,22 @@ define i16 @test_call_arg_attrs_indirect(i16 %0, ptr %1) {
   %3 = tail call signext i16 %1(i16 noundef signext %0)
   ret i16 %3
 }
+
+; // -----
+
+%struct.S = type { i8 }
+
+; CHECK-LABEL: @t
+define void @t(i1 %0) #0 {
+  %3 = alloca %struct.S, align 1
+  ; CHECK-NOT: llvm.call @z(%1) {no_unwind} : (!llvm.ptr) -> ()
+  ; CHECK: llvm.call @z(%1) : (!llvm.ptr) -> ()
+  call void @z(ptr %3)
+  ret void
+}
+
+define linkonce_odr void @z(ptr %0) #0 {
+  ret void
+}
+
+attributes #0 = { nounwind }