[OpenMP] AlwaysInline __kmpc_parallel_51 to improve inlining hueristics

[jhuber6]

Summary

This patch adds the AlwaysInline attribute to the __kmpc_parallel_51
device runtime call. This improves inlining heuristics which encourages
the indirect function pointer arguemnt to also be inlined. This greatly
improves performance for a few applications whose outlined regions were
not inlined otherwise.

[jdoerfert]

LG

llvm/include/llvm/Frontend/OpenMP/OMPKinds.def

__OMP_ATTRS_SET(InaccessibleArgOnlyAttrs,
                                    EnumAttr(WillReturn), EnumAttr(NoFree))
                     : AttributeSet(EnumAttr(NoUnwind)))
 
 __OMP_ATTRS_SET(NoCaptureAttrs,
                 OptimisticAttributes
                     ? AttributeSet(EnumAttr(NoCapture))
                     : AttributeSet(EnumAttr(NoCapture)))
 
+__OMP_ATTRS_SET(AlwaysInlineAttrs,
+                OptimisticAttributes
+                    ? AttributeSet(EnumAttr(AlwaysInline))
+                    : AttributeSet(EnumAttr(AlwaysInline)))
+
 #if 0
 __OMP_ATTRS_SET(InaccessibleOnlyAttrs,
                 OptimisticAttributes
                     ? AttributeSet(EnumAttr(NoUnwind), EnumAttr(NoSync),
                                    EnumAttr(InaccessibleMemOnly),
                                    EnumAttr(WillReturn), EnumAttr(NoFree))
                     : AttributeSet(EnumAttr(NoUnwind)))
 #endif
__OMP_RTL_ATTRS(__tgt_target_data_update_nowait_mapper, ForkAttrs,
                 AttributeSet(), ParamAttrs())
 __OMP_RTL_ATTRS(__tgt_mapper_num_components, ForkAttrs, AttributeSet(),
                 ParamAttrs())
 __OMP_RTL_ATTRS(__tgt_push_mapper_component, ForkAttrs, AttributeSet(),
                 ParamAttrs())
 __OMP_RTL_ATTRS(__kmpc_task_allow_completion_event, DefaultAttrs,
                 ReturnPtrAttrs, ParamAttrs(ReadOnlyPtrAttrs))
 
+__OMP_RTL_ATTRS(__kmpc_parallel_51, AlwaysInlineAttrs, AttributeSet(),
+                ParamAttrs())
+
 #undef __OMP_RTL_ATTRS
 #undef OMP_RTL_ATTRS
 #undef AttributeSet
 #undef EnumAttr
 #undef EnumAttrInt
 #undef ParamAttrs
 
 ///}

llvm/test/Transforms/OpenMP/parallel_level_fold.ll

 ;
   %level = call i8 @__kmpc_parallel_level()
   store i8 %level, i8* @G
   ret void
 }
 
 define internal void @__kmpc_parallel_51(%struct.ident_t*, i32, i32, i32, i32, i8*, i8*, i8**, i64) {
 ; CHECK-LABEL: define {{[^@]+}}@__kmpc_parallel_51
-; CHECK-SAME: (%struct.ident_t* noalias nocapture nofree readnone align 536870912 [[TMP0:%.*]], i32 [[TMP1:%.*]], i32 [[TMP2:%.*]], i32 [[TMP3:%.*]], i32 [[TMP4:%.*]], i8* noalias nocapture nofree readnone align 536870912 [[TMP5:%.*]], i8* noalias nocapture nofree readnone align 536870912 [[TMP6:%.*]], i8** noalias nocapture nofree readnone align 536870912 [[TMP7:%.*]], i64 [[TMP8:%.*]]) {
+; CHECK-SAME: (%struct.ident_t* noalias nocapture nofree readnone align 536870912 [[TMP0:%.*]], i32 [[TMP1:%.*]], i32 [[TMP2:%.*]], i32 [[TMP3:%.*]], i32 [[TMP4:%.*]], i8* noalias nocapture nofree readnone align 536870912 [[TMP5:%.*]], i8* noalias nocapture nofree readnone align 536870912 [[TMP6:%.*]], i8** noalias nocapture nofree readnone align 536870912 [[TMP7:%.*]], i64 [[TMP8:%.*]]) #[[ATTR0:[0-9]+]] {
 ; CHECK-NEXT:    call void @parallel_helper()
 ; CHECK-NEXT:    ret void
 ;
   call void @parallel_helper()
   ret void
 }
 
 define internal void @parallel_helper() {

 !nvvm.annotations = !{!2, !3, !4}
 
 !0 = !{i32 7, !"openmp", i32 50}
 !1 = !{i32 7, !"openmp-device", i32 50}
 !2 = !{void ()* @none_spmd, !"kernel", i32 1}
 !3 = !{void ()* @spmd, !"kernel", i32 1}
 !4 = !{void ()* @parallel, !"kernel", i32 1}
 ;.
+; CHECK: attributes #[[ATTR0]] = { alwaysinline }
+;.
 ; CHECK: [[META0:![0-9]+]] = !{i32 7, !"openmp", i32 50}
 ; CHECK: [[META1:![0-9]+]] = !{i32 7, !"openmp-device", i32 50}
 ; CHECK: [[META2:![0-9]+]] = !{void ()* @none_spmd, !"kernel", i32 1}
 ; CHECK: [[META3:![0-9]+]] = !{void ()* @spmd, !"kernel", i32 1}
 ; CHECK: [[META4:![0-9]+]] = !{void ()* @parallel, !"kernel", i32 1}
 ;.