From 29a74a39150ad0a041922431cda68f1afba830c9 Mon Sep 17 00:00:00 2001 From: Joseph Huber Date: Tue, 31 Aug 2021 15:03:33 -0400 Subject: [PATCH] [OpenMP] Add an option to always inline OpenMP device functions. Performance on GPU targets can be highly variable, sometimes inlining everything hurts performance and sometimes it greatly improves it. Add an option to toggle this behaviour to better investigate it. Reviewed By: jdoerfert Differential Revision: https://reviews.llvm.org/D109014 --- llvm/lib/Transforms/IPO/OpenMPOpt.cpp | 12 ++++ .../Transforms/OpenMP/always_inline_device.ll | 69 +++++++++++++++++++ 2 files changed, 81 insertions(+) create mode 100644 llvm/test/Transforms/OpenMP/always_inline_device.ll diff --git a/llvm/lib/Transforms/IPO/OpenMPOpt.cpp b/llvm/lib/Transforms/IPO/OpenMPOpt.cpp index c48ae6ec2f36..5167494293a3 100644 --- a/llvm/lib/Transforms/IPO/OpenMPOpt.cpp +++ b/llvm/lib/Transforms/IPO/OpenMPOpt.cpp @@ -97,6 +97,11 @@ static cl::opt PrintModuleAfterOptimizations( cl::desc("Print the current module after OpenMP optimizations."), cl::Hidden, cl::init(false)); +static cl::opt AlwaysInlineDeviceFunctions( + "openmp-opt-inline-device", cl::ZeroOrMore, + cl::desc("Inline all applicible functions on the device."), cl::Hidden, + cl::init(false)); + STATISTIC(NumOpenMPRuntimeCallsDeduplicated, "Number of OpenMP runtime calls deduplicated"); STATISTIC(NumOpenMPParallelRegionsDeleted, @@ -4481,6 +4486,13 @@ PreservedAnalyses OpenMPOptPass::run(Module &M, ModuleAnalysisManager &AM) { OpenMPOpt OMPOpt(SCC, CGUpdater, OREGetter, InfoCache, A); bool Changed = OMPOpt.run(true); + // Optionally inline device functions for potentially better performance. + if (AlwaysInlineDeviceFunctions && isOpenMPDevice(M)) + for (Function &F : M) + if (!F.isDeclaration() && !Kernels.contains(&F) && + !F.hasFnAttribute(Attribute::NoInline)) + F.addFnAttr(Attribute::AlwaysInline); + if (PrintModuleAfterOptimizations) LLVM_DEBUG(dbgs() << TAG << "Module after OpenMPOpt Module Pass:\n" << M); diff --git a/llvm/test/Transforms/OpenMP/always_inline_device.ll b/llvm/test/Transforms/OpenMP/always_inline_device.ll new file mode 100644 index 000000000000..7ffac2215a15 --- /dev/null +++ b/llvm/test/Transforms/OpenMP/always_inline_device.ll @@ -0,0 +1,69 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-attributes +; RUN: opt < %s -S -passes=openmp-opt -openmp-opt-inline-device | FileCheck %s + +%struct.ident_t = type { i32, i32, i32, i32, i8* } +@0 = private unnamed_addr constant [23 x i8] c";unknown;unknown;0;0;;\00", align 1 +@1 = private unnamed_addr constant %struct.ident_t { i32 0, i32 2, i32 0, i32 0, i8* getelementptr inbounds ([23 x i8], [23 x i8]* @0, i32 0, i32 0) }, align 8 +@__omp_offloading_fd02_c0934fc2_foo_l4_exec_mode = weak constant i8 1 +@llvm.compiler.used = appending global [1 x i8*] [i8* @__omp_offloading_fd02_c0934fc2_foo_l4_exec_mode], section "llvm.metadata" + +; Function Attrs: convergent norecurse nounwind +define weak void @__omp_offloading_fd02_c0934fc2_foo_l4() #0 { +; CHECK: Function Attrs: convergent norecurse nounwind +; CHECK-LABEL: @__omp_offloading_fd02_c0934fc2_foo_l4( +; CHECK-NEXT: entry: +; CHECK-NEXT: [[TMP0:%.*]] = call i32 @__kmpc_target_init(%struct.ident_t* @[[GLOB1:[0-9]+]], i1 true, i1 false, i1 false) +; CHECK-NEXT: [[EXEC_USER_CODE:%.*]] = icmp eq i32 [[TMP0]], -1 +; CHECK-NEXT: br i1 [[EXEC_USER_CODE]], label [[USER_CODE_ENTRY:%.*]], label [[WORKER_EXIT:%.*]] +; CHECK: user_code.entry: +; CHECK-NEXT: call void @__kmpc_target_deinit(%struct.ident_t* @[[GLOB1]], i1 true, i1 false) +; CHECK-NEXT: ret void +; CHECK: worker.exit: +; CHECK-NEXT: ret void +; +entry: + %0 = call i32 @__kmpc_target_init(%struct.ident_t* @1, i1 false, i1 true, i1 true) + %exec_user_code = icmp eq i32 %0, -1 + br i1 %exec_user_code, label %user_code.entry, label %worker.exit + +user_code.entry: ; preds = %entry + call void @bar() #2 + call void @__kmpc_target_deinit(%struct.ident_t* @1, i1 false, i1 true) + ret void + +worker.exit: ; preds = %entry + ret void +} + +declare i32 @__kmpc_target_init(%struct.ident_t*, i1, i1, i1) + +declare void @__kmpc_target_deinit(%struct.ident_t*, i1, i1) + +; Function Attrs: convergent nounwind +define hidden void @bar() #1 { +; CHECK: Function Attrs: alwaysinline convergent nounwind +; CHECK-LABEL: @bar( +; CHECK-NEXT: entry: +; CHECK-NEXT: ret void +; +entry: + ret void +} + +attributes #0 = { convergent norecurse nounwind "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="sm_70" "target-features"="+ptx32,+sm_70" } +attributes #1 = { convergent nounwind "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="sm_70" "target-features"="+ptx32,+sm_70" } +attributes #2 = { convergent } + +!omp_offload.info = !{!0} +!nvvm.annotations = !{!1} +!llvm.module.flags = !{!2, !3, !4, !5, !6} +!llvm.ident = !{!7} + +!0 = !{i32 0, i32 64770, i32 -1064087614, !"foo", i32 4, i32 0} +!1 = !{void ()* @__omp_offloading_fd02_c0934fc2_foo_l4, !"kernel", i32 1} +!2 = !{i32 1, !"wchar_size", i32 4} +!3 = !{i32 7, !"openmp", i32 50} +!4 = !{i32 7, !"openmp-device", i32 50} +!5 = !{i32 7, !"PIC Level", i32 2} +!6 = !{i32 7, !"frame-pointer", i32 2} +!7 = !{!"clang version 14.0.0"}