PR for llvm/llvm-project#56752

llvm/lib/Transforms/IPO/OpenMPOpt.cpp

@@ -499,6 +499,18 @@ struct OMPInformationCache : public InformationCache {
   }
 #include "llvm/Frontend/OpenMP/OMPKinds.def"
 
+    // Remove the `noinline` attribute from `__kmpc`, `_OMP::` and `omp_`
+    // functions, except if `optnone` is present.
+    if (isOpenMPDevice(M)) {
+      for (Function &F : M) {
+        for (StringRef Prefix : {"__kmpc", "_ZN4_OMP", "omp_"})
+          if (F.hasFnAttribute(Attribute::NoInline) &&
+              F.getName().startswith(Prefix) &&
+              !F.hasFnAttribute(Attribute::OptimizeNone))
+            F.removeFnAttr(Attribute::NoInline);
+      }
+    }
+
     // TODO: We should attach the attributes defined in OMPKinds.def.
   }
 

llvm/test/Transforms/OpenMP/remove_noinline_attributes.ll

@@ -0,0 +1,99 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-attributes
+; RUN: opt < %s -S -openmp-opt-cgscc        | FileCheck %s
+; RUN: opt < %s -S -passes=openmp-opt-cgscc | FileCheck %s
+
+declare void @unknown()
+
+; __kmpc functions
+define void @__kmpc_noinline() noinline nounwind {
+; CHECK: Function Attrs: nounwind
+; CHECK-LABEL: @__kmpc_noinline(
+; CHECK-NEXT:    call void @unknown()
+; CHECK-NEXT:    ret void
+;
+  call void @unknown()
+  ret void
+}
+; omp_X functions
+define void @omp_noinline() noinline nounwind {
+; CHECK: Function Attrs: nounwind
+; CHECK-LABEL: @omp_noinline(
+; CHECK-NEXT:    call void @unknown()
+; CHECK-NEXT:    ret void
+;
+  call void @unknown()
+  ret void
+}
+; _OMP namespace
+define void @_ZN4_OMP_noinline() noinline nounwind {
+; CHECK: Function Attrs: nounwind
+; CHECK-LABEL: @_ZN4_OMP_noinline(
+; CHECK-NEXT:    call void @unknown()
+; CHECK-NEXT:    ret void
+;
+  call void @unknown()
+  ret void
+}
+
+; Negative tests:
+
+define void @__kmpc_noinline_optnone() noinline optnone nounwind {
+; CHECK: Function Attrs: noinline nounwind optnone
+; CHECK-LABEL: @__kmpc_noinline_optnone(
+; CHECK-NEXT:    call void @unknown()
+; CHECK-NEXT:    ret void
+;
+  call void @unknown()
+  ret void
+}
+define void @omp_noinline_optnone() noinline optnone nounwind {
+; CHECK: Function Attrs: noinline nounwind optnone
+; CHECK-LABEL: @omp_noinline_optnone(
+; CHECK-NEXT:    call void @unknown()
+; CHECK-NEXT:    ret void
+;
+  call void @unknown()
+  ret void
+}
+; _OMP namespace
+define void @_ZN4_OMP_noinline_optnone() noinline optnone nounwind {
+; CHECK: Function Attrs: noinline nounwind optnone
+; CHECK-LABEL: @_ZN4_OMP_noinline_optnone(
+; CHECK-NEXT:    call void @unknown()
+; CHECK-NEXT:    ret void
+;
+  call void @unknown()
+  ret void
+}
+define void @a___kmpc_noinline() noinline nounwind {
+; CHECK: Function Attrs: noinline nounwind
+; CHECK-LABEL: @a___kmpc_noinline(
+; CHECK-NEXT:    call void @unknown()
+; CHECK-NEXT:    ret void
+;
+  call void @unknown()
+  ret void
+}
+define void @a_omp_noinline() noinline nounwind {
+; CHECK: Function Attrs: noinline nounwind
+; CHECK-LABEL: @a_omp_noinline(
+; CHECK-NEXT:    call void @unknown()
+; CHECK-NEXT:    ret void
+;
+  call void @unknown()
+  ret void
+}
+define void @a__ZN4_OMP_noinline() noinline nounwind {
+; CHECK: Function Attrs: noinline nounwind
+; CHECK-LABEL: @a__ZN4_OMP_noinline(
+; CHECK-NEXT:    call void @unknown()
+; CHECK-NEXT:    ret void
+;
+  call void @unknown()
+  ret void
+}
+
+!llvm.module.flags = !{!0, !1}
+
+!0 = !{i32 7, !"openmp", i32 50}
+!1 = !{i32 7, !"openmp-device", i32 50}

openmp/libomptarget/DeviceRTL/include/Synchronization.h

@@ -29,13 +29,15 @@ void threads();
 
 /// Synchronizing threads is allowed even if they all hit different instances of
 /// `synchronize::threads()`. However, `synchronize::threadsAligned()` is more
-/// restrictive in that it requires all threads to hit the same instance.
+/// restrictive in that it requires all threads to hit the same instance. The
+/// noinline is removed by the openmp-opt pass and helps to preserve the
+/// information till then.
 ///{
 #pragma omp begin assumes ext_aligned_barrier
 
 /// Synchronize all threads in a block, they are are reaching the same
 /// instruction (hence all threads in the block are "aligned").
-void threadsAligned();
+__attribute__((noinline)) void threadsAligned();
 
 #pragma omp end assumes
 ///}

openmp/libomptarget/DeviceRTL/src/Mapping.cpp

@@ -289,17 +289,17 @@ bool mapping::isGenericMode() { return !isSPMDMode(); }
 ///}
 
 extern "C" {
-uint32_t __kmpc_get_hardware_thread_id_in_block() {
+__attribute__((noinline)) uint32_t __kmpc_get_hardware_thread_id_in_block() {
   FunctionTracingRAII();
   return mapping::getThreadIdInBlock();
 }
 
-uint32_t __kmpc_get_hardware_num_threads_in_block() {
+__attribute__((noinline)) uint32_t __kmpc_get_hardware_num_threads_in_block() {
   FunctionTracingRAII();
   return impl::getNumHardwareThreadsInBlock();
 }
 
-uint32_t __kmpc_get_warp_size() {
+__attribute__((noinline)) uint32_t __kmpc_get_warp_size() {
   FunctionTracingRAII();
   return impl::getWarpSize();
 }

openmp/libomptarget/DeviceRTL/src/Parallelism.cpp

@@ -243,7 +243,8 @@ void __kmpc_parallel_51(IdentTy *ident, int32_t, int32_t if_expr,
     __kmpc_end_sharing_variables();
 }
 
-bool __kmpc_kernel_parallel(ParallelRegionFnTy *WorkFn) {
+__attribute__((noinline)) bool
+__kmpc_kernel_parallel(ParallelRegionFnTy *WorkFn) {
   FunctionTracingRAII();
   // Work function and arguments for L1 parallel region.
   *WorkFn = state::ParallelRegionFn;
@@ -258,7 +259,7 @@ bool __kmpc_kernel_parallel(ParallelRegionFnTy *WorkFn) {
   return ThreadIsActive;
 }
 
-void __kmpc_kernel_end_parallel() {
+__attribute__((noinline)) void __kmpc_kernel_end_parallel() {
   FunctionTracingRAII();
   // In case we have modified an ICV for this thread before a ThreadState was
   // created. We drop it now to not contaminate the next parallel region.

openmp/libomptarget/DeviceRTL/src/State.cpp

@@ -393,12 +393,12 @@ int omp_get_initial_device(void) { return -1; }
 }
 
 extern "C" {
-void *__kmpc_alloc_shared(uint64_t Bytes) {
+__attribute__((noinline)) void *__kmpc_alloc_shared(uint64_t Bytes) {
   FunctionTracingRAII();
   return memory::allocShared(Bytes, "Frontend alloc shared");
 }
 
-void __kmpc_free_shared(void *Ptr, uint64_t Bytes) {
+__attribute__((noinline)) void __kmpc_free_shared(void *Ptr, uint64_t Bytes) {
   FunctionTracingRAII();
   memory::freeShared(Ptr, Bytes, "Frontend free shared");
 }

openmp/libomptarget/DeviceRTL/src/Synchronization.cpp

@@ -358,12 +358,14 @@ void __kmpc_barrier(IdentTy *Loc, int32_t TId) {
   impl::namedBarrier();
 }
 
-void __kmpc_barrier_simple_spmd(IdentTy *Loc, int32_t TId) {
+__attribute__((noinline)) void __kmpc_barrier_simple_spmd(IdentTy *Loc,
+                                                          int32_t TId) {
   FunctionTracingRAII();
   synchronize::threadsAligned();
 }
 
-void __kmpc_barrier_simple_generic(IdentTy *Loc, int32_t TId) {
+__attribute__((noinline)) void __kmpc_barrier_simple_generic(IdentTy *Loc,
+                                                             int32_t TId) {
   FunctionTracingRAII();
   synchronize::threads();
 }