[OpenMP] Change analysis remarks to not emit on cold functions

[jhuber6]

Summary

The remarks will trigger on some functions that are marked cold, such as the
__muldc3 intrinsic functions. Change the remarks to avoid these functions.

[jdoerfert]

LG

llvm/lib/Transforms/IPO/OpenMPOpt.cpp

for (const User *U : F.users())
       if (!isa<BlockAddress>(U))
         return true;
     return false;
   };
 
   auto EmitRemark = [&](Function &F) {
     auto &ORE = FAM.getResult<OptimizationRemarkEmitterAnalysis>(F);
     ORE.emit([&]() {
-      OptimizationRemarkMissed ORM(DEBUG_TYPE, "InternalizationFailure", &F);
-      return ORM << "Could not internalize function. "
+      OptimizationRemarkAnalysis ORA(DEBUG_TYPE, "InternalizationFailure", &F);
+      return ORA << "Could not internalize function. "
                  << "Some optimizations may not be possible.";
     });
   };
 
   // Create internal copies of each function if this is a kernel Module. This
   // allows iterprocedural passes to see every call edge.
   DenseSet<const Function *> InternalizedFuncs;
   if (isOpenMPDevice(M))
     for (Function &F : M)
       if (!F.isDeclaration() && !Kernels.contains(&F) && IsCalled(F)) {
         if (Attributor::internalizeFunction(F, /* Force */ true)) {
           InternalizedFuncs.insert(&F);
-        } else if (!F.hasLocalLinkage()) {
+        } else if (!F.hasLocalLinkage() && !F.hasFnAttribute(Attribute::Cold)) {
           EmitRemark(F);
         }
       }
 
   // Look at every function in the Module unless it was internalized.
   SmallVector<Function *, 16> SCC;
   for (Function &F : M)
     if (!F.isDeclaration() && !InternalizedFuncs.contains(&F))

llvm/test/Transforms/OpenMP/single_threaded_execution.ll

 ; RUN: opt -passes=openmp-opt -debug-only=openmp-opt -disable-output < %s 2>&1 | FileCheck %s
-; RUN: opt -passes=openmp-opt -pass-remarks-missed=openmp-opt -disable-output < %s 2>&1 | FileCheck %s --check-prefix=REMARKS
+; RUN: opt -passes=openmp-opt -pass-remarks-analysis=openmp-opt -disable-output < %s 2>&1 | FileCheck %s --check-prefix=REMARKS
 ; REQUIRES: asserts
 ; ModuleID = 'single_threaded_exeuction.c'
 
 define weak void @kernel() {
   call void @__kmpc_kernel_init(i32 512, i16 1)
   call void @nvptx()
   call void @amdgcn()
   ret void
 }
 
 ; REMARKS: remark: single_threaded_execution.c:1:0: Could not internalize function. Some optimizations may not be possible.
+; REMARKS-NOT: remark: single_threaded_execution.c:1:0: Could not internalize function. Some optimizations may not be possible.
 
 ; CHECK-NOT: [openmp-opt] Basic block @nvptx entry is executed by a single thread.
 ; CHECK: [openmp-opt] Basic block @nvptx if.then is executed by a single thread.
 ; CHECK-NOT: [openmp-opt] Basic block @nvptx if.end is executed by a single thread.
 ; Function Attrs: noinline
 define internal void @nvptx() {
 entry:
   %call = call i32 @llvm.nvvm.read.ptx.sreg.tid.x()
   %cmp = icmp eq i32 %call, 0
   br i1 %cmp, label %if.then, label %if.end
 
 if.then:
   call void @foo()
   call void @bar()
   call void @baz()
+  call void @cold()
   br label %if.end
 
 if.end:
   ret void
 }
 
 ; CHECK-NOT: [openmp-opt] Basic block @amdgcn entry is executed by a single thread.
 ; CHECK: [openmp-opt] Basic block @amdgcn if.then is executed by a single thread.
 ; CHECK-NOT: [openmp-opt] Basic block @amdgcn if.end is executed by a single thread.
 ; Function Attrs: noinline
 define internal void @amdgcn() {
 entry:
   %call = call i32 @llvm.amdgcn.workitem.id.x()
   %cmp = icmp eq i32 %call, 0
   br i1 %cmp, label %if.then, label %if.end
 
 if.then:
   call void @foo()
   call void @bar()
   call void @baz()
+  call void @cold()
   br label %if.end
 
 if.end:
   ret void
 }
 
 ; CHECK: [openmp-opt] Basic block @foo entry is executed by a single thread.
 ; Function Attrs: noinline

 
 ; CHECK-NOT: [openmp-opt] Basic block @baz entry is executed by a single thread.
 ; Function Attrs: noinline
 define weak void @baz() !dbg !8 {
 entry:
   ret void
 }
 
+; CHECK-NOT: [openmp-opt] Basic block @cold entry is executed by a single thread.
+; Function Attrs: cold convergent noinline nounwind optnone mustprogress
+define weak void @cold() #0 !dbg !9 {
+entry:
+  ret void
+}
+
 declare i32 @llvm.nvvm.read.ptx.sreg.tid.x()
 
 declare i32 @llvm.amdgcn.workitem.id.x()
 
 declare void @__kmpc_kernel_init(i32, i16)
 
+attributes #0 = { cold noinline }
+
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!3, !4, !5, !6}
 !nvvm.annotations = !{!7}
 
-
 !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 12.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
 !1 = !DIFile(filename: "single_threaded_execution.c", directory: "/tmp/single_threaded_execution.c")
 !2 = !{}
 !3 = !{i32 2, !"Debug Info Version", i32 3}
 !4 = !{i32 1, !"wchar_size", i32 4}
 !5 = !{i32 7, !"openmp", i32 50}
 !6 = !{i32 7, !"openmp-device", i32 50}
 !7 = !{void ()* @kernel, !"kernel", i32 1}
-!8 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 8, type: !9, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
-!9 = !DISubroutineType(types: !2)
-!10 = !DILocation(line: 5, column: 7, scope: !8)
+!8 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 8, type: !10, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!9 = distinct !DISubprogram(name: "cold", scope: !1, file: !1, line: 8, type: !10, scopeLine: 2, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!10 = !DISubroutineType(types: !2)