Set isRequired true for CFGViewer/CFGPrinter passes

[wenju]

Summary

This PR allows function's cfg to be viewed/printed even if the function
has optnone attribute.

[MaskRay]

Consider a -passes=dot-cfg-quiet test. See llvm/test/Other for some examples.

[wenju]

update llvm/test/Other/cfg-printer-filter.ll to test optnone

llvm/include/llvm/Analysis/CFGPrinter.h

 #include "llvm/Support/DOTGraphTraits.h"
 #include "llvm/Support/FormatVariadic.h"
 
 namespace llvm {
 template <class GraphType> struct GraphTraits;
 class CFGViewerPass : public PassInfoMixin<CFGViewerPass> {
 public:
   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+  static bool isRequired() { return true; }
 };
 
 class CFGOnlyViewerPass : public PassInfoMixin<CFGOnlyViewerPass> {
 public:
   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+  static bool isRequired() { return true; }
 };
 
 class CFGPrinterPass : public PassInfoMixin<CFGPrinterPass> {
 public:
   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+  static bool isRequired() { return true; }
 };
 
 class CFGOnlyPrinterPass : public PassInfoMixin<CFGOnlyPrinterPass> {
 public:
   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+  static bool isRequired() { return true; }
 };
 
 class DOTFuncInfo {
 private:
   const Function *F;
   const BlockFrequencyInfo *BFI;
   const BranchProbabilityInfo *BPI;
   uint64_t MaxFreq;

llvm/test/Other/cfg-printer-filter.ll

 ; RUN: rm -f %t.other.dot %t-only.other.dot
 
 ;; Both f and func are dumped because their names contain the pattern 'f' as a substring.
+;; Also checks dot-cfg pass runs on func which has optnone attribute.
+
 ; RUN: opt < %s -passes=dot-cfg -cfg-dot-filename-prefix=%t -cfg-func-name=f 2>/dev/null > /dev/null
 ; RUN: FileCheck %s -input-file=%t.f.dot -check-prefix=F
 ; RUN: FileCheck %s -input-file=%t.func.dot -check-prefix=Func
 ; RUN: not test -f %t.other.dot
 
 ; RUN: opt < %s -passes=dot-cfg-only -cfg-dot-filename-prefix=%t-only -cfg-func-name=f 2>/dev/null > /dev/null
 ; RUN: FileCheck %s -input-file=%t-only.f.dot -check-prefix=F
 ; RUN: FileCheck %s -input-file=%t-only.func.dot -check-prefix=Func
 ; RUN: not test -f %t-only.other.dot
 
 ; F: digraph "CFG for 'f' function"
 define void @f(i32) {
 entry:
   %check = icmp sgt i32 %0, 0
   br i1 %check, label %if, label %exit
 if:                     ; preds = %entry
   br label %exit
 exit:                   ; preds = %entry, %if
   ret void
 }
 
 ; Func: digraph "CFG for 'func' function"
-define void @func(i32) {
+define void @func(i32) optnone noinline {
 entry:
   %check = icmp sgt i32 %0, 0
   br label %exit
 exit:                   ; preds = %entry
   ret void
 }
 
 define void @other(i32) {
 entry:
   %check = icmp sgt i32 %0, 0
   br label %exit
 exit:                   ; preds = %entry
   ret void
 }