[StructuralHashPrinter] Always print 16-digit hash (llvm#101655)

The hash may contain less than 14 significant digits, which caused the
test to fail.

llvm/lib/Analysis/StructuralHash.cpp

@@ -14,20 +14,20 @@
 #include "llvm/Analysis/StructuralHash.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/StructuralHash.h"
-#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Format.h"
 
 using namespace llvm;
 
 PreservedAnalyses StructuralHashPrinterPass::run(Module &M,
  ModuleAnalysisManager &MAM) {
  OS << "Module Hash: "
- << Twine::utohexstr(StructuralHash(M, EnableDetailedStructuralHash))
+ << format("%016" PRIx64, StructuralHash(M, EnableDetailedStructuralHash))
  << "\n";
  for (Function &F : M) {
  if (F.isDeclaration())
  continue;
  OS << "Function " << F.getName() << " Hash: "
- << Twine::utohexstr(StructuralHash(F, EnableDetailedStructuralHash))
+ << format("%016" PRIx64, StructuralHash(F, EnableDetailedStructuralHash))
  << "\n";
  }
  return PreservedAnalyses::all();

llvm/test/Analysis/StructuralHash/structural-hash-printer.ll

@@ -14,12 +14,11 @@ define i32 @f2(i32 %a) {
  ret i32 %b
 }
 
-; CHECK: Module Hash: {{([a-z0-9]{14,})}}
-; CHECK-NEXT: Function f1 Hash: [[F1H:([a-z0-9]{14,})]]
+; CHECK: Module Hash: {{([a-f0-9]{16,})}}
+; CHECK-NEXT: Function f1 Hash: [[F1H:([a-f0-9]{16,})]]
 ; CHECK-NEXT: Function f2 Hash: [[F1H]]
 
-; DETAILED-HASH: Module Hash: {{([a-z0-9]{14,})}}
-; DETAILED-HASH-NEXT: Function f1 Hash: [[DF1H:([a-z0-9]{14,})]]
+; DETAILED-HASH: Module Hash: {{([a-f0-9]{16,})}}
+; DETAILED-HASH-NEXT: Function f1 Hash: [[DF1H:([a-f0-9]{16,})]]
 ; DETAILED-HASH-NOT: [[DF1H]]
-; DETAILED-HASH-NEXT: Function f2 Hash: {{([a-z0-9]{14,})}}
-
+; DETAILED-HASH-NEXT: Function f2 Hash: {{([a-f0-9]{16,})}}