[llvm] Add diagnostic help for inline asm operand constraint 'H' (PR #88248)

[Matt Arsenault via llvm-commits]

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@@ -817,9 +817,15 @@ class AsmPrinter : public MachineFunctionPass {
   /// Print the specified operand of MI, an INLINEASM instruction, using the
   /// specified assembler variant.  Targets should override this to format as
   /// appropriate.  This method can return true if the operand is erroneous.
-  virtual bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
-                               const char *ExtraCode, raw_ostream &OS);
-
+  virtual AsmOperandErrorCode PrintAsmOperand(const MachineInstr *MI,
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arsenm wrote:

Ideally the mechanical change to use AsmOperandErrorCode instead of bool should be done first, before the behavior change 

https://github.com/llvm/llvm-project/pull/88248