[llvm] [CodeGen] Support --print-changed for legacy codegen IR passes (PR #202252)

[Arthur Eubanks via llvm-commits]

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@@ -137,54 +119,18 @@ bool MachineFunctionPass::runOnFunction(Function &F) {
 
   MFProps.set(SetProperties);
 
-  // For --print-changed, print if the serialized MF has changed. Modes other
-  // than quiet/verbose are unimplemented and treated the same as 'quiet'.
-  if (ShouldPrintChanged || !IsInterestingPass) {
-    if (ShouldPrintChanged) {
-      raw_svector_ostream OS(AfterStr);
-      MF.print(OS);
-    }
-    if (IsInterestingPass && BeforeStr != AfterStr) {
-      errs() << ("*** IR Dump After " + getPassName() + " (" + PassID +
-                 ") on " + MF.getName() + " ***\n");
-      switch (PrintChanged) {
-      case ChangePrinter::None:
-        llvm_unreachable("");
-      case ChangePrinter::Quiet:
-      case ChangePrinter::Verbose:
-      case ChangePrinter::DotCfgQuiet:   // unimplemented
-      case ChangePrinter::DotCfgVerbose: // unimplemented
-        errs() << AfterStr;
-        break;
-      case ChangePrinter::DiffQuiet:
-      case ChangePrinter::DiffVerbose:
-      case ChangePrinter::ColourDiffQuiet:
-      case ChangePrinter::ColourDiffVerbose: {
-        bool Color = llvm::is_contained(
-            {ChangePrinter::ColourDiffQuiet, ChangePrinter::ColourDiffVerbose},
-            PrintChanged.getValue());
-        StringRef Removed = Color ? "\033[31m-%l\033[0m\n" : "-%l\n";
-        StringRef Added = Color ? "\033[32m+%l\033[0m\n" : "+%l\n";
-        StringRef NoChange = " %l\n";
-        errs() << doSystemDiff(BeforeStr, AfterStr, Removed, Added, NoChange);
-        break;
-      }
-      }
-    } else if (llvm::is_contained({ChangePrinter::Verbose,
-                                   ChangePrinter::DiffVerbose,
-                                   ChangePrinter::ColourDiffVerbose},
-                                  PrintChanged.getValue())) {
-      const char *Reason =
-          IsInterestingPass ? " omitted because no change" : " filtered out";
-      errs() << "*** IR Dump After " << getPassName();
-      if (!PassID.empty())
-        errs() << " (" << PassID << ")";
-      errs() << " on " << MF.getName() + Reason + " ***\n";
-    }
-  }
   return RV;
 }
 
+bool MachineFunctionPass::printIRUnit(raw_ostream &OS, Function &F) {
+  // available_externally functions are not codegen'd (see runOnFunction).
+  if (F.hasAvailableExternallyLinkage())
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aeubanks wrote:

oh MachineFunctionPass inherits from FunctionPass and FPPassManager is the thing calling printIRUnit... that's annoying

https://github.com/llvm/llvm-project/pull/202252