[llvm] [NewPM][CodeGen] add TargetPassConfig like API (PR #70906)

[Arthur Eubanks via llvm-commits]

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@@ -869,9 +1018,23 @@ Error CodeGenPassBuilder<Derived>::addMachinePasses(
   // Run pre-ra passes.
   derived().addPreRegAlloc(addPass);
 
+  // Add a FSDiscriminator pass right before RA, so that we could get
+  // more precise SampleFDO profile for RA.
+  if (EnableFSDiscriminator) {
+    addPass(MIRAddFSDiscriminatorsPass(sampleprof::FSDiscriminatorPass::Pass1));
+    const std::string ProfileFile = getFSProfileFile();
+    if (!ProfileFile.empty() && !Opt.DisableRAFSProfileLoader)
+      addPass(MIRProfileLoaderNewPass(ProfileFile, getFSRemappingFile(),
+                                      sampleprof::FSDiscriminatorPass::Pass1,
+                                      nullptr));
+  }
+
   // Run register allocation and passes that are tightly coupled with it,
   // including phi elimination and scheduling.
-  if (*Opt.OptimizeRegAlloc) {
+  bool IsOptimizeRegAlloc = Opt.OptimizeRegAlloc.has_value()
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aeubanks wrote:

`.value_or(getOptLevel() != None)`

https://github.com/llvm/llvm-project/pull/70906