[llvm] [CodeGen] Preserve branch weights from PGO profile during instruction selection at -O0 (PR #161620)

[Grigory Pastukhov via llvm-commits]

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@@ -229,6 +229,17 @@ static bool dontUseFastISelFor(const Function &Fn) {
   });
 }
 
+static bool shouldRegisterPGOPasses(const TargetMachine &TM,
+                                    CodeGenOptLevel OptLevel) {
+  bool RegisterPGOPasses = OptLevel != CodeGenOptLevel::None;
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grigorypas wrote:

If I make this change it breaks a lot of test cases (1024 tests). Some of the test cases use PGO information embedded in IR without setting PGOOptions flags.  

https://github.com/llvm/llvm-project/pull/161620