[NewPM] Add missing LTO ArgPromotion pass

This is a followup to D96780 to add one more pass missing from the NewPM LTO pipeline. The missing ArgPromotion run is inserted at the same position as in the LegacyPM, resolving the already present FIXME: https://github.com/llvm/llvm-project/blob/16086d47c0d0cd08ffae8e69a69c88653e654d01/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp#L1096-L1098 The compile-time impact is minimal with ~0.1% geomean regression on CTMark. Differential Revision: https://reviews.llvm.org/D108866 (cherry picked from commit b28c3b9)

Author: nikic

llvm/lib/Passes/PassBuilder.cpp

@@ -1784,9 +1784,12 @@ PassBuilder::buildLTODefaultPipeline(OptimizationLevel Level,
  MPM.addPass(GlobalOptPass());
 
  // Garbage collect dead functions.
- // FIXME: Add ArgumentPromotion pass after once it's ported.
  MPM.addPass(GlobalDCEPass());
 
+ // If we didn't decide to inline a function, check to see if we can
+ // transform it to pass arguments by value instead of by reference.
+ MPM.addPass(createModuleToPostOrderCGSCCPassAdaptor(ArgumentPromotionPass()));
+
  FunctionPassManager FPM;
  // The IPO Passes may leave cruft around. Clean up after them.
  FPM.addPass(InstCombinePass());

llvm/test/Other/new-pm-lto-defaults.ll

@@ -73,6 +73,7 @@
 ; CHECK-O23SZ-NEXT: Running pass: InlinerPass
 ; CHECK-O23SZ-NEXT: Running pass: GlobalOptPass
 ; CHECK-O23SZ-NEXT: Running pass: GlobalDCEPass
+; CHECK-O23SZ-NEXT: Running pass: ArgumentPromotionPass
 ; CHECK-O23SZ-NEXT: Running pass: InstCombinePass
 ; CHECK-EP-Peephole-NEXT: Running pass: NoOpFunctionPass
 ; CHECK-O23SZ-NEXT: Running pass: JumpThreadingPass