[Transforms][IPO] Add remarks for ArgumentPromotion and DeadArgumentE…

llvm/lib/Transforms/IPO/ArgumentPromotion.cpp

@@ -42,6 +42,7 @@
 #include "llvm/Analysis/CallGraph.h"
 #include "llvm/Analysis/Loads.h"
 #include "llvm/Analysis/MemoryLocation.h"
+#include "llvm/Analysis/OptimizationRemarkEmitter.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/IR/Argument.h"
@@ -126,6 +127,7 @@ doPromotion(Function *F, FunctionAnalysisManager &FAM,
   // arguments.
   SmallVector<unsigned> NewArgIndices;
   AttributeList PAL = F->getAttributes();
+  OptimizationRemarkEmitter ORE(F);
 
   // First, determine the new argument list
   unsigned ArgNo = 0, NewArgNo = 0;
@@ -139,6 +141,12 @@ doPromotion(Function *F, FunctionAnalysisManager &FAM,
     } else if (I->use_empty()) {
       // Dead argument (which are always marked as promotable)
       ++NumArgumentsDead;
+      ORE.emit([&]() {
+        return OptimizationRemark(DEBUG_TYPE, "ArgumentRemoved", F)
+               << "eliminating argument " << ore::NV("ArgName", I->getName())
+               << "(" << ore::NV("ArgIndex", ArgNo) << ")";
+      });
+
       NewArgIndices.push_back((unsigned)-1);
     } else {
       const auto &ArgParts = ArgsToPromote.find(&*I)->second;
@@ -147,6 +155,13 @@ doPromotion(Function *F, FunctionAnalysisManager &FAM,
         ArgAttrVec.push_back(AttributeSet());
       }
       ++NumArgumentsPromoted;
+      ORE.emit([&]() {
+        return OptimizationRemark(DEBUG_TYPE, "ArgumentPromoted", F)
+               << "promoting argument " << ore::NV("ArgName", I->getName())
+               << "(" << ore::NV("ArgIndex", ArgNo) << ")"
+               << " to pass by value";
+      });
+
       NewArgIndices.push_back((unsigned)-1);
       NewArgNo += ArgParts.size();
     }

llvm/lib/Transforms/IPO/DeadArgumentElimination.cpp

@@ -19,6 +19,7 @@
 #include "llvm/Transforms/IPO/DeadArgumentElimination.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/OptimizationRemarkEmitter.h"
 #include "llvm/IR/Argument.h"
 #include "llvm/IR/AttributeMask.h"
 #include "llvm/IR/Attributes.h"
@@ -748,6 +749,7 @@ bool DeadArgumentEliminationPass::removeDeadStuffFromFunction(Function *F) {
   // Set up to build a new list of parameter attributes.
   SmallVector<AttributeSet, 8> ArgAttrVec;
   const AttributeList &PAL = F->getAttributes();
+  OptimizationRemarkEmitter ORE(F);
 
   // Remember which arguments are still alive.
   SmallVector<bool, 10> ArgAlive(FTy->getNumParams(), false);
@@ -765,6 +767,12 @@ bool DeadArgumentEliminationPass::removeDeadStuffFromFunction(Function *F) {
       HasLiveReturnedArg |= PAL.hasParamAttr(ArgI, Attribute::Returned);
     } else {
       ++NumArgumentsEliminated;
+
+      ORE.emit([&]() {
+        return OptimizationRemark(DEBUG_TYPE, "ArgumentRemoved", F)
+               << "eliminating argument " << ore::NV("ArgName", I->getName())
+               << "(" << ore::NV("ArgIndex", ArgI) << ")";
+      });
       LLVM_DEBUG(dbgs() << "DeadArgumentEliminationPass - Removing argument "
                         << ArgI << " (" << I->getName() << ") from "
                         << F->getName() << "\n");
@@ -810,6 +818,11 @@ bool DeadArgumentEliminationPass::removeDeadStuffFromFunction(Function *F) {
         NewRetIdxs[Ri] = RetTypes.size() - 1;
       } else {
         ++NumRetValsEliminated;
+
+        ORE.emit([&]() {
+          return OptimizationRemark(DEBUG_TYPE, "ReturnValueRemoved", F)
+                 << "removing return value " << std::to_string(Ri);
+        });
         LLVM_DEBUG(
             dbgs() << "DeadArgumentEliminationPass - Removing return value "
                    << Ri << " from " << F->getName() << "\n");

llvm/test/Transforms/ArgumentPromotion/2008-02-01-ReturnAttrs.ll

@@ -1,12 +1,22 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --function-signature --scrub-attributes
-; RUN: opt < %s -passes=argpromotion -S | FileCheck %s
+; RUN: opt < %s -passes=argpromotion -S -pass-remarks-output=%t | FileCheck %s
+; RUN: cat %t | FileCheck -check-prefix=REMARK %s
 
 define internal i32 @deref(ptr %x) nounwind {
 ; CHECK-LABEL: define {{[^@]+}}@deref
 ; CHECK-SAME: (i32 [[X_0_VAL:%.*]]) #[[ATTR0:[0-9]+]] {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    ret i32 [[X_0_VAL]]
 ;
+; REMARK-LABEL: Function: deref
+; REMARK:       Args:
+; REMARK-NEXT:    - String:   'promoting argument '
+; REMARK-NEXT:    - ArgName:  x
+; REMARK-NEXT:    - String:   '('
+; REMARK-NEXT:    - ArgIndex: '0'
+; REMARK-NEXT:    - String:   ')'
+; REMARK-NEXT:    - String:   ' to pass by value'
+;
 entry:
   %temp2 = load i32, ptr %x, align 4
   ret i32 %temp2

llvm/test/Transforms/DeadArgElim/2007-12-20-ParamAttrs.ll

@@ -1,10 +1,19 @@
-; RUN: opt < %s -passes=deadargelim -S | FileCheck %s
+; RUN: opt < %s -passes=deadargelim -S -pass-remarks-output=%t | FileCheck %s
+; RUN: cat %t | FileCheck -check-prefix=REMARK %s
 
 %struct = type { }
 
 @g = global i8 0
 
 ; CHECK: define internal void @foo(i8 signext %y) [[NUW:#[0-9]+]]
+;
+; REMARK-LABEL: Function: foo
+; REMARK:       Args:
+; REMARK-NEXT:    - String:   'eliminating argument '
+; REMARK-NEXT:    - ArgName:  p
+; REMARK-NEXT:    - String:   '('
+; REMARK-NEXT:    - ArgIndex: '0'
+; REMARK-NEXT:    - String:   ')'
 
 define internal zeroext i8 @foo(ptr inreg %p, i8 signext %y, ... )  nounwind {
   store i8 %y, ptr @g