address comments

Author: c-rhodes

llvm/lib/Transforms/AggressiveInstCombine/AggressiveInstCombine.cpp

@@ -1458,6 +1458,10 @@ static bool foldLibCalls(Instruction &I, TargetTransformInfo &TTI,
 }
 
 /// Match low part of 128-bit multiplication.
+///
+/// Use counts are checked to prevent total instruction count increase as per
+/// contributors guide:
+/// https://llvm.org/docs/InstCombineContributorGuide.html#multi-use-handling
 static bool foldMul128Low(Instruction &I) {
   auto *Ty = I.getType();
   if (!Ty->isIntegerTy(64))
@@ -1529,6 +1533,10 @@ static bool foldMul128Low(Instruction &I) {
 }
 
 /// Match high part of 128-bit multiplication.
+///
+/// Use counts are checked to prevent total instruction count increase as per
+/// contributors guide:
+/// https://llvm.org/docs/InstCombineContributorGuide.html#multi-use-handling
 static bool foldMul128High(Instruction &I) {
   auto *Ty = I.getType();
   if (!Ty->isIntegerTy(64))
@@ -1647,6 +1655,10 @@ static bool foldMul128High(Instruction &I) {
 ///   %u1_hi = lshr i64 %u1, 32
 ///   %u2 = add nuw i64 %u0_hi, %t3
 ///   %hw64 = add nuw i64 %u2, %u1_hi
+///
+/// Use counts are checked to prevent total instruction count increase as per
+/// contributors guide:
+/// https://llvm.org/docs/InstCombineContributorGuide.html#multi-use-handling
 static bool foldMul128HighVariant(Instruction &I) {
   auto *Ty = I.getType();
   if (!Ty->isIntegerTy(64))

llvm/test/Transforms/AggressiveInstCombine/umulh.ll

@@ -84,7 +84,7 @@ define i64 @umulh_variant(i64 %x, i64 %y) {
 
 ; Commutative ops should match in any order. Ops where operand order has been
 ; reversed from above are marked 'commuted'. As per instcombine contributors
-; guide, constants are always canonicalized to RHS, so don't both commuting
+; guide, constants are always canonicalized to RHS, so don't bother commuting
 ; constants.
 define i64 @umulh__commuted(i64 %x, i64 %y) {
 ; CHECK-LABEL: define i64 @umulh__commuted(