[InstCombine] Regard zext nneg as sext when folding add(zext neg(add))

Signed-off-by: ZelinMa557 <[email protected]>

Author: ZelinMa557

llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp

@@ -828,9 +828,10 @@ static Instruction *foldNoWrapAdd(BinaryOperator &Add,
 
   // More general combining of constants in the wide type.
   // (sext (X +nsw NarrowC)) + C --> (sext X) + (sext(NarrowC) + C)
+  // or (zext nneg (X +nsw NarrowC)) + C --> (sext X) + (sext(NarrowC) + C)
   Constant *NarrowC;
-  if (match(Op0,
-            m_OneUse(m_SExt(m_NSWAddLike(m_Value(X), m_Constant(NarrowC)))))) {
+  if (match(Op0, m_OneUse(m_SExtLike(
+                     m_NSWAddLike(m_Value(X), m_Constant(NarrowC)))))) {
     Value *WideC = Builder.CreateSExt(NarrowC, Ty);
     Value *NewC = Builder.CreateAdd(WideC, Op1C);
     Value *WideX = Builder.CreateSExt(X, Ty);
@@ -844,7 +845,6 @@ static Instruction *foldNoWrapAdd(BinaryOperator &Add,
     Value *WideX = Builder.CreateZExt(X, Ty);
     return BinaryOperator::CreateAdd(WideX, NewC);
   }
-
   return nullptr;
 }
 

llvm/test/Transforms/InstCombine/add.ll

@@ -4093,9 +4093,8 @@ define i32 @fold_zext_addition_fail2(i8 %x) {
 
 define i32 @fold_zext_nneg_add_const(i8 %x) {
 ; CHECK-LABEL: @fold_zext_nneg_add_const(
-; CHECK-NEXT:    [[XX:%.*]] = add nsw i8 [[X:%.*]], 123
-; CHECK-NEXT:    [[ZE:%.*]] = zext nneg i8 [[XX]] to i32
-; CHECK-NEXT:    [[R:%.*]] = add nsw i32 [[ZE]], -25
+; CHECK-NEXT:    [[TMP1:%.*]] = sext i8 [[X:%.*]] to i32
+; CHECK-NEXT:    [[R:%.*]] = add nsw i32 [[TMP1]], 98
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %xx = add nsw i8 %x, 123