[InstCombine] Fix bug when folding x + (x | -x) to x & (x - 1)

[marcauberer]

Summary

Addresses concern: https://reviews.llvm.org/rG09cdddea0c4d284c2c22f5dfade40a60850c5ea7

There was a copy/paste mistake in the code. Updated code and test ref.

[spatel]

LGTM

llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp

Instruction *InstCombinerImpl::visitAdd(BinaryOperator &I) {
   // (add A (or A, -A)) --> (and (add A, -1) A)
   // (add A (or -A, A)) --> (and (add A, -1) A)
   // (add (or A, -A) A) --> (and (add A, -1) A)
   // (add (or -A, A) A) --> (and (add A, -1) A)
   if (match(&I, m_c_BinOp(m_Value(A), m_OneUse(m_c_Or(m_Neg(m_Deferred(A)),
                                                       m_Deferred(A)))))) {
     Value *Add =
         Builder.CreateAdd(A, Constant::getAllOnesValue(A->getType()), "",
-                          I.hasNoSignedWrap(), I.hasNoSignedWrap());
+                          I.hasNoUnsignedWrap(), I.hasNoSignedWrap());
     return BinaryOperator::CreateAnd(Add, A);
   }
 
   // Canonicalize ((A & -A) - 1) --> ((A - 1) & ~A)
   // Forms all commutable operations, and simplifies ctpop -> cttz folds.
   if (match(&I,
             m_Add(m_OneUse(m_c_And(m_Value(A), m_OneUse(m_Neg(m_Deferred(A))))),
                   m_AllOnes()))) {

llvm/test/Transforms/InstCombine/add_or_sub.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -passes=instcombine -S | FileCheck %s
 
 declare void @use19(i19)
 declare void @use12(i12)
 declare void @use2(i2)
 
 define i32 @add_or_sub_comb_i32_commuted1_nuw(i32 %x) {
 ; CHECK-LABEL: @add_or_sub_comb_i32_commuted1_nuw(
-; CHECK-NEXT:    [[TMP1:%.*]] = add i32 [[X:%.*]], -1
-; CHECK-NEXT:    [[ADD:%.*]] = and i32 [[TMP1]], [[X]]
-; CHECK-NEXT:    ret i32 [[ADD]]
+; CHECK-NEXT:    ret i32 [[X:%.*]]
 ;
   %sub = sub i32 0, %x
   %or = or i32 %sub, %x
   %add = add nuw i32 %or, %x
   ret i32 %add
 }
 
 define i8 @add_or_sub_comb_i8_commuted2_nsw(i8 %p) {
 ; CHECK-LABEL: @add_or_sub_comb_i8_commuted2_nsw(
 ; CHECK-NEXT:    [[X:%.*]] = mul i8 [[P:%.*]], [[P]]
-; CHECK-NEXT:    ret i8 [[X]]
+; CHECK-NEXT:    [[TMP1:%.*]] = add nsw i8 [[X]], -1
+; CHECK-NEXT:    [[ADD:%.*]] = and i8 [[TMP1]], [[X]]
+; CHECK-NEXT:    ret i8 [[ADD]]
 ;
   %x = mul i8 %p, %p ; thwart complexity-based canonicalization
   %sub = sub i8 0, %x
   %or = or i8 %sub, %x
   %add = add nsw i8 %x, %or
   ret i8 %add
 }