[InstCombine] Support folding and/or/xor with a constant vector RHS into selects and phis

[craig.topper]

Summary

Currently we only fold with ConstantInt RHS. This generalizes to any Constant RHS.

[spatel]

Can you add or change the bitwise logic tests to not have splat constants? That should allow us to expose the difference in a regression test (SimplifyDemanded doesn't handle non-splat afaik).
Also, for the bitwise logic tests, please add tests with a phi op, so we have some coverage for that part.

And actually, that makes the add/sub part of this seem suspicious and probably worth splitting into a separate patch. I think those cases should be calling foldOpWithConstantIntoOperand() to cover both selects and phis.

[craig.topper]

Reduced to just the logic operations. Updated tests to include phis

[spatel]

LGTM. It would be nice to hoist transforms that are common to all of the bitwise logic ops into a shared helper as an NFC follow-up, so we're not duplicating code. We have something like that for the shift instructions.

[craig.topper]

Agreed. I'll do that.

lib/Transforms/InstCombine/InstCombineAddSub.cpp

if (LHS->hasOneUse() &&
       APInt AddRHSHighBitsAnd(AddRHSHighBits & C2->getValue());
 
       if (AddRHSHighBits == AddRHSHighBitsAnd) {
         // Okay, the xform is safe.  Insert the new add pronto.
         Value *NewAdd = Builder->CreateAdd(X, CRHS, LHS->getName());
         return BinaryOperator::CreateAnd(NewAdd, C2);
       }
     }
+  }
 
-    // Try to fold constant add into select arguments.
+  if (isa<Constant>(RHS))
     if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
       if (Instruction *R = FoldOpIntoSelect(I, SI))
         return R;
-  }
 
   // add (select X 0 (sub n A)) A  -->  select X A n
   {
     SelectInst *SI = dyn_cast<SelectInst>(LHS);
     Value *A = RHS;
     if (!SI) {
       SI = dyn_cast<SelectInst>(RHS);
       A = LHS;

lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

// immediate, transform it.  This frequently occurs for bitfield accesses.
         // This will fold the two constants together, which may allow
         // other simplifications.
         Value *NewCast = Builder->CreateTrunc(X, I.getType(), "and.shrunk");
         Constant *C3 = ConstantExpr::getTrunc(YC, I.getType());
         C3 = ConstantExpr::getAnd(C3, AndRHS);
         return BinaryOperator::CreateAnd(NewCast, C3);
       }
     }
+  }
 
+  if (isa<Constant>(Op1))
     if (Instruction *FoldedLogic = foldOpWithConstantIntoOperand(I))
       return FoldedLogic;
-  }
 
   if (Instruction *DeMorgan = matchDeMorgansLaws(I, Builder))
     return DeMorgan;
 
   {
     Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
     // (A|B) & ~(A&B) -> A^B
     if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
     // (X ^ C1) | C2 --> (X | C2) ^ (C1&~C2)
     if (match(Op0, m_Xor(m_Value(X), m_ConstantInt(C1))) &&
         Op0->hasOneUse()) {
       Value *Or = Builder->CreateOr(X, RHS);
       Or->takeName(Op0);
       return BinaryOperator::CreateXor(Or,
                             Builder->getInt(C1->getValue() & ~RHS->getValue()));
     }
+  }
 
+  if (isa<Constant>(Op1))
     if (Instruction *FoldedLogic = foldOpWithConstantIntoOperand(I))
       return FoldedLogic;
-  }
 
   // Given an OR instruction, check to see if this is a bswap.
   if (Instruction *BSwap = MatchBSwap(I))
     return BSwap;
 
   Value *A = nullptr, *B = nullptr;
   ConstantInt *C1 = nullptr, *C2 = nullptr;
 
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
             cast<Instruction>(Opnd0)->setDebugLoc(I.getDebugLoc());
             Value *FoldVal = ConstantInt::get(Opnd0->getType(), FoldConst);
 
             return BinaryOperator::CreateXor(Opnd0, FoldVal);
           }
         }
       }
     }
+  }
 
+  if (isa<Constant>(Op1))
     if (Instruction *FoldedLogic = foldOpWithConstantIntoOperand(I))
       return FoldedLogic;
-  }
 
   BinaryOperator *Op1I = dyn_cast<BinaryOperator>(Op1);
   if (Op1I) {
     Value *A, *B;
     if (match(Op1I, m_Or(m_Value(A), m_Value(B)))) {
       if (A == Op0) {              // B^(B|A) == (A|B)^B
         Op1I->swapOperands();
         I.swapOperands();

test/Transforms/InstCombine/add.ll

 ;
   %A = select i1 %C, i32 1000, i32 10
   %V = add i32 %A, 123
   ret i32 %V
 }
 
 define <2 x i32> @test19vec(i1 %C) {
 ; CHECK-LABEL: @test19vec(
-; CHECK-NEXT:    [[A:%.*]] = select i1 [[C:%.*]], <2 x i32> <i32 1000, i32 1000>, <2 x i32> <i32 10, i32 10>
-; CHECK-NEXT:    [[V:%.*]] = add nuw nsw <2 x i32> [[A]], <i32 123, i32 123>
+; CHECK-NEXT:    [[V:%.*]] = select i1 [[C:%.*]], <2 x i32> <i32 1123, i32 1123>, <2 x i32> <i32 133, i32 133>
 ; CHECK-NEXT:    ret <2 x i32> [[V]]
 ;
   %A = select i1 %C, <2 x i32> <i32 1000, i32 1000>, <2 x i32> <i32 10, i32 10>
   %V = add <2 x i32> %A, <i32 123, i32 123>
   ret <2 x i32> %V
 }
 
 ; This is an InstSimplify fold, but test it here to make sure that

test/Transforms/InstCombine/or.ll

 ;
   %A = select i1 %C, i32 1000, i32 10
   %V = or i32 %A, 123
   ret i32 %V
 }
 
 define <2 x i32> @test49vec(i1 %C) {
 ; CHECK-LABEL: @test49vec(
-; CHECK-NEXT:    [[A:%.*]] = select i1 [[C:%.*]], <2 x i32> <i32 896, i32 896>, <2 x i32> zeroinitializer
-; CHECK-NEXT:    [[V:%.*]] = or <2 x i32> [[A]], <i32 123, i32 123>
+; CHECK-NEXT:    [[V:%.*]] = select i1 [[C:%.*]], <2 x i32> <i32 1019, i32 1019>, <2 x i32> <i32 123, i32 123>
 ; CHECK-NEXT:    ret <2 x i32> [[V]]
 ;
   %A = select i1 %C, <2 x i32> <i32 1000, i32 1000>, <2 x i32> <i32 10, i32 10>
   %V = or <2 x i32> %A, <i32 123, i32 123>
   ret <2 x i32> %V
 }

test/Transforms/InstCombine/xor.ll

 ;
   %A = select i1 %C, i32 1000, i32 10
   %V = xor i32 %A, 123
   ret i32 %V
 }
 
 define <2 x i32> @test29vec(i1 %C) {
 ; CHECK-LABEL: @test29vec(
-; CHECK-NEXT:    [[A:%.*]] = select i1 [[C:%.*]], <2 x i32> <i32 1000, i32 1000>, <2 x i32> <i32 10, i32 10>
-; CHECK-NEXT:    [[V:%.*]] = xor <2 x i32> [[A]], <i32 123, i32 123>
+; CHECK-NEXT:    [[V:%.*]] = select i1 [[C:%.*]], <2 x i32> <i32 915, i32 915>, <2 x i32> <i32 113, i32 113>
 ; CHECK-NEXT:    ret <2 x i32> [[V]]
 ;
   %A = select i1 %C, <2 x i32> <i32 1000, i32 1000>, <2 x i32> <i32 10, i32 10>
   %V = xor <2 x i32> %A, <i32 123, i32 123>
   ret <2 x i32> %V
 }