[InstCombine] Canonicalize "and, add", "or, add", "xor, add"

Canonicalize ``` ((x + C1) & C2) --> ((x & C2) + C1) ((x + C1) ^ C2) --> ((x ^ C2) + C1) ((x + C1) | C2) --> ((x | C2) + C1) ``` for suitable constants `C1` and `C2`. Alive2 proofs: [[ https://alive2.llvm.org/ce/z/BqMDVZ | add, or --> or, add ]] [[ https://alive2.llvm.org/ce/z/BhAeCl | add, xor --> xor, add ]] [[ https://alive2.llvm.org/ce/z/jYRHEt | add, and --> and, add ]] Reviewed By: spatel Differential Revision: https://reviews.llvm.org/D131142
llvm · Aug 26, 2022 · eb1e2b3 · eb1e2b3
1 parent a310637
commit eb1e2b3
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Showing 4 changed files with 68 additions and 25 deletions.
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1767,6 +1767,49 @@ static Instruction *reassociateForUses(BinaryOperator &BO,
   return nullptr;
 }
 
+// Match
+// (X + C2) | C
+// (X + C2) ^ C
+// (X + C2) & C
+// and convert to do the bitwise logic first:
+// (X | C) + C2
+// (X ^ C) + C2
+// (X & C) + C2
+// iff bits affected by logic op are lower than last bit affected by math op
+static Instruction *canonicalizeLogicFirst(BinaryOperator &I,
+                                           InstCombiner::BuilderTy &Builder) {
+  Type *Ty = I.getType();
+  Instruction::BinaryOps OpC = I.getOpcode();
+  Value *Op0 = I.getOperand(0);
+  Value *Op1 = I.getOperand(1);
+  Value *X;
+  const APInt *C, *C2;
+
+  if (!(match(Op0, m_OneUse(m_Add(m_Value(X), m_APInt(C2)))) &&
+        match(Op1, m_APInt(C))))
+    return nullptr;
+
+  unsigned Width = Ty->getScalarSizeInBits();
+  unsigned LastOneMath = Width - C2->countTrailingZeros();
+
+  switch (OpC) {
+  case Instruction::And:
+    if (C->countLeadingOnes() < LastOneMath)
+      return nullptr;
+    break;
+  case Instruction::Xor:
+  case Instruction::Or:
+    if (C->countLeadingZeros() < LastOneMath)
+      return nullptr;
+    break;
+  default:
+    llvm_unreachable("Unexpected BinaryOp!");
+  }
+
+  Value *NewBinOp = Builder.CreateBinOp(OpC, X, ConstantInt::get(Ty, *C));
+  return BinaryOperator::CreateAdd(NewBinOp, ConstantInt::get(Ty, *C2));
+}
+
 // FIXME: We use commutative matchers (m_c_*) for some, but not all, matches
 // here. We should standardize that construct where it is needed or choose some
 // other way to ensure that commutated variants of patterns are not missed.
@@ -1888,14 +1931,6 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
         Value *NewAnd = Builder.CreateAnd(X, Op1);
         return BinaryOperator::CreateXor(NewAnd, Op1);
       }
-
-      // If all bits affected by the add are included in a high-bit-mask, do the
-      // mask op before the add. Example:
-      // (X + 16) & -4 --> (X & -4) + 16
-      if (Op0->hasOneUse() && C->isNegatedPowerOf2() && *AddC == (*AddC & *C)) {
-        Value *NewAnd = Builder.CreateAnd(X, Op1);
-        return BinaryOperator::CreateAdd(NewAnd, ConstantInt::get(Ty, *AddC));
-      }
     }
 
     // ((C1 OP zext(X)) & C2) -> zext((C1 OP X) & C2) if C2 fits in the
@@ -2238,6 +2273,9 @@ Instruction *InstCombinerImpl::visitAnd(BinaryOperator &I) {
   if (Instruction *R = reassociateForUses(I, Builder))
     return R;
 
+  if (Instruction *Canonicalized = canonicalizeLogicFirst(I, Builder))
+    return Canonicalized;
+
   return nullptr;
 }
 
@@ -3199,6 +3237,9 @@ Instruction *InstCombinerImpl::visitOr(BinaryOperator &I) {
   if (Instruction *R = reassociateForUses(I, Builder))
     return R;
 
+  if (Instruction *Canonicalized = canonicalizeLogicFirst(I, Builder))
+    return Canonicalized;
+
   return nullptr;
 }
 
@@ -3939,5 +3980,8 @@ Instruction *InstCombinerImpl::visitXor(BinaryOperator &I) {
   if (Instruction *R = reassociateForUses(I, Builder))
     return R;
 
+  if (Instruction *Canonicalized = canonicalizeLogicFirst(I, Builder))
+    return Canonicalized;
+
   return nullptr;
 }
diff --git a/llvm/test/Transforms/InstCombine/and-xor-or.ll b/llvm/test/Transforms/InstCombine/and-xor-or.ll
@@ -4358,8 +4358,8 @@ define i1 @PR56294(i8 %x) {
 define i32 @canonicalize_logic_first_or0(i32 %x) {
 ; CHECK-LABEL: define {{[^@]+}}@canonicalize_logic_first_or0
 ; CHECK-SAME: (i32 [[X:%.*]]) {
-; CHECK-NEXT:    [[A:%.*]] = add i32 [[X]], 112
-; CHECK-NEXT:    [[R:%.*]] = or i32 [[A]], 15
+; CHECK-NEXT:    [[TMP1:%.*]] = or i32 [[X]], 15
+; CHECK-NEXT:    [[R:%.*]] = add i32 [[TMP1]], 112
 ; CHECK-NEXT:    ret i32 [[R]]
 ;
   %a = add i32 %x, 112 ; 01110000
@@ -4370,8 +4370,8 @@ define i32 @canonicalize_logic_first_or0(i32 %x) {
 define <2 x i32> @canonicalize_logic_first_or_vector0(<2 x i32> %x) {
 ; CHECK-LABEL: define {{[^@]+}}@canonicalize_logic_first_or_vector0
 ; CHECK-SAME: (<2 x i32> [[X:%.*]]) {
-; CHECK-NEXT:    [[A:%.*]] = add <2 x i32> [[X]], <i32 112, i32 112>
-; CHECK-NEXT:    [[R:%.*]] = or <2 x i32> [[A]], <i32 15, i32 15>
+; CHECK-NEXT:    [[TMP1:%.*]] = or <2 x i32> [[X]], <i32 15, i32 15>
+; CHECK-NEXT:    [[R:%.*]] = add <2 x i32> [[TMP1]], <i32 112, i32 112>
 ; CHECK-NEXT:    ret <2 x i32> [[R]]
 ;
   %a = add <2 x i32> <i32 112, i32 112>, %x ; <0x00000070, 0x00000070>
@@ -4433,8 +4433,8 @@ define i32 @canonicalize_logic_first_or_bad_constraints2(i32 %x) {
 define i8 @canonicalize_logic_first_and0(i8 %x) {
 ; CHECK-LABEL: define {{[^@]+}}@canonicalize_logic_first_and0
 ; CHECK-SAME: (i8 [[X:%.*]]) {
-; CHECK-NEXT:    [[B:%.*]] = add i8 [[X]], 48
-; CHECK-NEXT:    [[R:%.*]] = and i8 [[B]], -10
+; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[X]], -10
+; CHECK-NEXT:    [[R:%.*]] = add i8 [[TMP1]], 48
 ; CHECK-NEXT:    ret i8 [[R]]
 ;
   %b = add i8 %x, 48    ;  00110000
@@ -4445,8 +4445,8 @@ define i8 @canonicalize_logic_first_and0(i8 %x) {
 define <2 x i8> @canonicalize_logic_first_and_vector0(<2 x i8> %x) {
 ; CHECK-LABEL: define {{[^@]+}}@canonicalize_logic_first_and_vector0
 ; CHECK-SAME: (<2 x i8> [[X:%.*]]) {
-; CHECK-NEXT:    [[A:%.*]] = add <2 x i8> [[X]], <i8 48, i8 48>
-; CHECK-NEXT:    [[R:%.*]] = and <2 x i8> [[A]], <i8 -10, i8 -10>
+; CHECK-NEXT:    [[TMP1:%.*]] = and <2 x i8> [[X]], <i8 -10, i8 -10>
+; CHECK-NEXT:    [[R:%.*]] = add <2 x i8> [[TMP1]], <i8 48, i8 48>
 ; CHECK-NEXT:    ret <2 x i8> [[R]]
 ;
   %a = add <2 x i8> <i8 48, i8 48>, %x
@@ -4522,8 +4522,8 @@ define i8 @canonicalize_logic_first_and_bad_constraints2(i8 %x) {
 define i8 @canonicalize_logic_first_xor_0(i8 %x) {
 ; CHECK-LABEL: define {{[^@]+}}@canonicalize_logic_first_xor_0
 ; CHECK-SAME: (i8 [[X:%.*]]) {
-; CHECK-NEXT:    [[A:%.*]] = add i8 [[X]], 96
-; CHECK-NEXT:    [[R:%.*]] = xor i8 [[A]], 31
+; CHECK-NEXT:    [[TMP1:%.*]] = xor i8 [[X]], 31
+; CHECK-NEXT:    [[R:%.*]] = add i8 [[TMP1]], 96
 ; CHECK-NEXT:    ret i8 [[R]]
 ;
   %a = add i8 %x, 96  ; 01100000
@@ -4534,8 +4534,8 @@ define i8 @canonicalize_logic_first_xor_0(i8 %x) {
 define <2 x i32> @canonicalize_logic_first_xor_vector0(<2 x i32> %x) {
 ; CHECK-LABEL: define {{[^@]+}}@canonicalize_logic_first_xor_vector0
 ; CHECK-SAME: (<2 x i32> [[X:%.*]]) {
-; CHECK-NEXT:    [[A:%.*]] = add <2 x i32> [[X]], <i32 -8388608, i32 -8388608>
-; CHECK-NEXT:    [[R:%.*]] = xor <2 x i32> [[A]], <i32 32783, i32 32783>
+; CHECK-NEXT:    [[TMP1:%.*]] = xor <2 x i32> [[X]], <i32 32783, i32 32783>
+; CHECK-NEXT:    [[R:%.*]] = add <2 x i32> [[TMP1]], <i32 -8388608, i32 -8388608>
 ; CHECK-NEXT:    ret <2 x i32> [[R]]
 ;
   %a = add <2 x i32> <i32 -8388608, i32 -8388608>, %x ; <0xFF800000, 0xFF800000>

diff --git a/llvm/test/Transforms/InstCombine/freeze.ll b/llvm/test/Transforms/InstCombine/freeze.ll
@@ -132,8 +132,7 @@ define i32 @early_freeze_test3(i32 %v1) {
 ; CHECK-LABEL: @early_freeze_test3(
 ; CHECK-NEXT:    [[V1_FR:%.*]] = freeze i32 [[V1:%.*]]
 ; CHECK-NEXT:    [[V2:%.*]] = shl i32 [[V1_FR]], 1
-; CHECK-NEXT:    [[V3:%.*]] = add i32 [[V2]], 2
-; CHECK-NEXT:    [[V4:%.*]] = or i32 [[V3]], 1
+; CHECK-NEXT:    [[V4:%.*]] = add i32 [[V2]], 3
 ; CHECK-NEXT:    ret i32 [[V4]]
 ;
   %v2 = shl i32 %v1, 1

diff --git a/llvm/test/Transforms/InstCombine/sub.ll b/llvm/test/Transforms/InstCombine/sub.ll
@@ -1517,10 +1517,10 @@ define i8 @sub_not_mask_lowbits(i8 %x) {
 
 define <2 x i8> @sub_mask_lowbits_splat_extra_use(<2 x i8> %x, <2 x i8>* %p) {
 ; CHECK-LABEL: @sub_mask_lowbits_splat_extra_use(
-; CHECK-NEXT:    [[A1:%.*]] = add <2 x i8> [[X:%.*]], <i8 -64, i8 -64>
-; CHECK-NEXT:    [[A2:%.*]] = and <2 x i8> [[X]], <i8 10, i8 10>
+; CHECK-NEXT:    [[A2:%.*]] = and <2 x i8> [[X:%.*]], <i8 10, i8 10>
 ; CHECK-NEXT:    store <2 x i8> [[A2]], <2 x i8>* [[P:%.*]], align 2
-; CHECK-NEXT:    [[R:%.*]] = and <2 x i8> [[A1]], <i8 -11, i8 -11>
+; CHECK-NEXT:    [[TMP1:%.*]] = and <2 x i8> [[X]], <i8 -11, i8 -11>
+; CHECK-NEXT:    [[R:%.*]] = add <2 x i8> [[TMP1]], <i8 -64, i8 -64>
 ; CHECK-NEXT:    ret <2 x i8> [[R]]
 ;
   %a1 = add <2 x i8> %x, <i8 192, i8 192> ; 0xc0