diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp index fa946e63ac6..a34b73ace49 100644 --- a/lib/Transforms/InstCombine/InstCombineSelect.cpp +++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp @@ -350,6 +350,67 @@ static Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp, return 0; } +/// foldSelectICmpAndOr - We want to turn: +/// (select (icmp eq (and X, C1), 0), Y, (or Y, C2)) +/// into: +/// (or (shl (and X, C1), C3), y) +/// iff: +/// C1 and C2 are both powers of 2 +/// where: +/// C3 = Log(C2) - Log(C1) +/// +/// This transform handles cases where: +/// 1. The icmp predicate is inverted +/// 2. The select operands are reversed +/// 3. The magnitude of C2 and C1 are flipped +static Value *foldSelectICmpAndOr(const SelectInst &SI, Value *TrueVal, + Value *FalseVal, + InstCombiner::BuilderTy *Builder) { + const ICmpInst *IC = dyn_cast(SI.getCondition()); + if (!IC || !IC->isEquality()) + return 0; + + Value *CmpLHS = IC->getOperand(0); + Value *CmpRHS = IC->getOperand(1); + + if (!match(CmpRHS, m_Zero())) + return 0; + + Value *X; + const APInt *C1; + if (!match(CmpLHS, m_And(m_Value(X), m_Power2(C1)))) + return 0; + + const APInt *C2; + bool OrOnTrueVal = false; + bool OrOnFalseVal = match(FalseVal, m_Or(m_Specific(TrueVal), m_Power2(C2))); + if (!OrOnFalseVal) + OrOnTrueVal = match(TrueVal, m_Or(m_Specific(FalseVal), m_Power2(C2))); + + if (!OrOnFalseVal && !OrOnTrueVal) + return 0; + + Value *V = CmpLHS; + Value *Y = OrOnFalseVal ? TrueVal : FalseVal; + + unsigned C1Log = C1->logBase2(); + unsigned C2Log = C2->logBase2(); + if (C2Log > C1Log) { + V = Builder->CreateZExtOrTrunc(V, Y->getType()); + V = Builder->CreateShl(V, C2Log - C1Log); + } else if (C1Log > C2Log) { + V = Builder->CreateLShr(V, C1Log - C2Log); + V = Builder->CreateZExtOrTrunc(V, Y->getType()); + } + + ICmpInst::Predicate Pred = IC->getPredicate(); + if ((Pred == ICmpInst::ICMP_NE && OrOnFalseVal) || + (Pred == ICmpInst::ICMP_EQ && OrOnTrueVal)) + V = Builder->CreateXor(V, *C2); + + return Builder->CreateOr(V, Y); +} + /// visitSelectInstWithICmp - Visit a SelectInst that has an /// ICmpInst as its first operand. /// @@ -521,6 +582,9 @@ Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI, } } + if (Value *V = foldSelectICmpAndOr(SI, TrueVal, FalseVal, Builder)) + return ReplaceInstUsesWith(SI, V); + return Changed ? &SI : 0; } diff --git a/test/Transforms/InstCombine/select.ll b/test/Transforms/InstCombine/select.ll index cc3aacdce3c..08487a3696d 100644 --- a/test/Transforms/InstCombine/select.ll +++ b/test/Transforms/InstCombine/select.ll @@ -863,3 +863,112 @@ while.body: ; CHECK: @test64 ; CHECK-NOT: select } + +; CHECK: @select_icmp_eq_and_1_0_or_2 +; CHECK-NEXT: [[SHL:%[a-z0-9]+]] = shl i32 %x, 1 +; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 [[SHL]], 2 +; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 [[AND]], %y +; CHECK-NEXT: ret i32 [[OR]] +define i32 @select_icmp_eq_and_1_0_or_2(i32 %x, i32 %y) { + %and = and i32 %x, 1 + %cmp = icmp eq i32 %and, 0 + %or = or i32 %y, 2 + %select = select i1 %cmp, i32 %y, i32 %or + ret i32 %select +} + +; CHECK: @select_icmp_eq_and_32_0_or_8 +; CHECK-NEXT: [[LSHR:%[a-z0-9]+]] = lshr i32 %x, 2 +; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 [[LSHR]], 8 +; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 [[AND]], %y +; CHECK-NEXT: ret i32 [[OR]] +define i32 @select_icmp_eq_and_32_0_or_8(i32 %x, i32 %y) { + %and = and i32 %x, 32 + %cmp = icmp eq i32 %and, 0 + %or = or i32 %y, 8 + %select = select i1 %cmp, i32 %y, i32 %or + ret i32 %select +} + +; CHECK: @select_icmp_ne_0_and_4096_or_4096 +; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 %x, 4096 +; CHECK-NEXT: [[XOR:%[a-z0-9]+]] = xor i32 [[AND]], 4096 +; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 [[XOR]], %y +; CHECK-NEXT: ret i32 [[OR]] +define i32 @select_icmp_ne_0_and_4096_or_4096(i32 %x, i32 %y) { + %and = and i32 %x, 4096 + %cmp = icmp ne i32 0, %and + %or = or i32 %y, 4096 + %select = select i1 %cmp, i32 %y, i32 %or + ret i32 %select +} + +; CHECK: @select_icmp_eq_and_4096_0_or_4096 +; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 %x, 4096 +; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 [[AND]], %y +; CHECK-NEXT: ret i32 [[OR]] +define i32 @select_icmp_eq_and_4096_0_or_4096(i32 %x, i32 %y) { + %and = and i32 %x, 4096 + %cmp = icmp eq i32 %and, 0 + %or = or i32 %y, 4096 + %select = select i1 %cmp, i32 %y, i32 %or + ret i32 %select +} + +; CHECK: @select_icmp_ne_0_and_4096_or_32 +; CHECK-NEXT: [[LSHR:%[a-z0-9]+]] = lshr i32 %x, 7 +; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 [[LSHR]], 32 +; CHECK-NEXT: [[XOR:%[a-z0-9]+]] = xor i32 [[AND]], 32 +; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 [[XOR]], %y +; CHECK-NEXT: ret i32 [[OR]] +define i32 @select_icmp_ne_0_and_4096_or_32(i32 %x, i32 %y) { + %and = and i32 %x, 4096 + %cmp = icmp ne i32 0, %and + %or = or i32 %y, 32 + %select = select i1 %cmp, i32 %y, i32 %or + ret i32 %select +} + +; CHECK: @select_icmp_ne_0_and_32_or_4096 +; CHECK-NEXT: [[SHL:%[a-z0-9]+]] = shl i32 %x, 7 +; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 [[SHL]], 4096 +; CHECK-NEXT: [[XOR:%[a-z0-9]+]] = xor i32 [[AND]], 4096 +; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 [[XOR]], %y +; CHECK-NEXT: ret i32 [[OR]] +define i32 @select_icmp_ne_0_and_32_or_4096(i32 %x, i32 %y) { + %and = and i32 %x, 32 + %cmp = icmp ne i32 0, %and + %or = or i32 %y, 4096 + %select = select i1 %cmp, i32 %y, i32 %or + ret i32 %select +} + +; CHECK: @select_icmp_ne_0_and_1073741824_or_8 +; CHECK-NEXT: [[LSHR:%[a-z0-9]+]] = lshr i32 %x, 27 +; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i32 [[LSHR]], 8 +; CHECK-NEXT: [[TRUNC:%[a-z0-9]+]] = trunc i32 [[AND]] to i8 +; CHECK-NEXT: [[XOR:%[a-z0-9]+]] = xor i8 [[TRUNC]], 8 +; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i8 [[XOR]], %y +; CHECK-NEXT: ret i8 [[OR]] +define i8 @select_icmp_ne_0_and_1073741824_or_8(i32 %x, i8 %y) { + %and = and i32 %x, 1073741824 + %cmp = icmp ne i32 0, %and + %or = or i8 %y, 8 + %select = select i1 %cmp, i8 %y, i8 %or + ret i8 %select +} + +; CHECK: @select_icmp_ne_0_and_8_or_1073741824 +; CHECK-NEXT: [[AND:%[a-z0-9]+]] = and i8 %x, 8 +; CHECK-NEXT: [[ZEXT:%[a-z0-9]+]] = zext i8 [[AND]] to i32 +; CHECK-NEXT: [[SHL:%[a-z0-9]+]] = shl nuw nsw i32 [[ZEXT]], 27 +; CHECK-NEXT: [[XOR:%[a-z0-9]+]] = xor i32 [[SHL]], 1073741824 +; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 [[XOR]], %y +; CHECK-NEXT: ret i32 [[OR]] +define i32 @select_icmp_ne_0_and_8_or_1073741824(i8 %x, i32 %y) { + %and = and i8 %x, 8 + %cmp = icmp ne i8 0, %and + %or = or i32 %y, 1073741824 + %select = select i1 %cmp, i32 %y, i32 %or + ret i32 %select +}