diff options
6 files changed, 31 insertions, 67 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp index 2086a840407..527ca038d06 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -1386,29 +1386,21 @@ Instruction *InstCombiner::foldICmpXorConstant(ICmpInst &Cmp, /// Fold icmp (and (sh X, Y), C2), C1. Instruction *InstCombiner::foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And, - const APInt *C1) { - // FIXME: This check restricts all folds under here to scalar types. - ConstantInt *RHS = dyn_cast<ConstantInt>(Cmp.getOperand(1)); - if (!RHS) - return nullptr; - - // FIXME: This could be passed in as APInt. - auto *C2 = dyn_cast<ConstantInt>(And->getOperand(1)); - if (!C2) + const APInt *C1, const APInt *C2) { + BinaryOperator *Shift = dyn_cast<BinaryOperator>(And->getOperand(0)); + if (!Shift || !Shift->isShift()) return nullptr; // If this is: (X >> C3) & C2 != C1 (where any shift and any compare could // exist), turn it into (X & (C2 << C3)) != (C1 << C3). This happens a LOT in // code produced by the clang front-end, for bitfield access. - BinaryOperator *Shift = dyn_cast<BinaryOperator>(And->getOperand(0)); - if (!Shift || !Shift->isShift()) - return nullptr; - // This seemingly simple opportunity to fold away a shift turns out to be // rather complicated. See PR17827 for details. - if (auto *ShAmt = dyn_cast<ConstantInt>(Shift->getOperand(1))) { + unsigned ShiftOpcode = Shift->getOpcode(); + bool IsShl = ShiftOpcode == Instruction::Shl; + const APInt *C3; + if (match(Shift->getOperand(1), m_APInt(C3))) { bool CanFold = false; - unsigned ShiftOpcode = Shift->getOpcode(); if (ShiftOpcode == Instruction::AShr) { // There may be some constraints that make this possible, but nothing // simple has been discovered yet. @@ -1418,35 +1410,23 @@ Instruction *InstCombiner::foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And, // also fold a signed comparison if the mask value and comparison value // are not negative. These constraints may not be obvious, but we can // prove that they are correct using an SMT solver. - if (!Cmp.isSigned() || (!C2->isNegative() && !RHS->isNegative())) + if (!Cmp.isSigned() || (!C2->isNegative() && !C1->isNegative())) CanFold = true; } else if (ShiftOpcode == Instruction::LShr) { // For a logical right shift, we can fold if the comparison is not signed. // We can also fold a signed comparison if the shifted mask value and the // shifted comparison value are not negative. These constraints may not be // obvious, but we can prove that they are correct using an SMT solver. - if (!Cmp.isSigned()) + if (!Cmp.isSigned() || + (!C2->shl(*C3).isNegative() && !C1->shl(*C3).isNegative())) CanFold = true; - else { - ConstantInt *ShiftedAndCst = - cast<ConstantInt>(ConstantExpr::getShl(C2, ShAmt)); - ConstantInt *ShiftedRHSCst = - cast<ConstantInt>(ConstantExpr::getShl(RHS, ShAmt)); - - if (!ShiftedAndCst->isNegative() && !ShiftedRHSCst->isNegative()) - CanFold = true; - } } if (CanFold) { - Constant *NewCst; - if (ShiftOpcode == Instruction::Shl) - NewCst = ConstantExpr::getLShr(RHS, ShAmt); - else - NewCst = ConstantExpr::getShl(RHS, ShAmt); - + APInt NewCst = IsShl ? C1->lshr(*C3) : C1->shl(*C3); + APInt SameAsC1 = IsShl ? NewCst.shl(*C3) : NewCst.lshr(*C3); // Check to see if we are shifting out any of the bits being compared. - if (ConstantExpr::get(ShiftOpcode, NewCst, ShAmt) != RHS) { + if (SameAsC1 != *C1) { // If we shifted bits out, the fold is not going to work out. As a // special case, check to see if this means that the result is always // true or false now. @@ -1455,13 +1435,9 @@ Instruction *InstCombiner::foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And, if (Cmp.getPredicate() == ICmpInst::ICMP_NE) return replaceInstUsesWith(Cmp, Builder->getTrue()); } else { - Cmp.setOperand(1, NewCst); - Constant *NewAndCst; - if (ShiftOpcode == Instruction::Shl) - NewAndCst = ConstantExpr::getLShr(C2, ShAmt); - else - NewAndCst = ConstantExpr::getShl(C2, ShAmt); - And->setOperand(1, NewAndCst); + Cmp.setOperand(1, ConstantInt::get(And->getType(), NewCst)); + APInt NewAndCst = IsShl ? C2->lshr(*C3) : C2->shl(*C3); + And->setOperand(1, ConstantInt::get(And->getType(), NewAndCst)); And->setOperand(0, Shift->getOperand(0)); Worklist.Add(Shift); // Shift is dead. return &Cmp; @@ -1475,18 +1451,12 @@ Instruction *InstCombiner::foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And, if (Shift->hasOneUse() && *C1 == 0 && Cmp.isEquality() && !Shift->isArithmeticShift() && !isa<Constant>(Shift->getOperand(0))) { // Compute C2 << Y. - Value *NS; - if (Shift->getOpcode() == Instruction::LShr) { - NS = Builder->CreateShl(C2, Shift->getOperand(1)); - } else { - // Insert a logical shift. - NS = Builder->CreateLShr(C2, Shift->getOperand(1)); - } + Value *NewShift = + IsShl ? Builder->CreateLShr(And->getOperand(1), Shift->getOperand(1)) + : Builder->CreateShl(And->getOperand(1), Shift->getOperand(1)); // Compute X & (C2 << Y). - Value *NewAnd = - Builder->CreateAnd(Shift->getOperand(0), NS, And->getName()); - + Value *NewAnd = Builder->CreateAnd(Shift->getOperand(0), NewShift); Cmp.setOperand(0, NewAnd); return &Cmp; } @@ -1529,7 +1499,7 @@ Instruction *InstCombiner::foldICmpAndConstConst(ICmpInst &Cmp, } } - if (Instruction *I = foldICmpAndShift(Cmp, And, C1)) + if (Instruction *I = foldICmpAndShift(Cmp, And, C1, C2)) return I; // (icmp pred (and (or (lshr A, B), A), 1), 0) --> diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h index 287ee4fddd5..c8825b821d8 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h +++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h @@ -582,7 +582,7 @@ private: Instruction *foldICmpAndConstConst(ICmpInst &Cmp, BinaryOperator *And, const APInt *C1); Instruction *foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And, - const APInt *C1); + const APInt *C1, const APInt *C2); Instruction *foldICmpEqualityWithConstant(ICmpInst &ICI); Instruction *foldICmpIntrinsicWithConstant(ICmpInst &ICI); diff --git a/llvm/test/Transforms/InstCombine/apint-shift.ll b/llvm/test/Transforms/InstCombine/apint-shift.ll index 50fbe7481a0..e1e6b7c48c4 100644 --- a/llvm/test/Transforms/InstCombine/apint-shift.ll +++ b/llvm/test/Transforms/InstCombine/apint-shift.ll @@ -205,11 +205,9 @@ define i1 @test16(i84 %X) { ret i1 %cmp } -; FIXME: Vectors should fold too. define <2 x i1> @test16vec(<2 x i84> %X) { ; CHECK-LABEL: @test16vec( -; CHECK-NEXT: [[SHR1:%.*]] = lshr <2 x i84> %X, <i84 4, i84 4> -; CHECK-NEXT: [[AND:%.*]] = and <2 x i84> [[SHR1]], <i84 1, i84 1> +; CHECK-NEXT: [[AND:%.*]] = and <2 x i84> %X, <i84 16, i84 16> ; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i84> [[AND]], zeroinitializer ; CHECK-NEXT: ret <2 x i1> [[CMP]] ; diff --git a/llvm/test/Transforms/InstCombine/apint-shl-trunc.ll b/llvm/test/Transforms/InstCombine/apint-shl-trunc.ll index c13ecb4da15..4d87183a9c1 100644 --- a/llvm/test/Transforms/InstCombine/apint-shl-trunc.ll +++ b/llvm/test/Transforms/InstCombine/apint-shl-trunc.ll @@ -25,12 +25,11 @@ define i1 @test1(i799 %X, i799 %A) { ret i1 %D } -; FIXME: Vectors should fold the same way. define <2 x i1> @test0vec(<2 x i39> %X, <2 x i39> %A) { ; CHECK-LABEL: @test0vec( -; CHECK-NEXT: [[B:%.*]] = lshr <2 x i39> %X, %A -; CHECK-NEXT: [[TMP1:%.*]] = and <2 x i39> [[B]], <i39 1, i39 1> -; CHECK-NEXT: [[D:%.*]] = icmp ne <2 x i39> [[TMP1]], zeroinitializer +; CHECK-NEXT: [[TMP1:%.*]] = shl <2 x i39> <i39 1, i39 1>, %A +; CHECK-NEXT: [[TMP2:%.*]] = and <2 x i39> [[TMP1]], %X +; CHECK-NEXT: [[D:%.*]] = icmp ne <2 x i39> [[TMP2]], zeroinitializer ; CHECK-NEXT: ret <2 x i1> [[D]] ; %B = lshr <2 x i39> %X, %A diff --git a/llvm/test/Transforms/InstCombine/icmp.ll b/llvm/test/Transforms/InstCombine/icmp.ll index 73059321a6b..59407154e6b 100644 --- a/llvm/test/Transforms/InstCombine/icmp.ll +++ b/llvm/test/Transforms/InstCombine/icmp.ll @@ -1521,12 +1521,10 @@ define i1 @icmp_add_and_shr_ne_0(i32 %X) { ret i1 %tobool } -; FIXME: Vectors should fold the same way. define <2 x i1> @icmp_add_and_shr_ne_0_vec(<2 x i32> %X) { ; CHECK-LABEL: @icmp_add_and_shr_ne_0_vec( -; CHECK-NEXT: [[SHR:%.*]] = lshr <2 x i32> %X, <i32 4, i32 4> -; CHECK-NEXT: [[AND:%.*]] = and <2 x i32> [[SHR]], <i32 15, i32 15> -; CHECK-NEXT: [[TOBOOL:%.*]] = icmp ne <2 x i32> [[AND]], <i32 14, i32 14> +; CHECK-NEXT: [[AND:%.*]] = and <2 x i32> %X, <i32 240, i32 240> +; CHECK-NEXT: [[TOBOOL:%.*]] = icmp ne <2 x i32> [[AND]], <i32 224, i32 224> ; CHECK-NEXT: ret <2 x i1> [[TOBOOL]] ; %shr = lshr <2 x i32> %X, <i32 4, i32 4> diff --git a/llvm/test/Transforms/InstCombine/pr17827.ll b/llvm/test/Transforms/InstCombine/pr17827.ll index 8c800126480..67596f8b792 100644 --- a/llvm/test/Transforms/InstCombine/pr17827.ll +++ b/llvm/test/Transforms/InstCombine/pr17827.ll @@ -80,12 +80,11 @@ define i1 @test_shift_and_cmp_changed2(i8 %p) { ret i1 %cmp } -; FIXME: Vectors should fold the same way. +; FIXME: icmp ult X, 1 -> icmp eq X, 0 define <2 x i1> @test_shift_and_cmp_changed2_vec(<2 x i8> %p) { ; CHECK-LABEL: @test_shift_and_cmp_changed2_vec( -; CHECK-NEXT: [[SHLP:%.*]] = shl <2 x i8> %p, <i8 5, i8 5> -; CHECK-NEXT: [[ANDP:%.*]] = and <2 x i8> [[SHLP]], <i8 -64, i8 -64> -; CHECK-NEXT: [[CMP:%.*]] = icmp ult <2 x i8> [[ANDP]], <i8 32, i8 32> +; CHECK-NEXT: [[ANDP:%.*]] = and <2 x i8> %p, <i8 6, i8 6> +; CHECK-NEXT: [[CMP:%.*]] = icmp ult <2 x i8> [[ANDP]], <i8 1, i8 1> ; CHECK-NEXT: ret <2 x i1> [[CMP]] ; %shlp = shl <2 x i8> %p, <i8 5, i8 5> |
