From 6fd764e6d9795234af3882ac5513aa6d525bd89f Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Sun, 18 Dec 2016 18:49:48 +0000 Subject: [PATCH] [InstCombine] use commutative matchers for patterns with commutative operators Background/motivation - I was circling back around to: https://llvm.org/bugs/show_bug.cgi?id=28296 I made a simple patch for that and noticed some regressions, so added test cases for those with rL281055, and this is hopefully the minimal fix for just those cases. But as you can see from the surrounding untouched folds, we are missing commuted patterns all over the place, and of course there are no regression tests to cover any of those cases. We could sprinkle "m_c_" dust all over this file and catch most of the missing folds, but then we still wouldn't have test coverage, and we'd still miss some fraction of commuted patterns because they require adjustments to the match order. I'm aware of the concern about the potential compile-time performance impact of adding matches like this (currently being discussed on llvm-dev), but I don't think there's any evidence yet to suggest that handling commutative pattern matching more thoroughly is not a worthwhile goal of InstCombine. Differential Revision: https://reviews.llvm.org/D24419 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@290067 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../InstCombine/InstCombineAndOrXor.cpp | 55 ++++++++++++------- test/Transforms/InstCombine/or-xor.ll | 23 +------- test/Transforms/InstCombine/or.ll | 23 ++------ test/Transforms/InstCombine/xor2.ll | 18 ++---- 4 files changed, 48 insertions(+), 71 deletions(-) diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp index e1e060b283e..cbcd459f582 100644 --- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -1345,6 +1345,9 @@ static Instruction *foldBoolSextMaskToSelect(BinaryOperator &I) { return nullptr; } +// 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. Instruction *InstCombiner::visitAnd(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); @@ -1543,8 +1546,9 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) { return BinaryOperator::CreateAnd(A, B); // ((~A) ^ B) & (A | B) -> (A & B) + // ((~A) ^ B) & (B | A) -> (A & B) if (match(Op0, m_Xor(m_Not(m_Value(A)), m_Value(B))) && - match(Op1, m_Or(m_Specific(A), m_Specific(B)))) + match(Op1, m_c_Or(m_Specific(A), m_Specific(B)))) return BinaryOperator::CreateAnd(A, B); } @@ -2161,6 +2165,9 @@ Instruction *InstCombiner::FoldXorWithConstants(BinaryOperator &I, Value *Op, return nullptr; } +// 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. Instruction *InstCombiner::visitOr(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); @@ -2250,8 +2257,9 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) { match(Op1, m_Not(m_Specific(A)))) return BinaryOperator::CreateOr(Builder->CreateNot(A), B); - // (A & (~B)) | (A ^ B) -> (A ^ B) - if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) && + // (A & ~B) | (A ^ B) -> (A ^ B) + // (~B & A) | (A ^ B) -> (A ^ B) + if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) && match(Op1, m_Xor(m_Specific(A), m_Specific(B)))) return BinaryOperator::CreateXor(A, B); @@ -2427,14 +2435,15 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) { return BinaryOperator::CreateOr(Not, Op0); } - // (A & B) | ((~A) ^ B) -> (~A ^ B) - if (match(Op0, m_And(m_Value(A), m_Value(B))) && - match(Op1, m_Xor(m_Not(m_Specific(A)), m_Specific(B)))) - return BinaryOperator::CreateXor(Builder->CreateNot(A), B); - - // ((~A) ^ B) | (A & B) -> (~A ^ B) - if (match(Op0, m_Xor(m_Not(m_Value(A)), m_Value(B))) && - match(Op1, m_And(m_Specific(A), m_Specific(B)))) + // (A & B) | (~A ^ B) -> (~A ^ B) + // (A & B) | (B ^ ~A) -> (~A ^ B) + // (B & A) | (~A ^ B) -> (~A ^ B) + // (B & A) | (B ^ ~A) -> (~A ^ B) + // The match order is important: match the xor first because the 'not' + // operation defines 'A'. We do not need to match the xor as Op0 because the + // xor was canonicalized to Op1 above. + if (match(Op1, m_c_Xor(m_Not(m_Value(A)), m_Value(B))) && + match(Op0, m_c_And(m_Specific(A), m_Specific(B)))) return BinaryOperator::CreateXor(Builder->CreateNot(A), B); if (SwappedForXor) @@ -2514,6 +2523,9 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) { return Changed ? &I : nullptr; } +// 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. Instruction *InstCombiner::visitXor(BinaryOperator &I) { bool Changed = SimplifyAssociativeOrCommutative(I); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); @@ -2736,20 +2748,22 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) { return BinaryOperator::CreateXor(A, B); } // (A | ~B) ^ (~A | B) -> A ^ B - if (match(Op0I, m_Or(m_Value(A), m_Not(m_Value(B)))) && - match(Op1I, m_Or(m_Not(m_Specific(A)), m_Specific(B)))) { + // (~B | A) ^ (~A | B) -> A ^ B + if (match(Op0I, m_c_Or(m_Value(A), m_Not(m_Value(B)))) && + match(Op1I, m_Or(m_Not(m_Specific(A)), m_Specific(B)))) return BinaryOperator::CreateXor(A, B); - } + // (~A | B) ^ (A | ~B) -> A ^ B if (match(Op0I, m_Or(m_Not(m_Value(A)), m_Value(B))) && match(Op1I, m_Or(m_Specific(A), m_Not(m_Specific(B))))) { return BinaryOperator::CreateXor(A, B); } // (A & ~B) ^ (~A & B) -> A ^ B - if (match(Op0I, m_And(m_Value(A), m_Not(m_Value(B)))) && - match(Op1I, m_And(m_Not(m_Specific(A)), m_Specific(B)))) { + // (~B & A) ^ (~A & B) -> A ^ B + if (match(Op0I, m_c_And(m_Value(A), m_Not(m_Value(B)))) && + match(Op1I, m_And(m_Not(m_Specific(A)), m_Specific(B)))) return BinaryOperator::CreateXor(A, B); - } + // (~A & B) ^ (A & ~B) -> A ^ B if (match(Op0I, m_And(m_Not(m_Value(A)), m_Value(B))) && match(Op1I, m_And(m_Specific(A), m_Not(m_Specific(B))))) { @@ -2785,9 +2799,10 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) { return BinaryOperator::CreateOr(A, B); } - Value *A = nullptr, *B = nullptr; - // (A & ~B) ^ (~A) -> ~(A & B) - if (match(Op0, m_And(m_Value(A), m_Not(m_Value(B)))) && + // (A & ~B) ^ ~A -> ~(A & B) + // (~B & A) ^ ~A -> ~(A & B) + Value *A, *B; + if (match(Op0, m_c_And(m_Value(A), m_Not(m_Value(B)))) && match(Op1, m_Not(m_Specific(A)))) return BinaryOperator::CreateNot(Builder->CreateAnd(A, B)); diff --git a/test/Transforms/InstCombine/or-xor.ll b/test/Transforms/InstCombine/or-xor.ll index 3ba51de7108..ec5b71656a4 100644 --- a/test/Transforms/InstCombine/or-xor.ll +++ b/test/Transforms/InstCombine/or-xor.ll @@ -140,14 +140,9 @@ define i32 @test12(i32 %x, i32 %y) { ret i32 %and } -; FIXME: We miss the fold because the pattern matching is inadequate. - define i32 @test12_commuted(i32 %x, i32 %y) { ; CHECK-LABEL: @test12_commuted( -; CHECK-NEXT: [[NEG:%.*]] = xor i32 %x, -1 -; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[NEG]], %y -; CHECK-NEXT: [[OR:%.*]] = or i32 %y, %x -; CHECK-NEXT: [[AND:%.*]] = and i32 [[XOR]], [[OR]] +; CHECK-NEXT: [[AND:%.*]] = and i32 %x, %y ; CHECK-NEXT: ret i32 [[AND]] ; %neg = xor i32 %x, -1 @@ -183,15 +178,9 @@ define i32 @test14(i32 %x, i32 %y) { ret i32 %xor } -; FIXME: We miss the fold because the pattern matching is inadequate. - define i32 @test14_commuted(i32 %x, i32 %y) { ; CHECK-LABEL: @test14_commuted( -; CHECK-NEXT: [[NOTY:%.*]] = xor i32 %y, -1 -; CHECK-NEXT: [[NOTX:%.*]] = xor i32 %x, -1 -; CHECK-NEXT: [[OR1:%.*]] = or i32 [[NOTY]], %x -; CHECK-NEXT: [[OR2:%.*]] = or i32 [[NOTX]], %y -; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[OR1]], [[OR2]] +; CHECK-NEXT: [[XOR:%.*]] = xor i32 %x, %y ; CHECK-NEXT: ret i32 [[XOR]] ; %noty = xor i32 %y, -1 @@ -216,15 +205,9 @@ define i32 @test15(i32 %x, i32 %y) { ret i32 %xor } -; FIXME: We miss the fold because the pattern matching is inadequate. - define i32 @test15_commuted(i32 %x, i32 %y) { ; CHECK-LABEL: @test15_commuted( -; CHECK-NEXT: [[NOTY:%.*]] = xor i32 %y, -1 -; CHECK-NEXT: [[NOTX:%.*]] = xor i32 %x, -1 -; CHECK-NEXT: [[AND1:%.*]] = and i32 [[NOTY]], %x -; CHECK-NEXT: [[AND2:%.*]] = and i32 [[NOTX]], %y -; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[AND1]], [[AND2]] +; CHECK-NEXT: [[XOR:%.*]] = xor i32 %x, %y ; CHECK-NEXT: ret i32 [[XOR]] ; %noty = xor i32 %y, -1 diff --git a/test/Transforms/InstCombine/or.ll b/test/Transforms/InstCombine/or.ll index 38b8ebc5adf..facd63019fe 100644 --- a/test/Transforms/InstCombine/or.ll +++ b/test/Transforms/InstCombine/or.ll @@ -570,14 +570,10 @@ define i32 @test42(i32 %a, i32 %b) { ret i32 %or } -; FIXME: We miss the fold because the pattern matching is inadequate. - define i32 @test42_commuted_and(i32 %a, i32 %b) { ; CHECK-LABEL: @test42_commuted_and( -; CHECK-NEXT: [[NEGA:%.*]] = xor i32 %a, -1 -; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[NEGA]], %b -; CHECK-NEXT: [[AND:%.*]] = and i32 %b, %a -; CHECK-NEXT: [[OR:%.*]] = or i32 [[XOR]], [[AND]] +; CHECK-NEXT: [[TMP1:%.*]] = xor i32 %a, -1 +; CHECK-NEXT: [[OR:%.*]] = xor i32 [[TMP1]], %b ; CHECK-NEXT: ret i32 [[OR]] ; %nega = xor i32 %a, -1 @@ -587,14 +583,10 @@ define i32 @test42_commuted_and(i32 %a, i32 %b) { ret i32 %or } -; FIXME: We miss the fold because the pattern matching is inadequate. - define i32 @test42_commuted_xor(i32 %a, i32 %b) { ; CHECK-LABEL: @test42_commuted_xor( -; CHECK-NEXT: [[NEGA:%.*]] = xor i32 %a, -1 -; CHECK-NEXT: [[XOR:%.*]] = xor i32 %b, [[NEGA]] -; CHECK-NEXT: [[AND:%.*]] = and i32 %a, %b -; CHECK-NEXT: [[OR:%.*]] = or i32 [[XOR]], [[AND]] +; CHECK-NEXT: [[TMP1:%.*]] = xor i32 %a, -1 +; CHECK-NEXT: [[OR:%.*]] = xor i32 [[TMP1]], %b ; CHECK-NEXT: ret i32 [[OR]] ; %nega = xor i32 %a, -1 @@ -618,14 +610,9 @@ define i32 @test43(i32 %a, i32 %b) { ret i32 %or } -; FIXME: We miss the fold because the pattern matching is inadequate. - define i32 @test43_commuted_and(i32 %a, i32 %b) { ; CHECK-LABEL: @test43_commuted_and( -; CHECK-NEXT: [[NEG:%.*]] = xor i32 %b, -1 -; CHECK-NEXT: [[AND:%.*]] = and i32 [[NEG]], %a -; CHECK-NEXT: [[XOR:%.*]] = xor i32 %a, %b -; CHECK-NEXT: [[OR:%.*]] = or i32 [[AND]], [[XOR]] +; CHECK-NEXT: [[OR:%.*]] = xor i32 %a, %b ; CHECK-NEXT: ret i32 [[OR]] ; %neg = xor i32 %b, -1 diff --git a/test/Transforms/InstCombine/xor2.ll b/test/Transforms/InstCombine/xor2.ll index 7ec84d8caf9..f3591ed9c8a 100644 --- a/test/Transforms/InstCombine/xor2.ll +++ b/test/Transforms/InstCombine/xor2.ll @@ -180,14 +180,10 @@ define i32 @test12(i32 %a, i32 %b) { ret i32 %xor } -; FIXME: We miss the fold because the pattern matching is inadequate. - define i32 @test12commuted(i32 %a, i32 %b) { ; CHECK-LABEL: @test12commuted( -; CHECK-NEXT: [[NEGB:%.*]] = xor i32 %b, -1 -; CHECK-NEXT: [[AND:%.*]] = and i32 [[NEGB]], %a -; CHECK-NEXT: [[NEGA:%.*]] = xor i32 %a, -1 -; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[AND]], [[NEGA]] +; CHECK-NEXT: [[TMP1:%.*]] = and i32 %a, %b +; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[TMP1]], -1 ; CHECK-NEXT: ret i32 [[XOR]] ; %negb = xor i32 %b, -1 @@ -198,7 +194,7 @@ define i32 @test12commuted(i32 %a, i32 %b) { } ; This is a test of canonicalization via operand complexity. -; The final xor has a binary operator and a (fake) unary operator, +; The final xor has a binary operator and a (fake) unary operator, ; so binary (more complex) should come first. define i32 @test13(i32 %a, i32 %b) { @@ -214,14 +210,10 @@ define i32 @test13(i32 %a, i32 %b) { ret i32 %xor } -; FIXME: We miss the fold because the pattern matching is inadequate. - define i32 @test13commuted(i32 %a, i32 %b) { ; CHECK-LABEL: @test13commuted( -; CHECK-NEXT: [[NEGA:%.*]] = xor i32 %a, -1 -; CHECK-NEXT: [[NEGB:%.*]] = xor i32 %b, -1 -; CHECK-NEXT: [[AND:%.*]] = and i32 [[NEGB]], %a -; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[AND]], [[NEGA]] +; CHECK-NEXT: [[TMP1:%.*]] = and i32 %a, %b +; CHECK-NEXT: [[XOR:%.*]] = xor i32 [[TMP1]], -1 ; CHECK-NEXT: ret i32 [[XOR]] ; %nega = xor i32 %a, -1 -- 2.49.0