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| author | Chris Lattner <sabre@nondot.org> | 2010-01-04 06:03:59 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2010-01-04 06:03:59 +0000 |
| commit | 4fcef8a8554259481cc451079eec65059fe68a2e (patch) | |
| tree | c9a87c184827577f46b5ab6a46bea23b70ee068b /lib | |
| parent | 991876a06d263c5fd22c99648c77a810bc0dea06 (diff) | |
| download | external_llvm-4fcef8a8554259481cc451079eec65059fe68a2e.zip external_llvm-4fcef8a8554259481cc451079eec65059fe68a2e.tar.gz external_llvm-4fcef8a8554259481cc451079eec65059fe68a2e.tar.bz2 | |
implement an instcombine xform needed by clang's codegen
on the example in PR4216. This doesn't trigger in the testsuite,
so I'd really appreciate someone scrutinizing the logic for
correctness.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92458 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Target/README.txt | 13 | ||||
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 20 |
2 files changed, 19 insertions, 14 deletions
diff --git a/lib/Target/README.txt b/lib/Target/README.txt index a6e05fa..22dadfe 100644 --- a/lib/Target/README.txt +++ b/lib/Target/README.txt @@ -282,19 +282,6 @@ this requires TBAA. //===---------------------------------------------------------------------===// -This should be optimized to one 'and' and one 'or', from PR4216: - -define i32 @test_bitfield(i32 %bf.prev.low) nounwind ssp { -entry: - %bf.prev.lo.cleared10 = or i32 %bf.prev.low, 32962 ; <i32> [#uses=1] - %0 = and i32 %bf.prev.low, -65536 ; <i32> [#uses=1] - %1 = and i32 %bf.prev.lo.cleared10, 40186 ; <i32> [#uses=1] - %2 = or i32 %1, %0 ; <i32> [#uses=1] - ret i32 %2 -} - -//===---------------------------------------------------------------------===// - This isn't recognized as bswap by instcombine (yes, it really is bswap): unsigned long reverse(unsigned v) { diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 363d879..03885a5 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -5213,12 +5213,30 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) { return ReplaceInstUsesWith(I, B); } } - V1 = 0; V2 = 0; V3 = 0; + + // ((V | N) & C1) | (V & C2) --> (V|N) & (C1|C2) + // iff (C1&C2) == 0 and (N&~C1) == 0 + if ((C1->getValue() & C2->getValue()) == 0) { + if (match(A, m_Or(m_Value(V1), m_Value(V2))) && + ((V1 == B && MaskedValueIsZero(V2, ~C1->getValue())) || // (V|N) + (V2 == B && MaskedValueIsZero(V1, ~C1->getValue())))) // (N|V) + return BinaryOperator::CreateAnd(A, + ConstantInt::get(A->getContext(), + C1->getValue()|C2->getValue())); + // Or commutes, try both ways. + if (match(B, m_Or(m_Value(V1), m_Value(V2))) && + ((V1 == A && MaskedValueIsZero(V2, ~C2->getValue())) || // (V|N) + (V2 == A && MaskedValueIsZero(V1, ~C2->getValue())))) // (N|V) + return BinaryOperator::CreateAnd(B, + ConstantInt::get(B->getContext(), + C1->getValue()|C2->getValue())); + } } // Check to see if we have any common things being and'ed. If so, find the // terms for V1 & (V2|V3). if (isOnlyUse(Op0) || isOnlyUse(Op1)) { + V1 = 0; if (A == B) // (A & C)|(A & D) == A & (C|D) V1 = A, V2 = C, V3 = D; else if (A == D) // (A & C)|(B & A) == A & (B|C) |