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author | Tim Northover <tnorthover@apple.com> | 2013-09-04 11:57:17 +0000 |
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committer | Tim Northover <tnorthover@apple.com> | 2013-09-04 11:57:17 +0000 |
commit | 0415b1810bbf93f434f1c561e172bf24c1cb37dc (patch) | |
tree | c2d7a5cda9e53e3e9e710e4b24749681a6ed8ac6 | |
parent | 7bfabdac4ebf82f9f6a9ee7a00fd948f729dc7fe (diff) | |
download | llvm-0415b1810bbf93f434f1c561e172bf24c1cb37dc.tar.gz llvm-0415b1810bbf93f434f1c561e172bf24c1cb37dc.tar.bz2 llvm-0415b1810bbf93f434f1c561e172bf24c1cb37dc.tar.xz |
InstCombine: allow unmasked icmps to be combined with logical ops
"(icmp op i8 A, B)" is equivalent to "(icmp op i8 (A & 0xff), B)" as a
degenerate case. Allowing this as a "masked" comparison when analysing "(icmp)
&/| (icmp)" allows us to combine them in more cases.
rdar://problem/7625728
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189931 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/Transforms/InstCombine/InstCombineAndOrXor.cpp | 38 | ||||
-rw-r--r-- | test/Transforms/InstCombine/icmp-logical.ll | 30 |
2 files changed, 59 insertions, 9 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp index 099a78085b..98a7b2df4d 100644 --- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -568,14 +568,22 @@ static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A, L21 = L22 = L1 = 0; } else { // Look for ANDs in the LHS icmp. - if (match(L1, m_And(m_Value(L11), m_Value(L12)))) { - if (!match(L2, m_And(m_Value(L21), m_Value(L22)))) - L21 = L22 = 0; - } else { - if (!match(L2, m_And(m_Value(L11), m_Value(L12)))) - return 0; - std::swap(L1, L2); + if (!L1->getType()->isIntegerTy()) { + // You can icmp pointers, for example. They really aren't masks. + L11 = L12 = 0; + } else if (!match(L1, m_And(m_Value(L11), m_Value(L12)))) { + // Any icmp can be viewed as being trivially masked; if it allows us to + // remove one, it's worth it. + L11 = L1; + L12 = Constant::getAllOnesValue(L1->getType()); + } + + if (!L2->getType()->isIntegerTy()) { + // You can icmp pointers, for example. They really aren't masks. L21 = L22 = 0; + } else if (!match(L2, m_And(m_Value(L21), m_Value(L22)))) { + L21 = L2; + L22 = Constant::getAllOnesValue(L2->getType()); } } @@ -596,7 +604,14 @@ static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A, return 0; } E = R2; R1 = 0; ok = true; - } else if (match(R1, m_And(m_Value(R11), m_Value(R12)))) { + } else if (R1->getType()->isIntegerTy()) { + if (!match(R1, m_And(m_Value(R11), m_Value(R12)))) { + // As before, model no mask as a trivial mask if it'll let us do an + // optimisation. + R11 = R1; + R12 = Constant::getAllOnesValue(R1->getType()); + } + if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { A = R11; D = R12; E = R2; ok = true; } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { @@ -609,7 +624,12 @@ static unsigned foldLogOpOfMaskedICmpsHelper(Value*& A, return 0; // Look for ANDs in on the right side of the RHS icmp. - if (!ok && match(R2, m_And(m_Value(R11), m_Value(R12)))) { + if (!ok && R2->getType()->isIntegerTy()) { + if (!match(R2, m_And(m_Value(R11), m_Value(R12)))) { + R11 = R2; + R12 = Constant::getAllOnesValue(R2->getType()); + } + if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { A = R11; D = R12; E = R1; ok = true; } else if (R12 == L11 || R12 == L12 || R12 == L21 || R12 == L22) { diff --git a/test/Transforms/InstCombine/icmp-logical.ll b/test/Transforms/InstCombine/icmp-logical.ll index c0c5a61ef0..d5d8cbc8c2 100644 --- a/test/Transforms/InstCombine/icmp-logical.ll +++ b/test/Transforms/InstCombine/icmp-logical.ll @@ -120,3 +120,33 @@ define i1 @masked_or_allzeroes_notoptimised(i32 %A) { ret i1 %res } +define i1 @nomask_lhs(i32 %in) { +; CHECK-LABEL: @nomask_lhs +; CHECK: [[MASK:%.*]] = and i32 %in, 1 +; CHECK: icmp eq i32 [[MASK]], 0 +; CHECK-NOT: icmp +; CHECK: ret i1 + %tst1 = icmp eq i32 %in, 0 + + %masked = and i32 %in, 1 + %tst2 = icmp eq i32 %masked, 0 + + %val = or i1 %tst1, %tst2 + ret i1 %val +} + + +define i1 @nomask_rhs(i32 %in) { +; CHECK-LABEL: @nomask_rhs +; CHECK: [[MASK:%.*]] = and i32 %in, 1 +; CHECK: icmp eq i32 [[MASK]], 0 +; CHECK-NOT: icmp +; CHECK: ret i1 + %masked = and i32 %in, 1 + %tst1 = icmp eq i32 %masked, 0 + + %tst2 = icmp eq i32 %in, 0 + + %val = or i1 %tst1, %tst2 + ret i1 %val +} |