[llvm] r189931 - InstCombine: allow unmasked icmps to be combined with logical ops
Tim Northover
tnorthover at apple.com
Wed Sep 4 04:57:17 PDT 2013
Author: tnorthover
Date: Wed Sep 4 06:57:17 2013
New Revision: 189931
URL: http://llvm.org/viewvc/llvm-project?rev=189931&view=rev
Log:
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
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
llvm/trunk/test/Transforms/InstCombine/icmp-logical.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=189931&r1=189930&r2=189931&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Wed Sep 4 06:57:17 2013
@@ -568,14 +568,22 @@ static unsigned foldLogOpOfMaskedICmpsHe
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 foldLogOpOfMaskedICmpsHe
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 foldLogOpOfMaskedICmpsHe
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) {
Modified: llvm/trunk/test/Transforms/InstCombine/icmp-logical.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp-logical.ll?rev=189931&r1=189930&r2=189931&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp-logical.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/icmp-logical.ll Wed Sep 4 06:57:17 2013
@@ -120,3 +120,33 @@ define i1 @masked_or_allzeroes_notoptimi
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
+}
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