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Teach GVN that x+y is the same as y+x and that x<y is the same as y>x.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151365 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -154,9 +154,24 @@ Expression ValueTable::create_expression(Instruction *I) {
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for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
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for (Instruction::op_iterator OI = I->op_begin(), OE = I->op_end();
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OI != OE; ++OI)
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OI != OE; ++OI)
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e.varargs.push_back(lookup_or_add(*OI));
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e.varargs.push_back(lookup_or_add(*OI));
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if (I->isCommutative()) {
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// Ensure that commutative instructions that only differ by a permutation
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// of their operands get the same value number by sorting the operand value
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// numbers. Since all commutative instructions have two operands it is more
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// efficient to sort by hand rather than using, say, std::sort.
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assert(I->getNumOperands() == 2 && "Unsupported commutative instruction!");
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if (e.varargs[0] > e.varargs[1])
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std::swap(e.varargs[0], e.varargs[1]);
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}
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if (CmpInst *C = dyn_cast<CmpInst>(I)) {
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if (CmpInst *C = dyn_cast<CmpInst>(I)) {
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e.opcode = (C->getOpcode() << 8) | C->getPredicate();
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// Sort the operand value numbers so x<y and y>x get the same value number.
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CmpInst::Predicate Predicate = C->getPredicate();
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if (e.varargs[0] > e.varargs[1]) {
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std::swap(e.varargs[0], e.varargs[1]);
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Predicate = CmpInst::getSwappedPredicate(Predicate);
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}
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e.opcode = (C->getOpcode() << 8) | Predicate;
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} else if (InsertValueInst *E = dyn_cast<InsertValueInst>(I)) {
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} else if (InsertValueInst *E = dyn_cast<InsertValueInst>(I)) {
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for (InsertValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
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for (InsertValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
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II != IE; ++II)
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II != IE; ++II)
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23
test/Transforms/GVN/commute.ll
Normal file
23
test/Transforms/GVN/commute.ll
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@ -0,0 +1,23 @@
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; RUN: opt -gvn -S < %s | FileCheck %s
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declare void @use(i32, i32)
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define void @foo(i32 %x, i32 %y) {
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; CHECK: @foo
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%add1 = add i32 %x, %y
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%add2 = add i32 %y, %x
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call void @use(i32 %add1, i32 %add2)
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; CHECK: @use(i32 %add1, i32 %add1)
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ret void
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}
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declare void @vse(i1, i1)
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define void @bar(i32 %x, i32 %y) {
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; CHECK: @bar
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%cmp1 = icmp ult i32 %x, %y
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%cmp2 = icmp ugt i32 %y, %x
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call void @vse(i1 %cmp1, i1 %cmp2)
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; CHECK: @vse(i1 %cmp1, i1 %cmp1)
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ret void
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}
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