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instcombine has always been miscompiling fcmp x, x, disregarding possible
NANs. This fixes PR1111 and Transforms/InstCombine/2007-01-14-FcmpSelf.ll git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33208 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1457,16 +1457,6 @@ static bool isTrueWhenEqual(ICmpInst &ICI) {
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pred == ICmpInst::ICMP_SLE;
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}
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/// @returns true if the specified compare instruction is
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/// true when both operands are equal...
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/// @brief Determine if the FCmpInst returns true if both operands are equal
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static bool isTrueWhenEqual(FCmpInst &FCI) {
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FCmpInst::Predicate pred = FCI.getPredicate();
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return pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ ||
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pred == FCmpInst::FCMP_OGE || pred == FCmpInst::FCMP_UGE ||
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pred == FCmpInst::FCMP_OLE || pred == FCmpInst::FCMP_ULE;
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}
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/// AssociativeOpt - Perform an optimization on an associative operator. This
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/// function is designed to check a chain of associative operators for a
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/// potential to apply a certain optimization. Since the optimization may be
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@ -4281,11 +4271,45 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
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bool Changed = SimplifyCompare(I);
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Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
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// fcmp pred X, X
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if (Op0 == Op1)
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return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
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isTrueWhenEqual(I)));
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// Fold trivial predicates.
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if (I.getPredicate() == FCmpInst::FCMP_FALSE)
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return ReplaceInstUsesWith(I, Constant::getNullValue(Type::Int1Ty));
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if (I.getPredicate() == FCmpInst::FCMP_TRUE)
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return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
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// Simplify 'fcmp pred X, X'
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if (Op0 == Op1) {
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switch (I.getPredicate()) {
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default: assert(0 && "Unknown predicate!");
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case FCmpInst::FCMP_UEQ: // True if unordered or equal
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case FCmpInst::FCMP_UGE: // True if unordered, greater than, or equal
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case FCmpInst::FCMP_ULE: // True if unordered, less than, or equal
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return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
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case FCmpInst::FCMP_OGT: // True if ordered and greater than
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case FCmpInst::FCMP_OLT: // True if ordered and less than
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case FCmpInst::FCMP_ONE: // True if ordered and operands are unequal
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return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 0));
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case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
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case FCmpInst::FCMP_ULT: // True if unordered or less than
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case FCmpInst::FCMP_UGT: // True if unordered or greater than
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case FCmpInst::FCMP_UNE: // True if unordered or not equal
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// Canonicalize these to be 'fcmp uno %X, 0.0'.
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I.setPredicate(FCmpInst::FCMP_UNO);
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I.setOperand(1, Constant::getNullValue(Op0->getType()));
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return &I;
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case FCmpInst::FCMP_ORD: // True if ordered (no nans)
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case FCmpInst::FCMP_OEQ: // True if ordered and equal
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case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
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case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
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// Canonicalize these to be 'fcmp ord %X, 0.0'.
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I.setPredicate(FCmpInst::FCMP_ORD);
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I.setOperand(1, Constant::getNullValue(Op0->getType()));
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return &I;
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}
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}
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if (isa<UndefValue>(Op1)) // fcmp pred X, undef -> undef
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return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));
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