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instcombine has always been miscompiling fcmp x, x, disregarding possible

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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
This commit is contained in:
Chris Lattner 2007-01-14 19:42:17 +00:00
parent b769d5657e
commit 58e9746ef3
1 changed files with 39 additions and 15 deletions
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54
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1457,16 +1457,6 @@ static bool isTrueWhenEqual(ICmpInst &ICI) {
pred == ICmpInst::ICMP_SLE;
}
/// @returns true if the specified compare instruction is
/// true when both operands are equal...
/// @brief Determine if the FCmpInst returns true if both operands are equal
static bool isTrueWhenEqual(FCmpInst &FCI) {
FCmpInst::Predicate pred = FCI.getPredicate();
return pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ ||
pred == FCmpInst::FCMP_OGE || pred == FCmpInst::FCMP_UGE ||
pred == FCmpInst::FCMP_OLE || pred == FCmpInst::FCMP_ULE;
}
/// AssociativeOpt - Perform an optimization on an associative operator. This
/// function is designed to check a chain of associative operators for a
/// potential to apply a certain optimization. Since the optimization may be
@ -4281,11 +4271,45 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) {
bool Changed = SimplifyCompare(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
// fcmp pred X, X
if (Op0 == Op1)
return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty,
isTrueWhenEqual(I)));
// Fold trivial predicates.
if (I.getPredicate() == FCmpInst::FCMP_FALSE)
return ReplaceInstUsesWith(I, Constant::getNullValue(Type::Int1Ty));
if (I.getPredicate() == FCmpInst::FCMP_TRUE)
return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
// Simplify 'fcmp pred X, X'
if (Op0 == Op1) {
switch (I.getPredicate()) {
default: assert(0 && "Unknown predicate!");
case FCmpInst::FCMP_UEQ: // True if unordered or equal
case FCmpInst::FCMP_UGE: // True if unordered, greater than, or equal
case FCmpInst::FCMP_ULE: // True if unordered, less than, or equal
return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 1));
case FCmpInst::FCMP_OGT: // True if ordered and greater than
case FCmpInst::FCMP_OLT: // True if ordered and less than
case FCmpInst::FCMP_ONE: // True if ordered and operands are unequal
return ReplaceInstUsesWith(I, ConstantInt::get(Type::Int1Ty, 0));
case FCmpInst::FCMP_UNO: // True if unordered: isnan(X) | isnan(Y)
case FCmpInst::FCMP_ULT: // True if unordered or less than
case FCmpInst::FCMP_UGT: // True if unordered or greater than
case FCmpInst::FCMP_UNE: // True if unordered or not equal
// Canonicalize these to be 'fcmp uno %X, 0.0'.
I.setPredicate(FCmpInst::FCMP_UNO);
I.setOperand(1, Constant::getNullValue(Op0->getType()));
return &I;
case FCmpInst::FCMP_ORD: // True if ordered (no nans)
case FCmpInst::FCMP_OEQ: // True if ordered and equal
case FCmpInst::FCMP_OGE: // True if ordered and greater than or equal
case FCmpInst::FCMP_OLE: // True if ordered and less than or equal
// Canonicalize these to be 'fcmp ord %X, 0.0'.
I.setPredicate(FCmpInst::FCMP_ORD);
I.setOperand(1, Constant::getNullValue(Op0->getType()));
return &I;
}
}
if (isa<UndefValue>(Op1)) // fcmp pred X, undef -> undef
return ReplaceInstUsesWith(I, UndefValue::get(Type::Int1Ty));