IR: introduce struct with CmpInst::Predicate and samesign (#116867)

Introduce llvm::CmpPredicate, an abstraction over a floating-point
predicate, and a pack of an integer predicate with samesign information,
in order to ease extending large portions of the codebase that take a
CmpInst::Predicate to respect the samesign flag.

We have chosen to demonstrate the utility of this new abstraction by
migrating parts of ValueTracking, InstructionSimplify, and InstCombine
from CmpInst::Predicate to llvm::CmpPredicate. There should be no
functional changes, as we don't perform any extra optimizations with
samesign in this patch, or use CmpPredicate::getMatching.

The design approach taken by this patch allows for unaudited callers of
APIs that take a llvm::CmpPredicate to silently drop the samesign
information; it does not pose a correctness issue, and allows us to
migrate the codebase piece-wise.

1 files changed, 5 insertions, 5 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index d81546d..f2c6949 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -9379,7 +9379,7 @@ static std::optional<bool> isImpliedCondICmps(const ICmpInst *LHS,
       (LPred == ICmpInst::ICMP_ULT || LPred == ICmpInst::ICMP_UGE) &&
       (RPred == ICmpInst::ICMP_ULT || RPred == ICmpInst::ICMP_UGE) &&
       match(L0, m_c_Add(m_Specific(L1), m_Specific(R1))))
-    return LPred == RPred;
+    return CmpPredicate::getMatching(LPred, RPred).has_value();
 
   if (LPred == RPred)
     return isImpliedCondOperands(LPred, L0, L1, R0, R1);
@@ -9392,7 +9392,7 @@ static std::optional<bool> isImpliedCondICmps(const ICmpInst *LHS,
 /// expect the RHS to be an icmp and the LHS to be an 'and', 'or', or a 'select'
 /// instruction.
 static std::optional<bool>
-isImpliedCondAndOr(const Instruction *LHS, CmpInst::Predicate RHSPred,
+isImpliedCondAndOr(const Instruction *LHS, CmpPredicate RHSPred,
                    const Value *RHSOp0, const Value *RHSOp1,
                    const DataLayout &DL, bool LHSIsTrue, unsigned Depth) {
   // The LHS must be an 'or', 'and', or a 'select' instruction.
@@ -9422,7 +9422,7 @@ isImpliedCondAndOr(const Instruction *LHS, CmpInst::Predicate RHSPred,
 }
 
 std::optional<bool>
-llvm::isImpliedCondition(const Value *LHS, CmpInst::Predicate RHSPred,
+llvm::isImpliedCondition(const Value *LHS, CmpPredicate RHSPred,
                          const Value *RHSOp0, const Value *RHSOp1,
                          const DataLayout &DL, bool LHSIsTrue, unsigned Depth) {
   // Bail out when we hit the limit.
@@ -9476,7 +9476,7 @@ std::optional<bool> llvm::isImpliedCondition(const Value *LHS, const Value *RHS,
 
   if (const ICmpInst *RHSCmp = dyn_cast<ICmpInst>(RHS)) {
     if (auto Implied = isImpliedCondition(
-            LHS, RHSCmp->getPredicate(), RHSCmp->getOperand(0),
+            LHS, RHSCmp->getCmpPredicate(), RHSCmp->getOperand(0),
             RHSCmp->getOperand(1), DL, LHSIsTrue, Depth))
       return InvertRHS ? !*Implied : *Implied;
     return std::nullopt;
@@ -9553,7 +9553,7 @@ std::optional<bool> llvm::isImpliedByDomCondition(const Value *Cond,
   return std::nullopt;
 }
 
-std::optional<bool> llvm::isImpliedByDomCondition(CmpInst::Predicate Pred,
+std::optional<bool> llvm::isImpliedByDomCondition(CmpPredicate Pred,
                                                   const Value *LHS,
                                                   const Value *RHS,
                                                   const Instruction *ContextI,