IR: introduce ICmpInst::isImpliedByMatchingCmp (#122597)

Create an abstraction over isImplied{True,False}ByMatchingCmp to
faithfully communicate the result of both functions, cleaning up code in
callsites. While at it, fix a bug in the implied-false version of the
function, which was inadvertedenly dropping samesign information.

1 files changed, 3 insertions, 16 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 0e50fc6..d03e6f5 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -9384,19 +9384,6 @@ isImpliedCondOperands(CmpInst::Predicate Pred, const Value *ALHS,
   }
 }
 
-/// Return true if "icmp1 LPred X, Y" implies "icmp2 RPred X, Y" is true.
-/// Return false if "icmp1 LPred X, Y" implies "icmp2 RPred X, Y" is false.
-/// Otherwise, return std::nullopt if we can't infer anything.
-static std::optional<bool> isImpliedCondMatchingOperands(CmpPredicate LPred,
-                                                         CmpPredicate RPred) {
-  if (ICmpInst::isImpliedTrueByMatchingCmp(LPred, RPred))
-    return true;
-  if (ICmpInst::isImpliedFalseByMatchingCmp(LPred, RPred))
-    return false;
-
-  return std::nullopt;
-}
-
 /// Return true if "icmp LPred X, LCR" implies "icmp RPred X, RCR" is true.
 /// Return false if "icmp LPred X, LCR" implies "icmp RPred X, RCR" is false.
 /// Otherwise, return std::nullopt if we can't infer anything.
@@ -9489,7 +9476,7 @@ isImpliedCondICmps(const ICmpInst *LHS, CmpPredicate RPred, const Value *R0,
 
   // Can we infer anything when the two compares have matching operands?
   if (L0 == R0 && L1 == R1)
-    return isImpliedCondMatchingOperands(LPred, RPred);
+    return ICmpInst::isImpliedByMatchingCmp(LPred, RPred);
 
   // It only really makes sense in the context of signed comparison for "X - Y
   // must be positive if X >= Y and no overflow".
@@ -9499,7 +9486,7 @@ isImpliedCondICmps(const ICmpInst *LHS, CmpPredicate RPred, const Value *R0,
        CmpPredicate::getMatching(LPred, ICmpInst::ICMP_SGE)) &&
       match(R0, m_NSWSub(m_Specific(L0), m_Specific(L1)))) {
     if (match(R1, m_NonPositive()) &&
-        isImpliedCondMatchingOperands(LPred, RPred) == false)
+        ICmpInst::isImpliedByMatchingCmp(LPred, RPred) == false)
       return false;
   }
 
@@ -9509,7 +9496,7 @@ isImpliedCondICmps(const ICmpInst *LHS, CmpPredicate RPred, const Value *R0,
        CmpPredicate::getMatching(LPred, ICmpInst::ICMP_SLE)) &&
       match(R0, m_NSWSub(m_Specific(L0), m_Specific(L1)))) {
     if (match(R1, m_NonNegative()) &&
-        isImpliedCondMatchingOperands(LPred, RPred) == true)
+        ICmpInst::isImpliedByMatchingCmp(LPred, RPred) == true)
       return true;
   }