1 files changed, 31 insertions, 12 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index b8f6066bf05..6a322438f5a 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4179,7 +4179,9 @@ static SelectPatternResult matchMinMaxOfMinMax(CmpInst::Predicate Pred,
   if (L.Flavor != R.Flavor)
     return {SPF_UNKNOWN, SPNB_NA, false};
 
-  // Match the compare to the min/max operations of the select operands.
+  // We have something like: x Pred y ? min(a, b) : min(c, d).
+  // Try to match the compare to the min/max operations of the select operands.
+  // First, make sure we have the right compare predicate.
   switch (L.Flavor) {
   case SPF_SMIN:
     if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) {
@@ -4217,21 +4219,38 @@ static SelectPatternResult matchMinMaxOfMinMax(CmpInst::Predicate Pred,
     return {SPF_UNKNOWN, SPNB_NA, false};
   }
 
-  // a pred c ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b))
-  if (CmpLHS == A && CmpRHS == C && D == B)
-    return {L.Flavor, SPNB_NA, false};
+  // If there is a common operand in the already matched min/max and the other
+  // min/max operands match the compare operands (either directly or inverted),
+  // then this is min/max of the same flavor.
 
+  // a pred c ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b))
+  // ~c pred ~a ? m(a, b) : m(c, b) --> m(m(a, b), m(c, b))
+  if (D == B) {
+    if ((CmpLHS == A && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) &&
+                                         match(A, m_Not(m_Specific(CmpRHS)))))
+      return {L.Flavor, SPNB_NA, false};
+  }
   // a pred d ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d))
-  if (CmpLHS == A && CmpRHS == D && C == B)
-    return {L.Flavor, SPNB_NA, false};
-
+  // ~d pred ~a ? m(a, b) : m(b, d) --> m(m(a, b), m(b, d))
+  if (C == B) {
+    if ((CmpLHS == A && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) &&
+                                         match(A, m_Not(m_Specific(CmpRHS)))))
+      return {L.Flavor, SPNB_NA, false};
+  }
   // b pred c ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a))
-  if (CmpLHS == B && CmpRHS == C && D == A)
-    return {L.Flavor, SPNB_NA, false};
-
+  // ~c pred ~b ? m(a, b) : m(c, a) --> m(m(a, b), m(c, a))
+  if (D == A) {
+    if ((CmpLHS == B && CmpRHS == C) || (match(C, m_Not(m_Specific(CmpLHS))) &&
+                                         match(B, m_Not(m_Specific(CmpRHS)))))
+      return {L.Flavor, SPNB_NA, false};
+  }
   // b pred d ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d))
-  if (CmpLHS == B && CmpRHS == D && C == A)
-    return {L.Flavor, SPNB_NA, false};
+  // ~d pred ~b ? m(a, b) : m(a, d) --> m(m(a, b), m(a, d))
+  if (C == A) {
+    if ((CmpLHS == B && CmpRHS == D) || (match(D, m_Not(m_Specific(CmpLHS))) &&
+                                         match(B, m_Not(m_Specific(CmpRHS)))))
+      return {L.Flavor, SPNB_NA, false};
+  }
 
   return {SPF_UNKNOWN, SPNB_NA, false};
 }