[InstCombine] add more SPFofSPF folding

Differential Revision: https://reviews.llvm.org/D49238

llvm-svn: 337143

1 files changed, 39 insertions, 24 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 42bf427..054f981 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4626,35 +4626,50 @@ static SelectPatternResult matchSelectPattern(CmpInst::Predicate Pred,
     case FCmpInst::FCMP_OLE: return {SPF_FMINNUM, NaNBehavior, Ordered};
     }
   }
-
-  // Sign-extending LHS does not change its sign, so TrueVal/FalseVal can
-  // match against either LHS or sext(LHS).
-  auto MaybeSExtLHS = m_CombineOr(m_Specific(CmpLHS),
-                                  m_SExt(m_Specific(CmpLHS)));
-  if ((match(TrueVal, MaybeSExtLHS) &&
-       match(FalseVal, m_Neg(m_Specific(TrueVal)))) ||
-      (match(FalseVal, MaybeSExtLHS) &&
-       match(TrueVal, m_Neg(m_Specific(FalseVal))))) {
-    // Set LHS and RHS so that RHS is the negated operand of the select
-    if (match(TrueVal, MaybeSExtLHS)) {
+  
+  if (isKnownNegation(TrueVal, FalseVal)) {
+    // Sign-extending LHS does not change its sign, so TrueVal/FalseVal can
+    // match against either LHS or sext(LHS).
+    auto MaybeSExtCmpLHS =
+        m_CombineOr(m_Specific(CmpLHS), m_SExt(m_Specific(CmpLHS)));
+    auto ZeroOrAllOnes = m_CombineOr(m_ZeroInt(), m_AllOnes());
+    auto ZeroOrOne = m_CombineOr(m_ZeroInt(), m_One());
+    if (match(TrueVal, MaybeSExtCmpLHS)) {
+      // Set the return values. If the compare uses the negated value (-X >s 0),
+      // swap the return values because the negated value is always 'RHS'.
       LHS = TrueVal;
       RHS = FalseVal;
-    } else {
+      if (match(CmpLHS, m_Neg(m_Specific(FalseVal))))
+        std::swap(LHS, RHS);
+
+      // (X >s 0) ? X : -X or (X >s -1) ? X : -X --> ABS(X)
+      // (-X >s 0) ? -X : X or (-X >s -1) ? -X : X --> ABS(X)
+      if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes))
+        return {SPF_ABS, SPNB_NA, false};
+
+      // (X <s 0) ? X : -X or (X <s 1) ? X : -X --> NABS(X)
+      // (-X <s 0) ? -X : X or (-X <s 1) ? -X : X --> NABS(X)
+      if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne))
+        return {SPF_NABS, SPNB_NA, false};
+    }
+    else if (match(FalseVal, MaybeSExtCmpLHS)) {
+      // Set the return values. If the compare uses the negated value (-X >s 0),
+      // swap the return values because the negated value is always 'RHS'.
       LHS = FalseVal;
       RHS = TrueVal;
+      if (match(CmpLHS, m_Neg(m_Specific(TrueVal))))
+        std::swap(LHS, RHS);
+
+      // (X >s 0) ? -X : X or (X >s -1) ? -X : X --> NABS(X)
+      // (-X >s 0) ? X : -X or (-X >s -1) ? X : -X --> NABS(X)
+      if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, ZeroOrAllOnes))
+        return {SPF_NABS, SPNB_NA, false};
+
+      // (X <s 0) ? -X : X or (X <s 1) ? -X : X --> ABS(X)
+      // (-X <s 0) ? X : -X or (-X <s 1) ? X : -X --> ABS(X)
+      if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, ZeroOrOne))
+        return {SPF_ABS, SPNB_NA, false};
     }
-
-    // (X >s 0) ? X : -X or (X >s -1) ? X : -X --> ABS(X)
-    // (X >s 0) ? -X : X or (X >s -1) ? -X : X --> NABS(X)
-    if (Pred == ICmpInst::ICMP_SGT &&
-        match(CmpRHS, m_CombineOr(m_ZeroInt(), m_AllOnes())))
-      return {(LHS == TrueVal) ? SPF_ABS : SPF_NABS, SPNB_NA, false};
-
-    // (X <s 0) ? -X : X or (X <s 1) ? -X : X --> ABS(X)
-    // (X <s 0) ? X : -X or (X <s 1) ? X : -X --> NABS(X)
-    if (Pred == ICmpInst::ICMP_SLT &&
-        match(CmpRHS, m_CombineOr(m_ZeroInt(), m_One())))
-      return {(LHS == FalseVal) ? SPF_ABS : SPF_NABS, SPNB_NA, false};
   }
 
   if (CmpInst::isIntPredicate(Pred))