1 files changed, 39 insertions, 28 deletions

diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 5652248a60c..0a056c0d086 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -2260,28 +2260,49 @@ static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS,
   if (!OpTy->getScalarType()->isIntegerTy(1))
     return nullptr;
 
-  switch (Pred) {
-  default:
-    break;
-  case ICmpInst::ICMP_EQ:
-    // X == 1 -> X
-    if (match(RHS, m_One()))
-      return LHS;
-    break;
-  case ICmpInst::ICMP_NE:
-    // X != 0 -> X
-    if (match(RHS, m_Zero()))
+  // A boolean compared to true/false can be simplified in 14 out of the 20
+  // (10 predicates * 2 constants) possible combinations. Cases not handled here
+  // require a 'not' of the LHS, so those must be transformed in InstCombine.
+  if (match(RHS, m_Zero())) {
+    switch (Pred) {
+    case CmpInst::ICMP_NE:  // X !=  0 -> X
+    case CmpInst::ICMP_UGT: // X >u  0 -> X
+    case CmpInst::ICMP_SLT: // X <s  0 -> X
       return LHS;
-    break;
-  case ICmpInst::ICMP_UGT:
-    // X >u 0 -> X
-    if (match(RHS, m_Zero()))
+
+    case CmpInst::ICMP_ULT: // X <u  0 -> false
+    case CmpInst::ICMP_SGT: // X >s  0 -> false
+      return getFalse(ITy);
+
+    case CmpInst::ICMP_UGE: // X >=u 0 -> true
+    case CmpInst::ICMP_SLE: // X <=s 0 -> true
+      return getTrue(ITy);
+
+    default: break;
+    }
+  } else if (match(RHS, m_One())) {
+    switch (Pred) {
+    case CmpInst::ICMP_EQ:  // X ==   1 -> X
+    case CmpInst::ICMP_UGE: // X >=u  1 -> X
+    case CmpInst::ICMP_SLE: // X <=s -1 -> X
       return LHS;
+
+    case CmpInst::ICMP_UGT: // X >u   1 -> false
+    case CmpInst::ICMP_SLT: // X <s  -1 -> false
+      return getFalse(ITy);
+
+    case CmpInst::ICMP_ULE: // X <=u  1 -> true
+    case CmpInst::ICMP_SGE: // X >=s -1 -> true
+      return getTrue(ITy);
+
+    default: break;
+    }
+  }
+
+  switch (Pred) {
+  default:
     break;
   case ICmpInst::ICMP_UGE:
-    // X >=u 1 -> X
-    if (match(RHS, m_One()))
-      return LHS;
     if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false))
       return getTrue(ITy);
     break;
@@ -2296,16 +2317,6 @@ static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS,
     if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
       return getTrue(ITy);
     break;
-  case ICmpInst::ICMP_SLT:
-    // X <s 0 -> X
-    if (match(RHS, m_Zero()))
-      return LHS;
-    break;
-  case ICmpInst::ICMP_SLE:
-    // X <=s -1 -> X
-    if (match(RHS, m_One()))
-      return LHS;
-    break;
   case ICmpInst::ICMP_ULE:
     if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
       return getTrue(ITy);