Fix assertion failure

Given that it's easier to handle than not handle these cases,
avoid the order-dependence of transforms.

Author: nikic

llvm/lib/Analysis/InstructionSimplify.cpp

@@ -3201,14 +3201,12 @@ static Value *simplifyICmpWithBinOpOnLHS(CmpInst::Predicate Pred,
         break;
       case ICmpInst::ICMP_EQ:
       case ICmpInst::ICMP_UGE:
+      case ICmpInst::ICMP_UGT:
         return getFalse(ITy);
       case ICmpInst::ICMP_NE:
       case ICmpInst::ICMP_ULT:
-        return getTrue(ITy);
-      case ICmpInst::ICMP_UGT:
       case ICmpInst::ICMP_ULE:
-        // UGT/ULE are handled by the more general case just above
-        llvm_unreachable("Unexpected UGT/ULE, should have been handled");
+        return getTrue(ITy);
       }
     }
   }

llvm/test/Transforms/InstSimplify/compare.ll

@@ -780,6 +780,32 @@ define i1 @lshr_nonzero_ult(i32 %x) {
   ret i1 %cmp
 }
 
+define i1 @lshr_nonzero_ugt(i32 %x) {
+; CHECK-LABEL: @lshr_nonzero_ugt(
+; CHECK-NEXT:    [[X_NE_0:%.*]] = icmp ne i32 [[X:%.*]], 0
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_NE_0]])
+; CHECK-NEXT:    ret i1 false
+;
+  %x_ne_0 = icmp ne i32 %x, 0
+  call void @llvm.assume(i1 %x_ne_0)
+  %lhs = lshr i32 %x, 1
+  %cmp = icmp ugt i32 %lhs, %x
+  ret i1 %cmp
+}
+
+define i1 @lshr_nonzero_ule(i32 %x) {
+; CHECK-LABEL: @lshr_nonzero_ule(
+; CHECK-NEXT:    [[X_NE_0:%.*]] = icmp ne i32 [[X:%.*]], 0
+; CHECK-NEXT:    call void @llvm.assume(i1 [[X_NE_0]])
+; CHECK-NEXT:    ret i1 true
+;
+  %x_ne_0 = icmp ne i32 %x, 0
+  call void @llvm.assume(i1 %x_ne_0)
+  %lhs = lshr i32 %x, 1
+  %cmp = icmp ule i32 %lhs, %x
+  ret i1 %cmp
+}
+
 ; Negative test - unknown shift amount
 define i1 @lshr_nonzero_neg_unknown(i32 %x, i32 %c) {
 ; CHECK-LABEL: @lshr_nonzero_neg_unknown(