[X86] In shrinkAndImmediate, place the new constant into the topological sort.

Revert the change to use APInt::isSignedIntN from
5ff5cf8.

Its clear that the games we were playing to avoid the topological
sort aren't working. So just fix it once and for all.

Fixes PR48888.

Author: topperc

llvm/lib/Target/X86/X86ISelDAGToDAG.cpp

@@ -617,7 +617,7 @@ X86DAGToDAGISel::IsProfitableToFold(SDValue N, SDNode *U, SDNode *Root) const {
         // best of both worlds.
         if (U->getOpcode() == ISD::AND &&
             Imm->getAPIntValue().getBitWidth() == 64 &&
-            Imm->getAPIntValue().isSignedIntN(32))
+            Imm->getAPIntValue().isIntN(32))
           return false;
 
         // If this really a zext_inreg that can be represented with a movzx
@@ -4282,6 +4282,7 @@ bool X86DAGToDAGISel::shrinkAndImmediate(SDNode *And) {
 
   // A negative mask allows a smaller encoding. Create a new 'and' node.
   SDValue NewMask = CurDAG->getConstant(NegMaskVal, SDLoc(And), VT);
+  insertDAGNode(*CurDAG, SDValue(And, 0), NewMask);
   SDValue NewAnd = CurDAG->getNode(ISD::AND, SDLoc(And), VT, And0, NewMask);
   ReplaceNode(And, NewAnd.getNode());
   SelectCode(NewAnd.getNode());

llvm/test/CodeGen/X86/pr48458.ll

@@ -4,8 +4,8 @@
 define i1 @foo(i64* %0) {
 ; CHECK-LABEL: foo:
 ; CHECK:       # %bb.0: # %top
-; CHECK-NEXT:    movq (%rdi), %rax
-; CHECK-NEXT:    andq $-2147483648, %rax # imm = 0x80000000
+; CHECK-NEXT:    movq $-2147483648, %rax # imm = 0x80000000
+; CHECK-NEXT:    testq %rax, (%rdi)
 ; CHECK-NEXT:    sete %al
 ; CHECK-NEXT:    retq
 top:

llvm/test/CodeGen/X86/pr48888.ll

@@ -0,0 +1,36 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
+
+define void @test(i64* %p) nounwind {
+; CHECK-LABEL: test:
+; CHECK:       # %bb.0: # %bb
+; CHECK-NEXT:    movq (%rdi), %rax
+; CHECK-NEXT:    andl $-2, %eax
+; CHECK-NEXT:    cmpq $2, %rax
+; CHECK-NEXT:    cmpl $2, %eax
+; CHECK-NEXT:    retq
+bb:
+  %i = load i64, i64* %p, align 8, !range !0
+  %i1 = and i64 %i, 6
+  %i2 = icmp eq i64 %i1, 2
+  br i1 %i2, label %bb3, label %bb5
+
+bb3:                                              ; preds = %bb
+  %i4 = icmp ne {}* undef, null
+  br label %bb5
+
+bb5:                                              ; preds = %bb3, %bb
+  br label %bb6
+
+bb6:                                              ; preds = %bb5
+  br i1 %i2, label %bb7, label %bb9
+
+bb7:                                              ; preds = %bb6
+  %i8 = getelementptr inbounds i64, i64* undef, i64 5
+  br label %bb9
+
+bb9:                                              ; preds = %bb7, %bb6
+  ret void
+}
+
+!0 = !{i64 0, i64 5}