[InstCombine] Move test to instcombine; NFC

This test uses -instcombine, so move it into the appropriate
directory. Also fork it for expensive checks enabled/disabled.

Author: nikic

…sis/ValueTracking/known-signbit-shift.ll …forms/InstCombine/known-signbit-shift.llllvm/test/Analysis/ValueTracking/known-signbit-shift.ll renamed to llvm/test/Transforms/InstCombine/known-signbit-shift.ll llvm/test/Analysis/ValueTracking/known-signbit-shift.ll renamed to llvm/test/Transforms/InstCombine/known-signbit-shift.ll

@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -instcombine -S | FileCheck %s
+; RUN: opt < %s -instcombine -expensive-combines=0 -S | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-OFF
+; RUN: opt < %s -instcombine -expensive-combines=1 -S | FileCheck %s --check-prefixes=CHECK,EXPENSIVE-ON
 
 ; Result of left shifting a non-negative integer
 ; with nsw flag should also be non-negative
@@ -29,8 +30,12 @@ define i1 @test_shift_negative(i32 %a, i32 %b) {
 ; If sign bit is a known zero, it cannot be a known one.
 ; This test should not crash opt. The shift produces poison.
 define i32 @test_no_sign_bit_conflict1(i1 %b) {
-; CHECK-LABEL: @test_no_sign_bit_conflict1(
-; CHECK-NEXT:    ret i32 0
+; EXPENSIVE-OFF-LABEL: @test_no_sign_bit_conflict1(
+; EXPENSIVE-OFF-NEXT:    [[SEL:%.*]] = select i1 [[B:%.*]], i32 -2147221504, i32 -2147483648
+; EXPENSIVE-OFF-NEXT:    ret i32 [[SEL]]
+;
+; EXPENSIVE-ON-LABEL: @test_no_sign_bit_conflict1(
+; EXPENSIVE-ON-NEXT:    ret i32 0
 ;
   %sel = select i1 %b, i32 8193, i32 8192
   %mul = shl nsw i32 %sel, 18
@@ -40,8 +45,12 @@ define i32 @test_no_sign_bit_conflict1(i1 %b) {
 ; If sign bit is a known one, it cannot be a known zero.
 ; This test should not crash opt. The shift produces poison.
 define i32 @test_no_sign_bit_conflict2(i1 %b) {
-; CHECK-LABEL: @test_no_sign_bit_conflict2(
-; CHECK-NEXT:    ret i32 0
+; EXPENSIVE-OFF-LABEL: @test_no_sign_bit_conflict2(
+; EXPENSIVE-OFF-NEXT:    [[SEL:%.*]] = select i1 [[B:%.*]], i32 2147221504, i32 2146959360
+; EXPENSIVE-OFF-NEXT:    ret i32 [[SEL]]
+;
+; EXPENSIVE-ON-LABEL: @test_no_sign_bit_conflict2(
+; EXPENSIVE-ON-NEXT:    ret i32 0
 ;
   %sel = select i1 %b, i32 -8193, i32 -8194
   %mul = shl nsw i32 %sel, 18