Reintroduce the SelectionDAG scheduler test for r233351.

This test returns nonnative integer types which aren't supported on all targets.
The real issue with the SelectionDAG scheduler is with x86 EFLAGS.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233355 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/X86/scheduler-backtracking.ll

@@ -0,0 +1,51 @@
+; RUN: llc -march=x86-64 < %s -pre-RA-sched=list-ilp    | FileCheck %s
+; RUN: llc -march=x86-64 < %s -pre-RA-sched=list-hybrid | FileCheck %s
+; RUN: llc -march=x86-64 < %s -pre-RA-sched=source      | FileCheck %s
+; RUN: llc -march=x86-64 < %s -pre-RA-sched=list-burr   | FileCheck %s
+; RUN: llc -march=x86-64 < %s -pre-RA-sched=linearize   | FileCheck %s
+
+; PR22304 https://llvm.org/bugs/show_bug.cgi?id=22304
+; Tests checking backtracking in source scheduler. llc used to crash on them.
+
+; CHECK-LABEL: test1
+define i256 @test1(i256 %a) {
+  %b = add i256 %a, 1 
+  %m = shl i256 %b, 1
+  %p = add i256 %m, 1
+  %v = lshr i256 %b, %p
+  %t = trunc i256 %v to i1
+  %c = shl i256 1, %p
+  %f = select i1 %t, i256 undef, i256 %c
+  ret i256 %f
+}
+
+; CHECK-LABEL: test2
+define i256 @test2(i256 %a) {
+  %b = sub i256 0, %a
+  %c = and i256 %b, %a
+  %d = call i256 @llvm.ctlz.i256(i256 %c, i1 false)
+  ret i256 %d
+}
+
+; CHECK-LABEL: test3
+define i256 @test3(i256 %n) {
+  %m = sub i256 -1, %n
+  %x = sub i256 0, %n
+  %y = and i256 %x, %m
+  %z = call i256 @llvm.ctlz.i256(i256 %y, i1 false)
+  ret i256 %z
+}
+
+declare i256 @llvm.ctlz.i256(i256, i1) nounwind readnone
+
+; CHECK-LABEL: test4
+define i64 @test4(i64 %a, i64 %b) {
+  %r = zext i64 %b to i256
+  %u = add i256 %r, 1
+  %w = and i256 %u, 1461501637330902918203684832716283019655932542975
+  %x = zext i64 %a to i256
+  %c = icmp uge i256 %w, %x
+  %y = select i1 %c, i64 0, i64 1
+  %z = add i64 %y, 1
+  ret i64 %z
+}