[X86] Remove isel predicates for xgetbv/xsetbv instructions so they can work on Windows.

https://reviews.llvm.org/D56686  was supposed to allow these to
work on Windows without needing to enable the xsave feature to
match MSVC. It seems this didn't work because the backend isel
patterns would still block it.

This patch removes the predicates from the isel patterns.

Fixes PR51706.

Reviewed By: pengfei

Differential Revision: https://reviews.llvm.org/D109097

Author: topperc

llvm/lib/Target/X86/X86InstrSystem.td

@@ -529,16 +529,17 @@ let SchedRW = [WriteSystem] in {
 //===----------------------------------------------------------------------===//
 // XSAVE instructions
 let SchedRW = [WriteSystem] in {
-let Predicates = [HasXSAVE] in {
+// NOTE: No HasXSAVE predicate so that these can be used with _xgetbv/_xsetbv
+// on Windows without needing to enable the xsave feature to be compatible with
+// MSVC.
 let Defs = [EDX, EAX], Uses = [ECX] in
-  def XGETBV : I<0x01, MRM_D0, (outs), (ins), "xgetbv", []>, PS;
+def XGETBV : I<0x01, MRM_D0, (outs), (ins), "xgetbv", []>, PS;
 
 let Uses = [EDX, EAX, ECX] in
-  def XSETBV : I<0x01, MRM_D1, (outs), (ins),
-                "xsetbv",
-                [(int_x86_xsetbv ECX, EDX, EAX)]>, PS;
+def XSETBV : I<0x01, MRM_D1, (outs), (ins),
+              "xsetbv",
+              [(int_x86_xsetbv ECX, EDX, EAX)]>, PS;
 
-} // HasXSAVE
 
 let Uses = [EDX, EAX] in {
 def XSAVE : I<0xAE, MRM4m, (outs), (ins opaquemem:$dst),

llvm/test/CodeGen/X86/system-intrinsics-xsetbv.ll

@@ -1,5 +1,5 @@
-; RUN: llc < %s -mtriple=i686-unknown-unknown -mattr=+xsave | FileCheck %s
-; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=+xsave | FileCheck %s --check-prefix=CHECK64
+; RUN: llc < %s -mtriple=i686-unknown-unknown | FileCheck %s
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s --check-prefix=CHECK64
 
 define void @test_xsetbv(i32 %in, i32 %high, i32 %low) {
 ; CHECK-LABEL: test_xsetbv