Add new test to confirm no pragma on older ptx version

Author: dakersnar

llvm/test/CodeGen/NVPTX/used-bytes-mask.ll

@@ -0,0 +1,36 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
+; RUN: llc < %s -march=nvptx64 -mcpu=sm_50 -mattr=+ptx82 | FileCheck %s -check-prefixes=NOMASK
+; RUN: %if ptxas-sm_50 && ptxas-isa-8.2 %{ llc < %s -march=nvptx64 -mcpu=sm_50 -mattr=+ptx82 | %ptxas-verify -arch=sm_50 %}
+; RUN: llc < %s -march=nvptx64 -mcpu=sm_50 -mattr=+ptx83 | FileCheck %s -check-prefixes=MASK
+; RUN: %if ptxas-sm_50 && ptxas-isa-8.3 %{ llc < %s -march=nvptx64 -mcpu=sm_50 -mattr=+ptx83 | %ptxas-verify -arch=sm_50 %}
+
+; On older architectures and versions, we shouldn't be seeing a used bytes mask pragma.
+
+define i32 @global_8xi32(ptr %a, ptr %b) {
+; NOMASK-LABEL: global_8xi32(
+; NOMASK:       {
+; NOMASK-NEXT:    .reg .b32 %r<5>;
+; NOMASK-NEXT:    .reg .b64 %rd<2>;
+; NOMASK-EMPTY:
+; NOMASK-NEXT:  // %bb.0:
+; NOMASK-NEXT:    ld.param.b64 %rd1, [global_8xi32_param_0];
+; NOMASK-NEXT:    ld.v4.b32 {%r1, %r2, %r3, %r4}, [%rd1];
+; NOMASK-NEXT:    st.param.b32 [func_retval0], %r1;
+; NOMASK-NEXT:    ret;
+;
+; MASK-LABEL: global_8xi32(
+; MASK:       {
+; MASK-NEXT:    .reg .b32 %r<5>;
+; MASK-NEXT:    .reg .b64 %rd<2>;
+; MASK-EMPTY:
+; MASK-NEXT:  // %bb.0:
+; MASK-NEXT:    ld.param.b64 %rd1, [global_8xi32_param_0];
+; MASK-NEXT:    .pragma "used_bytes_mask 0xfff";
+; MASK-NEXT:    ld.v4.b32 {%r1, %r2, %r3, %r4}, [%rd1];
+; MASK-NEXT:    st.param.b32 [func_retval0], %r1;
+; MASK-NEXT:    ret;
+  %a.load = tail call <4 x i32> @llvm.masked.load.v4i32.p0(ptr align 16 %a, <4 x i1> <i1 true, i1 true, i1 true, i1 false>, <4 x i32> poison)
+  %first = extractelement <4 x i32> %a.load, i32 0
+  ret i32 %first
+}
+declare <4 x i32> @llvm.masked.load.v4i32.p0(ptr , <4 x i1>, <4 x i32>)