[NVPTX] convert pointers in byval kernel arguments to global

Summary:
For example, in

  struct S {
    int *x;
    int *y;
  };
  __global__ void foo(S s) {
    int *b = s.y;
    // use b
  }

"b" is guaranteed to point to global. NVPTX should emit ld.global/st.global for
accessing "b".

Reviewers: jholewinski

Subscribers: llvm-commits, jholewinski

Differential Revision: http://reviews.llvm.org/D11505

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243790 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/NVPTX/lower-kernel-ptr-arg.ll

@@ -1,7 +1,7 @@
 ; RUN: llc < %s -march=nvptx64 -mcpu=sm_20 | FileCheck %s
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v16:16:16-v32:32:32-v64:64:64-v128:128:128-n16:32:64"
-target triple = "nvptx64-unknown-unknown"
+target triple = "nvptx64-nvidia-cuda"
 
 ; Verify that both %input and %output are converted to global pointers and then
 ; addrspacecast'ed back to the original type.
@@ -26,6 +26,22 @@ define void @kernel2(float addrspace(1)* %input, float addrspace(1)* %output) {
   ret void
 }
 
-!nvvm.annotations = !{!0, !1}
+%struct.S = type { i32*, i32* }
+
+define void @ptr_in_byval(%struct.S* byval %input, i32* %output) {
+; CHECK-LABEL: .visible .entry ptr_in_byval(
+; CHECK: cvta.to.global.u64
+; CHECK: cvta.to.global.u64
+  %b_ptr = getelementptr inbounds %struct.S, %struct.S* %input, i64 0, i32 1
+  %b = load i32*, i32** %b_ptr, align 4
+  %v = load i32, i32* %b, align 4
+; CHECK: ld.global.u32
+  store i32 %v, i32* %output, align 4
+; CHECK: st.global.u32
+  ret void
+}
+
+!nvvm.annotations = !{!0, !1, !2}
 !0 = !{void (float*, float*)* @kernel, !"kernel", i32 1}
 !1 = !{void (float addrspace(1)*, float addrspace(1)*)* @kernel2, !"kernel", i32 1}
+!2 = !{void (%struct.S*, i32*)* @ptr_in_byval, !"kernel", i32 1}