[NVPTX] Fix sign/zero-extending ldg/ldu instruction selection

Summary:
We don't have sign-/zero-extending ldg/ldu instructions defined,
so we need to emulate them with explicit CVTs. We were originally
handling the i8 case, but not any other cases.

Fixes PR26185

Reviewers: jingyue, jlebar

Subscribers: jholewinski

Differential Revision: http://reviews.llvm.org/D19615

llvm-svn: 268272

1 files changed, 34 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/NVPTX/bug26185-2.ll b/llvm/test/CodeGen/NVPTX/bug26185-2.ll
new file mode 100644
index 00000000000..55e9dad96c0
--- /dev/null
+++ b/llvm/test/CodeGen/NVPTX/bug26185-2.ll
@@ -0,0 +1,34 @@
+; RUN: llc < %s -march=nvptx -mcpu=sm_35 | FileCheck %s
+
+; Verify that we correctly emit code for extending ldg/ldu. We do not expose
+; extending variants in the backend, but the ldg/ldu selection code may pick
+; extending loads as candidates. We do want to support this, so make sure we
+; emit the necessary cvt.* instructions to implement the extension and let ptxas
+; emit the real extending loads.
+
+target datalayout = "e-i64:64-v16:16-v32:32-n16:32:64"
+target triple = "nvptx64-nvidia-cuda"
+
+; CHECK-LABEL: spam
+define ptx_kernel void @spam(i8 addrspace(1)* noalias nocapture readonly %arg, i8 addrspace(1)* noalias nocapture %arg1, i64 %arg2, i64 %arg3) #0 {
+bb:
+  %tmp = bitcast i8 addrspace(1)* %arg to i16 addrspace(1)*
+  %tmp4 = bitcast i8 addrspace(1)* %arg1 to i64 addrspace(1)*
+  %tmp5 = add nsw i64 %arg3, 8
+  %tmp6 = getelementptr i16, i16 addrspace(1)* %tmp, i64 %tmp5
+; CHECK: ld.global.nc.u16
+  %tmp7 = load i16, i16 addrspace(1)* %tmp6, align 2
+; CHECK: cvt.s32.s16
+  %tmp8 = sext i16 %tmp7 to i64
+  %tmp9 = mul nsw i64 %tmp8, %tmp8
+  %tmp10 = load i64, i64 addrspace(1)* %tmp4, align 8
+  %tmp11 = add nsw i64 %tmp9, %tmp10
+  store i64 %tmp11, i64 addrspace(1)* %tmp4, align 8
+  ret void
+}
+
+attributes #0 = { norecurse nounwind "polly.skip.fn" }
+
+!nvvm.annotations = !{!0}
+
+!0 = !{void (i8 addrspace(1)*, i8 addrspace(1)*, i64, i64)* @spam, !"maxntidx", i64 1, !"maxntidy", i64 1, !"maxntidz", i64 1}