From a4c1394dea4c503dff6363da891478cbe38be5e6 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault@amd.com>
Date: Mon, 3 Sep 2018 14:01:03 +0000
Subject: [PATCH] DAG: Handle extract_vector_elt in isKnownNeverNaN

llvm-svn: 341317
---
 lib/CodeGen/SelectionDAG/SelectionDAG.cpp |  3 +++
 test/CodeGen/AMDGPU/known-never-nan.ll    | 25 +++++++++++++++++++++++
 2 files changed, 28 insertions(+)
 create mode 100644 test/CodeGen/AMDGPU/known-never-nan.ll

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 19d569a83fa..4236001f893 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3715,6 +3715,9 @@ bool SelectionDAG::isKnownNeverNaN(SDValue Op, bool SNaN, unsigned Depth) const
 
   // TODO: Handle FMINNUM/FMAXNUM/FMINNAN/FMAXNAN when there is an agreement on
   // what they should do.
+  case ISD::EXTRACT_VECTOR_ELT: {
+    return isKnownNeverNaN(Op.getOperand(0), SNaN, Depth + 1);
+  }
   default:
     if (Opcode >= ISD::BUILTIN_OP_END ||
         Opcode == ISD::INTRINSIC_WO_CHAIN ||
diff --git a/test/CodeGen/AMDGPU/known-never-nan.ll b/test/CodeGen/AMDGPU/known-never-nan.ll
new file mode 100644
index 00000000000..567208e4c81
--- /dev/null
+++ b/test/CodeGen/AMDGPU/known-never-nan.ll
@@ -0,0 +1,25 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=fiji -verify-machineinstrs < %s | FileCheck -enable-var-scope -check-prefix=GCN %s
+
+define half @known_nnan_extract_vector_elt(float %a, float %b, i32 %idx, half %c) {
+; GCN-LABEL: known_nnan_extract_vector_elt:
+; GCN:       ; %bb.0:
+; GCN-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
+; GCN-NEXT:    v_cvt_pkrtz_f16_f32 v0, v0, v1
+; GCN-NEXT:    v_lshlrev_b32_e32 v1, 4, v2
+; GCN-NEXT:    v_lshrrev_b32_e32 v0, v1, v0
+; GCN-NEXT:    v_add_f16_e32 v1, 1.0, v3
+; GCN-NEXT:    v_cmp_lt_f16_e32 vcc, v0, v1
+; GCN-NEXT:    v_cndmask_b32_e32 v0, v1, v0, vcc
+; GCN-NEXT:    s_setpc_b64 s[30:31]
+  %cvt = call nnan <2 x half> @llvm.amdgcn.cvt.pkrtz(float %a, float %b)
+  %extract = extractelement <2 x half> %cvt, i32 %idx
+  %canon = call half @llvm.canonicalize.f16(half %extract)
+  %nnan.c = fadd nnan nsz half %c, 1.0
+  %cmp = fcmp olt half %extract, %nnan.c
+  %select = select i1 %cmp, half %extract, half %nnan.c
+  ret half %select
+}
+
+declare <2 x half> @llvm.amdgcn.cvt.pkrtz(float, float) #0
+declare half @llvm.canonicalize.f16(half) #0