[AMDGPU] Expand `br_cc` for f16

[kzhuravl]

Summary

Follow up for D26714

[• tstellarAMD]

LGTM.

lib/Target/AMDGPU/SIISelLowering.cpp

if (Subtarget->has16BitInsts()) {
     setOperationAction(ISD::STORE, MVT::f16, Promote);
     AddPromotedToType(ISD::STORE, MVT::f16, MVT::i16);
 
     // F16 - VOP1 Actions.
     setOperationAction(ISD::FCOS, MVT::f16, Promote);
     setOperationAction(ISD::FSIN, MVT::f16, Promote);
 
     // F16 - VOP2 Actions.
+    setOperationAction(ISD::BR_CC, MVT::f16, Expand);
     setOperationAction(ISD::SELECT_CC, MVT::f16, Expand);
     setOperationAction(ISD::FMAXNUM, MVT::f16, Legal);
     setOperationAction(ISD::FMINNUM, MVT::f16, Legal);
     setOperationAction(ISD::FDIV, MVT::f16, Promote);
 
     // F16 - VOP3 Actions.
     setOperationAction(ISD::FMA, MVT::f16, Legal);
     if (!Subtarget->hasFP16Denormals())

test/CodeGen/AMDGPU/br_cc.f16.ll

+; RUN: llc -march=amdgcn -verify-machineinstrs < %s | FileCheck -check-prefix=GCN -check-prefix=SI %s
+; RUN: llc -march=amdgcn -mcpu=fiji -verify-machineinstrs < %s | FileCheck -check-prefix=GCN -check-prefix=VI %s
+
+; GCN-LABEL: {{^}}br_cc_f16
+; GCN: buffer_load_ushort v[[A_F16:[0-9]+]]
+; GCN: buffer_load_ushort v[[B_F16:[0-9]+]]
+
+; SI:  v_cvt_f32_f16_e32 v[[A_F32:[0-9]+]], v[[A_F16]]
+; SI:  v_cvt_f32_f16_e32 v[[B_F32:[0-9]+]], v[[B_F16]]
+; SI:  v_cmp_nlt_f32_e32 vcc, v[[A_F32]], v[[B_F32]]
+; VI:  v_cmp_nlt_f16_e32 vcc, v[[A_F16]], v[[B_F16]]
+; GCN: s_cbranch_vccnz
+
+; GCN: one{{$}}
+; SI:  v_cvt_f16_f32_e32 v[[A_F16:[0-9]+]], v[[A_F32]]
+; GCN: buffer_store_short v[[A_F16]]
+; GCN: s_endpgm
+
+; GCN: two{{$}}
+; SI:  v_cvt_f16_f32_e32 v[[B_F16:[0-9]+]], v[[B_F32]]
+; GCN: buffer_store_short v[[B_F16]]
+; GCN: s_endpgm
+define void @br_cc_f16(
+    half addrspace(1)* %r,
+    half addrspace(1)* %a,
+    half addrspace(1)* %b) {
+entry:
+  %a.val = load half, half addrspace(1)* %a
+  %b.val = load half, half addrspace(1)* %b
+  %fcmp = fcmp olt half %a.val, %b.val
+  br i1 %fcmp, label %one, label %two
+
+one:
+  store half %a.val, half addrspace(1)* %r
+  ret void
+
+two:
+  store half %b.val, half addrspace(1)* %r
+  ret void
+}
+
+; GCN-LABEL: {{^}}br_cc_f16_imm_a
+; GCN: v_mov_b32_e32 v[[A_F16:[0-9]+]], 0x380{{0|1}}{{$}}
+; SI:  v_cvt_f32_f16_e32 v[[A_F32:[0-9]+]], v[[A_F16]]
+; GCN: buffer_load_ushort v[[B_F16:[0-9]+]]
+
+; SI:  v_cvt_f32_f16_e32 v[[B_F32:[0-9]+]], v[[B_F16]]
+; SI:  v_cmp_ngt_f32_e32 vcc, v[[B_F32]], v[[A_F32]]
+; VI:  v_cmp_nle_f16_e32 vcc, v[[A_F16]], v[[B_F16]]
+; GCN: s_cbranch_vccnz
+
+; GCN: one{{$}}
+; VI:  v_mov_b32_e32 v[[A_F16:[0-9]+]], 0x3800{{$}}
+; GCN: buffer_store_short v[[A_F16]]
+; GCN: s_endpgm
+
+; GCN: two{{$}}
+; SI:  v_cvt_f16_f32_e32 v[[B_F16:[0-9]+]], v[[B_F32]]
+; GCN: buffer_store_short v[[B_F16]]
+; GCN: s_endpgm
+define void @br_cc_f16_imm_a(
+    half addrspace(1)* %r,
+    half addrspace(1)* %b) {
+entry:
+  %b.val = load half, half addrspace(1)* %b
+  %fcmp = fcmp olt half 0xH3800, %b.val
+  br i1 %fcmp, label %one, label %two
+
+one:
+  store half 0xH3800, half addrspace(1)* %r
+  ret void
+
+two:
+  store half %b.val, half addrspace(1)* %r
+  ret void
+}
+
+; GCN-LABEL: {{^}}br_cc_f16_imm_b
+; GCN: v_mov_b32_e32 v[[B_F16:[0-9]+]], {{0x37ff|0x3800}}{{$}}
+; SI:  v_cvt_f32_f16_e32 v[[B_F32:[0-9]+]], v[[B_F16]]
+; GCN: buffer_load_ushort v[[A_F16:[0-9]+]]
+
+; SI:  v_cvt_f32_f16_e32 v[[A_F32:[0-9]+]], v[[A_F16]]
+; SI:  v_cmp_nlt_f32_e32 vcc, v[[A_F32]], v[[B_F32]]
+; VI:  v_cmp_nge_f16_e32 vcc, v[[B_F16]], v[[A_F16]]
+; GCN: s_cbranch_vccnz
+
+; GCN: one{{$}}
+; SI:  v_cvt_f16_f32_e32 v[[A_F16:[0-9]+]], v[[A_F32]]
+; GCN: buffer_store_short v[[A_F16]]
+; GCN: s_endpgm
+
+; GCN: two{{$}}
+; VI:  v_mov_b32_e32 v[[B_F16:[0-9]+]], 0x3800{{$}}
+; GCN: buffer_store_short v[[B_F16]]
+; GCN: s_endpgm
+define void @br_cc_f16_imm_b(
+    half addrspace(1)* %r,
+    half addrspace(1)* %a) {
+entry:
+  %a.val = load half, half addrspace(1)* %a
+  %fcmp = fcmp olt half %a.val, 0xH3800
+  br i1 %fcmp, label %one, label %two
+
+one:
+  store half %a.val, half addrspace(1)* %r
+  ret void
+
+two:
+  store half 0xH3800, half addrspace(1)* %r
+  ret void
+}