AMDGPU: Add missing test coverage for control flow breaks

[arsenm]

Summary

None of the current lit tests hit si_break handling.

[arsenm]

ping

[nhaehnle]

LGTM

[arsenm]

r276129

test/CodeGen/AMDGPU/loop_break.ll

+; RUN: opt -mtriple=amdgcn-- -S -structurizecfg -si-annotate-control-flow %s | FileCheck -check-prefix=OPT %s
+; RUN: llc -march=amdgcn -verify-machineinstrs < %s | FileCheck -check-prefix=GCN %s
+
+; Uses llvm.amdgcn.break
+
+; OPT-LABEL: @break_loop(
+; OPT: bb1:
+; OPT: call i64 @llvm.amdgcn.break(i64
+; OPT-NEXT: br i1 %cmp0, label %bb4, label %Flow
+
+; OPT: bb4:
+; OPT: load volatile
+; OPT: xor i1 %cmp1
+; OPT: call i64 @llvm.amdgcn.if.break(
+; OPT: br label %Flow
+
+; OPT: Flow:
+; OPT: call i1 @llvm.amdgcn.loop(i64
+; OPT: br i1 %{{[0-9]+}}, label %bb9, label %bb1
+
+; OPT: bb9:
+; OPT: call void @llvm.amdgcn.end.cf(i64
+
+; TODO: Can remove exec fixes in return block
+; GCN-LABEL: {{^}}break_loop:
+; GCN: s_mov_b64 [[INITMASK:s\[[0-9]+:[0-9]+\]]], 0{{$}}
+
+; GCN: [[LOOP_ENTRY:BB[0-9]+_[0-9]+]]: ; %bb1
+; GCN: s_or_b64 [[MASK:s\[[0-9]+:[0-9]+\]]], exec, [[INITMASK]]
+; GCN: v_cmp_lt_i32_e32 vcc,
+; GCN: s_and_b64 vcc, exec, vcc
+; GCN-NEXT: s_cbranch_vccnz [[FLOW:BB[0-9]+_[0-9]+]]
+
+; GCN: ; BB#2: ; %bb4
+; GCN: buffer_load_dword
+; GCN: v_cmp_ge_i32_e32 vcc,
+; GCN: s_or_b64 [[MASK]], vcc, [[INITMASK]]
+
+; GCN: [[FLOW]]:
+; GCN: s_mov_b64 [[INITMASK]], [[MASK]]
+; GCN: s_andn2_b64 exec, exec, [[MASK]]
+; GCN-NEXT: s_cbranch_execnz [[LOOP_ENTRY]]
+
+; GCN: ; BB#4: ; %bb9
+; GCN-NEXT: s_or_b64 exec, exec, [[MASK]]
+; GCN-NEXT: s_endpgm
+define void @break_loop(i32 %arg) #0 {
+bb:
+  %id = call i32 @llvm.amdgcn.workitem.id.x()
+  %tmp = sub i32 %id, %arg
+  br label %bb1
+
+bb1:
+  %lsr.iv = phi i32 [ undef, %bb ], [ %lsr.iv.next, %bb4 ]
+  %lsr.iv.next = add i32 %lsr.iv, 1
+  %cmp0 = icmp slt i32 %lsr.iv.next, 0
+  br i1 %cmp0, label %bb4, label %bb9
+
+bb4:
+  %load = load volatile i32, i32 addrspace(1)* undef, align 4
+  %cmp1 = icmp slt i32 %tmp, %load
+  br i1 %cmp1, label %bb1, label %bb9
+
+bb9:
+  ret void
+}
+
+declare i32 @llvm.amdgcn.workitem.id.x() #1
+
+attributes #0 = { nounwind }
+attributes #1 = { nounwind readnone }