Support sub-register code-gen for XADD is like supporting any other Load
and Store patterns.
No new instruction is introduced.
lock *(u32 *)(r1 + 0) += w2
has exactly the same underlying insn as:
lock *(u32 *)(r1 + 0) += r2
BPF_W width modifier has guaranteed they behave the same at runtime. This
patch merely teaches BPF back-end that BPF_W width modifier could work
GPR32 register class and that's all needed for sub-register code-gen
support for XADD.
test/CodeGen/BPF/xadd.ll updated to include sub-register code-gen tests.
A new testcase test/CodeGen/BPF/xadd_legal.ll is added to make sure the
legal case could pass on all code-gen modes. It could also test dead Def
check on GPR32. If there is no proper handling like what has been done
inside BPFMIChecking.cpp:hasLivingDefs, then this testcase will fail.
Signed-off-by: Jiong Wang <jiong.wang@xxxxxxxxxxxxx>
---
lib/Target/BPF/BPFInstrInfo.td | 28 ++++++++++++++++++++++++----
lib/Target/BPF/BPFMIChecking.cpp | 4 +++-
test/CodeGen/BPF/xadd.ll | 2 ++
test/CodeGen/BPF/xadd_legal.ll | 26 ++++++++++++++++++++++++++
4 files changed, 55 insertions(+), 5 deletions(-)
create mode 100644 test/CodeGen/BPF/xadd_legal.ll
diff --git a/lib/Target/BPF/BPFInstrInfo.td b/lib/Target/BPF/BPFInstrInfo.td
index 36724b8..c44702a 100644
--- a/lib/Target/BPF/BPFInstrInfo.td
+++ b/lib/Target/BPF/BPFInstrInfo.td
@@ -614,11 +614,31 @@ class XADD<BPFWidthModifer SizeOp, string OpcodeStr, PatFrag OpNode>
let BPFClass = BPF_STX;
}
+class XADD32<BPFWidthModifer SizeOp, string OpcodeStr, PatFrag OpNode>
+ : TYPE_LD_ST<BPF_XADD.Value, SizeOp.Value,
+ (outs GPR32:$dst),
+ (ins MEMri:$addr, GPR32:$val),
+ "lock *("#OpcodeStr#" *)($addr) += $val",
+ [(set GPR32:$dst, (OpNode ADDRri:$addr, GPR32:$val))]> {
+ bits<4> dst;
+ bits<20> addr;
+
+ let Inst{51-48} = addr{19-16}; // base reg
+ let Inst{55-52} = dst;
+ let Inst{47-32} = addr{15-0}; // offset
+ let BPFClass = BPF_STX;
+}
+
let Constraints = "$dst = $val" in {
-def XADD32 : XADD<BPF_W, "u32", atomic_load_add_32>;
-def XADD64 : XADD<BPF_DW, "u64", atomic_load_add_64>;
-// undefined def XADD16 : XADD<1, "xadd16", atomic_load_add_16>;
-// undefined def XADD8 : XADD<2, "xadd8", atomic_load_add_8>;
+ let Predicates = [BPFNoALU32] in {
+ def XADDW : XADD<BPF_W, "u32", atomic_load_add_32>;
+ }
+
+ let Predicates = [BPFHasALU32], DecoderNamespace = "BPFALU32" in {
+ def XADDW32 : XADD32<BPF_W, "u32", atomic_load_add_32>;
+ }
+
+ def XADDD : XADD<BPF_DW, "u64", atomic_load_add_64>;
}
// bswap16, bswap32, bswap64
diff --git a/lib/Target/BPF/BPFMIChecking.cpp b/lib/Target/BPF/BPFMIChecking.cpp
index 7a4ba96..938e539 100644
--- a/lib/Target/BPF/BPFMIChecking.cpp
+++ b/lib/Target/BPF/BPFMIChecking.cpp
@@ -165,7 +165,9 @@ static bool hasLivingDefs(const MachineInstr &MI,
void BPFMIPreEmitChecking::checkingIllegalXADD(void) {
for (MachineBasicBlock &MBB : *MF) {
for (MachineInstr &MI : MBB) {
- if (MI.getOpcode() != BPF::XADD32 && MI.getOpcode() != BPF::XADD64)
+ if (MI.getOpcode() != BPF::XADDW &&
+ MI.getOpcode() != BPF::XADDD &&
+ MI.getOpcode() != BPF::XADDW32)
continue;
LLVM_DEBUG(MI.dump());
diff --git a/test/CodeGen/BPF/xadd.ll b/test/CodeGen/BPF/xadd.ll
index c5f2620..49f0c10 100644
--- a/test/CodeGen/BPF/xadd.ll
+++ b/test/CodeGen/BPF/xadd.ll
@@ -1,5 +1,7 @@
; RUN: not llc -march=bpfel < %s 2>&1 | FileCheck %s
; RUN: not llc -march=bpfeb < %s 2>&1 | FileCheck %s
+; RUN: not llc -march=bpfel -mattr=+alu32 < %s 2>&1 | FileCheck %s
+; RUN: not llc -march=bpfeb -mattr=+alu32 < %s 2>&1 | FileCheck %s
; This file is generated with the source command and source
; $ clang -target bpf -O2 -g -S -emit-llvm t.c
diff --git a/test/CodeGen/BPF/xadd_legal.ll b/test/CodeGen/BPF/xadd_legal.ll
new file mode 100644
index 0000000..0d30084
--- /dev/null
+++ b/test/CodeGen/BPF/xadd_legal.ll
@@ -0,0 +1,26 @@
+; RUN: llc -march=bpfel < %s 2>&1 | FileCheck --check-prefix=CHECK-64 %s
+; RUN: llc -march=bpfeb < %s 2>&1 | FileCheck --check-prefix=CHECK-64 %s
+; RUN: llc -march=bpfel -mattr=+alu32 < %s 2>&1 | FileCheck --check-prefix=CHECK-32 %s
+; RUN: llc -march=bpfeb -mattr=+alu32 < %s 2>&1 | FileCheck --check-prefix=CHECK-32 %s
+
+; This file is generated with the source command and source
+; $ clang -target bpf -O2 -S -emit-llvm t.c
+; $ cat t.c
+; int test(int *ptr, unsigned long long a) {
+; __sync_fetch_and_add(ptr, a);
+; return *ptr;
+; }
+;
+; NOTE: passing unsigned long long as the second operand of __sync_fetch_and_add
+; could effectively create sub-register reference coming from indexing a full
+; register which could then exerceise hasLivingDefs inside BPFMIChecker.cpp.
+
+define dso_local i32 @test(i32* nocapture %ptr, i64 %a) {
+entry:
+ %conv = trunc i64 %a to i32
+ %0 = atomicrmw add i32* %ptr, i32 %conv seq_cst
+; CHECK-64: lock *(u32 *)(r1 + 0) += r2
+; CHECK-32: lock *(u32 *)(r1 + 0) += w2
+ %1 = load i32, i32* %ptr, align 4
+ ret i32 %1
+}
--
2.7.4
