From d3b522f5197df708e42e6debc718b3eb70e30f60 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Tue, 3 Apr 2018 03:56:37 +0000 Subject: [PATCH] bpf: fix incorrect SELECT_CC lowering Commit 37962a331c77 ("bpf: Improve expanding logic in LowerSELECT_CC") intended to improve code quality for certain jmp conditions. The commit, however, has a couple of issues: (1). In code, just swap is not enough, ConditionalCode CC should also be swapped, otherwise incorrect code will be generated. (2). The ConditionalCode swap should be subject to getHasJmpExt(). If getHasJmpExt() is False, certain conditional codes will not be supported and swap may generate incorrect code. The original goal for this patch is to optimize jmp operations which does not have JmpExt turned on. If JmpExt is on, better code could be generated. For example, the test select_ri.ll is introduced to demonstrate the optimization. The same result can be achieved with -mcpu=v2 flag. Signed-off-by: Yonghong Song Acked-by: Alexei Starovoitov llvm-svn: 329043 --- llvm/lib/Target/BPF/BPFISelLowering.cpp | 6 ------ llvm/test/CodeGen/BPF/32-bit-subreg-peephole.ll | 2 +- llvm/test/CodeGen/BPF/cmp.ll | 2 +- llvm/test/CodeGen/BPF/select_ri.ll | 2 +- 4 files changed, 3 insertions(+), 9 deletions(-) diff --git a/llvm/lib/Target/BPF/BPFISelLowering.cpp b/llvm/lib/Target/BPF/BPFISelLowering.cpp index e02cdf5..e81c2f5 100644 --- a/llvm/lib/Target/BPF/BPFISelLowering.cpp +++ b/llvm/lib/Target/BPF/BPFISelLowering.cpp @@ -502,13 +502,7 @@ SDValue BPFTargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const { NegateCC(LHS, RHS, CC); SDValue TargetCC = DAG.getConstant(CC, DL, LHS.getValueType()); - SDVTList VTs = DAG.getVTList(Op.getValueType(), MVT::Glue); - - // The constant is expected at RHS in Select_Ri pattern. - if (isa(LHS.getNode())) - std::swap(LHS, RHS); - SDValue Ops[] = {LHS, RHS, TargetCC, TrueV, FalseV}; return DAG.getNode(BPFISD::SELECT_CC, DL, VTs, Ops); diff --git a/llvm/test/CodeGen/BPF/32-bit-subreg-peephole.ll b/llvm/test/CodeGen/BPF/32-bit-subreg-peephole.ll index ed52684..cf68ec5 100644 --- a/llvm/test/CodeGen/BPF/32-bit-subreg-peephole.ll +++ b/llvm/test/CodeGen/BPF/32-bit-subreg-peephole.ll @@ -1,4 +1,4 @@ -; RUN: llc -O2 -march=bpfel -mattr=+alu32 < %s | FileCheck %s +; RUN: llc -O2 -march=bpfel -mcpu=v2 -mattr=+alu32 < %s | FileCheck %s ; ; long long select_u(unsigned a, unsigned b, long long c, long long d) ; { diff --git a/llvm/test/CodeGen/BPF/cmp.ll b/llvm/test/CodeGen/BPF/cmp.ll index d86f190..44f00ff 100644 --- a/llvm/test/CodeGen/BPF/cmp.ll +++ b/llvm/test/CodeGen/BPF/cmp.ll @@ -97,7 +97,7 @@ define zeroext i8 @minu(i8 zeroext %a, i8 zeroext %b) #0 { %a.b = select i1 %1, i8 %a, i8 %b ret i8 %a.b ; CHECK-LABEL:minu: -; CHECK: if r{{[0-9]+}} {{<|>}} 100 +; CHECK: if r{{[0-9]+}} {{<|>}} r{{[0-9]+}} } ; Function Attrs: nounwind readnone uwtable diff --git a/llvm/test/CodeGen/BPF/select_ri.ll b/llvm/test/CodeGen/BPF/select_ri.ll index dbd2111..61e852d 100644 --- a/llvm/test/CodeGen/BPF/select_ri.ll +++ b/llvm/test/CodeGen/BPF/select_ri.ll @@ -1,4 +1,4 @@ -; RUN: llc < %s -march=bpf -verify-machineinstrs | FileCheck %s +; RUN: llc < %s -march=bpf -mcpu=v2 -verify-machineinstrs | FileCheck %s ; ; Source file: ; int b, c; -- 2.7.4