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bpf: fix bug on silently truncating 64-bit immediate 

We came across an llvm bug when compiling some testcases that 64-bit
immediates are silently truncated into 32-bit and then packed into
BPF_JMP | BPF_K encoding.  This caused comparison with wrong value.

This bug looks to be introduced by r308080.  The Select_Ri pattern is
supposed to be lowered into J*_Ri while the latter only support 32-bit
immediate encoding, therefore Select_Ri should have similar immediate
predicate check as what J*_Ri are doing.

Reported-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Reviewed-by: Yonghong Song <yhs@fb.com>
llvm-svn: 315889
This commit is contained in:
Yonghong Song 2017-10-16 04:14:53 +00:00
parent e3a3e3c9e9
commit 6621cf67cf
3 changed files with 42 additions and 3 deletions
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8
llvm/lib/Target/BPF/BPFISelLowering.cpp
View File

@ -611,11 +611,15 @@ BPFTargetLowering::EmitInstrWithCustomInserter(MachineInstr &MI,
.addReg(LHS) .addReg(LHS)
.addReg(MI.getOperand(2).getReg()) .addReg(MI.getOperand(2).getReg())
.addMBB(Copy1MBB); .addMBB(Copy1MBB);
else else {
int64_t imm32 = MI.getOperand(2).getImm();
// sanity check before we build J*_ri instruction.
assert (isInt<32>(imm32));
BuildMI(BB, DL, TII.get(NewCC)) BuildMI(BB, DL, TII.get(NewCC))
.addReg(LHS) .addReg(LHS)
.addImm(MI.getOperand(2).getImm()) .addImm(imm32)
.addMBB(Copy1MBB); .addMBB(Copy1MBB);
}
// Copy0MBB: // Copy0MBB:
// %FalseValue = ... // %FalseValue = ...

2
llvm/lib/Target/BPF/BPFInstrInfo.td
View File

@ -460,7 +460,7 @@ let usesCustomInserter = 1 in {
(ins GPR:$lhs, i64imm:$rhs, i64imm:$imm, GPR:$src, GPR:$src2), (ins GPR:$lhs, i64imm:$rhs, i64imm:$imm, GPR:$src, GPR:$src2),
"# Select PSEUDO $dst = $lhs $imm $rhs ? $src : $src2", "# Select PSEUDO $dst = $lhs $imm $rhs ? $src : $src2",
[(set i64:$dst, [(set i64:$dst,
(BPFselectcc i64:$lhs, (i64 imm:$rhs), (i64 imm:$imm), i64:$src, i64:$src2))]>; (BPFselectcc i64:$lhs, (i64immSExt32:$rhs), (i64 imm:$imm), i64:$src, i64:$src2))]>;
} }
// load 64-bit global addr into register // load 64-bit global addr into register

35
llvm/test/CodeGen/BPF/select_ri.ll
View File

@ -25,3 +25,38 @@ entry:
} }
attributes #0 = { norecurse nounwind readonly } attributes #0 = { norecurse nounwind readonly }
; test immediate out of 32-bit range
; Source file:
; unsigned long long
; load_word(void *buf, unsigned long long off)
; asm("llvm.bpf.load.word");
;
; int
; foo(void *buf)
; {
; unsigned long long sum = 0;
;
; sum += load_word(buf, 100);
; sum += load_word(buf, 104);
;
; if (sum != 0x1ffffffffULL)
; return ~0U;
;
; return 0;
;}
; Function Attrs: nounwind readonly
define i32 @foo(i8*) local_unnamed_addr #0 {
%2 = tail call i64 @llvm.bpf.load.word(i8* %0, i64 100)
%3 = tail call i64 @llvm.bpf.load.word(i8* %0, i64 104)
%4 = add i64 %3, %2
%5 = icmp ne i64 %4, 8589934591
; CHECK: r{{[0-9]+}} = 8589934591 ll
%6 = sext i1 %5 to i32
ret i32 %6
}
; Function Attrs: nounwind readonly
declare i64 @llvm.bpf.load.word(i8*, i64) #1