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b609feb61f
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 <yhs@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
llvm-svn: 329043
88 lines
1.9 KiB
LLVM
88 lines
1.9 KiB
LLVM
; RUN: llc < %s -march=bpf -mcpu=v2 -verify-machineinstrs | FileCheck %s
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;
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; Source file:
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; int b, c;
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; int test() {
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; int a = b;
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; if (a)
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; a = c;
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; return a;
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; }
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@b = common local_unnamed_addr global i32 0, align 4
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@c = common local_unnamed_addr global i32 0, align 4
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; Function Attrs: norecurse nounwind readonly
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define i32 @test() local_unnamed_addr #0 {
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entry:
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%0 = load i32, i32* @b, align 4
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%tobool = icmp eq i32 %0, 0
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%1 = load i32, i32* @c, align 4
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%. = select i1 %tobool, i32 0, i32 %1
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; CHECK: r1 = b
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; CHECK: r1 = *(u32 *)(r1 + 0)
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; CHECK: if r1 == 0 goto
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ret i32 %.
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}
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attributes #0 = { norecurse nounwind readonly }
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; test immediate out of 32-bit range
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; Source file:
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; unsigned long long
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; load_word(void *buf, unsigned long long off)
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; asm("llvm.bpf.load.word");
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;
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; int
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; foo(void *buf)
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; {
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; unsigned long long sum = 0;
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;
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; sum += load_word(buf, 100);
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; sum += load_word(buf, 104);
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;
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; if (sum != 0x1ffffffffULL)
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; return ~0U;
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;
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; return 0;
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;}
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; Function Attrs: nounwind readonly
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define i32 @foo(i8*) local_unnamed_addr #0 {
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%2 = tail call i64 @llvm.bpf.load.word(i8* %0, i64 100)
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%3 = tail call i64 @llvm.bpf.load.word(i8* %0, i64 104)
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%4 = add i64 %3, %2
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%5 = icmp ne i64 %4, 8589934591
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; CHECK: r{{[0-9]+}} = 8589934591 ll
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%6 = sext i1 %5 to i32
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ret i32 %6
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}
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; Function Attrs: nounwind readonly
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declare i64 @llvm.bpf.load.word(i8*, i64) #1
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; Source file:
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; int m, n;
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; int test2() {
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; int a = m;
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; if (a < 6)
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; a = n;
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; return a;
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; }
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@m = common local_unnamed_addr global i32 0, align 4
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@n = common local_unnamed_addr global i32 0, align 4
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; Function Attrs: norecurse nounwind readonly
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define i32 @test2() local_unnamed_addr #0 {
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entry:
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%0 = load i32, i32* @m, align 4
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%cmp = icmp slt i32 %0, 6
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; CHECK: if r{{[0-9]+}} s{{<|>}} 6 goto
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%1 = load i32, i32* @n, align 4
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%spec.select = select i1 %cmp, i32 %1, i32 %0
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ret i32 %spec.select
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}
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attributes #0 = { norecurse nounwind readonly }
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