f63405f6e3
Commit acabad9ff6bf ("[InstCombine] try to canonicalize icmp with
trunc op into mask and cmp") added a transformation to
convert "(conv)a < power_2_const" to "a & <const>" in certain
cases and bpf kernel verifier has to handle the resulted code
conservatively and this may reject otherwise legitimate program.
This commit tries to prevent such a transformation. A bpf backend
builtin llvm.bpf.compare is added. The ICMP insn, which is subject to
above InstCombine transformation, is converted to the builtin
function. The builtin function is later lowered to original ICMP insn,
certainly after InstCombine pass.
With this change, all affected bpf strobemeta* selftests are
passed now.
Differential Revision: https://reviews.llvm.org/D112938
86 lines
2.6 KiB
LLVM
86 lines
2.6 KiB
LLVM
; RUN: opt -O2 -S -mtriple=bpf-pc-linux %s -o %t1
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; RUN: llc %t1 -o - | FileCheck -check-prefixes=CHECK,CHECK-V1 %s
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; RUN: opt -O2 -S -mtriple=bpf-pc-linux %s -o %t1
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; RUN: llc %t1 -mcpu=v3 -o - | FileCheck -check-prefixes=CHECK,CHECK-V3 %s
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;
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; Source:
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; int test1(unsigned long a) {
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; if ((unsigned)a <= 3) return 2;
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; return 3;
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; }
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; int test2(unsigned long a) {
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; if ((unsigned)a < 4) return 2;
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; return 3;
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; }
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; Compilation flag:
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; clang -target bpf -O2 -S -emit-llvm -Xclang -disable-llvm-passes test.c
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; Function Attrs: nounwind
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define dso_local i32 @test1(i64 %a) #0 {
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entry:
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%retval = alloca i32, align 4
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%a.addr = alloca i64, align 8
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store i64 %a, i64* %a.addr, align 8, !tbaa !3
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%0 = load i64, i64* %a.addr, align 8, !tbaa !3
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%conv = trunc i64 %0 to i32
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%cmp = icmp ule i32 %conv, 3
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br i1 %cmp, label %if.then, label %if.end
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if.then: ; preds = %entry
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store i32 2, i32* %retval, align 4
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br label %return
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if.end: ; preds = %entry
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store i32 3, i32* %retval, align 4
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br label %return
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return: ; preds = %if.end, %if.then
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%1 = load i32, i32* %retval, align 4
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ret i32 %1
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}
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; CHECK-LABEL: test1
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; CHECK-V1: if r[[#]] > r[[#]] goto
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; CHECK-V3: if w[[#]] < 4 goto
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; Function Attrs: nounwind
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define dso_local i32 @test2(i64 %a) #0 {
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entry:
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%retval = alloca i32, align 4
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%a.addr = alloca i64, align 8
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store i64 %a, i64* %a.addr, align 8, !tbaa !3
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%0 = load i64, i64* %a.addr, align 8, !tbaa !3
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%conv = trunc i64 %0 to i32
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%cmp = icmp ult i32 %conv, 4
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br i1 %cmp, label %if.then, label %if.end
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if.then: ; preds = %entry
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store i32 2, i32* %retval, align 4
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br label %return
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if.end: ; preds = %entry
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store i32 3, i32* %retval, align 4
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br label %return
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return: ; preds = %if.end, %if.then
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%1 = load i32, i32* %retval, align 4
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ret i32 %1
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}
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; CHECK-LABEL: test2
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; CHECK-V1: if r[[#]] > r[[#]] goto
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; CHECK-V3: if w[[#]] < 4 goto
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attributes #0 = { nounwind "frame-pointer"="all" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" }
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!llvm.module.flags = !{!0, !1}
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!llvm.ident = !{!2}
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!0 = !{i32 1, !"wchar_size", i32 4}
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!1 = !{i32 7, !"frame-pointer", i32 2}
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!2 = !{!"clang version 14.0.0 (https://github.com/llvm/llvm-project.git b7892f95881c891032742e0cd81861b845512653)"}
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!3 = !{!4, !4, i64 0}
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!4 = !{!"long", !5, i64 0}
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!5 = !{!"omnipotent char", !6, i64 0}
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!6 = !{!"Simple C/C++ TBAA"}
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