LLI不会对Rust的LLVM IR手软

Question

我有以下的 Rust 代码。

$ cat hello.rs
fn main() {
  println!("Hello world!");
}
$ rustc hello.rs; ./hello
Hello world!

我正在使用--emit=ir选项生成llvm字节码。

$ rustc --emit=ir hello.rs
$ cat hello.ll
; ModuleID = 'hello.rs'
target datalayout = "e-i64:64-f80:128-n8:16:32:64"
target triple = "x86_64-apple-darwin"

%str_slice = type { i8*, i64 }
%"struct.core::fmt::Argument<[]>[#3]" = type { %"enum.core::result::Result<[(), core::fmt::FormatError]>[#3]" (%"enum.core::fmt::Void<[]>[#3]"*, %"struct.core::fmt::Formatter<[]>[#3]"*)*, %"enum.core::fmt::Void<[]>[#3]"* }
%"enum.core::result::Result<[(), core::fmt::FormatError]>[#3]" = type { i8, [0 x i8], [1 x i8] }
%"struct.core::fmt::Formatter<[]>[#3]" = type { i64, i32, i8, %"enum.core::option::Option<[uint]>[#3]", %"enum.core::option::Option<[uint]>[#3]", { void (i8*)**, i8* }, %"struct.core::slice::Items<[core::fmt::Argument]>[#3]", { %"struct.core::fmt::Argument<[]>[#3]"*, i64 } }
%"enum.core::option::Option<[uint]>[#3]" = type { i8, [7 x i8], [1 x i64] }
%"struct.core::slice::Items<[core::fmt::Argument]>[#3]" = type { %"struct.core::fmt::Argument<[]>[#3]"*, %"struct.core::fmt::Argument<[]>[#3]"*, %"struct.core::kinds::marker::ContravariantLifetime<[]>[#3]" }
%"struct.core::kinds::marker::ContravariantLifetime<[]>[#3]" = type {}
%"enum.core::fmt::Void<[]>[#3]" = type {}
%"struct.core::fmt::Arguments<[]>[#3]" = type { { %"enum.core::fmt::rt::Piece<[]>[#3]"*, i64 }, { %"struct.core::fmt::Argument<[]>[#3]"*, i64 } }
%"enum.core::fmt::rt::Piece<[]>[#3]" = type { i8, [7 x i8], [8 x i64] }

@str1364 = internal constant [12 x i8] c"Hello world!"
@_ZN4main15__STATIC_FMTSTR20h3b67a4ad8efbb398oaaE = internal unnamed_addr constant { { i8, %str_slice, [48 x i8] } } { { i8, %str_slice, [48 x i8] } { i8 0, %str_slice { i8* getelementptr inbounds ([12 x i8]* @str1364, i32 0, i32 0), i64 12 }, [48 x i8] undef } }

; Function Attrs: uwtable
define internal void @_ZN4main20he3565cca0bc2f101eaaE() unnamed_addr #0 {
entry-block:
  %match = alloca {}
  %__args_vec = alloca { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }
  %0 = alloca %"struct.core::fmt::Argument<[]>[#3]", i64 0
  %__args = alloca %"struct.core::fmt::Arguments<[]>[#3]"
  %__adjust = alloca { %"enum.core::fmt::rt::Piece<[]>[#3]"*, i64 }
  %__adjust1 = alloca { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }
  br label %case_body

case_body:                                        ; preds = %entry-block
  %1 = getelementptr inbounds { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %__args_vec, i32 0, i32 0
  store %"struct.core::fmt::Argument<[]>[#3]"* %0, %"struct.core::fmt::Argument<[]>[#3]"** %1
  %2 = getelementptr inbounds { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %__args_vec, i32 0, i32 1
  store i64 0, i64* %2
  %3 = getelementptr inbounds { %"enum.core::fmt::rt::Piece<[]>[#3]"*, i64 }* %__adjust, i32 0, i32 0
  store %"enum.core::fmt::rt::Piece<[]>[#3]"* getelementptr inbounds ([1 x %"enum.core::fmt::rt::Piece<[]>[#3]"]* bitcast ({ { i8, %str_slice, [48 x i8] } }* @_ZN4main15__STATIC_FMTSTR20h3b67a4ad8efbb398oaaE to [1 x %"enum.core::fmt::rt::Piece<[]>[#3]"]*), i32 0, i32 0), %"enum.core::fmt::rt::Piece<[]>[#3]"** %3
  %4 = getelementptr inbounds { %"enum.core::fmt::rt::Piece<[]>[#3]"*, i64 }* %__adjust, i32 0, i32 1
  store i64 1, i64* %4
  %5 = getelementptr inbounds { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %__args_vec, i32 0, i32 0
  %6 = load %"struct.core::fmt::Argument<[]>[#3]"** %5
  %7 = getelementptr inbounds { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %__args_vec, i32 0, i32 1
  %8 = load i64* %7
  %9 = getelementptr inbounds { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %__adjust1, i32 0, i32 0
  store %"struct.core::fmt::Argument<[]>[#3]"* %6, %"struct.core::fmt::Argument<[]>[#3]"** %9
  %10 = getelementptr inbounds { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %__adjust1, i32 0, i32 1
  store i64 %8, i64* %10
  call void @"_ZN3fmt22Arguments$LT$$x27a$GT$3new20h30af698883d0f4c86aaE"(%"struct.core::fmt::Arguments<[]>[#3]"* noalias nocapture sret dereferenceable(32) %__args, { %"enum.core::fmt::rt::Piece<[]>[#3]"*, i64 }* noalias nocapture dereferenceable(16) %__adjust, { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* noalias nocapture dereferenceable(16) %__adjust1)
  call void @_ZN2io5stdio12println_args20hecac3fc58fb73442EvmE(%"struct.core::fmt::Arguments<[]>[#3]"* noalias nocapture dereferenceable(32) %__args)
  br label %join

join:                                             ; preds = %case_body
  ret void
}

define i64 @main(i64, i8**) unnamed_addr #1 {
top:
  %2 = call i64 @_ZN10lang_start20h7823875e69d425d0BueE(i8* bitcast (void ()* @_ZN4main20he3565cca0bc2f101eaaE to i8*), i64 %0, i8** %1)
  ret i64 %2
}

declare i64 @_ZN10lang_start20h7823875e69d425d0BueE(i8*, i64, i8**) unnamed_addr #1

; Function Attrs: inlinehint uwtable
define internal void @"_ZN3fmt22Arguments$LT$$x27a$GT$3new20h30af698883d0f4c86aaE"(%"struct.core::fmt::Arguments<[]>[#3]"* noalias nocapture sret dereferenceable(32), { %"enum.core::fmt::rt::Piece<[]>[#3]"*, i64 }* noalias nocapture dereferenceable(16), { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* noalias nocapture dereferenceable(16)) unnamed_addr #2 {
entry-block:
  %__adjust = alloca { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }
  %3 = getelementptr inbounds %"struct.core::fmt::Arguments<[]>[#3]"* %0, i32 0, i32 0
  %4 = bitcast { %"enum.core::fmt::rt::Piece<[]>[#3]"*, i64 }* %1 to i8*
  %5 = bitcast { %"enum.core::fmt::rt::Piece<[]>[#3]"*, i64 }* %3 to i8*
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %5, i8* %4, i64 16, i32 8, i1 false)
  %6 = getelementptr inbounds %"struct.core::fmt::Arguments<[]>[#3]"* %0, i32 0, i32 1
  %7 = getelementptr inbounds { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %2, i32 0, i32 0
  %8 = load %"struct.core::fmt::Argument<[]>[#3]"** %7
  %9 = getelementptr inbounds { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %2, i32 0, i32 1
  %10 = load i64* %9
  %11 = getelementptr inbounds { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %__adjust, i32 0, i32 0
  store %"struct.core::fmt::Argument<[]>[#3]"* %8, %"struct.core::fmt::Argument<[]>[#3]"** %11
  %12 = getelementptr inbounds { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %__adjust, i32 0, i32 1
  store i64 %10, i64* %12
  %13 = bitcast { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %__adjust to i8*
  %14 = bitcast { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* %6 to i8*
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* %14, i8* %13, i64 16, i32 8, i1 false)
  ret void
}

; Function Attrs: nounwind
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i32, i1) unnamed_addr #3

declare void @_ZN2io5stdio12println_args20hecac3fc58fb73442EvmE(%"struct.core::fmt::Arguments<[]>[#3]"* noalias nocapture dereferenceable(32)) unnamed_addr #1

attributes #0 = { uwtable "split-stack" }
attributes #1 = { "split-stack" }
attributes #2 = { inlinehint uwtable "split-stack" }
attributes #3 = { nounwind "split-stack" }

然而，lli 不会接受这个字节码。

$ lli hello.ll
lli: hello.ll:47:138: error: expected value token
  call void @"_ZN3fmt22Arguments$LT$$x27a$GT$3new20h30af698883d0f4c86aaE"(%"struct.core::fmt::Arguments<[]>[#3]"* noalias nocapture sret dereferenceable(32) %__args, { %"enum.core::fmt::rt::Piece<[]>[#3]"*, i64 }* noalias nocapture dereferenceable(16) %__adjust, { %"struct.core::fmt::Argument<[]>[#3]"*, i64 }* noalias nocapture dereferenceable(16) %__adjust1)
                                                                                                                                         ^

有什么想法吗？

- Jordan Scales

---

你使用的 lli 版本是哪个？ - huon

（另外，--emit=ir不会生成字节码；它只会生成其中的文本表示形式，您可以尝试使用--emit=bc来生成字节码。） - huon

@dbaupp，“lli” 将完美地吃掉文本表示。 - Oak

Answer 1

< p >“dereferenceable”属性是在LLVM中最近一个月(2014年7月)添加的。我假设你使用的rustc基于全新的LLVM代码，而你的lli稍微有些陈旧。为了解决这个问题，请更新你的代码并重新构建。

- Oak

Answer 2

在 OP 一个月前的 commit 中添加了可解引用属性，因此，如果您正在使用已发布的 LLVM 软件包，则可能没有使用足够新的软件包。尝试使用从主干构建的 LLVM 软件包。

- zr.