Re: What's lacking: a good intermediate form

Tony wrote:
> I read the tutorial and it showed that with LLVM, one creates the
> lexing and parsing code via the LLVM API.


Sorry to flog a dead horse, but there must be some confusion.
I am 100% sure that LLVM does not have an API that deals with
lexing and parsing. Which tutorial do you mean?


  > I'm not sure
> what you mean by "text representation of the IL" and wonder if it's about as
> difficult as emitting native assembly.


Take the following source file:


-----------------------------
int f(int x) {
      return x+1;
}
-----------------------------


Here is the corresponding textual LLVM IR. If your compiler
produces something like this in a text file, the LLVM tools
can take over from there and produce the native binary.


-----------------------------
; ModuleID = 'f.bc'
target datalayout =
"e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
target triple = "i686-pc-linux-gnu"


define i32 @f(i32 %x) nounwind {
entry:
%tmp2 = add i32 %x, 1 ; <i32> [#uses=1]
ret i32 %tmp2
}
-----------------------------


To compare, here is the x86 assembly produced from the
same source. This you can feed to the native assembler
(and linker) to produce a binary.


-----------------------------
.file "f.c"
.text
.p2align 4,,15
.globl f
.type f, @function
f:
pushl %ebp
movl %esp, %ebp
movl 8(%ebp), %eax
popl %ebp
addl $1, %eax
ret
.size f, .-f
.ident "GCC: (GNU) 4.2.4 (Ubuntu 4.2.4-1ubuntu3)"
.section .note.GNU-stack,"",@progbits
-----------------------------


--
Pertti

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