I have a problem.
I'm writing a C compiler in my favorite programming language (don't ask
:-)
I have made a .s file, which can be correctly assembled
and run with lli. But when I optimize it I get no errors
from the optimizer, but the resultant file is incorrect.
Here's what happens:
llvm-as test2_gen.s %% no errors test2_gen.s.bc is produced
lli test2_gen.s.bc
n=887459712 %% no errors
opt -std-compile-opts -S test2_gen.s.bc > test2_opt.s.bc
%% no errors
%% But now the generated file cannon be disassembled or run
lli test2_opt.s.bc
lli: error loading program 'test2_opt.s.bc': Bitcode stream should be a
multiple
of 4 bytes in length
llvm-dis test2_opt.s.bc
llvm-dis: Bitcode stream should be a multiple of 4 bytes in length
The generated .s file is as follows:
; ----- start
; Compiled by the amazing Ericsson C->LLVM compiler
; Hand crafted in Erlang
; ModuleID = 'test2.c'
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-n8:16:32"
target triple = "i386-pc-linux-gnu"
; Sock it to me baby
;; globals
declare i32 @printf(i8* , ...)
@main.str1 = private constant [6x i8] c"n=%i\0A\00"
;; code
define i32 @main() nounwind {
;;return register
%tmp_1 = alloca i32 ,align 4
%i = alloca i32 ,align 4
%max = alloca i32 ,align 4
%n = alloca i32 ,align 4
%tmp_2 = add i32 0,0
store i32 %tmp_2 ,i32* %i
%tmp_3 = add i32 0,100000000
store i32 %tmp_3 ,i32* %max
%tmp_4 = add i32 0,0
store i32 %tmp_4 ,i32* %n
br label %initfor_1
initfor_1:
%tmp_5 = add i32 0,0
store i32 %tmp_5 ,i32* %i
br label %testfor_3
updatefor_2:
%tmp_6 = load i32* %i
%tmp_7 = add i32 0,1
%tmp_8 = add i32 %tmp_6 ,%tmp_7
store i32 %tmp_8 ,i32* %i
br label %testfor_3
testfor_3:
%tmp_9 = load i32* %i
%tmp_10 = load i32* %max
%tmp_11 = icmp slt i32 %tmp_9 ,%tmp_10
br i1 %tmp_11 ,label %bodyfor_4,label %endfor_5
bodyfor_4:
%tmp_12 = load i32* %n
%tmp_13 = load i32* %i
%tmp_14 = add i32 %tmp_12 ,%tmp_13
store i32 %tmp_14 ,i32* %n
br label %updatefor_2
endfor_5:
%tmp_15 = getelementptr [6 x i8]* @main.str1, i32 0, i32 0
%tmp_16 = load i32* %n
%tmp_17 = call i32 (i8* , ...)* @printf(i8* %tmp_15 , i32 %tmp_16 )
%tmp_18 = add i32 0,0
ret i32 %tmp_18
}
The C code was as follows:
int printf(const char * format, ...);
int main()
{
int i=0, max=100000000,n=0;
for(i = 0; i < max; i = i + 1){
n = n + i;
}
printf("n=%i\n", n);
return(0);
}
/Joe
Hi Joe,> I have made a .s file, which can be correctly assembled > and run with lli. But when I optimize it I get no errors > from the optimizer, but the resultant file is incorrect. > > Here's what happens: > > llvm-as test2_gen.s %% no errors test2_gen.s.bc is producedthere's actually no need to assemble this to bitcode: you can pass test2_gen.s directly to opt. At least you can in recent versions of LLVM.> opt -std-compile-opts -S test2_gen.s.bc> test2_opt.s.bcBy using -S you ask opt to produce human readable IR rather than bitcode, so you should really output to test2_opt.s.> > %% no errors > %% But now the generated file cannon be disassembled or run > > lli test2_opt.s.bc > lli: error loading program 'test2_opt.s.bc': Bitcode stream should be a > multiple > of 4 bytes in lengthThis means that it doesn't contain bitcode. And indeed it doesn't, it contains human readable IR due to your using -S above.> llvm-dis test2_opt.s.bc > llvm-dis: Bitcode stream should be a multiple of 4 bytes in lengthSame problem. That said, in latest LLVM lli accepts human readable IR as well as bitcode, so I'm guessing that you are using an older version that does not have this feature. Of course I may also have misdiagnosed the problem :) Ciao, Duncan.
On Wed, Mar 16, 2011 at 1:14 PM, Joe armstrong <joearms at gmail.com> wrote:> opt -std-compile-opts -S test2_gen.s.bc > test2_opt.s.bc >You have produced .ll, not .bc. This is die -S flag. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20110316/ee773385/attachment.html>
Hello> opt -std-compile-opts -S test2_gen.s.bc > test2_opt.s.bcI believe -S will yield the text output. -- With best regards, Anton Korobeynikov Faculty of Mathematics and Mechanics, Saint Petersburg State University
On Wed, Mar 16, 2011 at 2:59 PM, Duncan Sands <baldrick at free.fr> wrote:> Hi Joe, > >> I have made a .s file, which can be correctly assembled >> and run with lli. But when I optimize it I get no errors >> from the optimizer, but the resultant file is incorrect. >> >> Here's what happens: >> >> llvm-as test2_gen.s %% no errors test2_gen.s.bc is produced > > there's actually no need to assemble this to bitcode: you can pass > test2_gen.s directly to opt. At least you can in recent versions of > LLVM. > >> opt -std-compile-opts -S test2_gen.s.bc> test2_opt.s.bc > > By using -S you ask opt to produce human readable IR rather than > bitcode, so you should really output to test2_opt.s. > >> >> %% no errors >> %% But now the generated file cannon be disassembled or run >> >> lli test2_opt.s.bc >> lli: error loading program 'test2_opt.s.bc': Bitcode stream should be a >> multiple >> of 4 bytes in length > > This means that it doesn't contain bitcode. And indeed it doesn't, it > contains human readable IR due to your using -S above.Silly me I didn't think to look - you're right. This is very cool - my C compiler spits out lousy code, but after "opt'ing" the result more or less results in what as optimising C compiler would have spit out. Which means that language interoperability becomes really easy - just parse and de-sugar the input (form any language) and your're away. Thanks for you help /Joe> >> llvm-dis test2_opt.s.bc >> llvm-dis: Bitcode stream should be a multiple of 4 bytes in length > > Same problem. > > That said, in latest LLVM lli accepts human readable IR as well as bitcode, > so I'm guessing that you are using an older version that does not have this > feature. Of course I may also have misdiagnosed the problem :) > > Ciao, Duncan. > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >
On Mar 16, 2011, at 3:14 AM, Joe armstrong wrote:> I have made a .s file, which can be correctly assembled > and run with lli. But when I optimize it I get no errors > from the optimizer, but the resultant file is incorrect. > > Here's what happens: > > llvm-as test2_gen.s %% no errors test2_gen.s.bc is produced > > lli test2_gen.s.bc > n=887459712 %% no errors > > opt -std-compile-opts -S test2_gen.s.bc > test2_opt.s.bcWe normally reserve the .s suffix for native assembly files and use .ll for LLVM IR assembly. The .bc suffix implies binary bitcode. llvm-as: .ll -> .bc llvm-dis: .bc -> .ll llc: .ll/.bc -> .s I don't think the tools require these suffixes, but it helps avoid confusion. /jakob