[LLVMdev] Disable optimization
raad_7007 at yahoo.com
Fri Nov 28 00:36:44 PST 2008
I want to disable optimizations because, i'm going to implement a framework in JAVA for educational purposes.
I have planned to do followings:
1) Create LLVM-IR and export it as Assembly (without optimizing the source-code)
2) Transform the LLVM-Assembly to a data-structure, similar to LLVM
data structure (Module, Function, BB ...) but implemented in Java
3) Optimizing the code (should be performed by students :-) )
4) Transform my data-structure to LLVM-Assembly.
5) Generate machine code using "llvm-as"
Could you list me the other optimizations, which are performed by front-end?
From: Eli Friedman <eli.friedman at gmail.com>
To: LLVM Developers Mailing List <llvmdev at cs.uiuc.edu>
Sent: Thursday, November 27, 2008 10:39:21 PM
Subject: Re: [LLVMdev] Disable optimization
On Thu, Nov 27, 2008 at 6:14 AM, RAAD B <raad_7007 at yahoo.com> wrote:
> Hello together,
> although i use the "-O0" flag as follow, the llvm perform dead code
> How can i disable optimizing completely?
Sorry, it's not possible; the gcc front-end does some optimizations
which the LLVM backend can't do anything about, and dead code
elimination can arise naturally out of the approach LLVM uses for code
generation. Note that -O0 really means "generate code as quickly as
possible, and don't do any optimizations which reduce the quality of
Why exactly do you want to disable dead code elimination anyway? I
can't see any reason why you'd want dead code in the generated
program, unless you're abusing asm statements or something like that.
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