[LLVMdev] Passing llc options to Clang

[Ziqiang Patrick Huang]

Hi, 

Is there a way to passing llc options to clang, for example -march -mcpu, etc. ? 

Some threads suggested using -mllvm flag,

I tried ./clang -mllvm -march=X86-64 -mcpu=core2 -o hello hello.c, but got "Unknown command line argument"

Thanks,

Ziqiang 

[Daniil Troshkov]

maybe try to use -mllvm for each arg

./clang -mllvm -march=X86-64 -mllvm -mcpu=core2 -o hello hello.c

[Ziqiang Patrick Huang]

Thanks, Daniil

I've tried that, still not working. 

2014-10-13 16:11 GMT-04:00 Daniil Troshkov <troshk...@gmail.com>:

maybe try to use -mllvm for each arg

./clang -mllvm -march=X86-64 -mllvm -mcpu=core2 -o hello hello.c

--

Ziqiang Huang

Electrical and Computer Engineering

Hudson 213c, Duke University

Tel: 919-491-3677

Email: ziqian...@duke.edu

[Daniil Troshkov]

I've looked at test/CodeGen/X86
; RUN: llc < %s -march=x86-64 -mcpu=core2 ...

they use x86-64 (with small letter)

[Reid Kleckner]

You'll be a lot better off if you use the gcc-style flags that clang accepts. If you bypass clang, it will generate LLVM IR for the default target, and then attempt to compile that IR using the triple you provided to llc.

Try 'clang --target=x86_64-linux-gnu' or whatever your target is.

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[Ziqiang Patrick Huang]

Thanks, Reid

The reason I want to pass -mcpu is that I want to specify the subtarget so that when llc does the instruction scheduling, it would takes the subtarget scheduling information into consideration. I'm not sure --target flag will get what I want ...