Default target

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1

Currently, if you have BitCode that does not
specify a target, it gets a default architecture.
This is especially odd if you are doing
llvm-ld -native
but it first applies optimizations for
a target other than what it is currently compiling for.

Ideally, target-specific optimizations wouldn't be
applied until a target was given.
This would allow simple programs to be target-agnostic.
(And therefore more likely to work for newcomers.)

Why is there a default target?
Why can't those optimizations just be skipped until there is one?
(To be clear: I am assuming there is a reason for this.
I am asking what it is.)

Especially in the case of llvm-ld -native,
why doesn't it set the target to the platform
it is compiling for?
Failing that, it could use the platform it is
currently running on as the target.

- --
main(){char s="+~{Y$-:>2vp5z^",c=244,i;int j=44404;
for(;j>0;j--)for(i=0;i<14;i++)c+=s[i]-=c;puts(s);}

2

Hi S3,

Currently, if you have BitCode that does not
specify a target, it gets a default architecture.
This is especially odd if you are doing
llvm-ld -native
but it first applies optimizations for
a target other than what it is currently compiling for.

there has been some work on this, especially for "opt",
but I don't know the status.

Ciao,

Duncan.

3

Why is there a default target?
Why can't those optimizations just be skipped until there is one?
(To be clear: I am assuming there is a reason for this.
I am asking what it is.)

This has recently been fixed on trunk. The opt tool no longer adds a
default target if a Module has no target attributes, and the optimizers
now know how to be conservative when there's no target information.

Especially in the case of llvm-ld -native,
why doesn't it set the target to the platform
it is compiling for?

This sounds like it could be called a bug. Please file a bugzilla report.

Dan

4

Why is there a default target?
Why can't those optimizations just be skipped until there is one?
(To be clear: I am assuming there is a reason for this.
I am asking what it is.)

This has recently been fixed on trunk. The opt tool no longer adds a
default target if a Module has no target attributes, and the optimizers
now know how to be conservative when there's no target information.

Great. That should make everything a lot easier.

Especially in the case of llvm-ld -native,
why doesn't it set the target to the platform
it is compiling for?

This sounds like it could be called a bug. Please file a bugzilla report.

Filed:
http://llvm.org/bugs/show_bug.cgi?id=6401

- --
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<<<<<]>++++++++.>-------.<--.>>.---.>++.>-----.>+++
+++++[->++++<]>.<<<<<<<<.>>++.>.>.>.>>++++++++++.