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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45388 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-12-28 22:30:05 +00:00
parent 9bfcc624ba
commit a1643ba71a
1 changed files with 32 additions and 0 deletions
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32
lib/Target/README.txt
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@ -480,6 +480,38 @@ int i;
}
}
//===---------------------------------------------------------------------===//
We should investigate an instruction sinking pass. Consider this silly
example in pic mode:
#include <assert.h>
void foo(int x) {
assert(x);
//...
}
we compile this to:
_foo:
subl $28, %esp
call "L1$pb"
"L1$pb":
popl %eax
cmpl $0, 32(%esp)
je LBB1_2 # cond_true
LBB1_1: # return
# ...
addl $28, %esp
ret
LBB1_2: # cond_true
...
The PIC base computation (call+popl) is only used on one path through the
code, but is currently always computed in the entry block. It would be
better to sink the picbase computation down into the block for the
assertion, as it is the only one that uses it. This happens for a lot of
code with early outs.
In this case, whole-function-isel would also handle this.
//===---------------------------------------------------------------------===//