This is a repeat of 1880092722 from 2009. We should have less risk
of hitting bugs at this point because we auto-generate positive CHECK
lines only, but this makes things consistent.
Copying the original commit msg:
"Change tests from "opt %s" to "opt < %s" so that opt doesn't see the
input filename so that opt doesn't print the input filename in the
output so that grep lines in the tests don't unintentionally match
strings in the input filename."
Summary:
This is again motivated by D67122 sanitizer check enhancement.
That patch seemingly worsens `-fsanitize=pointer-overflow`
overhead from 25% to 50%, which strongly implies missing folds.
For
```
#include <cassert>
char* test(char& base, signed long offset) {
__builtin_assume(offset < 0);
return &base + offset;
}
```
We produce
https://godbolt.org/z/r40U47
and again those two icmp's can be merged:
```
Name: 0
Pre: C != 0
%adjusted = add i8 %base, C
%not_null = icmp ne i8 %adjusted, 0
%no_underflow = icmp ult i8 %adjusted, %base
%r = and i1 %not_null, %no_underflow
=>
%neg_offset = sub i8 0, C
%r = icmp ugt i8 %base, %neg_offset
```
https://rise4fun.com/Alive/ALaphttps://rise4fun.com/Alive/slnN
There are 3 other variants of this pattern,
i believe they all will go into InstSimplify.
https://bugs.llvm.org/show_bug.cgi?id=43259
Reviewers: spatel, xbolva00, nikic
Reviewed By: spatel
Subscribers: efriedma, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67849
llvm-svn: 372768
Sanjay Patel