[GlobalOpt] Don't replace the aliasee if it has other references.

As long as aliasee has `@llvm.used` or `@llvm.compiler.used` references, we cannot do the related replace or delete operations. Even

[GlobalOpt] Don't replace the aliasee if it has other references.

As long as aliasee has `@llvm.used` or `@llvm.compiler.used` references, we cannot do the related replace or delete operations. Even if it is a Local Linkage, we cannot infer if there is no other use for it, such as asm or other future added cases.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D145293

show more ...

[GlobalOpts] Convert tests to opaque pointers (NFC)

[GlobalOpt] Don't replace alias with aliasee if either alias/aliasee may be preemptible

Generalize D99629 for ELF. A default visibility non-local symbol is preemptible
in a -shared link. `isInterpos

[GlobalOpt] Don't replace alias with aliasee if either alias/aliasee may be preemptible

Generalize D99629 for ELF. A default visibility non-local symbol is preemptible
in a -shared link. `isInterposable` is an insufficient condition.

Moreover, a non-preemptible alias may be referenced in a sub constant expression
which intends to lower to a PC-relative relocation. Replacing the alias with a
preemptible aliasee may introduce a linker error.

Respect dso_preemptable and suppress optimization to fix the abose issues. With
the change, `alias = 345` will not be rewritten to use aliasee in a `-fpic`
compile.
```
int aliasee;
extern int alias __attribute__((alias("aliasee"), visibility("hidden")));
void foo() { alias = 345; } // intended to access the local copy
```

While here, refine the condition for the alias as well.

For some binary formats like COFF, `isInterposable` is a sufficient condition.
But I think canonicalization for the changed case has little advantage, so I
don't bother to add the `Triple(M.getTargetTriple()).isOSBinFormatELF()` or
`getPICLevel/getPIELevel` complexity.

For instrumentations, it's recommended not to create aliases that refer to
globals that have a weak linkage or is preemptible. However, the following is
supported and the IR needs to handle such cases.
```
int aliasee __attribute__((weak));
extern int alias __attribute__((alias("aliasee")));
```

There are other places where GlobalAlias isInterposable usage may need to be
fixed.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D107249

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Revert "[GlobalOpt] Don't replace alias with aliasee if either alias/aliasee may be preemptible"

This reverts commit 30e8f83c84c5a302a559722fc0d2973dc3f425ee.

Causes huge compile time regressions o

Revert "[GlobalOpt] Don't replace alias with aliasee if either alias/aliasee may be preemptible"

This reverts commit 30e8f83c84c5a302a559722fc0d2973dc3f425ee.

Causes huge compile time regressions on certain large files. Will followup offline with author.

show more ...

[GlobalOpt] Don't replace alias with aliasee if either alias/aliasee may be preemptible

Generalize D99629 for ELF. A default visibility non-local symbol is preemptible
in a -shared link. `isInterpos

[GlobalOpt] Don't replace alias with aliasee if either alias/aliasee may be preemptible

Generalize D99629 for ELF. A default visibility non-local symbol is preemptible
in a -shared link. `isInterposable` is an insufficient condition.

Moreover, a non-preemptible alias may be referenced in a sub constant expression
which intends to lower to a PC-relative relocation. Replacing the alias with a
preemptible aliasee may introduce a linker error.

Respect dso_preemptable and suppress optimization to fix the abose issues. With
the change, `alias = 345` will not be rewritten to use aliasee in a `-fpic`
compile.
```
int aliasee;
extern int alias __attribute__((alias("aliasee"), visibility("hidden")));
void foo() { alias = 345; } // intended to access the local copy
```

While here, refine the condition for the alias as well.

For some binary formats like COFF, `isInterposable` is a sufficient condition.
But I think canonicalization for the changed case has little advantage, so I
don't bother to add the `Triple(M.getTargetTriple()).isOSBinFormatELF()` or
`getPICLevel/getPIELevel` complexity.

For instrumentations, it's recommended not to create aliases that refer to
globals that have a weak linkage or is preemptible. However, the following is
supported and the IR needs to handle such cases.
```
int aliasee __attribute__((weak));
extern int alias __attribute__((alias("aliasee")));
```

There are other places where GlobalAlias isInterposable usage may need to be
fixed.

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D107249

show more ...

[test] Use -passes syntax when specifying pipeline in some more tests

The legacy PM is deprecated, so update a bunch of lit tests running
opt to use the new PM syntax when specifying the pipeline.
I

[test] Use -passes syntax when specifying pipeline in some more tests

The legacy PM is deprecated, so update a bunch of lit tests running
opt to use the new PM syntax when specifying the pipeline.
In this patch focus has been put on test cases for ConstantMerge,
ConstraintElimination, CorrelatedValuePropagation, GlobalDCE,
GlobalOpt, SCCP, TailCallElim and PredicateInfo.

Differential Revision: https://reviews.llvm.org/D114516

show more ...

Revert "Temporarily Revert "Add basic loop fusion pass.""

The reversion apparently deleted the test/Transforms directory.

Will be re-reverting again.

llvm-svn: 358552

IR: Introduce local_unnamed_addr attribute.

If a local_unnamed_addr attribute is attached to a global, the address
is known to be insignificant within the module. It is distinct from the
existing un

IR: Introduce local_unnamed_addr attribute.

If a local_unnamed_addr attribute is attached to a global, the address
is known to be insignificant within the module. It is distinct from the
existing unnamed_addr attribute in that it only describes a local property
of the module rather than a global property of the symbol.

This attribute is intended to be used by the code generator and LTO to allow
the linker to decide whether the global needs to be in the symbol table. It is
possible to exclude a global from the symbol table if three things are true:
- This attribute is present on every instance of the global (which means that
the normal rule that the global must have a unique address can be broken without
being observable by the program by performing comparisons against the global's
address)
- The global has linkonce_odr linkage (which means that each linkage unit must have
its own copy of the global if it requires one, and the copy in each linkage unit
must be the same)
- It is a constant or a function (which means that the program cannot observe that
the unique-address rule has been broken by writing to the global)

Although this attribute could in principle be computed from the module
contents, LTO clients (i.e. linkers) will normally need to be able to compute
this property as part of symbol resolution, and it would be inefficient to
materialize every module just to compute it.

See:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160509/356401.html
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160516/356738.html
for earlier discussion.

Part of the fix for PR27553.

Differential Revision: http://reviews.llvm.org/D20348

llvm-svn: 272709

show more ...

[opaque pointer type] Add textual IR support for explicit type parameter for global aliases

update.py:
import fileinput
import sys
import re

alias_match_prefix = r"(.*(?:=|:|^)\s*(?:external |)(?:(

[opaque pointer type] Add textual IR support for explicit type parameter for global aliases

update.py:
import fileinput
import sys
import re

alias_match_prefix = r"(.*(?:=|:|^)\s*(?:external |)(?:(?:private|internal|linkonce|linkonce_odr|weak|weak_odr|common|appending|extern_weak|available_externally) )?(?:default |hidden |protected )?(?:dllimport |dllexport )?(?:unnamed_addr |)(?:thread_local(?:\([a-z]*\))? )?alias"
plain = re.compile(alias_match_prefix + r" (.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|addrspacecast|\[\[[a-zA-Z]|\{\{).*$)")
cast = re.compile(alias_match_prefix + r") ((?:bitcast|inttoptr|addrspacecast)\s*\(.* to (.*?)(| addrspace\(\d+\) *)\*\)\s*(?:;.*)?$)")
gep = re.compile(alias_match_prefix + r") ((?:getelementptr)\s*(?:inbounds)?\s*\((?P<type>.*), (?P=type)(?:\s*addrspace\(\d+\)\s*)?\* .*\)\s*(?:;.*)?$)")

def conv(line):
m = re.match(cast, line)
if m:
return m.group(1) + " " + m.group(3) + ", " + m.group(2)
m = re.match(gep, line)
if m:
return m.group(1) + " " + m.group(3) + ", " + m.group(2)
m = re.match(plain, line)
if m:
return m.group(1) + ", " + m.group(2) + m.group(3) + "*" + m.group(4) + "\n"
return line

for line in sys.stdin:
sys.stdout.write(conv(line))

apply.sh:
for name in "$@"
do
python3 `dirname "$0"`/update.py < "$name" > "$name.tmp" && mv "$name.tmp" "$name"
rm -f "$name.tmp"
done

The actual commands:
From llvm/src:
find test/ -name *.ll | xargs ./apply.sh
From llvm/src/tools/clang:
find test/ -name *.mm -o -name *.m -o -name *.cpp -o -name *.c | xargs -I '{}' ../../apply.sh "{}"
From llvm/src/tools/polly:
find test/ -name *.ll | xargs ./apply.sh

llvm-svn: 247378

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Use "weak alias" instead of "alias weak"

Before this patch we had

@a = weak global ...
but
@b = alias weak ...

The patch changes aliases to look more like global variables.

Looking at some really

Use "weak alias" instead of "alias weak"

Before this patch we had

@a = weak global ...
but
@b = alias weak ...

The patch changes aliases to look more like global variables.

Looking at some really old code suggests that the reason was that the old
bison based parser had a reduction for alias linkages and another one for
global variable linkages. Putting the alias first avoided the reduce/reduce
conflict.

The days of the old .ll parser are long gone. The new one parses just "linkage"
and a later check is responsible for deciding if a linkage is valid in a
given context.

llvm-svn: 214355

show more ...

Fix addrspacecast with metadata globals

llvm-svn: 198345