This is a partial revert of r244615 (http://reviews.llvm.org/D11942),
which caused a major regression in debug info quality.
Turning the artificial __MergedGlobal symbols into private symbols
(l__MergedGlobal) means that the linker will not include them in the
symbol table of the final executable. Without a symbol table entry
dsymutil is not be able to process the debug info for any of the
merged globals and thus drops the debug info for all of them.
This patch is enabling the old behavior for all MachO targets while
leaving all other targets unaffected.
rdar://problem/29160481
https://reviews.llvm.org/D26531
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286607 91177308-0d34-0410-b5e6-96231b3b80d8
This code crashed on funclet-style EH instructions such as catchpad,
catchswitch, and cleanuppad. Just treat all EH pad instructions
equivalently and avoid merging the globals they reference through any
use.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@284633 91177308-0d34-0410-b5e6-96231b3b80d8
This patch reverses the edge from DIGlobalVariable to GlobalVariable.
This will allow us to more easily preserve debug info metadata when
manipulating global variables.
Fixes PR30362. A program for upgrading test cases is attached to that
bug.
Differential Revision: http://reviews.llvm.org/D20147
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281284 91177308-0d34-0410-b5e6-96231b3b80d8
This was a flawed change - it just caused the getElementType call to be
deferred until later, when we really need to remove it. Now that the IR
for GlobalAliases has been updated, the root cause is addressed that way
instead and this change is no longer needed (and in fact gets in the way
- because we want to pass the pointee type directly down further).
Follow up patches to push this through GlobalValue, bitcode format, etc,
will come along soon.
This reverts commit 236160.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@247585 91177308-0d34-0410-b5e6-96231b3b80d8
On Mach-O emitting aliases for the variables that make up a MergedGlobals
variable can cause problems when linking with dead stripping enabled so don't
do that, except for external variables where we must emit an alias.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244748 91177308-0d34-0410-b5e6-96231b3b80d8
Other objects can never reference the MergedGlobals symbol so external linkage
is never needed. Using private instead of internal linkage means the object is
more similar to what it looks like when global merging is not enabled, with
the only difference being that the merged variables are addressed indirectly
relative to the start of the section they are in.
Also add aliases for merged variables with internal linkage, as this also makes
the object be more like what it is when they are not merged.
Differential Revision: http://reviews.llvm.org/D11942
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244615 91177308-0d34-0410-b5e6-96231b3b80d8
Adjust the GlobalMergeOnExternal option so that the default behaviour is to
do whatever the Target thinks is best. Explicitly enabled or disabling the
option will override this default.
Differential Revision: http://reviews.llvm.org/D10965
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@243873 91177308-0d34-0410-b5e6-96231b3b80d8
The global-merge pass was crashing because it assumes that all ConstantExprs
(reached via the global variables that they use) have at least one user.
I haven't worked out a way to test this, as an unused ConstantExpr cannot be
represented by serialised IR, and global-merge can only be run in llc, which
does not run any passes which can make a ConstantExpr dead.
This (reduced to the point of silliness) C code triggers this bug when compiled
for arm-none-eabi at -O1:
static a = 7;
static volatile b[10] = {&a};
c;
main() {
c = 0;
for (; c < 10;)
printf(b[c]);
}
Differential Revision: http://reviews.llvm.org/D10314
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239308 91177308-0d34-0410-b5e6-96231b3b80d8
Now that we can look at users, we can trivially do this: when we would
have otherwise disabled GlobalMerge (currently -O<3), we can just run
it for minsize functions, as it's usually a codesize win.
Differential Revision: http://reviews.llvm.org/D10054
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239087 91177308-0d34-0410-b5e6-96231b3b80d8
Many of the callers already have the pointer type anyway, and for the
couple of callers that don't it's pretty easy to call PointerType::get
on the pointee type and address space.
This avoids LLParser from using PointerType::getElementType when parsing
GlobalAliases from IR.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236160 91177308-0d34-0410-b5e6-96231b3b80d8
Instead of merging everything together, look at the users of
GlobalVariables, and try to group them by function, to create
sets of globals used "together".
Using that information, a less-aggressive alternative is to keep merging
everything together *except* globals that are only ever used alone, that
is, those for which it's clearly non-profitable to merge with others.
In my testing, grouping by Function is too aggressive, but grouping by
BasicBlock is too conservative. Anything in-between isn't trivially
available, so stick with Function grouping for now.
cl::opts are added for testing; both enabled by default.
A few of the testcases aren't testing the merging proper, but just
various edge cases when merging does occur. Update them to use the
previous grouping behavior. Also, one of the tests is unrelated to
GlobalMerge; change it accordingly.
While there, switch to r234666' flags rather than the brutal -O3.
Differential Revision: http://reviews.llvm.org/D8070
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235249 91177308-0d34-0410-b5e6-96231b3b80d8
Currently, there's a single flag, checked by the pass itself.
It can't force-enable the pass (and is on by default), because it
might not even have been created, as that's the targets decision.
Instead, have separate explicit flags, so that the decision is
consistently made in the target.
Keep the flag as a last-resort "force-disable GlobalMerge" for now,
for backwards compatibility.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234666 91177308-0d34-0410-b5e6-96231b3b80d8
Adrian Prantl
Reid Kleckner
Mehdi Amini
Peter Collingbourne
Benjamin Kramer
Duncan P. N. Exon Smith
David Blaikie
Sanjay Patel
John Brawn
Oliver Stannard
Ahmed Bougacha