Register masks will be used as a compact representation of large clobber
lists. Currently, an x86 call instruction has some 40 operands
representing call-clobbered registers. That's more than 1kB of useless
operands per call site.
A register mask operand references a bit mask of call-preserved
registers, everything else is clobbered. The bit mask will typically
come from TargetRegisterInfo::getCallPreservedMask().
By abandoning ImplicitDefs for call-clobbered registers, it also becomes
possible to share call instruction descriptions between calling
conventions, and we can get rid of the WINCALL* instructions.
This patch introduces the new operand kind. Future patches will add
RegMask support to target-independent passes before finally the fixed
clobber lists can be removed from call instruction descriptions.
llvm-svn: 148250
or Clang is using this, and it would be hard to use it correctly given
the thread hostility of the function. Also, it never checked the return
which is rather dangerous with chdir. If someone was in fact using this,
please let me know, as well as what the usecase actually is so that
I can add it back and make it more correct and secure to use. (That
said, it's never going to be "safe" per-se, but we could at least
document the risks...)
llvm-svn: 148211
The hook returns a bit-mask of call-preserved registers that will
eventually replace the current list of implicit defs on call
instructions. This will make it possible to support multiple calling
conventions without duplicating call instruction descriptors.
The call-preserved mask is slightly different from the list returned by
the getCalleeSavedRegs() hook, it includes all aliases that are
preserved by calls.
The hook takes a CallingConv::ID argument instead of a MachineFunction
pointer, so it can provide information about calls to extern functions,
and even indirect function calls.
TRI::getCalleeSavedRegs() returns information about the function
currently being compiled. TRI::getCallPreservedMask() returns
information about the functions it is calling.
llvm-svn: 148165
Consider this code:
int h() {
int x;
try {
x = f();
g();
} catch (...) {
return x+1;
}
return x;
}
The variable x is undefined on the first edge to the landing pad, but it
has the f() return value on the second edge to the landing pad.
SplitAnalysis::getLastSplitPoint() would assume that the return value
from f() was live into the landing pad when f() throws, which is of
course impossible.
Detect these cases, and treat them as if the landing pad wasn't there.
This allows spill code to be inserted after the function call to f().
<rdar://problem/10664933>
llvm-svn: 147912
Delete the alternative implementation in LiveIntervalAnalysis.
These functions computed the same thing, but SplitAnalysis caches the
result.
llvm-svn: 147911
with other symbols.
An object in the __cfstring section is suppoed to be filled with CFString
objects, which have a pointer to ___CFConstantStringClassReference followed by a
pointer to a __cstring. If we allow the object in the __cstring section to be
merged with another global, then it could end up in any section. Because the
linker is going to remove these symbols in the final executable, we shouldn't
bother to merge them.
<rdar://problem/10564621>
llvm-svn: 147899
functional change in r147860 to use DW_TAG_label's instead TAG_subprogram's.
This only changes names and updates comments. No functional change.
llvm-svn: 147877
of several newly un-defaulted switches. This also helps optimizers
(including LLVM's) recognize that every case is covered, and we should
assume as much.
llvm-svn: 147861
These heuristics are sufficient for enabling IV chains by
default. Performance analysis has been done for i386, x86_64, and
thumbv7. The optimization is rarely important, but can significantly
speed up certain cases by eliminating spill code within the
loop. Unrolled loops are prime candidates for IV chains. In many
cases, the final code could still be improved with more target
specific optimization following LSR. The goal of this feature is for
LSR to make the best choice of induction variables.
Instruction selection may not completely take advantage of this
feature yet. As a result, there could be cases of slight code size
increase.
Code size can be worse on x86 because it doesn't support postincrement
addressing. In fact, when chains are formed, you may see redundant
address plus stride addition in the addressing mode. GenerateIVChains
tries to compensate for the common cases.
On ARM, code size increase can be mitigated by using postincrement
addressing, but downstream codegen currently misses some opportunities.
llvm-svn: 147826
file error checking. Use that to error on an unfinished cfi_startproc.
The error is not nice, but is already better than a segmentation fault.
llvm-svn: 147717
opportunities that only present themselves after late optimizations
such as tail duplication .e.g.
## BB#1:
movl %eax, %ecx
movl %ecx, %eax
ret
The register allocator also leaves some of them around (due to false
dep between copies from phi-elimination, etc.)
This required some changes in codegen passes. Post-ra scheduler and the
pseudo-instruction expansion passes have been moved after branch folding
and tail merging. They were before branch folding before because it did
not always update block livein's. That's fixed now. The pass change makes
independently since we want to properly schedule instructions after
branch folding / tail duplication.
rdar://10428165
rdar://10640363
llvm-svn: 147716
The register allocators don't currently support adding reserved
registers while they are running. Extend the MRI API to keep track of
the set of reserved registers when register allocation started.
Target hooks like hasFP() and needsStackRealignment() can look at this
set to avoid reserving more registers during register allocation.
llvm-svn: 147577
Using DenseMap iterators isn't free as they have to check for empty
buckets. Dominator queries are common so this gives a minor speedup.
llvm-svn: 147544
Get back getHostTriple.
For JIT compilation, use the host triple instead of the default
target: this fixes some JIT testcases that used to fail when the
compiler has been configured as a cross compiler.
llvm-svn: 147542
Jakob Stoklund Olesen