GEP instructions are there for the compiler and shouldn't really output much
code (if any at all). When a GEP is stored in the entry block, Fast ISel (for
one) will not know that it could fold it into further uses. For instance, inside
of the EH handling code. This results in a lot of unnecessary spills and loads
which bloat code and slows down pretty much everything.
<rdar://problem/10694814>
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mid-level constant folding APIs instead of doing its own analysis.
This makes it more general (e.g. can now share a <2 x i64> with a
<4 x i32>) and avoid duplicating a bunch of logic.
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we're at it, allow PatternMatch's "neg" pattern to match integer
vector negations, and enhance ComputeNumSigned bits to handle
shl of vectors.
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MachineBasicBlock::canFallThrough(). We're interested in the state of the
instruction (i.e., is this a barrier or not?), not if the instruction is
predicable or not.
rdar://10501092
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The live range of the source register may be extended when a redundant
copy is eliminated. Make sure any kill flags between the two copies are
cleared.
This fixes PR11765.
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This enables the linker to match concrete relocation types (absolute or relative) with whatever library or C++ support code is being linked against.
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more robust) ways to do what it was doing now. Also, add static methods
for decoding a ShuffleVector mask.
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This boils down to using MachineOperand::readsReg() more.
This fixes PR11829 where a use ended up after the first def when
lowering REG_SEQUENCE instructions involving IMPLICIT_DEFs.
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function. They don't appear to be used, and are inconsistent with handling of
other physreg intervals (i.e. intervals that are not live-in) where ranges are
not inserted for aliases.
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A REG_SEQUENCE instruction is lowered into a sequence of partial defs:
%vreg7:ssub_0<def,undef> = COPY %vreg20:ssub_0
%vreg7:ssub_1<def> = COPY %vreg2
%vreg7:ssub_2<def> = COPY %vreg2
%vreg7:ssub_3<def> = COPY %vreg2
The first def needs an <undef> flag to indicate it is the beginning of
the live range, while the other defs are read-modify-write. Previously,
we depended on LiveIntervalAnalysis to notice and fix the missing
<def,undef>, but that solution was never robust, it was causing problems
with ProcessImplicitDefs and the lowering of chained REG_SEQUENCE
instructions.
This fixes PR11841.
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This change adds an new option --arm-enable-ehabi-descriptors that
enables emitting unwinding descriptors. This provides a mode with a
working backtrace() without the (currently broken) exception support.
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and clean up some other misc stuff. Unlike ConstantArray, we will
prefer to emit .fill directives for "String" arrays that all have
the same value, since they are denser than emitting a .ascii
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violation -- MC cannot depend on CodeGen.
Specifically, the MCTargetDesc component of each target is actually
a subcomponent of the MC library. As such, it cannot depend on the
target-independent code generator, because MC itself cannot depend on
the target-independent code generator. This change moved a flag from the
ARM MCTargetDesc file ARMMCAsmInfo.cpp to the CodeGen layer in
ARMException.cpp, leaving behind an 'extern' to refer back to it. That
layering order isn't viable givin the constraints outlined above.
Commandline flags are designed to be static specifically to avoid these
types of bugs.
Fixing this is likely going to require some non-trivial refactoring.
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This change adds an new value to the --arm-enable-ehabi option that
disables emitting unwinding descriptors. This mode gives a working
backtrace() without the (currently broken) exception support.
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A register mask operand kills any live physreg that isn't preserved.
Unlike an implicit-def operand, the clobbered physregs are never live
afterwards.
This means LiveVariables has to track a much smaller number of live
physregs, and it should spend much less time in addRegisterDead().
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Problem: LLVM needs more function attributes than currently available (32 bits).
One such proposed attribute is "address_safety", which shows that a function is being checked for address safety (by AddressSanitizer, SAFECode, etc).
Solution:
- extend the Attributes from 32 bits to 64-bits
- wrap the object into a class so that unsigned is never erroneously used instead
- change "unsigned" to "Attributes" throughout the code, including one place in clang.
- the class has no "operator uint64 ()", but it has "uint64_t Raw() " to support packing/unpacking.
- the class has "safe operator bool()" to support the common idiom: if (Attributes attr = getAttrs()) useAttrs(attr);
- The CTOR from uint64_t is marked explicit, so I had to add a few explicit CTOR calls
- Add the new attribute "address_safety". Doing it in the same commit to check that attributes beyond first 32 bits actually work.
- Some of the functions from the Attribute namespace are worth moving inside the class, but I'd prefer to have it as a separate commit.
Tested:
"make check" on Linux (32-bit and 64-bit) and Mac (10.6)
built/run spec CPU 2006 on Linux with clang -O2.
This change will break clang build in lib/CodeGen/CGCall.cpp.
The following patch will fix it.
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'insertvalue' instructions that recreate the structure returned by the
'landingpad' instruction. Because the 'insertvalue' instruction isn't supported
by FastISel, this can save a bit of time during -O0 compilation.
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to instruction right after the last instruction in the bundle.
- Add a finalizeBundle() variant that doesn't specify LastMI. Instead, the code
will find the last instruction in the bundle by following the 'InsideBundle'
marker. This is useful in case bundles are formed early (i.e. during MI
scheduling) but finalized later (i.e. after register allocator has finished
rewriting virtual registers with physical registers).
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This SelectionDAG node will be attached to call nodes by LowerCall(),
and eventually becomes a MO_RegisterMask MachineOperand on the
MachineInstr representing the call instruction.
LowerCall() will attach a register mask that depends on the calling
convention.
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or clang bootstrap.
I will keep an eye on the bots.
Original message:
Only emit the Leh_func_endN symbol when needed.
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(This time I believe I've checked all the -Wreturn-type warnings from GCC & added the couple of llvm_unreachables necessary to silence them. If I've missed any, I'll happily fix them as soon as I know about them)
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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.
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We know that the blend instructions only use the MSB, so if the mask is
sign-extended then we can convert it into a SHL instruction. This is a
common pattern because the type-legalizer sign-extends the i1 type which
is used by the LLVM-IR for the condition.
Added a new optimization in SimplifyDemandedBits for SIGN_EXTEND_INREG -> SHL.
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non-determinism in the 32 bit dragonegg buildbot. Original commit
message:
Only emit the Leh_func_endN symbol when needed.
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live across BBs before register allocation. This miscompiled 197.parser
when a cmp + b are optimized to a cbnz instruction even though the CPSR def
is live-in a successor.
cbnz r6, LBB89_12
...
LBB89_12:
ble LBB89_1
The fix consists of two parts. 1) Teach LiveVariables that some unallocatable
registers might be liveouts so don't mark their last use as kill if they are.
2) ARM constantpool island pass shouldn't form cbz / cbnz if the conditional
branch does not kill CPSR.
rdar://10676853
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overly conservative. It was concerned about cases where it would prohibit
folding simple [r, c] addressing modes. e.g.
ldr r0, [r2]
ldr r1, [r2, #4]
=>
ldr r0, [r2], #4
ldr r1, [r2]
Change the logic to look for such cases which allows it to form indexed memory
ops more aggressively.
rdar://10674430
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The registers are placed into the saved registers list in the reverse order,
which is why the original loop was written to loop backwards.
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killed registers are needed below the insertion point, then unset the kill
marker.
Sorry I'm not able to find a reduced test case.
rdar://10660944
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When we load the v12i32 type, the GenWidenVectorLoads method generates two loads: v8i32 and v4i32
and attempts to use CONCAT_VECTORS to join them. In this fix I concat undef values to widen
the smaller value. The test "widen_load-2.ll" also exposes this bug on AVX.
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detect a pattern which can be implemented with a small 'shl' embedded in
the addressing mode scale. This happens in real code as follows:
unsigned x = my_accelerator_table[input >> 11];
Here we have some lookup table that we look into using the high bits of
'input'. Each entity in the table is 4-bytes, which means this
implicitly gets turned into (once lowered out of a GEP):
*(unsigned*)((char*)my_accelerator_table + ((input >> 11) << 2));
The shift right followed by a shift left is canonicalized to a smaller
shift right and masking off the low bits. That hides the shift right
which x86 has an addressing mode designed to support. We now detect
masks of this form, and produce the longer shift right followed by the
proper addressing mode. In addition to saving a (rather large)
instruction, this also reduces stalls in Intel chips on benchmarks I've
measured.
In order for all of this to work, one part of the DAG needs to be
canonicalized *still further* than it currently is. This involves
removing pointless 'trunc' nodes between a zextload and a zext. Without
that, we end up generating spurious masks and hiding the pattern.
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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>
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