The peephole tries to reorder MOV32r0 instructions such that they are
before the instruction that modifies EFLAGS.
The problem is that the peephole does not consider the case where the
instruction that modifies EFLAGS also depends on the previous state of
EFLAGS.
Instead, walk backwards until we find an instruction that has a def for
EFLAGS but does not have a use.
If we find such an instruction, insert the MOV32r0 before it.
If it cannot find such an instruction, skip the optimization.
llvm-svn: 182184
Shuffles that only move an element into position 0 of the vector are common in
the output of the loop vectorizer and often generate suboptimal code when SSSE3
is not available. Lower them to vector shifts if possible.
We still prefer palignr over psrldq because it has higher throughput on
sandybridge.
llvm-svn: 182102
Increase the number of instructions LLVM recognizes as setting the ZF
flag. This allows us to remove test instructions that redundantly
recalculate the flag.
llvm-svn: 181937
It was just a less powerful and more confusing version of
MCCFIInstruction. A side effect is that, since MCCFIInstruction uses
dwarf register numbers, calls to getDwarfRegNum are pushed out, which
should allow further simplifications.
I left the MachineModuleInfo::addFrameMove interface unchanged since
this patch was already fairly big.
llvm-svn: 181680
The issue was that the MatchingInlineAsm and VariantID args to the
MatchInstructionImpl function weren't being set properly. Specifically, when
parsing intel syntax, the parser thought it was parsing inline assembly in the
at&t dialect; that will never be the case.
The crash was caused when the emitter tried to emit the instruction, but the
operands weren't set. When parsing inline assembly we only set the opcode, not
the operands, which is used to lookup the instruction descriptor.
rdar://13854391 and PR15945
Also, this commit reverts r176036. Now that we're correctly parsing the intel
syntax the pushad/popad don't match properly. I've reimplemented that fix using
a MnemonicAlias.
llvm-svn: 181620
We generate a `push' of a random register (%rax) if the stack needs to be
aligned by the size of that register. However, this could mess up compact unwind
generation. In particular, we want to still generate compact unwind in the
presence of this monstrosity.
Check if the push of of the %rax/%eax register. If it is and it's marked with
the `FrameSetup' flag, then we can generate a compact unwind encoding for the
function only if the push is the last FrameSetup instruction.
llvm-svn: 181540
The compact unwind registers were defined in two different
places. It's better just to place them in the function that uses them
and specify that this is a 64-bit or 32-bit machine.
No functionality change.
llvm-svn: 181529
X86ISelLowering has support to treat:
(icmp ne (and (xor %flags, -1), (shl 1, flag)), 0)
as if it were actually:
(icmp eq (and %flags, (shl 1, flag)), 0)
However, r179386 has code at the InstCombine level to handle this.
llvm-svn: 181145
the "identifier" parsed by the frontend callback by skipping forward
until we've consumed a token that ends at the point dictated by the
callback.
In addition, inform the callback when it's parsing an unevaluated
operand (e.g. mov eax, LENGTH A::x) as opposed to an evaluated one
(e.g. mov eax, [A::x]).
This commit depends on a clang commit.
llvm-svn: 180978
latency for certain models of the Intel Atom family, by converting
instructions into their equivalent LEA instructions, when it is both
useful and possible to do so.
llvm-svn: 180573
I think it's almost impossible to fold atomic fences profitably under
LLVM/C++11 semantics. As a result, this is now unused and just
cluttering up the target interface.
llvm-svn: 179940
David Majnemer