is preparatory to having PEI's scavenged frame index value reuse logic
properly distinguish types of frame values (e.g., whether the value is
stack-pointer relative or frame-pointer relative).
No functionality change.
llvm-svn: 98086
Extracting the low element of a vector is now done with EXTRACT_SUBREG,
and the zero-extension performed by load movss is now modeled with
SUBREG_TO_REG, and so on.
Register-to-register movss and movsd are no longer considered copies;
they are two-address instructions which insert a scalar into a vector.
llvm-svn: 97354
function can support dynamic stack realignment. That's a much easier question
to answer at instruction selection stage than whether the function actually
will have dynamic alignment prologue. This allows the removal of the
stack alignment heuristic pass, and improves code quality for cases where
the heuristic would result in dynamic alignment code being generated when
it was not strictly necessary.
llvm-svn: 93885
a virtual register to eliminate a frame index, it can return that register
and the constant stored there to PEI to track. When scavenging to allocate
for those registers, PEI then tracks the last-used register and value, and
if it is still available and matches the value for the next index, reuses
the existing value rather and removes the re-materialization instructions.
Fancier tracking and adjustment of scavenger allocations to keep more
values live for longer is possible, but not yet implemented and would likely
be better done via a different, less special-purpose, approach to the
problem.
eliminateFrameIndex() is modified so the target implementations can return
the registers they wish to be tracked for reuse.
ARM Thumb1 implements and utilizes the new mechanism. All other targets are
simply modified to adjust for the changed eliminateFrameIndex() prototype.
llvm-svn: 83467
registers based on dynamic conditions. For example, X86 EBP/RBP, when used as
frame register has to be spilled in the first fixed object. It should inform
PEI this so it doesn't get allocated another stack object. Also, it should not
be spilled as other callee-saved registers but rather its spilling and restoring
are being handled by emitPrologue and emitEpilogue. Avoid spilling it twice.
llvm-svn: 75116
DWARF requires frame moves be specified at specific times. If you have a
prologue like this:
__Z3fooi:
Leh_func_begin1:
LBB1_0: ## entry
pushl %ebp
Llabel1:
movl %esp, %ebp
Llabel2:
pushl %esi
Llabel3:
subl $20, %esp
call "L1$pb"
"L1$pb":
popl %esi
The "pushl %ebp" needs a table entry specifying the offset. The "movl %esp,
%ebp" makes %ebp the new stack frame register, so that needs to be specified in
DWARF. And "pushl %esi" saves the callee-saved %esi register, which also needs
to be specified in DWARF.
Before, all of this logic was in one method. This didn't work too well, because
as you can see there are multiple FDE line entries that need to be created.
This fix creates the "MachineMove" objects directly when they're needed; instead
of waiting until the end, and losing information.
There is some ugliness where we generate code like this:
LBB22_0: ## entry
pushl %ebp
Llabel280:
movl %esp, %ebp
Llabel281:
Llabel284:
pushl %ebp <----------
pushl %ebx
pushl %edi
pushl %esi
Llabel282:
subl $328, %esp
Notice the extra "pushl %ebp". If we generate a "machine move" instruction in
the FDE for that pushl, the linker may get very confused about what value %ebp
should have when exitting the function. I.e., it'll give it the value %esp
instead of the %ebp value from the first "pushl". Not to mention that, in this
case, %ebp isn't modified in the function (that's a separate bug). I put a small
hack in to get it to work. It might be the only solution, but should be
revisited once the above case is fixed.
llvm-svn: 75047
U lib/Target/X86/X86RegisterInfo.cpp
U lib/Target/X86/X86RegisterInfo.h
Temporarily revert. This was causing an infinite loop in the linker on Leopard.
llvm-svn: 74970
prologue like this:
__Z3fooi:
Leh_func_begin1:
LBB1_0: ## entry
pushl %ebp
Llabel1:
movl %esp, %ebp
Llabel2:
pushl %esi
Llabel3:
subl $20, %esp
call "L1$pb"
"L1$pb":
popl %esi
The "pushl %ebp" needs a table entry specifying the offset. The "movl %esp,
%ebp" makes %ebp the new stack frame register, so that needs to be specified in
DWARF. And "pushl %esi" saves the callee-saved %esi register, which also needs
to be specified in DWARF.
Before, all of this logic was in one method. This didn't work too well, because
as you can see there are multiple FDE line entries that need to be created.
This fix creates the "MachineMove" objects directly when they're needed; instead
of waiting until the end, and losing information.
llvm-svn: 74952
- Add patterns for h-register extract, which avoids a shift and mask,
and in some cases a temporary register.
- Add address-mode matching for turning (X>>(8-n))&(255<<n), where
n is a valid address-mode scale value, into an h-register extract
and a scaled-offset address.
- Replace X86's MOV32to32_ and related instructions with the new
target-independent COPY_TO_SUBREG instruction.
On x86-64 there are complicated constraints on h registers, and
CodeGen doesn't currently provide a high-level way to express all of them,
so they are handled with a bunch of special code. This code currently only
supports extracts where the result is used by a zero-extend or a store,
though these are fairly common.
These transformations are not always beneficial; since there are only
4 h registers, they sometimes require extra move instructions, and
this sometimes increases register pressure because it can force out
values that would otherwise be in one of those registers. However,
this appears to be relatively uncommon.
llvm-svn: 68962
and better control the abstraction. Rename the type
to MVT. To update out-of-tree patches, the main
thing to do is to rename MVT::ValueType to MVT, and
rewrite expressions like MVT::getSizeInBits(VT) in
the form VT.getSizeInBits(). Use VT.getSimpleVT()
to extract a MVT::SimpleValueType for use in switch
statements (you will get an assert failure if VT is
an extended value type - these shouldn't exist after
type legalization).
This results in a small speedup of codegen and no
new testsuite failures (x86-64 linux).
llvm-svn: 52044
Change insert/extract subreg instructions to be able to be used in TableGen patterns.
Use the above features to reimplement an x86-64 pseudo instruction as a pattern.
llvm-svn: 48130
This makes DwarfRegNum to accept list of numbers instead.
Added three different "flavours", but only slightly tested on x86-32/linux.
Please check another subtargets if possible,
llvm-svn: 43997
Turn a store folding instruction into a load folding instruction. e.g.
xorl %edi, %eax
movl %eax, -32(%ebp)
movl -36(%ebp), %eax
orl %eax, -32(%ebp)
=>
xorl %edi, %eax
orl -36(%ebp), %eax
mov %eax, -32(%ebp)
This enables the unfolding optimization for a subsequent instruction which will
also eliminate the newly introduced store instruction.
llvm-svn: 43192
