This is a recommit of r256004 which was reverted in r256160. The issue was the
incorrect promotion for half and byte loads transformed into mov instructions.
This fix will replace half and byte type loads only with bit field extracts.
Original commit message:
This change promotes load instructions which directly read from stored by
replacing them with mov instructions. If the store is wider than the load,
the load will be replaced with a bitfield extract.
For example :
STRWui %W1, %X0, 1
%W0 = LDRHHui %X0, 3
becomes
STRWui %W1, %X0, 1
%W0 = UBFMWri %W1, 16, 31
llvm-svn: 256249
This change promotes load instructions which directly read from stores by
replacing them with mov instructions. If the store is wider than the load,
the load will be replaced with a bitfield extract.
For example :
STRWui %W1, %X0, 1
%W0 = LDRHHui %X0, 3
becomes
STRWui %W1, %X0, 1
%W0 = UBFMWri %W1, 16, 31
llvm-svn: 256004
This change merges adjacent zero stores into a wider single store.
For example :
strh wzr, [x0]
strh wzr, [x0, #2]
becomes
str wzr, [x0]
This will fix PR25410.
llvm-svn: 253711
Summary :
* Rename isSmallTypeLdMerge() to isNarrowLoad().
* Rename NumSmallTypeMerged to NumNarrowTypePromoted.
* Use Subtarget defined as a member variable.
llvm-svn: 253587
This change extends r251438 to handle more narrow load promotions
including byte type, unscaled, and signed. For example, this change will
convert :
ldursh w1, [x0, #-2]
ldurh w2, [x0, #-4]
into
ldur w2, [x0, #-4]
asr w1, w2, #16
and w2, w2, #0xffff
llvm-svn: 253577
For big-endian targets, when we merge two halfword loads into a word load, the
order of the halfwords in the loaded value is reversed compared to
little-endian, so the load-store optimiser needs to swap the destination
registers.
This does not affect merging of two word loads, as we use ldp, which treats the
memory as two separate 32-bit words.
llvm-svn: 252597
The benefit from converting narrow loads into a wider load (r251438) could be
micro-architecturally dependent, as it assumes that a single load with two bitfield
extracts is cheaper than two narrow loads. Currently, this conversion is
enabled only in cortex-a57 on which performance benefits were verified.
llvm-svn: 252316
This recommits r250719, which caused a failure in SPEC2000.gcc
because of the incorrect insert point for the new wider load.
Convert two halfword loads into a single 32-bit word load with bitfield extract
instructions. For example :
ldrh w0, [x2]
ldrh w1, [x2, #2]
becomes
ldr w0, [x2]
ubfx w1, w0, #16, #16
and w0, w0, #ffff
llvm-svn: 251438
Convert two halfword loads into a single 32-bit word load with bitfield extract
instructions. For example :
ldrh w0, [x2]
ldrh w1, [x2, #2]
becomes
ldr w0, [x2]
ubfx w1, w0, #16, #16
and w0, w0, #ffff
llvm-svn: 250719
Support for pairing unscaled loads and stores has been enabled since the
original ARM64 port. This feature is no longer experimental, AFAICT.
llvm-svn: 249049
Previously, the index was constrained to the size of the memory operation for
no apparent reason. This change removes that constraint so that we can form
pre-index instructions with any valid offset.
llvm-svn: 248931
The immediate in the load/store should be scaled by the size of the memory
operation, not the size of the register being loaded/stored. This change gets
us one step closer to forming LDPSW instructions. This change also enables
pre- and post-indexing for halfword and byte loads and stores.
llvm-svn: 248804
This patch allows the mixing of scaled and unscaled load/stores to form
load/store pairs.
PR24465
http://reviews.llvm.org/D12116
Many thanks to Ahmed and Michael for fixes and code review.
llvm-svn: 246769
At this point the given Opc must be valid, otherwise we should
not look for a matching pair to form paired load or store.
Thanks to Chad to point out this piece of code!
llvm-svn: 244366
Summary: Among other things, this allows -print-after-all/-print-before-all to
dump IR around this pass.
This is the AArch64 version of r243052.
llvm-svn: 244041
Store instructions do not modify register values and therefore it's safe
to form a store pair even if the source register has been read in between
the two store instructions.
Previously, the read of w1 (see below) prevented the formation of a stp.
str w0, [x2]
ldr w8, [x2, #8]
add w0, w8, w1
str w1, [x2, #4]
ret
We now generate the following code.
stp w0, w1, [x2]
ldr w8, [x2, #8]
add w0, w8, w1
ret
All correctness tests with -Ofast on A57 with Spec200x and EEMBC pass.
Performance results for SPEC2K were within noise.
llvm-svn: 239432
This was previously returning int. However there are no negative opcode
numbers and more importantly this was needlessly different from
MCInstrDesc::getOpcode() (which even is the value returned here) and
SDValue::getOpcode()/SDNode::getOpcode().
llvm-svn: 237611
Teach the load store optimizer how to sign extend a result of a load pair when
it helps creating more pairs.
The rational is that loads are more expensive than sign extensions, so if we
gather some in one instruction this is better!
<rdar://problem/20072968>
llvm-svn: 231527
This patch adds the missing LD[U]RSW variants to the load store optimizer, so
that we generate LDPSW when possible.
<rdar://problem/19583480>
llvm-svn: 226978
Jun Bum Lim