Rename SIMDThreeSameMult (etc.) to SIMDThreeSameVectorFML (etc.) to follow
usual naming convention, and add some comments in the .td files.
llvm-svn: 345515
- Add support to generate AUTIBSP, PACIBSP, RETAB instructions for return
address signing
- The key used to sign the function is controlled by the function attribute
"sign-return-address-key"
Differential Revision: https://reviews.llvm.org/D51427
llvm-svn: 345511
Add ARM64 unwind codes to MCLayer, as well SEH directives that will be emitted
by the frame lowering patch to follow. We only emit unwind codes into object
object files for now.
Differential Revision: https://reviews.llvm.org/D50166
llvm-svn: 345450
Add LLVM intrinsics for the ARMv8.2-A FP16FML vector-form instructions. Add a
DAG pattern to define the indexed-form intrinsics in terms of the vector-form
ones, similarly to how the Dot Product intrinsics were implemented.
Based on a patch by Gao Yiling.
Differential Revision: https://reviews.llvm.org/D53632
llvm-svn: 345337
Include all of the store's source vector operands when creating the
MachineMemOperand. Previously, we were missing the first operand,
making the store size seem smaller than it really is.
Differential Revision: https://reviews.llvm.org/D52816
llvm-svn: 345315
Summary:
Currently, Legalizer is trying to lower G_LOAD with a vector type
that has more than two elements due to the incorrect LegalityPredicate.
This patch fixes the issue by removing the multiplication by 8
as `MemDesc.Size` already contains the size in bits.
Reviewers: dsanders, aemerson
Reviewed By: dsanders
Subscribers: rovka, javed.absar, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D53679
llvm-svn: 345282
If we have a 64-bit EXT where one of the operands is a subvector of a 128-bit
vector then in some cases we can eliminate an extract_subvector by converting
to a 128-bit EXT of the 128-bit vector.
Differential Revision: https://reviews.llvm.org/D53582
llvm-svn: 345275
Using a multiclass reduces duplication, and makes it easier to add new patterns
later. This refactoring does add some new patterns, but as far as I can tell
there's no IR that will end up triggering them so this is effectively NFC.
Differential Revision: https://reviews.llvm.org/D53580
llvm-svn: 345271
Currently a vector move of 0 or -1 will use different instructions depending on
the size of the vector. Using a single instruction (the 128-bit one) for both
gives more opportunity for Machine CSE to eliminate instructions.
Differential Revision: https://reviews.llvm.org/D53579
llvm-svn: 345270
I noticed while fixing PR39368 that we don't have generic shuffle costs for broadcast style shuffles.
This patch adds SK_BROADCAST handling, but exposes ARM/AARCH64 lack of handling of this type, which I've added a fix for at the same time.
Differential Revision: https://reviews.llvm.org/D53570
llvm-svn: 345253
Summary:
Changes all uses of minnan/maxnan to minimum/maximum
globally. These names emphasize that the semantic difference between
these operations is more than just NaN-propagation.
Reviewers: arsenm, aheejin, dschuff, javed.absar
Subscribers: jholewinski, sdardis, wdng, sbc100, jgravelle-google, jrtc27, atanasyan, llvm-commits
Differential Revision: https://reviews.llvm.org/D53112
llvm-svn: 345218
AARCH64 equivalent to D53257 - uses widening pairwise adds on vXi8 CTPOP to support i16/i32/i64 vectors.
This is a blocker for generic vector CTPOP expansion (P32655) - this will remove the aarch64 diff from D53258.
Differential Revision: https://reviews.llvm.org/D53259
llvm-svn: 344554
interleave-group
The vectorizer currently does not attempt to create interleave-groups that
contain predicated loads/stores; predicated strided accesses can currently be
vectorized only using masked gather/scatter or scalarization. This patch makes
predicated loads/stores candidates for forming interleave-groups during the
Loop-Vectorizer's analysis, and adds the proper support for masked-interleave-
groups to the Loop-Vectorizer's planning and transformation stages. The patch
also extends the TTI API to allow querying the cost of masked interleave groups
(which each target can control); Targets that support masked vector loads/
stores may choose to enable this feature and allow vectorizing predicated
strided loads/stores using masked wide loads/stores and shuffles.
Reviewers: Ayal, hsaito, dcaballe, fhahn, javed.absar
Reviewed By: Ayal
Differential Revision: https://reviews.llvm.org/D53011
llvm-svn: 344472
Summary:
AArch64 can fold some shift+extend operations on the RHS operand of
comparisons, so swap the operands if that makes sense.
This provides a fix for https://bugs.llvm.org/show_bug.cgi?id=38751
Reviewers: efriedma, t.p.northover, javed.absar
Subscribers: mcrosier, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D53067
llvm-svn: 344439
The ARM64 elf emitter would omit printing data
symbol for zero filled constant data. This patch
overrides the emitFill method as to enforce that
the symbol is correctly printed.
Differential revision: https://reviews.llvm.org/D53132
llvm-svn: 344248
When branch target identification is enabled, we can only do indirect
tail-calls through x16 or x17. This means that the outliner can't
transform a BLR instruction at the end of an outlined region into a BR.
Differential revision: https://reviews.llvm.org/D52869
llvm-svn: 343969
When branch target identification is enabled, all indirectly-callable
functions start with a BTI C instruction. this instruction can only be
the target of certain indirect branches (direct branches and
fall-through are not affected):
- A BLR instruction, in either a protected or unprotected page.
- A BR instruction in a protected page, using x16 or x17.
- A BR instruction in an unprotected page, using any register.
Without BTI, we can use any non call-preserved register to hold the
address for an indirect tail call. However, when BTI is enabled, then
the code being compiled might be loaded into a BTI-protected page, where
only x16 and x17 can be used for indirect tail calls.
Legacy code withiout this restriction can still indirectly tail-call
BTI-protected functions, because they will be loaded into an unprotected
page, so any register is allowed.
Differential revision: https://reviews.llvm.org/D52868
llvm-svn: 343968
The Branch Target Identification extension, introduced to AArch64 in
Armv8.5-A, adds the BTI instruction, which is used to mark valid targets
of indirect branches. When enabled, the processor will trap if an
instruction in a protected page tries to perform an indirect branch to
any instruction other than a BTI. The BTI instruction uses encodings
which were NOPs in earlier versions of the architecture, so BTI-enabled
code will still run on earlier hardware, just without the extra
protection.
There are 3 variants of the BTI instruction, which are valid targets for
different kinds or branches:
- BTI C can be targeted by call instructions, and is inteneded to be
used at function entry points. These are the BLR instruction, as well
as BR with x16 or x17. These BR instructions are allowed for use in
PLT entries, and we can also use them to allow indirect tail-calls.
- BTI J can be targeted by BR only, and is intended to be used by jump
tables.
- BTI JC acts ab both a BTI C and a BTI J instruction, and can be
targeted by any BLR or BR instruction.
Note that RET instructions are not restricted by branch target
identification, the reason for this is that return addresses can be
protected more effectively using return address signing. Direct branches
and calls are also unaffected, as it is assumed that an attacker cannot
modify executable pages (if they could, they wouldn't need to do a
ROP/JOP attack).
This patch adds a MachineFunctionPass which:
- Adds a BTI C at the start of every function which could be indirectly
called (either because it is address-taken, or externally visible so
could be address-taken in another translation unit).
- Adds a BTI J at the start of every basic block which could be
indirectly branched to. This could be either done by a jump table, or
by taking the address of the block (e.g. the using GCC label values
extension).
We only need to use BTI JC when a function is indirectly-callable, and
takes the address of the entry block. I've not been able to trigger this
from C or IR, but I've included a MIR test just in case.
Using BTI C at function entries relies on the fact that no other code in
BTI-protected pages uses indirect tail-calls, unless they use x16 or x17
to hold the address. I'll add that code-generation restriction as a
separate patch.
Differential revision: https://reviews.llvm.org/D52867
llvm-svn: 343967
The MachineOutliner for AArch64 transforms indirect calls into indirect
tail calls, replacing the call with the TCRETURNri pseudo-instruction.
This pseudo lowers to a BR, but has the isCall and isReturn flags set.
The problem is that TCRETURNri takes a tcGPR64 as the register argument,
to prevent indiret tail-calls from using caller-saved registers. The
indirect calls transformed by the outliner could use caller-saved
registers. This is fine, because the outliner ensures that the register
is available at all call sites. However, this causes a verifier failure
when the register is not in tcGPR64. The fix is to add a new
pseudo-instruction like TCRETURNri, but which accepts any GPR.
Differential revision: https://reviews.llvm.org/D52829
llvm-svn: 343959
This rebases and recommits r343520. hwasan should be fixed now and this
shouldn't break the tests anymore.
Spill/reload instructions are artificially generated by the compiler and
have no relation to the original source code. So the best thing to do is
not attach any debug location to them (instead of just taking the next
debug location we find on following instructions).
Differential Revision: https://reviews.llvm.org/D52125
llvm-svn: 343895
Finally all targets are enabling multiple regalloc hints, so the hook to
disable this can now be removed.
NFC.
Review: Simon Pilgrim
https://reviews.llvm.org/D52316
llvm-svn: 343851
- Fix spill/reloads of XSeqPairs failing with vregs (only physregs
worked correctly)
- Add missing spill/reload code for WSeqPairs class
Differential Revision: https://reviews.llvm.org/D52761
llvm-svn: 343799
Summary: Depends on D45541
Reviewers: ab, aditya_nandakumar, bogner, rtereshin, volkan, rovka, javed.absar, aemerson
Subscribers: aemerson, rengolin, mgorny, javed.absar, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D45543
The previous commit failed portions of the test-suite on GreenDragon due to
duplicate COPY instructions and iterator invalidation. Both issues have now
been fixed. To assist with this, a helper (cloneVirtualRegister) has been added
to MachineRegisterInfo that can be used to get another register that has the same
type and class/bank as an existing one.
llvm-svn: 343654
This adds new instructions to manipluate tagged pointers, and to load
and store the tags associated with memory.
Patch by Pablo Barrio, David Spickett and Oliver Stannard!
Differential revision: https://reviews.llvm.org/D52490
llvm-svn: 343572
This adds new system registers introduced by the Memory Tagging
extension.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52488
llvm-svn: 343571
The Memory Tagging Extension adds system instructions for data cache
maintenance, implemented as new operands to the DC instruction.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52487
llvm-svn: 343570
This adds the memory tagging extension, which is an optional extension
introduced in v8.5A. The new instructions and registers will be added by
subsequent patches.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52486
llvm-svn: 343563
There's a strange assertion on two of the Green Dragon bots that goes away when
this is reverted. The assertion is in RegBankAlloc and if it is this commit then
-verify-machine-instrs should have caught it earlier in the pipeline.
llvm-svn: 343546
Spill/reload instructions are artificially generated by the compiler and
have no relation to the original source code. So the best thing to do is
not attach any debug location to them (instead of just taking the next
debug location we find on following instructions).
Differential Revision: https://reviews.llvm.org/D52125
llvm-svn: 343520
Split the `zcz` feature into specific ones got GP and FP registers, `zcz-gp`
and `zcz-fp`, respectively, while retaining the original feature option to
mean both.
Differential revision: https://reviews.llvm.org/D52621
llvm-svn: 343354
- Add fix so that all code paths that create DWARFContext
with an ObjectFile initialise the target architecture in the context
- Add an assert that the Arch is known in the Dwarf CallFrameString method
llvm-svn: 343317
Bits [23-22] are used in Add and Sub to specify the shift. The value of the
shift field must be 0x; values of 1x are unallocated. MTE adds some instructions
that use such encodings, and this patch refactors the Add/Sub class so that
another class could derive from this one to implement other encodings and other
formats of bitfields.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52489
llvm-svn: 343231
This adds two new barrier instructions which can be used to restrict
speculative execution of load instructions.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52483
llvm-svn: 343229
This adds new instructions used by the Branch Target Identification
feature. When this is enabled, these are the only instructions which can
be targeted by indirect branch instructions.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52485
llvm-svn: 343225
This adds some new system registers which can be used to restrict
certain types of speculative execution.
Patch by Pablo Barrio and David Spickett!
Differential revision: https://reviews.llvm.org/D52482
llvm-svn: 343218
This adds two new system registers, used to generate random numbers.
This is an optional extension to v8.5-A, and will be controlled by the
"+rng" modifier of the -march= and -mcpu= options.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52481
llvm-svn: 343217
This adds a new variant of the DC system instruction for persistent
memory.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52480
llvm-svn: 343216
This adds new system instructions which act as barriers to speculative
execution based on earlier execution within a particular execution
context.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52479
llvm-svn: 343214
This is a new barrier which limits speculative execution of the
instructions following it.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52476
llvm-svn: 343211
These are some new variants of the "Floating-point Round to Integral"
family of instructions, which round to the nearest floating-point value
which fits in a 32- or 64-bit integer.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52475
llvm-svn: 343209
These new instructions manipluate the NZCV bits, to convert between the
regular Arm floating-point comare format and an alternative format.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52473
llvm-svn: 343187
The Armv8.3-A reference manual defines floating-point data-processing
instructions with one source operand to have an opcode of 6 bits
[20:15]. The current class in tablegen, BaseSingleOperandFPData, only
allows [18:15]. This was ok because [20:19] could only be '00', with
other encodings unallocated. Armv8.5-A brings in the FRINT group of
instructions which use other values for these bits.
This patch refactors the existing class a bit to allow using the full 6
bits of the opcode, as defined in the Arm ARM.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52474
llvm-svn: 343120
Reuse some code in preparation for the v8.5A XAFlag/AXFlag instructions,
which shares part of the encoding of the MSR-immediate.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52472
llvm-svn: 343113
Parsing of the system instructions (IC, DC, AT and TLBI) uses this
function to show the required architecture when the operand is valid,
but the architecture is not enabled. Armv8.5A adds a few different
system instructions as part of optional features, so we need to extend
it to show individual features, not just base architectures.
This is NFC for now, but will be used by three different features added
in v8.5A, and will be tested by them.
Patch by David Spickett!
Differential revision: https://reviews.llvm.org/D52478
llvm-svn: 343109
This caused the DebugInfo/Sparc/gnu-window-save.ll test to fail.
> Functions that have signed return addresses need additional dwarf support:
> - After signing the LR, and before authenticating it, the LR register is in a
> state the is unusable by a debugger or unwinder
> - To account for this a new directive, .cfi_negate_ra_state, is added
> - This directive says the signed state of the LR register has now changed,
> i.e. unsigned -> signed or signed -> unsigned
> - This directive has the same CFA code as the SPARC directive GNU_window_save
> (0x2d), adding a macro to account for multiply defined codes
> - This patch matches the gcc implementation of this support:
> https://patchwork.ozlabs.org/patch/800271/
>
> Differential Revision: https://reviews.llvm.org/D50136
llvm-svn: 343103
This patch allows targeting Armv8.5-A, adding the architecture to
tablegen and setting the options to be identical to Armv8.4-A for the
time being. Subsequent patches will add support for the different
features included in the Armv8.5-A Reference Manual.
Patch by Pablo Barrio!
Differential revision: https://reviews.llvm.org/D52470
llvm-svn: 343102
Functions that have signed return addresses need additional dwarf support:
- After signing the LR, and before authenticating it, the LR register is in a
state the is unusable by a debugger or unwinder
- To account for this a new directive, .cfi_negate_ra_state, is added
- This directive says the signed state of the LR register has now changed,
i.e. unsigned -> signed or signed -> unsigned
- This directive has the same CFA code as the SPARC directive GNU_window_save
(0x2d), adding a macro to account for multiply defined codes
- This patch matches the gcc implementation of this support:
https://patchwork.ozlabs.org/patch/800271/
Differential Revision: https://reviews.llvm.org/D50136
llvm-svn: 343089
Share predecessor search bookkeeping in both perform PostLD1Combine
and performNEONPostLDSTCombine. This should be approximately a 4x and
2x performance improvement.
llvm-svn: 342986
Summary:
Specifying X[8-15,18] registers as callee-saved is used to support
CONFIG_ARM64_LSE_ATOMICS in Linux kernel. As part of this patch we:
- use custom CSR list/mask when user specifies custom CSRs
- update Machine Register Info's list of CSRs with additional custom CSRs in
LowerCall and LowerFormalArguments.
Reviewers: srhines, nickdesaulniers, efriedma, javed.absar
Reviewed By: nickdesaulniers
Subscribers: kristof.beyls, jfb, llvm-commits
Differential Revision: https://reviews.llvm.org/D52216
llvm-svn: 342824
This involves changing the shouldExpandAtomicCmpXchgInIR interface, but I have
updated the in-tree backends using this hook (ARM, AArch64, Hexagon) so they
will see no functional change. Previously this hook returned bool, but it now
returns AtomicExpansionKind.
This hook allows targets to select how a given cmpxchg is to be expanded.
D48131 uses this to expand part-word cmpxchg to a target-specific intrinsic.
See my associated RFC for more info on the motivation for this change
<http://lists.llvm.org/pipermail/llvm-dev/2018-June/123993.html>.
Differential Revision: https://reviews.llvm.org/D48130
llvm-svn: 342550
This tries to make use of evaluateAsRelocatable in AArch64AsmParser::classifySymbolRef
to parse more complex expressions as relocatable operands. It is hopefully better than
the existing code which only handles Symbol +- Constant.
This allows us to parse more complex adr/adrp, mov, ldr/str and add operands. It also
loosens the requirements on parsing addends in ld/st and mov's and adds a number of
tests.
Differential Revision: https://reviews.llvm.org/D51792
llvm-svn: 342455
This patch adds codegen support for the saving/restoring
V8-V23 for functions specified with the aarch64_vector_pcs
calling convention attribute, as added in patch D51477.
Reviewers: t.p.northover, gberry, thegameg, rengolin, javed.absar, MatzeB
Reviewed By: thegameg
Differential Revision: https://reviews.llvm.org/D51479
llvm-svn: 342049
This patch refactors several parts of AArch64FrameLowering
so that it can be easily extended to support saving/restoring
of FPR128 (Q) registers.
Reviewers: t.p.northover, gberry, thegameg, rengolin, javed.absar
Reviewed By: thegameg
Differential Revision: https://reviews.llvm.org/D51478
llvm-svn: 342038
This patch adds parsing support for the 'aarch64_vector_pcs'
calling convention attribute to calls and function declarations.
More information describing the vector ABI and procedure call standard
can be found here:
https://developer.arm.com/products/software-development-tools/\
hpc/arm-compiler-for-hpc/vector-function-abi
Reviewers: t.p.northover, rnk, rengolin, javed.absar, thegameg, SjoerdMeijer
Reviewed By: SjoerdMeijer
Differential Revision: https://reviews.llvm.org/D51477
llvm-svn: 342030
The was previously committed as r341749 then reverted as r341750 because
bit_cast needed to do its own thing to check is_trivially_copyable on GCC 4.x.
This is now done and std;:array should now get accepted.
llvm-svn: 341897
Disassemblers cannot depend on main target headers. The same is true for
MCTargetDesc, but there's a lot more cleanup needed for that.
llvm-svn: 341822
Summary: I saw a few places that were punning through a union of FP and integer, and that made me sad. Luckily, C++20 adds bit_cast for exactly that purpose. Implement our own version in ADT (without constexpr, leaving us a bit sad), and use it in the few places my grep-fu found silly union punning.
This was originally committed as r341728 and reverted in r341730.
Reviewers: javed.absar, steven_wu, srhines
Subscribers: dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D51693
llvm-svn: 341741
Summary: I saw a few places that were punning through a union of FP and integer, and that made me sad. Luckily, C++20 adds bit_cast for exactly that purpose. Implement our own version in ADT (without constexpr, leaving us a bit sad), and use it in the few places my grep-fu found silly union punning.
Reviewers: javed.absar
Subscribers: dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D51693
llvm-svn: 341728
Summary:
Reserving registers x1-7 is used to support CONFIG_ARM64_LSE_ATOMICS in Linux kernel. This change adds support for reserving registers x1 through x7.
Reviewers: javed.absar, phosek, srhines, nickdesaulniers, efriedma
Reviewed By: nickdesaulniers, efriedma
Subscribers: niravd, jfb, manojgupta, nickdesaulniers, jyknight, efriedma, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D48580
llvm-svn: 341706
Summary:
I added a few ARM64 memset codegen tests in r341406 and r341493, and annotated
where the generated code was bad. This patch fixes the majority of the issues by
requesting that a 2xi64 vector be used for memset of 32 bytes and above.
The patch leaves the former request for f128 unchanged, despite f128
materialization being suboptimal: doing otherwise runs into other asserts in
isel and makes this patch too broad.
This patch hides the issue that was present in bzero_40_stack and bzero_72_stack
because the code now generates in a better order which doesn't have the store
offset issue. I'm not aware of that issue appearing elsewhere at the moment.
<rdar://problem/44157755>
Reviewers: t.p.northover, MatzeB, javed.absar
Subscribers: eraman, kristof.beyls, chrib, dexonsmith, llvm-commits
Differential Revision: https://reviews.llvm.org/D51706
llvm-svn: 341558
On Windows, if shouldAssumeDSOLocal returns false, it's either a
dllimport reference, or a reference that we should treat as non-local
and create a stub for.
Clean up AArch64Subtarget::ClassifyGlobalReference a little while
touching the flag handling relating to dllimport.
Differential Revision: https://reviews.llvm.org/D51590
llvm-svn: 341402
The runtime pseudo relocations can't handle the AArch64 format PC
relative addressing in adrp+add/ldr pairs. By using stubs, the potentially
dllimported addresses can be touched up by the runtime pseudo relocation
framework.
Differential Revision: https://reviews.llvm.org/D51452
llvm-svn: 341401
When initial support for dllimport was added for aarch64 in
SVN r316555, ClassifyGlobalReference didn't set the MO_DLLIMPORT
flag - that was only completed in SVN r323810. Reuse the return
value from ClassifyGlobalReference for this purpose as well.
llvm-svn: 341310
Summary:
This is a continuation of https://reviews.llvm.org/D49727
Below the original text, current changes in the comments:
Currently, in line with GCC, when specifying reserved registers like sp or pc on an inline asm() clobber list, we don't always preserve the original value across the statement. And in general, overwriting reserved registers can have surprising results.
For example:
extern int bar(int[]);
int foo(int i) {
int a[i]; // VLA
asm volatile(
"mov r7, #1"
:
:
: "r7"
);
return 1 + bar(a);
}
Compiled for thumb, this gives:
$ clang --target=arm-arm-none-eabi -march=armv7a -c test.c -o - -S -O1 -mthumb
...
foo:
.fnstart
@ %bb.0: @ %entry
.save {r4, r5, r6, r7, lr}
push {r4, r5, r6, r7, lr}
.setfp r7, sp, #12
add r7, sp, #12
.pad #4
sub sp, #4
movs r1, #7
add.w r0, r1, r0, lsl #2
bic r0, r0, #7
sub.w r0, sp, r0
mov sp, r0
@APP
mov.w r7, #1
@NO_APP
bl bar
adds r0, #1
sub.w r4, r7, #12
mov sp, r4
pop {r4, r5, r6, r7, pc}
...
r7 is used as the frame pointer for thumb targets, and this function needs to restore the SP from the FP because of the variable-length stack allocation a. r7 is clobbered by the inline assembly (and r7 is included in the clobber list), but LLVM does not preserve the value of the frame pointer across the assembly block.
This type of behavior is similar to GCC's and has been discussed on the bugtracker: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=11807 . No consensus seemed to have been reached on the way forward. Clang behavior has briefly been discussed on the CFE mailing (starting here: http://lists.llvm.org/pipermail/cfe-dev/2018-July/058392.html). I've opted for following Eli Friedman's advice to print warnings when there are reserved registers on the clobber list so as not to diverge from GCC behavior for now.
The patch uses MachineRegisterInfo's target-specific knowledge of reserved registers, just before we convert the inline asm string in the AsmPrinter.
If we find a reserved register, we print a warning:
repro.c:6:7: warning: inline asm clobber list contains reserved registers: R7 [-Winline-asm]
"mov r7, #1"
^
Reviewers: efriedma, olista01, javed.absar
Reviewed By: efriedma
Subscribers: eraman, kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D51165
llvm-svn: 341062
Providing that the load is known to be 4 byte aligned, we can optimise a
ldr(adr address) to just ldr address.
Differential Revision: https://reviews.llvm.org/D51030
llvm-svn: 341058
