Some targets (e.g. PPC and Hexagon) already did this. I think it's best
to do this consistently so that frontend authors don't run into
inconsistent results when they emit `naked` functions. For example, in
Zig, we had to change our emit code to also set `frame-pointer=none` to
get reliable results across targets.
Note: I don't have commit access.
When the base pointer r30 is used to hold the stack pointer, r30 is
spilled in the prologue. On AIX registers are saved from highest to
lowest, so r31 also needs to be saved.
Fixes https://github.com/llvm/llvm-project/issues/96411
MachineFunction's probably should not include a backreference to
the owning MachineModuleInfo. Most of these references were used
just to query the MCContext, which MachineFunction already directly
stores. Other contexts are using it to query the LLVMContext, which
can already be accessed through the IR function reference.
https://github.com/llvm/llvm-project/pull/79940 put calls to
recomputeLiveIns into
a loop, to repeatedly call the function until the computation converges.
However,
this repeats a lot of code. This changes moves the loop into a function
to simplify
the handling.
Note that this changes the order in which recomputeLiveIns is called.
For example,
```
bool anyChange = false;
do {
anyChange = recomputeLiveIns(*ExitMBB) || recomputeLiveIns(*LoopMBB);
} while (anyChange);
```
only begins to recompute the live-ins for LoopMBB after the computation
for ExitMBB
has converged. With this change, all basic blocks have a recomputation
of the live-ins
for each loop iteration. This can result in less or more calls,
depending on the
situation.
Delete the code that skips the CFI for the condition register on ELF32.
The code checked !MustSaveCR, which happened only when
Subtarget.is32BitELFABI(), where spillCalleeSavedRegisters is spilling
cr in a different way. The spill was missing CFI. After deleting this
code, a spill of cr2 to cr4 gets CFI in the same way as a spill of r14
to r31.
Fixes#83094
This is a fix for the regression seen in
https://github.com/llvm/llvm-project/pull/79498
> Currently, the way that recomputeLiveIns works is that it will
recompute the livein registers for that MachineBasicBlock but it matters
what order you call recomputeLiveIn which can result in incorrect
register allocations down the line.
Now we do not recompute the entire CFG but we do ensure that the newly
added MBB do reach convergence.
Currently, the way that recomputeLiveIns works is that it will recompute
the livein registers for that MachineBasicBlock but it matters what
order you call recomputeLiveIn which can result in incorrect register
allocations down the line.
This PR fixes that by simply recomputing the liveins for the entire CFG
until convergence is achieved. This makes it harder to introduce subtle
bugs which alter liveness.
This was modifying a container as it iterated it, which tripped a check
in libstdc++'s debug checks.
Instead, just assign to the item via the reference we already have.
This fixes the following expensive checks failures on my machine:
LLVM :: CodeGen/PowerPC/fp-strict.ll
LLVM :: CodeGen/PowerPC/pr55463.ll
LLVM :: CodeGen/PowerPC/register-pressure.ll
LLVM :: CodeGen/PowerPC/spe.ll
Which are some of the tests noted by #68594.
Track the live register state immediately before, instead of after,
MBBI. This makes it simple to track the state at the start or end of a
basic block without a separate (and poorly named) Tracking flag.
This changes the API of the backward(MachineBasicBlock::iterator I)
method, which now recedes to the state just before, instead of just
after, *I. Some clients are simplified by this change.
There is one small functional change shown in the lit tests where
multiple spilled registers all need to be reloaded before the same
instruction. The reloads will now be inserted in the opposite order.
This should not affect correctness.
PPC64 allows stack size up to ((2^63)-1) bytes. Currently llc reports
```
warning: stack frame size (4294967568) exceeds limit (4294967295) in function 'main'
```
if the stack allocated is larger than 4G.
With D134950, targets get notified when a virtual register is created and/or
cloned. Targets can do the needful with the delegate callback. AMDGPU propagates
the virtual register flags maintained in the target file itself. They are useful
to identify a certain type of machine operands while inserting spill stores and
reloads. Since RegAllocFast spills the physical register itself, there is no way
its virtual register can be mapped back to retrieve the flags. It can be solved
by passing the virtual register as an additional argument. This argument has no
use when the spill interfaces are called during the greedy allocator or even the
PrologEpilogInserter and can pass a null register in such cases.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D138656
mflr is kind of expensive on Power version smaller than 10, so we should
schedule the store for the mflr's def away from mflr.
In epilogue, the expensive mtlr has no user for its def, so it doesn't
matter that the load and the mtlr are back-to-back.
Reviewed By: RolandF
Differential Revision: https://reviews.llvm.org/D137423
LLVM contains a helpful function for getting the size of a C-style
array: `llvm::array_lengthof`. This is useful prior to C++17, but not as
helpful for C++17 or later: `std::size` already has support for C-style
arrays.
Change call sites to use `std::size` instead.
Differential Revision: https://reviews.llvm.org/D133429
Support allocation of huge stack frame(>2g) on PPC64.
For ELFv2 ABI on Linux, quoted from the spec 2.2.3.1 General Stack Frame Requirements
> There is no maximum stack frame size defined.
On AIX, XL allows such huge frame.
Reviewed By: #powerpc, nemanjai
Differential Revision: https://reviews.llvm.org/D107886
Add the calling convention for the vector pair registers.
These registers overlap with the vector registers.
Part of an original patch by: Lei Huang
Reviewed By: nemanjai, #powerpc
Differential Revision: https://reviews.llvm.org/D117225
This reverts commit 7f230feeeac8a67b335f52bd2e900a05c6098f20.
Breaks CodeGenCUDA/link-device-bitcode.cu in check-clang,
and many LLVM tests, see comments on https://reviews.llvm.org/D121169
This reverts commit ef8206320769ad31422a803a0d6de6077fd231d2.
- It conflicts with the existing llvm::size in STLExtras, which will now
never be called.
- Calling it without llvm:: breaks C++17 compat
Add support for Return Oriented Programming (ROP) protection for 32 bit.
This patch also adds a testing for AIX on both 64 and 32 bit.
Reviewed By: amyk
Differential Revision: https://reviews.llvm.org/D111362
This is the first step to enable PPC64 support huge frame size(>2G). Also fix an assertion error for frame size, i.e.,`int x; !isInt<32>(x);` should be always evaluated false, so the guard code for frame size is impossible to hit.
Reviewed By: jsji
Differential Revision: https://reviews.llvm.org/D107435
When `-fstack-clash-protection` is enabled and stack has to be realigned, some parts of redzone is written prior the probe, so probe might overwrite content already written in redzone. To avoid it, we have to make sure the first probe is at full probe size or is the last probe so that we can skip redzone.
It also fixes violation of ABI under PPC where `r1` isn't updated atomically.
This fixes https://bugs.llvm.org/show_bug.cgi?id=49903.
Reviewed By: jsji
Differential Revision: https://reviews.llvm.org/D100290
Added hashst to the prologue and hashchk to the epilogue.
The hash for the prologue and epilogue must always be stored as the first
element in the local variable space on the stack.
Reviewed By: nemanjai, #powerpc
Differential Revision: https://reviews.llvm.org/D99377
The stack frame update code does not take into consideration spilling
to registers for callee saved registers. The option -ppc-enable-pe-vector-spills
turns on spilling to registers for callee saved registers and may expose a bug
in the code that moves a stack frame pointer update instruction.
Reviewed By: nemanjai, #powerpc
Differential Revision: https://reviews.llvm.org/D101366
This patch exploits mtvsrdd instruction (available in ISA3.0+) to save
two callee-saved GPR registers into a single VSR, making it more
efficient.
Reviewed By: jsji, nemanjai
Differential Revision: https://reviews.llvm.org/D62565
Summary:
Currently Shrinkwrap is not enabled on AIX.
This patch enables shrink wrap on 32 and 64 bit AIX, and 64 bit ELF.
Reviewed By: sfertile, nemanjai
Differential Revision: https://reviews.llvm.org/D95094
On subtargets that have a red zone, we will copy the stack pointer to the base
pointer in the prologue prior to updating the stack pointer. There are no other
updates to the base pointer after that. This suggests that we should be able to
restore the stack pointer from the base pointer rather than loading it from the
back chain or adding the frame size back to either the stack pointer or the
frame pointer.
This came about because functions that call setjmp need to restore the SP from
the FP because the back chain might have been clobbered
(see https://reviews.llvm.org/D92906). However, if the stack is realigned, the
restored SP might be incorrect (which is what caused the failures in the two
ASan test cases).
This patch was tested quite extensivelly both with sanitizer runtimes and
general code.
Differential revision: https://reviews.llvm.org/D93327
If a function happens to:
- call setjmp
- do a 16-byte stack allocation
- call a function that sets up a stack frame and longjmp's back
The stack pointer that is restores by setjmp will no longer point to a valid
back chain. According to the ABI, stack accesses in such a function are to be
frame pointer based - so it is an error (quite obviously) to restore the stack
from the back chain.
We already restore the stack from the frame pointer when there are calls to
fast_cc functions. We just need to also do that when there are calls to setjmp.
This patch simply does that.
This was pointed out by the Julia team.
Differential revision: https://reviews.llvm.org/D92906
During reviewing https://reviews.llvm.org/D84419, @efriedma mentioned the gap between realigned stack pointer and origin stack pointer should be probed too whatever the alignment is. This patch fixes the issue for PPC64.
Reviewed By: jsji
Differential Revision: https://reviews.llvm.org/D88078
This patch is the initial patch for support of the AIX extended vector ABI. The extended ABI treats vector registers V20-V31 as non-volatile and we add them as callee saved registers in this patch.
Reviewed By: sfertile
Differential Revision: https://reviews.llvm.org/D88676
After removal of Darwin as a PowerPC subtarget, the VRSAVE
save/restore/spill/update code is no longer needed by any supported
subtarget, so remove it while keeping support for vrsave and related instruction
aliases for inline asm. I've pre-commited tests to document the existing vrsave
handling in relation to @llvm.eh.unwind.init and inline asm usage, as
well as a test which shows a beahviour change on AIX related to
returning vector type as we were wrongly emiting VRSAVE_UPDATE on AIX.
General purpose registers 30 and 31 are handled differently when they are
reserved as the base-pointer and frame-pointer respectively. This fixes the
offset of their fixed-stack objects when there are fpr calle-saved registers.
Differential Revision: https://reviews.llvm.org/D85850
Current powerpc backend generates wrong code sequence if stack pointer
has to realign if -fstack-clash-protection enabled. When probing in
prologue, backend should generate a subtraction instruction rather
than a `stux` instruction to realign the stack pointer.
This patch is part of fix of
https://bugs.llvm.org/show_bug.cgi?id=46759.
Differential Revision: https://reviews.llvm.org/D84218
