Following discussions in #110443, and the following earlier discussions
in https://lists.llvm.org/pipermail/llvm-dev/2017-October/117907.html,
https://reviews.llvm.org/D38482, https://reviews.llvm.org/D38489, this
PR attempts to overhaul the `TargetMachine` and `LLVMTargetMachine`
interface classes. More specifically:
1. Makes `TargetMachine` the only class implemented under
`TargetMachine.h` in the `Target` library.
2. `TargetMachine` contains target-specific interface functions that
relate to IR/CodeGen/MC constructs, whereas before (at least on paper)
it was supposed to have only IR/MC constructs. Any Target that doesn't
want to use the independent code generator simply does not implement
them, and returns either `false` or `nullptr`.
3. Renames `LLVMTargetMachine` to `CodeGenCommonTMImpl`. This renaming
aims to make the purpose of `LLVMTargetMachine` clearer. Its interface
was moved under the CodeGen library, to further emphasis its usage in
Targets that use CodeGen directly.
4. Makes `TargetMachine` the only interface used across LLVM and its
projects. With these changes, `CodeGenCommonTMImpl` is simply a set of
shared function implementations of `TargetMachine`, and CodeGen users
don't need to static cast to `LLVMTargetMachine` every time they need a
CodeGen-specific feature of the `TargetMachine`.
5. More importantly, does not change any requirements regarding library
linking.
cc @arsenm @aeubanks
The node was introduced in 59c39dc1 and was intended to allow writing
patterns like this:
`[(set AL, (mul AL, GR8:$src1)), (implicit EFLAGS)]`
However, it does not introduce new functionality because the same
pattern can be equivalently expressed as:
`[(set AL, EFLAGS, (mul AL, GR8:$src1))]`
The latter form is also more flexible as it allows reordering output
operands.
In most places uses of `implicit` were redundant -- removing them didn't
change anything in the generated DAG tables. The only three cases where
it did have effect are in X86InstrArithmetic.td and X86InstrSystem.td --
those were rewritten to use `set` node.
Removing `implicit` from some patterns made them importable by GISel,
hence the change in a test.
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.
Ever since 6859685a87ad093d60c8bed60b116143c0a684c7 (or, precisely,
84428dafc0941e3a31303fa1b286835ab2b8e234) relative jumps emitted by the
AVR codegen are off by two bytes - this pull request fixes it.
## Abstract
As compared to absolute jumps, relative jumps - such as rjmp, rcall or
brsh - have an implied `pc+2` behavior; that is, `jmp 100` is `pc =
100`, but `rjmp 100` gets understood as `pc = pc + 100 + 2`.
This is not reflected in the AVR codegen:
f95026dbf6/llvm/lib/Target/AVR/MCTargetDesc/AVRAsmBackend.cpp (L89)
... which always emits relative jumps that are two bytes too far - or
rather it _would_ emit such jumps if not for this check:
f95026dbf6/llvm/lib/Target/AVR/MCTargetDesc/AVRAsmBackend.cpp (L517)
... which causes most of the relative jumps to be actually resolved
late, by the linker, which applies the offsetting logic on its own,
hiding the issue within LLVM.
[Some time
ago](697a162fa6)
we've had a similar "jumps are off" problem that got solved by touching
`shouldForceRelocation()`, but I think that has worked only by accident.
It's exploited the fact that absolute vs relative jumps in the parsed
assembly can be distinguished through a "side channel" check relying on
the existence of labels (i.e. absolute jumps happen to named labels, but
relative jumps are anonymous, so to say). This was an alright idea back
then, but it got broken by 6859685a87ad093d60c8bed60b116143c0a684c7.
I propose a different approach:
- when emitting relative jumps, offset them by `-2` (well, `-1`,
strictly speaking, because those instructions rely on right-shifted
offset),
- when parsing relative jumps, treat `.` as `+2` and read `rjmp .+1234`
as `rjmp (1234 + 2)`.
This approach seems to be sound and now we generate the same assembly as
avr-gcc, which can be confirmed with:
```cpp
// avr-gcc test.c -O3 && avr-objdump -d a.out
int main() {
asm(
" foo:\n\t"
" rjmp .+2\n\t"
" rjmp .-2\n\t"
" rjmp foo\n\t"
" rjmp .+8\n\t"
" rjmp end\n\t"
" rjmp .+0\n\t"
" end:\n\t"
" rjmp .-4\n\t"
" rjmp .-6\n\t"
" x:\n\t"
" rjmp x\n\t"
" .short 0xc00f\n\t"
);
}
```
avr-gcc is also how I got the opcodes for all new tests like `inst-brbc.s`, so we should be good.
The renamable flag is useful during MachineCopyPropagation but renamable
flag will be dropped after lowerCopy in some case.
This patch introduces extra arguments to pass the renamable flag to
copyPhysReg.
The parameter is confusing as it duplicates MCStreamer::isVeboseAsm
(initialized from MCTargetOptions::AsmVerbose). After
233cca169237b91d16092c82bd55ee6a283afe98, no in-tree target uses the
parameter.
Summary:
These Libcalls represent which functions are available to the backend.
If a runtime call is not available, the target sets the the name to
`nullptr`. Currently, this logic is spread around the various targets.
This patch pulls all of the locations that disable libcalls into the
intializer. This patch is effectively NFC.
The motivation behind this patch is that currently the LTO handling uses
the list of all runtime calls to determine which functions cannot be
internalized and must be extracted from static libraries. We do not want
this to happen for libcalls that are not emitted by the backend. A
follow-up patch will move out this logic so the LTO pass can know which
rtlib calls are actually used by the backend.
and replace MCAssembler::Layout with a bool.
This mostly completes "[MC] Start merging MCAsmLayout into MCAssembler".
Note: BOLT used a dummy `MCAsmLayout` to call `getSymbolOffset`, which
is technically not supported. There is some discussion in
https://reviews.llvm.org/D154604 .
The revert f80a4072ced41b52363c63df28fea9a649f7f89e is incorrect and
actually broke bots.
- Fix build with `EXPENSIVE_CHECKS`
- Remove unused `PassName::ID` to resolve warning
- Mark `~SelectionDAGISel` virtual so AArch64 backend can work properly
This reverts commit de37c06f01772e02465ccc9f538894c76d89a7a1 to
de37c06f01772e02465ccc9f538894c76d89a7a1
It still breaks EXPENSIVE_CHECKS build. Sorry.
Port selection dag isel to new pass manager.
Only `AMDGPU` and `X86` support new pass version. `-verify-machineinstrs` in new pass manager belongs to verify instrumentation, it is enabled by default.
Related to clean-up opportunities discussed at #90013.
After these cleanups, the `RelaxAll` parameter from
`createMCObjectStreamer` can be removed as well. As
`createMCObjectStreamer` is a more user-facing API and used by two files
in mlir/, we postpone the cleanup to the future.
This follows on from #76708, allowing
`cast<ConstantSDNode>(N)->getZExtValue()` to be replaced with just
`N->getAsZextVal();`
Introduced via `git grep -l "cast<ConstantSDNode>\(.*\).*getZExtValue" |
xargs sed -E -i
's/cast<ConstantSDNode>\((.*)\)->getZExtValue/\1->getAsZExtVal/'` and
then using `git clang-format` on the result.
This helper function shortens examples like
`cast<ConstantSDNode>(Node->getOperand(1))->getZExtValue();` to
`Node->getConstantOperandVal(1);`.
Implemented with:
`git grep -l
"cast<ConstantSDNode>\(.*->getOperand\(.*\)\)->getZExtValue\(\)" | xargs
sed -E -i
's/cast<ConstantSDNode>\((.*)->getOperand\((.*)\)\)->getZExtValue\(\)/\1->getConstantOperandVal(\2)/`
and `git grep -l
"cast<ConstantSDNode>\(.*\.getOperand\(.*\)\)->getZExtValue\(\)" | xargs
sed -E -i
's/cast<ConstantSDNode>\((.*)\.getOperand\((.*)\)\)->getZExtValue\(\)/\1.getConstantOperandVal(\2)/'`.
With a couple of simple manual fixes needed. Result then processed by
`git clang-format`.
This patch replaces uses of StringRef::{starts,ends}with with
StringRef::{starts,ends}_with for consistency with
std::{string,string_view}::{starts,ends}_with in C++20.
I'm planning to deprecate and eventually remove
StringRef::{starts,ends}with.
