As discussed on D18441 - auto brief is used so we don't need /brief, we don't need to include the function name and added some missing descriptions.
llvm-svn: 265785
This is the same change on PPC64 as r255821 on AArch64. I have even borrowed
his commit message.
The access function has a short entry and a short exit, the initialization
block is only run the first time. To improve the performance, we want to
have a short frame at the entry and exit.
We explicitly handle most of the CSRs via copies. Only the CSRs that are not
handled via copies will be in CSR_SaveList.
Frame lowering and prologue/epilogue insertion will generate a short frame
in the entry and exit according to CSR_SaveList. The majority of the CSRs will
be handled by register allcoator. Register allocator will try to spill and
reload them in the initialization block.
We add CSRsViaCopy, it will be explicitly handled during lowering.
1> we first set FunctionLoweringInfo->SplitCSR if conditions are met (the target
supports it for the given machine function and the function has only return
exits). We also call TLI->initializeSplitCSR to perform initialization.
2> we call TLI->insertCopiesSplitCSR to insert copies from CSRsViaCopy to
virtual registers at beginning of the entry block and copies from virtual
registers to CSRsViaCopy at beginning of the exit blocks.
3> we also need to make sure the explicit copies will not be eliminated.
Author: Tom Jablin (tjablin)
Reviewers: hfinkel kbarton cycheng
http://reviews.llvm.org/D17533
llvm-svn: 265781
This reverts commit r265765, reapplying r265759 after changing a call from
LocalAsMetadata::get to ValueAsMetadata::get (and adding a unit test). When a
local value is mapped to a constant (like "i32 %a" => "i32 7"), the new debug
intrinsic operand may no longer be pointing at a local.
http://lab.llvm.org:8080/green/job/clang-stage1-configure-RA_build/19020/
The previous coommit message follows:
--
This is a partial re-commit -- maybe more of a re-implementation -- of
r265631 (reverted in r265637).
This makes RF_IgnoreMissingLocals behave (almost) consistently between
the Value and the Metadata hierarchy. In particular:
- MapValue returns nullptr or "metadata !{}" for missing locals in
MetadataAsValue/LocalAsMetadata bridging paris, depending on
the RF_IgnoreMissingLocals flag.
- MapValue doesn't memoize LocalAsMetadata-related results.
- MapMetadata no longer deals with LocalAsMetadata or
RF_IgnoreMissingLocals at all. (This wasn't in r265631 at all, but
I realized during testing it would make the patch simpler with no
loss of generality.)
r265631 went too far, making both functions universally ignore
RF_IgnoreMissingLocals. This broke building (e.g.) compiler-rt.
Reassociate (and possibly other passes) don't currently maintain
dominates-use invariants for metadata operands, resulting in IR like
this:
define void @foo(i32 %arg) {
call void @llvm.some.intrinsic(metadata i32 %x)
%x = add i32 1, i32 %arg
}
If the inliner chooses to inline @foo into another function, then
RemapInstruction will call `MapValue(metadata i32 %x)` and assert that
the return is not nullptr.
I've filed PR27273 to add a Verifier check and fix the underlying
problem in the optimization passes.
As a workaround, return `!{}` instead of nullptr for unmapped
LocalAsMetadata when RF_IgnoreMissingLocals is unset. Otherwise, match
the behaviour of r265631.
Original commit message:
ValueMapper: Make LocalAsMetadata match function-local Values
Start treating LocalAsMetadata similarly to function-local members of
the Value hierarchy in MapValue and MapMetadata.
- Don't memoize them.
- Return nullptr if they are missing.
This also cleans up ConstantAsMetadata to stop listening to the
RF_IgnoreMissingLocals flag.
llvm-svn: 265768
Summary:
Fixes PR26774.
If you're aware of the issue, feel free to skip the "Motivation"
section and jump directly to "This patch".
Motivation:
I define "refinement" as discarding behaviors from a program that the
optimizer has license to discard. So transforming:
```
void f(unsigned x) {
unsigned t = 5 / x;
(void)t;
}
```
to
```
void f(unsigned x) { }
```
is refinement, since the behavior went from "if x == 0 then undefined
else nothing" to "nothing" (the optimizer has license to discard
undefined behavior).
Refinement is a fundamental aspect of many mid-level optimizations done
by LLVM. For instance, transforming `x == (x + 1)` to `false` also
involves refinement since the expression's value went from "if x is
`undef` then { `true` or `false` } else { `false` }" to "`false`" (by
definition, the optimizer has license to fold `undef` to any non-`undef`
value).
Unfortunately, refinement implies that the optimizer cannot assume
that the implementation of a function it can see has all of the
behavior an unoptimized or a differently optimized version of the same
function can have. This is a problem for functions with comdat
linkage, where a function can be replaced by an unoptimized or a
differently optimized version of the same source level function.
For instance, FunctionAttrs cannot assume a comdat function is
actually `readnone` even if it does not have any loads or stores in
it; since there may have been loads and stores in the "original
function" that were refined out in the currently visible variant, and
at the link step the linker may in fact choose an implementation with
a load or a store. As an example, consider a function that does two
atomic loads from the same memory location, and writes to memory only
if the two values are not equal. The optimizer is allowed to refine
this function by first CSE'ing the two loads, and the folding the
comparision to always report that the two values are equal. Such a
refined variant will look like it is `readonly`. However, the
unoptimized version of the function can still write to memory (since
the two loads //can// result in different values), and selecting the
unoptimized version at link time will retroactively invalidate
transforms we may have done under the assumption that the function
does not write to memory.
Note: this is not just a problem with atomics or with linking
differently optimized object files. See PR26774 for more realistic
examples that involved neither.
This patch:
This change introduces a new set of linkage types, predicated as
`GlobalValue::mayBeDerefined` that returns true if the linkage type
allows a function to be replaced by a differently optimized variant at
link time. It then changes a set of IPO passes to bail out if they see
such a function.
Reviewers: chandlerc, hfinkel, dexonsmith, joker.eph, rnk
Subscribers: mcrosier, llvm-commits
Differential Revision: http://reviews.llvm.org/D18634
llvm-svn: 265762
This patch closes a gap in the DWARF backend that caused LLVM to drop
debug info for floating point variables that were constant for part of
their scope. Floating point constants are emitted as one or more
DW_OP_constu joined via DW_OP_piece.
This fixes a regression caught by the LLDB testsuite that I introduced
in r262247 when we stopped blindly expanding the range of singular
DBG_VALUEs to span the entire scope and started to emit location lists
with accurate ranges instead.
Also deletes a now-impossible testcase (debug-loc-empty-entries).
<rdar://problem/25448338>
llvm-svn: 265760
This is a partial re-commit -- maybe more of a re-implementation -- of
r265631 (reverted in r265637).
This makes RF_IgnoreMissingLocals behave (almost) consistently between
the Value and the Metadata hierarchy. In particular:
- MapValue returns nullptr or "metadata !{}" for missing locals in
MetadataAsValue/LocalAsMetadata bridging paris, depending on
the RF_IgnoreMissingLocals flag.
- MapValue doesn't memoize LocalAsMetadata-related results.
- MapMetadata no longer deals with LocalAsMetadata or
RF_IgnoreMissingLocals at all. (This wasn't in r265631 at all, but
I realized during testing it would make the patch simpler with no
loss of generality.)
r265631 went too far, making both functions universally ignore
RF_IgnoreMissingLocals. This broke building (e.g.) compiler-rt.
Reassociate (and possibly other passes) don't currently maintain
dominates-use invariants for metadata operands, resulting in IR like
this:
define void @foo(i32 %arg) {
call void @llvm.some.intrinsic(metadata i32 %x)
%x = add i32 1, i32 %arg
}
If the inliner chooses to inline @foo into another function, then
RemapInstruction will call `MapValue(metadata i32 %x)` and assert that
the return is not nullptr.
I've filed PR27273 to add a Verifier check and fix the underlying
problem in the optimization passes.
As a workaround, return `!{}` instead of nullptr for unmapped
LocalAsMetadata when RF_IgnoreMissingLocals is unset. Otherwise, match
the behaviour of r265631.
Original commit message:
ValueMapper: Make LocalAsMetadata match function-local Values
Start treating LocalAsMetadata similarly to function-local members of
the Value hierarchy in MapValue and MapMetadata.
- Don't memoize them.
- Return nullptr if they are missing.
This also cleans up ConstantAsMetadata to stop listening to the
RF_IgnoreMissingLocals flag.
llvm-svn: 265759
specific type.
This will be used to find the default mapping of the instruction.
Also, this information is recorded, instead of computed, because it is
expensive from a type to know which register bank maps it.
Indeed, we need to iterate through all the register classes of all the
register banks to find the one that maps the given type.
llvm-svn: 265736
from a register.
On top of duplicating the logic, it was buggy! It would assert on
physical registers, since MachineRegisterInfo does not have any
information regarding register classes/banks for them.
llvm-svn: 265727
Summary:
EHPad BB are not entered the classic way and therefor do not need to be placed after their predecessors. This patch make sure EHPad BB are not chosen amongst successors to form chains, and are selected as last resort when selecting the best candidate.
EHPad are scheduled in reverse probability order in order to have them flow into each others naturally.
Reviewers: chandlerc, majnemer, rafael, MatzeB, escha, silvas
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D17625
llvm-svn: 265726
Standard load/store instructions with GLC bit set.
Reviewers: tstellardAMD, arsenm
Differential Revision: http://reviews.llvm.org/D18760
llvm-svn: 265709
The pass walk through the machine function and assign the register banks
using the default mapping. In other words, there is no attempt to reduce
cross register copies.
llvm-svn: 265707
the mapping of an instruction on register bank.
For most instructions, it is possible to guess the mapping of the
instruciton by using the encoding constraints.
It remains instructions without encoding constraints.
For copy-like instructions, we try to propagate the information we get
from the other operands. Otherwise, the target has to give this
information.
llvm-svn: 265703
helper class.
The default constructor creates invalid (isValid() == false) instances
and may be used to communicate that a mapping was not found.
llvm-svn: 265699
A virtual register may have either a register bank or a register class.
This is represented by a PointerUnion between the related classes.
Typically, a virtual register went through the following states
regarding register class and register bank:
1. Creation: None is set. Virtual registers are fully generic.
2. Register bank assignment: Register bank is set. Virtual registers
live into a register bank, but we do not know the constraints they need
to fulfil.
3. Instruction selection: Register class is set. Virtual registers are
bound by encoding constraints.
To map these states to GlobalISel, the IRTranslator implements #1,
RegBankSelect #2, and Select #3.
llvm-svn: 265696
Return is now considered a predicable instruction, and is converted
to a newly-added CondReturn (which maps to BCR to %r14) instruction by
the if conversion pass.
Also, fused compare-and-branch transform knows about conditional
returns, emitting the proper fused instructions for them.
This transform triggers on a *lot* of tests, hence the huge diffstat.
The changes are mostly jX to br %r14 -> bXr %r14.
Author: koriakin
Differential Revision: http://reviews.llvm.org/D17339
llvm-svn: 265689
As suggested by Chandler in his review comments for D18662, this
follow-on patch renames some variables in GetLoadValueForLoad and
CoerceAvailableValueToLoadType to hopefully make it more obvious
which variables hold value sizes and which hold load/store sizes.
No functional change intended.
llvm-svn: 265687
When GVN wants to re-interpret an already available value in a smaller
type, it needs to right-shift the value on big-endian systems to ensure
the correct bytes are accessed. The shift value is the difference of
the sizes of the two types.
This is correct as long as both types occupy multiples of full bytes.
However, when one of them is a sub-byte type like i1, this no longer
holds true: we still need to shift, but only to access the correct
*byte*. Accessing bits within the byte requires no shift in either
endianness; e.g. an i1 resides in the least-significant bit of its
containing byte on both big- and little-endian systems.
Therefore, the appropriate shift value to be used is the difference of
the *storage* sizes of the two types. This is already handled correctly
in one place where such a shift takes place (GetStoreValueForLoad), but
is incorrect in two other places: GetLoadValueForLoad and
CoerceAvailableValueToLoadType.
This patch changes both places to use the storage size as well.
Differential Revision: http://reviews.llvm.org/D18662
llvm-svn: 265684
http://reviews.llvm.org/D18562
A large number of testcases has been modified so they pass after this test.
One testcase is deleted, because I realized even after undoing the original
change that was committed with this testcase, the testcase still passes. So
I removed it. The change to one other testcase (test/CodeGen/PowerPC/pr25802.ll)
is an arbitrary change to keep it passing. Given the original intention of the
testcase, and the fact that fixing it will require some time to change the testcase,
we concluded that this quick change will be enough.
llvm-svn: 265683
Summary: This makes it possible to insert nops at the end of blocks.
Reviewers: arsenm
Subscribers: arsenm, llvm-commits
Differential Revision: http://reviews.llvm.org/D18549
llvm-svn: 265678
Simon Pilgrim