This commit adds the isnan intrinsic and provides a default expansion
for it in the SDAG. However, it makes the assumption that types
it operates on are IEEE-compliant types. This is not always the case.
An example of that is PPC "double double" which has a representation
that
- Does not need to conform to IEEE requirements for isnan as it is
not an IEEE-compliant type
- Does not have a representation that allows for straightforward
reinterpreting as an integer and use of integer operations
The result was that this commit broke __builtin_isnan for ppc_fp128
making many valid numeric values report a NaN.
This patch simply changes the expansion to always expand to unordered
comparison (regardless of whether FP exceptions are tracked). This
is inline with previous semantics.
This is recommit of the patch 16ff91ebccda1128c43ff3cee104e2c603569fb2,
reverted in 0c28a7c990c5218d6aec47c5052a51cba686ec5e because it had
an error in call of getFastMathFlags (base type should be FPMathOperator
but not Instruction). The original commit message is duplicated below:
Clang has builtin function '__builtin_isnan', which implements C
library function 'isnan'. This function now is implemented entirely in
clang codegen, which expands the function into set of IR operations.
There are three mechanisms by which the expansion can be made.
* The most common mechanism is using an unordered comparison made by
instruction 'fcmp uno'. This simple solution is target-independent
and works well in most cases. It however is not suitable if floating
point exceptions are tracked. Corresponding IEEE 754 operation and C
function must never raise FP exception, even if the argument is a
signaling NaN. Compare instructions usually does not have such
property, they raise 'invalid' exception in such case. So this
mechanism is unsuitable when exception behavior is strict. In
particular it could result in unexpected trapping if argument is SNaN.
* Another solution was implemented in https://reviews.llvm.org/D95948.
It is used in the cases when raising FP exceptions by 'isnan' is not
allowed. This solution implements 'isnan' using integer operations.
It solves the problem of exceptions, but offers one solution for all
targets, however some can do the check in more efficient way.
* Solution implemented by https://reviews.llvm.org/D96568 introduced a
hook 'clang::TargetCodeGenInfo::testFPKind', which injects target
specific code into IR. Now only SystemZ implements this hook and it
generates a call to target specific intrinsic function.
Although these mechanisms allow to implement 'isnan' with enough
efficiency, expanding 'isnan' in clang has drawbacks:
* The operation 'isnan' is hidden behind generic integer operations or
target-specific intrinsics. It complicates analysis and can prevent
some optimizations.
* IR can be created by tools other than clang, in this case treatment
of 'isnan' has to be duplicated in that tool.
Another issue with the current implementation of 'isnan' comes from the
use of options '-ffast-math' or '-fno-honor-nans'. If such option is
specified, 'fcmp uno' may be optimized to 'false'. It is valid
optimization in general, but it results in 'isnan' always returning
'false'. For example, in some libc++ implementations the following code
returns 'false':
std::isnan(std::numeric_limits<float>::quiet_NaN())
The options '-ffast-math' and '-fno-honor-nans' imply that FP operation
operands are never NaNs. This assumption however should not be applied
to the functions that check FP number properties, including 'isnan'. If
such function returns expected result instead of actually making
checks, it becomes useless in many cases. The option '-ffast-math' is
often used for performance critical code, as it can speed up execution
by the expense of manual treatment of corner cases. If 'isnan' returns
assumed result, a user cannot use it in the manual treatment of NaNs
and has to invent replacements, like making the check using integer
operations. There is a discussion in https://reviews.llvm.org/D18513#387418,
which also expresses the opinion, that limitations imposed by
'-ffast-math' should be applied only to 'math' functions but not to
'tests'.
To overcome these drawbacks, this change introduces a new IR intrinsic
function 'llvm.isnan', which realizes the check as specified by IEEE-754
and C standards in target-agnostic way. During IR transformations it
does not undergo undesirable optimizations. It reaches instruction
selection, where is lowered in target-dependent way. The lowering can
vary depending on options like '-ffast-math' or '-ffp-model' so the
resulting code satisfies requested semantics.
Differential Revision: https://reviews.llvm.org/D104854
Fixes issue where late materialized constants can be more strictly
aligned then their containing csect.
Differential Revision: https://reviews.llvm.org/D103103
This reverts commit 16ff91ebccda1128c43ff3cee104e2c603569fb2.
Several errors were reported mainly test-suite execution time. Reverted
for investigation.
Clang has builtin function '__builtin_isnan', which implements C
library function 'isnan'. This function now is implemented entirely in
clang codegen, which expands the function into set of IR operations.
There are three mechanisms by which the expansion can be made.
* The most common mechanism is using an unordered comparison made by
instruction 'fcmp uno'. This simple solution is target-independent
and works well in most cases. It however is not suitable if floating
point exceptions are tracked. Corresponding IEEE 754 operation and C
function must never raise FP exception, even if the argument is a
signaling NaN. Compare instructions usually does not have such
property, they raise 'invalid' exception in such case. So this
mechanism is unsuitable when exception behavior is strict. In
particular it could result in unexpected trapping if argument is SNaN.
* Another solution was implemented in https://reviews.llvm.org/D95948.
It is used in the cases when raising FP exceptions by 'isnan' is not
allowed. This solution implements 'isnan' using integer operations.
It solves the problem of exceptions, but offers one solution for all
targets, however some can do the check in more efficient way.
* Solution implemented by https://reviews.llvm.org/D96568 introduced a
hook 'clang::TargetCodeGenInfo::testFPKind', which injects target
specific code into IR. Now only SystemZ implements this hook and it
generates a call to target specific intrinsic function.
Although these mechanisms allow to implement 'isnan' with enough
efficiency, expanding 'isnan' in clang has drawbacks:
* The operation 'isnan' is hidden behind generic integer operations or
target-specific intrinsics. It complicates analysis and can prevent
some optimizations.
* IR can be created by tools other than clang, in this case treatment
of 'isnan' has to be duplicated in that tool.
Another issue with the current implementation of 'isnan' comes from the
use of options '-ffast-math' or '-fno-honor-nans'. If such option is
specified, 'fcmp uno' may be optimized to 'false'. It is valid
optimization in general, but it results in 'isnan' always returning
'false'. For example, in some libc++ implementations the following code
returns 'false':
std::isnan(std::numeric_limits<float>::quiet_NaN())
The options '-ffast-math' and '-fno-honor-nans' imply that FP operation
operands are never NaNs. This assumption however should not be applied
to the functions that check FP number properties, including 'isnan'. If
such function returns expected result instead of actually making
checks, it becomes useless in many cases. The option '-ffast-math' is
often used for performance critical code, as it can speed up execution
by the expense of manual treatment of corner cases. If 'isnan' returns
assumed result, a user cannot use it in the manual treatment of NaNs
and has to invent replacements, like making the check using integer
operations. There is a discussion in https://reviews.llvm.org/D18513#387418,
which also expresses the opinion, that limitations imposed by
'-ffast-math' should be applied only to 'math' functions but not to
'tests'.
To overcome these drawbacks, this change introduces a new IR intrinsic
function 'llvm.isnan', which realizes the check as specified by IEEE-754
and C standards in target-agnostic way. During IR transformations it
does not undergo undesirable optimizations. It reaches instruction
selection, where is lowered in target-dependent way. The lowering can
vary depending on options like '-ffast-math' or '-ffp-model' so the
resulting code satisfies requested semantics.
Differential Revision: https://reviews.llvm.org/D104854
Regsier hints when copying to a UACC register do not always produce VSRp
registers. This patch makes sure that we do not produce hints in cases
where the subregsiter of the UACC is not a VSRp.
Reviewed By: nemanjai, #powerpc
Differential Revision: https://reviews.llvm.org/D107101
If a target lists both a subreg and a superreg in a callee-saved
register mask, the prolog will spill both aliasing registers. Instead,
don't spill the subreg if a superreg is being spilled. This case is hit by the
PowerPC SPE code, as well as a modified RISC-V backend for CHERI I maintain out
of tree.
Reviewed By: jhibbits
Differential Revision: https://reviews.llvm.org/D73170
Using split-file does not work with update_llc_test_checks.py. It's also
mostly redundant, as the single and double tests can just use a single
llc and FileCheck invocation for each FPU type using -check-prefixes
rather than -check-prefix, and update_llc_test_checks.py will merge what
it can. Only test_dasmconst needs to be SPE-only and so is pulled out
into its own mall file (rather than using sed to preprocess the file and
keep it commented out for EFPU2, which would work, but is ugly).
As well as cutting down on the number of RUN lines, this also results in
test_fma's CHECK lines being merged for both FPUs.
Reviewed By: kiausch
Differential Revision: https://reviews.llvm.org/D106969
The dst/dstt/dstst/dststt instructions are nop's on all PowerPC
cores that AIX supports. The AIX assembler also does not accept
these mnemonics. Turn them into nop's on AIX (similar to dstall).
All floating point values in registers are in double precision
representation. In order to materialize the correct single precision
value, we need to convert the APFloat that represents the value
to double precision first.
Reviewed By: amyk, NeHuang
Differential Revision: https://reviews.llvm.org/D106812
Before MASSV only supported P8 and P9 on AIX ans Linux . This patch proposes
MASSV to add support of P7 and P10 only on AIX too.
Differential: https://reviews.llvm.org/D106678
This is a followup patch for D105930 to add implicit-def of RM for
mtfsb[01] instructions as per review comments.
Reviewed By: nemanjai
Differential Revision: https://reviews.llvm.org/D106603
This patch is in a series of patches to provide builtins for compatibility
with the XL compiler. This patch adds the builtin and intrinsic for "__stbcx".
Reviewed By: nemanjai, #powerpc
Differential revision: https://reviews.llvm.org/D106484
Implemented builtins for mtmsr, mfspr, mtspr on PowerPC;
the patch is intended for XL Compatibility.
Differential revision: https://reviews.llvm.org/D106130
This patch implements store, load, move from and to registers related
builtins, as well as the builtin for stfiw. The patch aims to provide
feature parady with xlC on AIX.
Differential revision: https://reviews.llvm.org/D105946
This patch is in a series of patches to provide builtins for compatibility
with the XL compiler. This patch add the builtin and emit target independent
code for __cmpb.
Reviewed By: nemanjai, #powerpc
Differential revision: https://reviews.llvm.org/D105194
This patch is in a series of patches to provide builtins for compatibility with the XL compiler.
This patch adds semachecking for an already implemented builtin, `__icbt`. `__icbt` is only
valid for Power8 and up.
Reviewed By: #powerpc, nemanjai
Differential Revision: https://reviews.llvm.org/D105834
ACC registers are a combination of four consecutive vector registers.
If the vector registers are assigned first this often forces a number
of copies to appear just before the ACC register is created. If the ACC
register is assigned first then fewer copies are generated when the vector
registers are assigned.
This patch tries to force the register allocator to assign the ACC registers first
and then the UACC registers and then the vector pair registers. It does this
by changing the priority of the register classes.
This patch also adds hints to help the register allocator assign UACC registers from
known ACC registers and vector pair registers from known UACC registers.
Reviewed By: nemanjai
Differential Revision: https://reviews.llvm.org/D105854
This provides intrinsics for emitting instructions that set the FPSCR (`mtfsf/mtfsfi`).
The patch also conservatively marks the rounding mode as an implicit def for both since they both may set the rounding mode depending on the operands.
Reviewed By: #powerpc, qiucf
Differential Revision: https://reviews.llvm.org/D105957
Implement a subset of builtins required for compatiblilty with AIX XL compiler.
Reviewed By: nemanjai
Differential Revision: https://reviews.llvm.org/D105930
This patch includes the following updates to the load/store refactoring effort introduced in D93370:
- Update various VSX patterns that use to "force" an XForm, to instead just XForm.
This allows the ability for the patterns to compute the most optimal addressing
mode (and to produce a DForm instruction when possible)
- Update pattern and test case for the LXVD2X/STXVD2X intrinsics
- Update LIT test cases that use to use the XForm instruction to use the DForm instruction
Differential Revision: https://reviews.llvm.org/D95115
This patch is in a series of patches to provide builtins for compatibility
with the XL compiler. This patch adds the builtins and instrisics for population
count, reversed load and store related operations.
Reviewed By: nemanjai, #powerpc
Differential revision: https://reviews.llvm.org/D106021
Summary:
in the function PPCFunctionInfo::getParmsType(), there is if (Bits > 31 || (Bits > 30 && (Elt != FixedType || hasVectorParms())))
when the Bit is 31 and the Elt is not FixedType(for example the Elt is FloatingType) , the 31th bit will be not encoded, it leave the bit as zero, when the function Expected<SmallString<32>> XCOFF::parseParmsType() the original implement
**// unsigned ParmsNum = FixedParmsNum + FloatingParmsNum;
while (Bits < 32 && ParsedNum < ParmsNum) {
...
}//**
it will look the 31 bits (zero) as FixedType. which should be FloatingType, and get a error.
Reviewers: Jason Liu,ZarkoCA
Differential Revision: https://reviews.llvm.org/D105023
This patch implements the `__popcntb` XL compatibility builtin for 32bit in the frontend and backend. This patch also updates tests for `__popcntb` and other XL Compat sync related builtins.
Reviewed By: #powerpc, nemanjai, amyk
Differential Revision: https://reviews.llvm.org/D105360
This patch adds the forward scan for finding redundant DBG_VALUEs.
This analysis aims to remove redundant DBG_VALUEs by going forward
in the basic block by considering the first DBG_VALUE as a valid
until its first (location) operand is not clobbered/modified.
For example:
(1) DBG_VALUE $edi, !"var1", ...
(2) <block of code that does affect $edi>
(3) DBG_VALUE $edi, !"var1", ...
...
in this case, we can remove (3).
Differential Revision: https://reviews.llvm.org/D105280
This patch uses AtomicExpandPass to implement quadword lock free atomic operations. It adopts the method introduced in https://reviews.llvm.org/D47882, which expand atomic operations post RA to avoid spilling that might prevent LL/SC progress.
Reviewed By: jsji
Differential Revision: https://reviews.llvm.org/D103614
$ is used as PC for PowerPC inlineasm, ELF use it,
enable it for AIX XCOFF as well.
Reviewed By: #powerpc, amyk, nemanjai
Differential Revision: https://reviews.llvm.org/D105956
This new MIR pass removes redundant DBG_VALUEs.
After the register allocator is done, more precisely, after
the Virtual Register Rewriter, we end up having duplicated
DBG_VALUEs, since some virtual registers are being rewritten
into the same physical register as some of existing DBG_VALUEs.
Each DBG_VALUE should indicate (at least before the LiveDebugValues)
variables assignment, but it is being clobbered for function
parameters during the SelectionDAG since it generates new DBG_VALUEs
after COPY instructions, even though the parameter has no assignment.
For example, if we had a DBG_VALUE $regX as an entry debug value
representing the parameter, and a COPY and after the COPY,
DBG_VALUE $virt_reg, and after the virtregrewrite the $virt_reg gets
rewritten into $regX, we'd end up having redundant DBG_VALUE.
This breaks the definition of the DBG_VALUE since some analysis passes
might be built on top of that premise..., and this patch tries to fix
the MIR with the respect to that.
This first patch performs bacward scan, by trying to detect a sequence of
consecutive DBG_VALUEs, and to remove all DBG_VALUEs describing one
variable but the last one:
For example:
(1) DBG_VALUE $edi, !"var1", ...
(2) DBG_VALUE $esi, !"var2", ...
(3) DBG_VALUE $edi, !"var1", ...
...
in this case, we can remove (1).
By combining the forward scan that will be introduced in the next patch
(from this stack), by inspecting the statistics, the RemoveRedundantDebugValues
removes 15032 instructions by using gdb-7.11 as a testbed.
Differential Revision: https://reviews.llvm.org/D105279
ACC regsiters are a combination of 4 consecutive vector regsiters and therefore
somtimes require special treatment for register allocation. This patch only
adds a test.
This patch is in a series of patches to provide builtins for compatibility
with the XL compiler. This patch adds the builtins and instrisics for compare
and multiply related operations.
Reviewed By: nemanjai, #powerpc
Differential revision: https://reviews.llvm.org/D102875
This patch adds a function that checks whether or not the frame index
is aligned when the computed addressing mode is an aligned D-Form (DS, or DQ-Form).
If the frame index appears to be unaligned, within these two modes, reset
the mode to X-Form in order to fall back to selection X-Form loads.
A test case is added to ensure that the test emits X-Form loads and not DQ-Form
loads since the frame index is not aligned within the test case.
Differential Revision: https://reviews.llvm.org/D105661
LDARX and LWARX sometimes gets optimized out by the compiler
when it is critical to the correctness of the code. This inline asm generation
ensures that it preserved.
Differential Revision: https://reviews.llvm.org/D105754
An assertion of the following can occur because Altivec and VSX splats use a different operand number for the immediate:
```
int64_t llvm::MachineOperand::getImm() const: Assertion `isImm() && "Wrong MachineOperand accessor"' failed.
```
This patch updates PPCMIPeephole.cpp assign the correct splat immediate.
Differential Revision: https://reviews.llvm.org/D105790
