Commit 1fed131660 assumed that shuffle vector canonicalization will
always ensure that the shuffle mask will be ordered so that element
zero comes from the LHS vector. However there is code out there for
which this is not the case. This patch simply removes that unsafe
assumption and makes the code work regardless of the source of the
first element.
We currently miss a number of opportunities to emit single-instruction
VMRG[LH][BHW] instructions for shuffles on little endian subtargets. Although
this in itself is not a huge performance opportunity since loading the permute
vector for a VPERM can always be pulled out of loops, producing such merge
instructions is useful to downstream optimizations.
Since VPERM is essentially opaque to all subsequent optimizations, we want to
avoid it as much as possible. Other permute instructions have semantics that can
be reasoned about much more easily in later optimizations.
This patch does the following:
- Canonicalize shuffles so that the first element comes from the first vector
(since that's what most of the mask matching functions want)
- Switch the elements that come from splat vectors so that they match the
corresponding elements from the other vector (to allow for merges)
- Adds debugging messages for when a shuffle is matched to a VPERM so that
anyone interested in improving this further can get the info for their code
Differential revision: https://reviews.llvm.org/D77448
Summary: A bug is reported in bugzilla-45628, where the swap_with_shift case can’t be matched to a single HW instruction xxswapd as expected.
In fact the case matches the idiom of rotate. We have MatchRotate to handle an ‘or’ of two operands and generate a rot[lr] if the case matches the idiom of rotate. While PPC doesn’t support ROTL v1i128. We can custom lower ROTL v1i128 to the vector_shuffle. The vector_shuffle will be matched to a single HW instruction during the phase of instruction selection.
Reviewed By: steven.zhang
Differential Revision: https://reviews.llvm.org/D81076
This patch adds handling of constrained FP intrinsics about round,
truncate and extend for PowerPC target, with necessary tests.
Reviewed By: steven.zhang
Differential Revision: https://reviews.llvm.org/D64193
On PowerPC, we have vnmsubfp Altivec instruction for fnmsub operation on
v4f32 type. Default pattern for this instruction never works since we
don't have legal fneg for v4f32 when VSX disabled.
Reviewed By: steven.zhang
Differential Revision: https://reviews.llvm.org/D80617
On PowerPC, FNMSUB (both VSX and non-VSX version) means -(a*b-c). But
the backend used to generate these instructions regardless whether nsz
flag exists or not. If a*b-c==0, such transformation changes sign of
zero.
This patch introduces PPC specific FNMSUB ISD opcode, which may help
improving combined FMA code sequence.
Reviewed By: steven.zhang
Differential Revision: https://reviews.llvm.org/D76585
These two nodes were added by 69caef2b78 in 2005
and they are not used by PowerPC backend anymore. And the ISD::FMA is a prefer
way for VMADDFP if we really want to create that node. For VNMSUBFP, we will
also add a more generic node FNMSUB in D76585 if we really want it.
Reviewed By: qiucf
Differential Revision: https://reviews.llvm.org/D80429
Summary: Exploit vabsd* for for absolute difference of vectors on P9,
for example:
void foo (char *restrict p, char *restrict q, char *restrict t)
{
for (int i = 0; i < 16; i++)
t[i] = abs (p[i] - q[i]);
}
this case should be matched to the HW instruction vabsdub.
Reviewed By: steven.zhang
Differential Revision: https://reviews.llvm.org/D80271
Let the codegen recognized the nomerge attribute and disable branch folding when the attribute is given
Differential Revision: https://reviews.llvm.org/D79537
Summary:
This patch simply adds support for the new CPU in anticipation of
Power10. There isn't really any functionality added so there are no
associated test cases at this time.
Reviewers: stefanp, nemanjai, amyk, hfinkel, power-llvm-team, #powerpc
Reviewed By: stefanp, nemanjai, amyk, #powerpc
Subscribers: NeHuang, steven.zhang, hiraditya, llvm-commits, wuzish, shchenz, cfe-commits, kbarton, echristo
Tags: #clang, #powerpc, #llvm
Differential Revision: https://reviews.llvm.org/D80020
Summary:
This patch simply adds support for the new CPU in anticipation of
Power10. There isn't really any functionality added so there are no
associated test cases at this time.
Reviewers: stefanp, nemanjai, amyk, hfinkel, power-llvm-team, #powerpc
Reviewed By: stefanp, nemanjai, amyk, #powerpc
Subscribers: NeHuang, steven.zhang, hiraditya, llvm-commits, wuzish, shchenz, cfe-commits, kbarton, echristo
Tags: #clang, #powerpc, #llvm
Differential Revision: https://reviews.llvm.org/D80020
As reported in PR45186, we could be in a situation where we don't
want to handle unaligned memory accesses for FP scalars but still
have VSX (which allows unaligned access for vectors). Change the
default to only apply to scalars.
Fixes: https://bugs.llvm.org/show_bug.cgi?id=45186
As reported in https://bugs.llvm.org/show_bug.cgi?id=45709 we can hit an
infinite loop in legalization since we set the legalization action for
ISD::SELECT_CC for all fixed length vector types to Promote. Without some
different legalization action for the type being promoted to, the legalizer
simply loops. Since we don't have patterns to match the node, the right
legalization action should be Expand.
Differential revision: https://reviews.llvm.org/D79854
This patch introduces a TargetLowering query, isMulhCheaperThanMulShift.
Currently in DAG Combine, it will transform mulhs/mulhu into a
wider multiply and a shift if the wide multiply is legal.
This TLI function is implemented on 64-bit PowerPC, as it is more desirable to
have multiply-high over multiply + shift for words and doublewords. Having
multiply-high can also aid in further transformations that can be done.
Differential Revision: https://reviews.llvm.org/D78271
The fix for PR39865 took care of some of the handling for half precision
but it missed a number of issues that still exist. This patch fixes the
remaining issues that cause crashes in the PPC back end.
Fixes: https://bugs.llvm.org/show_bug.cgi?id=45776
Differential revision: https://reviews.llvm.org/D79283
SplitCSR was only suppored for functions with CXX_FAST_TLS calling
convention. Clang only emits that calling convention for Darwin which is
no longer supported by the PowerPC backend. Another IR producer could
use the calling convention, but considering the calling convention is
meant to be an optimization and the codegen for SplitCSR can be
attrocious on Power (see the modifed lit test) it is best to remove it
and codegen CXX_FAST_TLS same as the C calling convention.
Differential Revision: https://reviews.llvm.org/D79018
Legalizer should respect both command-line options or SDNode-level
fast-math flags.
Also, this patch propagates other flags during custom simplifying.
Reviewed By: steven.zhang
Differential Revision: https://reviews.llvm.org/D79074
This patch adds strict-fp intrinsics support for fma, fsqrt, fmaxnum and
fminnum on PowerPC.
Reviewed By: hfinkel
Differential Revision: https://reviews.llvm.org/D72749
Summary:
This patch will set the variable PredictableSelectIsExpensive to do the
select to if based on BranchProbability in CodeGenPrepare.
When the BranchProbability more than MinPercentageForPredictableBranch,
PPC will convert SELECT to branch.
Reviewed By: nemanjai
Differential Revision: https://reviews.llvm.org/D71883
This patch stores the alignment for ConstantPoolSDNode as an
Align and updates the getConstantPool interface to take a MaybeAlign.
Removing getAlignment() will be done as a follow up.
Differential Revision: https://reviews.llvm.org/D79436
Implement passing of ByVal formal arguments when the argument is passed
partly in the argument registers, with the remainder of the argument
passed on the stack.
Differential Revision: https://reviews.llvm.org/D78515
This method has been commented as deprecated for a while. Remove
it and replace all uses with the equivalent getCalledOperand().
I also made a few cleanups in here. For example, to removes use
of getElementType on a pointer when we could just use getFunctionType
from the call.
Differential Revision: https://reviews.llvm.org/D78882
Tail Calls were initially disabled for PC Relative code because it was not safe
to make certain assumptions about the tail calls (namely that all compiled
functions no longer used the TOC pointer in R2). However, once all of the
TOC pointer references have been removed it is safe to tail call everything
that was tail called prior to the PC relative additions as well as a number of
new cases.
For example, it is now possible to tail call indirect functions as there is no
need to save and restore the TOC pointer for indirect functions if the caller
is marked as may clobber R2 (st_other=1). For the same reason it is now also
possible to tail call functions that are external.
Differential Revision: https://reviews.llvm.org/D77788
1. Use Subtarget.isUsingPCRelativeCalls() in LowerConstantPool to
check if using PCRelative addressing.
2. Change MO_GOT_FLAG = 32 to MO_GOT_FLAG = 8 in PPC.h to use
consecutive bits.
Differential Revision: https://reviews.llvm.org/D78406
Currently an indirect call produces the following sequence on PCRelative mode:
extern void function( );
extern void (*ptrfunc) ( );
void g() {
ptrfunc=function;
}
void f() {
(*ptrfunc) ( );
}
Producing
paddi 3, 0, .LC0@PCREL, 1
ld 3, 0(3)
std 2, 24(1)
ld 12, 0(3)
mtctr 12
bctrl
ld 2, 24(1)
Though the caller does not use or preserve r2, it is still saved and restored
across a function call. This patch is added to remove these redundant save and
restores for indirect calls.
Differential Revision: https://reviews.llvm.org/D77749
Add initial support for PC Relative addressing to get jump table base
address instead of using TOC.
Differential Revision: https://reviews.llvm.org/D75931
This is an optimization that applies to global addresses and
allows for the following transformation:
Convert this:
paddi r3, 0, symbol@PCREL, 1
ld r4, 8(r3)
To this:
pld r4, symbol@PCREL+8(0), 1
An instruction is saved and the linker can do the addition when
the symbol is resolved.
Differential Revision: https://reviews.llvm.org/D76160
Adds support for passing a ByVal formal argument completely on the stack
(ie after all argument registers are exhausted).
Differential Revision: https://reviews.llvm.org/D78263
Add initial support for PC Relative addressing for global values that
require GOT indirect addressing. This patch adds PCRelative support for
global addresses that may not be known at link time and may require
access through the GOT.
Differential Revision: https://reviews.llvm.org/D76064
This patch adds PC Relative support for global values that are known at link
time. If a global value requires access through the global offset table (GOT)
it is not covered in this patch.
Differential Revision: https://reviews.llvm.org/D75280
In LowerFP_TO_INTForReuse, when emitting `stfiwx`, alignment of 4 is
set for the `MachineMemOperand`, but RLI(ReuseLoadInfo)'s alignment is
not updated for following loads.
It's related to failed alignment check reported in
https://bugs.llvm.org/show_bug.cgi?id=45297
Differential Revision: https://reviews.llvm.org/D77624
Summary:
This patch adds support for handling of variadic functions for AIX.
This includes ensuring that use and consume correct type of
va_list (char *va_list) for AIX.
Authored by: ZarkoCA
Reviewers: cebowleratibm, sfertile, jasonliu
Reviewed by: jasonliu
Differential Revision: https://reviews.llvm.org/D76130
Add initial support for PC Relative addressing for constant pool loads.
This includes adding a new relocation for @pcrel and adding a new PowerPC flag
to identify PC relative addressing.
Differential Revision: https://reviews.llvm.org/D74486
Any or all the argument registers can be used to pass a byval formal
argument, with the limitation that the argument must fit in the
available registers (ie: is not split between registers and stack).
Differential Revision: https://reviews.llvm.org/D76902
On PowerPC most functions require a valid TOC pointer.
This is the case because either the function itself needs to use this
pointer to access the TOC or because other functions that are called
from that function expect a valid TOC pointer in the register R2.
The main exception to this is leaf functions that do not access the TOC
since they are guaranteed not to need a valid TOC pointer.
This patch introduces a feature that will allow more functions to not
require a valid TOC pointer in R2.
Differential Revision: https://reviews.llvm.org/D73664
Summary:
For current architect, we always require setContainingCsect to be
called on every MCSymbol got used in XCOFF context.
This is very hard to achieve because symbols gets created everywhere
and other MCSymbol types(ELF, COFF) do not have similar rules.
It's very easy to miss setting the containing csect, and we would
need to add a lot of XCOFF specialized code around some common code area.
This patch intendeds to do
1. Rely on getFragment().getParent() to get csect from labels.
2. Only use get/setRepresentedCsect (was get/setContainingCsect)
if symbol itself represents a csect.
Reviewers: DiggerLin, hubert.reinterpretcast, daltenty
Differential Revision: https://reviews.llvm.org/D77080
Summary:
In https://bugs.llvm.org/show_bug.cgi?id=45297, it fails selecting
instructions for `PPCISD::ST_VSR_SCAL_INT`. The reason it generate the
`PPCISD::ST_VSR_SCAL_INT` with `-power8-vector` in IR is PPC's
combiner checks `hasP8Altivec` rather than `hasP8Vector`. This patch
should resolve PR45297.
Differential Revision: https://reviews.llvm.org/D76773
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790
Reviewers: courbet
Subscribers: jyknight, sdardis, nemanjai, hiraditya, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, jfb, PkmX, jocewei, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77059
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790
Reviewers: courbet
Subscribers: arsenm, dschuff, sdardis, nemanjai, jvesely, nhaehnle, sbc100, jgravelle-google, hiraditya, aheejin, kbarton, jrtc27, atanasyan, jfb, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D76925
We can legalize the operation MUL for v8i16 with instruction (vmladduhm A, B, 0)
if altivec enabled. Now, it is set as custom and expand it later, which is not
the right way. And then, we can add the pattern to match the mul + add with (vmladduhm A, B, C)
Reviewed By: Nemanjai
Differential Revision: https://reviews.llvm.org/D76751
On Powerpc fma is faster than fadd + fmul for some types,
(PPCTargetLowering::isFMAFasterThanFMulAndFAdd). we should implement target
hook isProfitableToHoist to prevent simplifyCFGpass from breaking fma
pattern by hoisting fmul to predecessor block.
Reviewed By: nemanjai
Differential Revision: https://reviews.llvm.org/D76207
This is the first of a series of patches that adds caller support for
by-value arguments. This patch add support for arguments that are passed in a
single GPR.
There are 3 limitation cases:
-The by-value argument is larger than a single register.
-There are no remaining GPRs even though the by-value argument would
otherwise fit in a single GPR.
-The by-value argument requires alignment greater than register width.
Future patches will be required to add support for these cases as well
as for the callee handling (in LowerFormalArguments_AIX) that
corresponds to this work.
Differential Revision: https://reviews.llvm.org/D75863
The PPCISD::SExtVElems was added by commit https://reviews.llvm.org/D34009. However,
we have another ISD node ISD::SIGN_EXTEND_INREG that perfectly match the semantics
of SExtVElems. And the DAGCombiner has some combine rules for SIGN_EXTEND_INREG
that produce better code.
Differential Revision: https://reviews.llvm.org/D70771
Summary:
On 32-bit PPC target[AIX and BE], when we convert an `i64` to `f32`, a `setcc` operand expansion is needed. The expansion will set the result type of expanded `setcc` operation based on if the subtarget use CRBits or not. If the subtarget does use the CRBits, like AIX and BE, then it will set the result type to `i1`, leading to an inconsistency with original `setcc` result type[i32].
And the reason why it crashed underneath is because we don't set result type of setcc consistent in those two places.
This patch fixes this problem by setting original setcc opnode result type also with `getSetCCResultType` interface.
Reviewers: sfertile, cebowleratibm, hubert.reinterpretcast, Xiangling_L
Reviewed By: sfertile
Subscribers: wuzish, nemanjai, hiraditya, kbarton, jsji, shchenz, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75702
This is a follow up to the previous patch: [AIX] Implement caller
arguments passed in stack memory.
This corrects a defect in AIX 64-bit where an i32 is written to the
stack with stw (4 bytes) rather than the expected std (8 bytes.) Integer
arguments pass on the stack as images of their register representation.
I also took the opportunity to tidy up some of the calling convention
AIX tests I added in my last commit. This patch adds the missed assembly
expected output for the stack arg int case, which would have caught this
problem.
Differential Revision: https://reviews.llvm.org/D75126
Allow all ExternalSymbolSDNode on AIX, and rely on the linker error to find
symbols which we don't have definitions from any library/compiler-rt.
Differential Revision: https://reviews.llvm.org/D75075
Summary:
The patch D62993 : `[PowerPC] Emit scalar min/max instructions with unsafe fp math`
has modified the functionality when `Subtarget.hasP9Vector() && (!HasNoInfs || !HasNoNaNs)`,
this modification is not expected.
Reviewed By: nemanjai
Differential Revision: https://reviews.llvm.org/D74701
This node reads the rounding control which means it needs to be ordered properly with operations that change the rounding control. So it needs to be chained to maintain order.
This patch adds a chain input and output to the node and connects it to the chain in SelectionDAGBuilder. I've update all in-tree targets to connect their chain through their lowering code.
Differential Revision: https://reviews.llvm.org/D75132
Exploit native VSX rounding instruction, x(v|s)r(d|s)pic, which does
rounding using current rounding mode.
According to C standard library, rint may raise INEXACT exception while
nearbyint won't.
Reviewed By: lkail
Differential Revision: https://reviews.llvm.org/D72685
Remove code from LegalizeTypes that allowed this to work.
We were already using BUILD_PAIR for this in some places so this
standardizes on a single way to do this.
Summary: This patch introduces an API for MemOp in order to simplify and tighten the client code.
Reviewers: courbet
Subscribers: arsenm, nemanjai, jvesely, nhaehnle, hiraditya, kbarton, jsji, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73964
This patch implements the caller side of placing function call arguments
in stack memory. This removes the current limitation where LLVM on AIX
will report fatal error when arguments can't be contained in registers.
There is a particular oddity that a float argument that passes in a
register and also in stack memory requires that the caller initialize
both. From what AIX "ABI" documentation I have it's not clear that this
needs to be done, however, it is necessary for compatibility with the
AIX XL compiler so I think it's best to implement it the same way.
Note a later patch will follow to address the callee side.
Differential Revision: https://reviews.llvm.org/D73209
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790
Reviewers: courbet
Subscribers: arsenm, dschuff, jyknight, sdardis, nemanjai, jvesely, nhaehnle, sbc100, jgravelle-google, hiraditya, aheejin, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, jsji, Jim, lenary, s.egerton, pzheng, sameer.abuasal, apazos, luismarques, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73885
Summary: This is a first step before changing the types to llvm::Align and introduce functions to ease client code.
Reviewers: courbet
Subscribers: arsenm, sdardis, nemanjai, jvesely, nhaehnle, hiraditya, kbarton, jrtc27, atanasyan, jsji, kerbowa, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73785
Summary:
This is a follow up on https://reviews.llvm.org/D71473#inline-647262.
There's a caveat here that `Align(1)` relies on the compiler understanding of `Log2_64` implementation to produce good code. One could use `Align()` as a replacement but I believe it is less clear that the alignment is one in that case.
Reviewers: xbolva00, courbet, bollu
Subscribers: arsenm, dylanmckay, sdardis, nemanjai, jvesely, nhaehnle, hiraditya, kbarton, jrtc27, atanasyan, jsji, Jim, kerbowa, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D73099
Collect the calling convention and a number of boolean arguments into a
structure to slightly reduces the number of arguments passed around between
LowerCall_<Subtarget>, FinishCall and a few of the helpers. Also
calulates if a call is indirect once using the exisitng helper and caches the
result replacing several instances where we duplicated the logic determining if
a call is indirect.
These intrinsics and the corresponding ISD nodes were recently added. PPC has
instructions that do this for vectors. Legalize them and add patterns to emit
the satuarting instructions.
Differential revision: https://reviews.llvm.org/D71940
For memcpy/memset/memmove etc., replace ExternalSymbolSDNode with a
MCSymbolSDNode, which have a prefix dot before function name as entry
point symbol.
Differential Revision: https://reviews.llvm.org/D70718
Summary:
This patch pushes the AIX vararg unimplemented error diagnostic later
and allows vararg calls so long as all the arguments can be passed in register.
This patch extends the AIX calling convention implementation to initialize
GPR(s) for vararg float arguments. On AIX, both GPR(s) and FPR are allocated
for floating point arguments. The GPR(s) are only initialized for vararg calls,
otherwise the callee is expected to retrieve the float argument in the FPR.
f64 in AIX PPC32 requires special handling in order to allocated and
initialize 2 GPRs. This is performed with bitcast, SRL, truncation to
initialize one GPR for the MSW and bitcast, truncations to initialize
the other GPR for the LSW.
A future patch will follow to add support for arguments passed on the stack.
Patch provided by: cebowleratibm
Reviewers: sfertile, ZarkoCA, hubert.reinterpretcast
Differential Revision: https://reviews.llvm.org/D71013
Only PPC seems to be using it, and only checks some simple cases and
doesn't distinguish between FP. Just switch to using LLT to simplify
use from GlobalISel.
We use o suffix to indicate record form instuctions,
(as it is similar to dot '.' in mne?)
This was fine before, as we did not support XO-form.
However, with https://reviews.llvm.org/D66902,
we now have XO-form support.
It becomes confusing now to still use 'o' for record form,
and it is weird to have something like 'Oo' .
This patch rename all 'o' instructions to use '_rec' instead.
Also rename `isDot` to `isRecordForm`.
Reviewed By: #powerpc, hfinkel, nemanjai, steven.zhang, lkail
Differential Revision: https://reviews.llvm.org/D70758
When the "disable-tail-calls" attribute was added, checks were added for
it in various backends. Now this code has proliferated, and it is
something the target is responsible for checking. Move that
responsibility back to the ISels (fast, global, and SD).
There's no major functionality change, except for targets that never
implemented this check.
This LLVM attribute was originally added in
d9699bc7bd (2015).
Reviewers: echristo, MaskRay
Differential Revision: https://reviews.llvm.org/D72118
Commit 0f0330a787 legalized these nodes on PPC without consideration of
unsafe math which means that we get inexact exceptions raised for nearbyint.
Since this doesn't conform to the standard, switch this legalization to depend
on unsafe fp math.
VSX provides a full complement of rounding instructions yet we somehow ended up
with some of them legal and others not. This just legalizes all of the FP
rounding nodes and the FP -> int rounding nodes with unsafe math.
Differential revision: https://reviews.llvm.org/D69949
This is a fix for https://bugs.llvm.org/show_bug.cgi?id=40554
Some CPU's trap to the kernel on unaligned floating point access and there are
kernels that do not handle the interrupt. The program then fails with a SIGBUS
according to the PR. This just switches the default for unaligned access to only
allow it on recent server CPUs that are known to allow this.
Differential revision: https://reviews.llvm.org/D71954
The custom node PPCISD::XXREVERSE has completely the same semantics of generic node ISD::BSWAP.
We need to clean up it as we have the combine rules for bswap in the base class, while nothing for xxreverse.
Differential Revision: https://reviews.llvm.org/D70657
Summary:
Currently, we set legalization action of `ISD::ROTL` vectors as
`Expand` in `PPCISelLowering`. However, we can exploit `vrl(b|h|w|d)`
to lower `ISD::ROTL` directly.
Differential Revision: https://reviews.llvm.org/D71324
static void *ifunc(void) __attribute__((ifunc("resolver")));
void foo() { ifunc(); }
The relocation produced by the ifunc() call:
1. gcc -msecure-plt -fPIC => R_PPC_PLTREL24 r_addend=0x8000
2. gcc -msecure-plt -PIE => R_PPC_PLTREL24 r_addend=0x8000
3. clang -msecure-plt -fPIC => R_PPC_PLTREL24 r_addend=0x8000
4. clang -msecure-plt -fPIE => R_PPC_REL24
4 is incorrect. The R_PPC_REL24 needs a call stub due to ifunc. If this
relocation is mixed with other R_PPC_PLTREL24(r_addend=0x8000) in a
function, both GNU ld and lld (after D71621 fix) may produce a wrong
result.
This patch fixes 4 to use R_PPC_PLTREL24, which matches GCC.
Both GNU ld and lld (after D71621) will be happy.
Reviewed By: sfertile
Differential Revision: https://reviews.llvm.org/D71649
Guillaume Chatelet