diff options
| author | dim <dim@FreeBSD.org> | 2017-09-26 19:56:36 +0000 |
|---|---|---|
| committer | Luiz Souza <luiz@netgate.com> | 2018-02-21 15:12:19 -0300 |
| commit | 1dcd2e8d24b295bc73e513acec2ed1514bb66be4 (patch) | |
| tree | 4bd13a34c251e980e1a6b13584ca1f63b0dfe670 /contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp | |
| parent | f45541ca2a56a1ba1202f94c080b04e96c1fa239 (diff) | |
| download | FreeBSD-src-1dcd2e8d24b295bc73e513acec2ed1514bb66be4.zip FreeBSD-src-1dcd2e8d24b295bc73e513acec2ed1514bb66be4.tar.gz | |
Merge clang, llvm, lld, lldb, compiler-rt and libc++ 5.0.0 release.
MFC r309126 (by emaste):
Correct lld llvm-tblgen dependency file name
MFC r309169:
Get rid of separate Subversion mergeinfo properties for llvm-dwarfdump
and llvm-lto. The mergeinfo confuses Subversion enormously, and these
directories will just use the mergeinfo for llvm itself.
MFC r312765:
Pull in r276136 from upstream llvm trunk (by Wei Mi):
Use ValueOffsetPair to enhance value reuse during SCEV expansion.
In D12090, the ExprValueMap was added to reuse existing value during
SCEV expansion. However, const folding and sext/zext distribution can
make the reuse still difficult.
A simplified case is: suppose we know S1 expands to V1 in
ExprValueMap, and
S1 = S2 + C_a
S3 = S2 + C_b
where C_a and C_b are different SCEVConstants. Then we'd like to
expand S3 as V1 - C_a + C_b instead of expanding S2 literally. It is
helpful when S2 is a complex SCEV expr and S2 has no entry in
ExprValueMap, which is usually caused by the fact that S3 is
generated from S1 after const folding.
In order to do that, we represent ExprValueMap as a mapping from SCEV
to ValueOffsetPair. We will save both S1->{V1, 0} and S2->{V1, C_a}
into the ExprValueMap when we create SCEV for V1. When S3 is
expanded, it will first expand S2 to V1 - C_a because of S2->{V1,
C_a} in the map, then expand S3 to V1 - C_a + C_b.
Differential Revision: https://reviews.llvm.org/D21313
This should fix assertion failures when building OpenCV >= 3.1.
PR: 215649
MFC r312831:
Revert r312765 for now, since it causes assertions when building
lang/spidermonkey24.
Reported by: antoine
PR: 215649
MFC r316511 (by jhb):
Add an implementation of __ffssi2() derived from __ffsdi2().
Newer versions of GCC include an __ffssi2() symbol in libgcc and the
compiler can emit calls to it in generated code. This is true for at
least GCC 6.2 when compiling world for mips and mips64.
Reviewed by: jmallett, dim
Sponsored by: DARPA / AFRL
Differential Revision: https://reviews.freebsd.org/D10086
MFC r318601 (by adrian):
[libcompiler-rt] add bswapdi2/bswapsi2
This is required for mips gcc 6.3 userland to build/run.
Reviewed by: emaste, dim
Approved by: emaste
Differential Revision: https://reviews.freebsd.org/D10838
MFC r318884 (by emaste):
lldb: map TRAP_CAP to a trace trap
In the absense of a more specific handler for TRAP_CAP (generated by
ENOTCAPABLE or ECAPMODE while in capability mode) treat it as a trace
trap.
Example usage (testing the bug in PR219173):
% proccontrol -m trapcap lldb usr.bin/hexdump/obj/hexdump -- -Cv -s 1 /bin/ls
...
(lldb) run
Process 12980 launching
Process 12980 launched: '.../usr.bin/hexdump/obj/hexdump' (x86_64)
Process 12980 stopped
* thread #1, stop reason = trace
frame #0: 0x0000004b80c65f1a libc.so.7`__sys_lseek + 10
...
In the future we should have LLDB control the trapcap procctl itself
(as it does with ASLR), as well as report a specific stop reason.
This change eliminates an assertion failure from LLDB for now.
MFC r319796:
Remove a few unneeded files from libllvm, libclang and liblldb.
MFC r319885 (by emaste):
lld: ELF: Fix ICF crash on absolute symbol relocations.
If two sections contained relocations to absolute symbols with the same
value we would crash when trying to access their sections. Add a check that
both symbols point to sections before accessing their sections, and treat
absolute symbols as equal if their values are equal.
Obtained from: LLD commit r292578
MFC r319918:
Revert r319796 for now, it can cause undefined references when linking
in some circumstances.
Reported by: Shawn Webb <shawn.webb@hardenedbsd.org>
MFC r319957 (by emaste):
lld: Add armelf emulation mode
Obtained from: LLD r305375
MFC r321369:
Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
5.0.0 (trunk r308421). Upstream has branched for the 5.0.0 release,
which should be in about a month. Please report bugs and regressions,
so we can get them into the release.
Please note that from 3.5.0 onwards, clang, llvm and lldb require C++11
support to build; see UPDATING for more information.
MFC r321420:
Add a few more object files to liblldb, which should solve errors when
linking the lldb executable in some cases. In particular, when the
-ffunction-sections -fdata-sections options are turned off, or
ineffective.
Reported by: Shawn Webb, Mark Millard
MFC r321433:
Cleanup stale Options.inc files from the previous libllvm build for
clang 4.0.0. Otherwise, these can get included before the two newly
generated ones (which are different) for clang 5.0.0.
Reported by: Mark Millard
MFC r321439 (by bdrewery):
Move llvm Options.inc hack from r321433 for NO_CLEAN to lib/clang/libllvm.
The files are only ever generated to .OBJDIR, not to WORLDTMP (as a
sysroot) and are only ever included from a compilation. So using
a beforebuild target here removes the file before the compilation
tries to include it.
MFC r321664:
Pull in r308891 from upstream llvm trunk (by Benjamin Kramer):
[CodeGenPrepare] Cut off FindAllMemoryUses if there are too many uses.
This avoids excessive compile time. The case I'm looking at is
Function.cpp from an old version of LLVM that still had the giant
memcmp string matcher in it. Before r308322 this compiled in about 2
minutes, after it, clang takes infinite* time to compile it. With
this patch we're at 5 min, which is still bad but this is a
pathological case.
The cut off at 20 uses was chosen by looking at other cut-offs in LLVM
for user scanning. It's probably too high, but does the job and is
very unlikely to regress anything.
Fixes PR33900.
* I'm impatient and aborted after 15 minutes, on the bug report it was
killed after 2h.
Pull in r308986 from upstream llvm trunk (by Simon Pilgrim):
[X86][CGP] Reduce memcmp() expansion to 2 load pairs (PR33914)
D35067/rL308322 attempted to support up to 4 load pairs for memcmp
inlining which resulted in regressions for some optimized libc memcmp
implementations (PR33914).
Until we can match these more optimal cases, this patch reduces the
memcmp expansion to a maximum of 2 load pairs (which matches what we
do for -Os).
This patch should be considered for the 5.0.0 release branch as well
Differential Revision: https://reviews.llvm.org/D35830
These fix a hang (or extremely long compile time) when building older
LLVM ports.
Reported by: antoine
PR: 219139
MFC r321719:
Pull in r309503 from upstream clang trunk (by Richard Smith):
PR33902: Invalidate line number cache when adding more text to
existing buffer.
This led to crashes as the line number cache would report a bogus
line number for a line of code, and we'd try to find a nonexistent
column within the line when printing diagnostics.
This fixes an assertion when building the graphics/champlain port.
Reported by: antoine, kwm
PR: 219139
MFC r321723:
Upgrade our copies of clang, llvm, lld and lldb to r309439 from the
upstream release_50 branch. This is just after upstream's 5.0.0-rc1.
MFC r322320:
Upgrade our copies of clang, llvm and libc++ to r310316 from the
upstream release_50 branch.
MFC r322326 (by emaste):
lldb: Make i386-*-freebsd expression work on JIT path
* Enable i386 ABI creation for freebsd
* Added an extra argument in ABISysV_i386::PrepareTrivialCall for mmap
syscall
* Unlike linux, the last argument of mmap is actually 64-bit(off_t).
This requires us to push an additional word for the higher order bits.
* Prior to this change, ktrace dump will show mmap failures due to
invalid argument coming from the 6th mmap argument.
Submitted by: Karnajit Wangkhem
Differential Revision: https://reviews.llvm.org/D34776
MFC r322360 (by emaste):
lldb: Report inferior signals as signals, not exceptions, on FreeBSD
This is the FreeBSD equivalent of LLVM r238549.
This serves 2 purposes:
* LLDB should handle inferior process signals SIGSEGV/SIGILL/SIGBUS/
SIGFPE the way it is suppose to be handled. Prior to this fix these
signals will neither create a coredump, nor exit from the debugger
or work for signal handling scenario.
* eInvalidCrashReason need not report "unknown crash reason" if we have
a valid si_signo
llvm.org/pr23699
Patch by Karnajit Wangkhem
Differential Revision: https://reviews.llvm.org/D35223
Submitted by: Karnajit Wangkhem
Obtained from: LLVM r310591
MFC r322474 (by emaste):
lld: Add `-z muldefs` option.
Obtained from: LLVM r310757
MFC r322740:
Upgrade our copies of clang, llvm, lld and libc++ to r311219 from the
upstream release_50 branch.
MFC r322855:
Upgrade our copies of clang, llvm, lldb and compiler-rt to r311606 from
the upstream release_50 branch.
As of this version, lib/msun's trig test should also work correctly
again (see bug 220989 for more information).
PR: 220989
MFC r323112:
Upgrade our copies of clang, llvm, lldb and compiler-rt to r312293 from
the upstream release_50 branch. This corresponds to 5.0.0 rc4.
As of this version, the cad/stepcode port should now compile in a more
reasonable time on i386 (see bug 221836 for more information).
PR: 221836
MFC r323245:
Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
5.0.0 release (upstream r312559).
Release notes for llvm, clang and lld will be available here soon:
<http://releases.llvm.org/5.0.0/docs/ReleaseNotes.html>
<http://releases.llvm.org/5.0.0/tools/clang/docs/ReleaseNotes.html>
<http://releases.llvm.org/5.0.0/tools/lld/docs/ReleaseNotes.html>
Relnotes: yes
(cherry picked from commit 12cd91cf4c6b96a24427c0de5374916f2808d263)
Diffstat (limited to 'contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp | 472 |
1 files changed, 183 insertions, 289 deletions
diff --git a/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp b/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp index 32c57e3..e272d25 100644 --- a/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp +++ b/contrib/llvm/lib/CodeGen/ExecutionDepsFix.cpp @@ -6,21 +6,9 @@ // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// -// -// This file contains the execution dependency fix pass. -// -// Some X86 SSE instructions like mov, and, or, xor are available in different -// variants for different operand types. These variant instructions are -// equivalent, but on Nehalem and newer cpus there is extra latency -// transferring data between integer and floating point domains. ARM cores -// have similar issues when they are configured with both VFP and NEON -// pipelines. -// -// This pass changes the variant instructions to minimize domain crossings. -// -//===----------------------------------------------------------------------===// -#include "llvm/CodeGen/Passes.h" +#include "llvm/CodeGen/ExecutionDepsFix.h" + #include "llvm/ADT/PostOrderIterator.h" #include "llvm/ADT/iterator_range.h" #include "llvm/CodeGen/LivePhysRegs.h" @@ -35,193 +23,18 @@ using namespace llvm; -#define DEBUG_TYPE "execution-fix" - -/// A DomainValue is a bit like LiveIntervals' ValNo, but it also keeps track -/// of execution domains. -/// -/// An open DomainValue represents a set of instructions that can still switch -/// execution domain. Multiple registers may refer to the same open -/// DomainValue - they will eventually be collapsed to the same execution -/// domain. -/// -/// A collapsed DomainValue represents a single register that has been forced -/// into one of more execution domains. There is a separate collapsed -/// DomainValue for each register, but it may contain multiple execution -/// domains. A register value is initially created in a single execution -/// domain, but if we were forced to pay the penalty of a domain crossing, we -/// keep track of the fact that the register is now available in multiple -/// domains. -namespace { -struct DomainValue { - // Basic reference counting. - unsigned Refs; - - // Bitmask of available domains. For an open DomainValue, it is the still - // possible domains for collapsing. For a collapsed DomainValue it is the - // domains where the register is available for free. - unsigned AvailableDomains; - - // Pointer to the next DomainValue in a chain. When two DomainValues are - // merged, Victim.Next is set to point to Victor, so old DomainValue - // references can be updated by following the chain. - DomainValue *Next; - - // Twiddleable instructions using or defining these registers. - SmallVector<MachineInstr*, 8> Instrs; - - // A collapsed DomainValue has no instructions to twiddle - it simply keeps - // track of the domains where the registers are already available. - bool isCollapsed() const { return Instrs.empty(); } - - // Is domain available? - bool hasDomain(unsigned domain) const { - assert(domain < - static_cast<unsigned>(std::numeric_limits<unsigned>::digits) && - "undefined behavior"); - return AvailableDomains & (1u << domain); - } - - // Mark domain as available. - void addDomain(unsigned domain) { - AvailableDomains |= 1u << domain; - } - - // Restrict to a single domain available. - void setSingleDomain(unsigned domain) { - AvailableDomains = 1u << domain; - } - - // Return bitmask of domains that are available and in mask. - unsigned getCommonDomains(unsigned mask) const { - return AvailableDomains & mask; - } - - // First domain available. - unsigned getFirstDomain() const { - return countTrailingZeros(AvailableDomains); - } - - DomainValue() : Refs(0) { clear(); } - - // Clear this DomainValue and point to next which has all its data. - void clear() { - AvailableDomains = 0; - Next = nullptr; - Instrs.clear(); - } -}; -} - -namespace { -/// Information about a live register. -struct LiveReg { - /// Value currently in this register, or NULL when no value is being tracked. - /// This counts as a DomainValue reference. - DomainValue *Value; - - /// Instruction that defined this register, relative to the beginning of the - /// current basic block. When a LiveReg is used to represent a live-out - /// register, this value is relative to the end of the basic block, so it - /// will be a negative number. - int Def; -}; -} // anonymous namespace - -namespace { -class ExeDepsFix : public MachineFunctionPass { - static char ID; - SpecificBumpPtrAllocator<DomainValue> Allocator; - SmallVector<DomainValue*,16> Avail; - - const TargetRegisterClass *const RC; - MachineFunction *MF; - const TargetInstrInfo *TII; - const TargetRegisterInfo *TRI; - RegisterClassInfo RegClassInfo; - std::vector<SmallVector<int, 1>> AliasMap; - const unsigned NumRegs; - LiveReg *LiveRegs; - typedef DenseMap<MachineBasicBlock*, LiveReg*> LiveOutMap; - LiveOutMap LiveOuts; - - /// List of undefined register reads in this block in forward order. - std::vector<std::pair<MachineInstr*, unsigned> > UndefReads; - - /// Storage for register unit liveness. - LivePhysRegs LiveRegSet; - - /// Current instruction number. - /// The first instruction in each basic block is 0. - int CurInstr; - - /// True when the current block has a predecessor that hasn't been visited - /// yet. - bool SeenUnknownBackEdge; - -public: - ExeDepsFix(const TargetRegisterClass *rc) - : MachineFunctionPass(ID), RC(rc), NumRegs(RC->getNumRegs()) {} - - void getAnalysisUsage(AnalysisUsage &AU) const override { - AU.setPreservesAll(); - MachineFunctionPass::getAnalysisUsage(AU); - } - - bool runOnMachineFunction(MachineFunction &MF) override; - - MachineFunctionProperties getRequiredProperties() const override { - return MachineFunctionProperties().set( - MachineFunctionProperties::Property::NoVRegs); - } - - StringRef getPassName() const override { return "Execution dependency fix"; } - -private: - iterator_range<SmallVectorImpl<int>::const_iterator> - regIndices(unsigned Reg) const; - - // DomainValue allocation. - DomainValue *alloc(int domain = -1); - DomainValue *retain(DomainValue *DV) { - if (DV) ++DV->Refs; - return DV; - } - void release(DomainValue*); - DomainValue *resolve(DomainValue*&); - - // LiveRegs manipulations. - void setLiveReg(int rx, DomainValue *DV); - void kill(int rx); - void force(int rx, unsigned domain); - void collapse(DomainValue *dv, unsigned domain); - bool merge(DomainValue *A, DomainValue *B); - - void enterBasicBlock(MachineBasicBlock*); - void leaveBasicBlock(MachineBasicBlock*); - void visitInstr(MachineInstr*); - void processDefs(MachineInstr*, bool Kill); - void visitSoftInstr(MachineInstr*, unsigned mask); - void visitHardInstr(MachineInstr*, unsigned domain); - void pickBestRegisterForUndef(MachineInstr *MI, unsigned OpIdx, - unsigned Pref); - bool shouldBreakDependence(MachineInstr*, unsigned OpIdx, unsigned Pref); - void processUndefReads(MachineBasicBlock*); -}; -} - -char ExeDepsFix::ID = 0; +#define DEBUG_TYPE "execution-deps-fix" /// Translate TRI register number to a list of indices into our smaller tables /// of interesting registers. iterator_range<SmallVectorImpl<int>::const_iterator> -ExeDepsFix::regIndices(unsigned Reg) const { +ExecutionDepsFix::regIndices(unsigned Reg) const { assert(Reg < AliasMap.size() && "Invalid register"); const auto &Entry = AliasMap[Reg]; return make_range(Entry.begin(), Entry.end()); } -DomainValue *ExeDepsFix::alloc(int domain) { +DomainValue *ExecutionDepsFix::alloc(int domain) { DomainValue *dv = Avail.empty() ? new(Allocator.Allocate()) DomainValue : Avail.pop_back_val(); @@ -234,7 +47,7 @@ DomainValue *ExeDepsFix::alloc(int domain) { /// Release a reference to DV. When the last reference is released, /// collapse if needed. -void ExeDepsFix::release(DomainValue *DV) { +void ExecutionDepsFix::release(DomainValue *DV) { while (DV) { assert(DV->Refs && "Bad DomainValue"); if (--DV->Refs) @@ -254,7 +67,7 @@ void ExeDepsFix::release(DomainValue *DV) { /// Follow the chain of dead DomainValues until a live DomainValue is reached. /// Update the referenced pointer when necessary. -DomainValue *ExeDepsFix::resolve(DomainValue *&DVRef) { +DomainValue *ExecutionDepsFix::resolve(DomainValue *&DVRef) { DomainValue *DV = DVRef; if (!DV || !DV->Next) return DV; @@ -271,7 +84,7 @@ DomainValue *ExeDepsFix::resolve(DomainValue *&DVRef) { } /// Set LiveRegs[rx] = dv, updating reference counts. -void ExeDepsFix::setLiveReg(int rx, DomainValue *dv) { +void ExecutionDepsFix::setLiveReg(int rx, DomainValue *dv) { assert(unsigned(rx) < NumRegs && "Invalid index"); assert(LiveRegs && "Must enter basic block first."); @@ -283,7 +96,7 @@ void ExeDepsFix::setLiveReg(int rx, DomainValue *dv) { } // Kill register rx, recycle or collapse any DomainValue. -void ExeDepsFix::kill(int rx) { +void ExecutionDepsFix::kill(int rx) { assert(unsigned(rx) < NumRegs && "Invalid index"); assert(LiveRegs && "Must enter basic block first."); if (!LiveRegs[rx].Value) @@ -294,7 +107,7 @@ void ExeDepsFix::kill(int rx) { } /// Force register rx into domain. -void ExeDepsFix::force(int rx, unsigned domain) { +void ExecutionDepsFix::force(int rx, unsigned domain) { assert(unsigned(rx) < NumRegs && "Invalid index"); assert(LiveRegs && "Must enter basic block first."); if (DomainValue *dv = LiveRegs[rx].Value) { @@ -317,7 +130,7 @@ void ExeDepsFix::force(int rx, unsigned domain) { /// Collapse open DomainValue into given domain. If there are multiple /// registers using dv, they each get a unique collapsed DomainValue. -void ExeDepsFix::collapse(DomainValue *dv, unsigned domain) { +void ExecutionDepsFix::collapse(DomainValue *dv, unsigned domain) { assert(dv->hasDomain(domain) && "Cannot collapse"); // Collapse all the instructions. @@ -333,7 +146,7 @@ void ExeDepsFix::collapse(DomainValue *dv, unsigned domain) { } /// All instructions and registers in B are moved to A, and B is released. -bool ExeDepsFix::merge(DomainValue *A, DomainValue *B) { +bool ExecutionDepsFix::merge(DomainValue *A, DomainValue *B) { assert(!A->isCollapsed() && "Cannot merge into collapsed"); assert(!B->isCollapsed() && "Cannot merge from collapsed"); if (A == B) @@ -359,10 +172,7 @@ bool ExeDepsFix::merge(DomainValue *A, DomainValue *B) { } /// Set up LiveRegs by merging predecessor live-out values. -void ExeDepsFix::enterBasicBlock(MachineBasicBlock *MBB) { - // Detect back-edges from predecessors we haven't processed yet. - SeenUnknownBackEdge = false; - +void ExecutionDepsFix::enterBasicBlock(MachineBasicBlock *MBB) { // Reset instruction counter in each basic block. CurInstr = 0; @@ -397,18 +207,21 @@ void ExeDepsFix::enterBasicBlock(MachineBasicBlock *MBB) { // Try to coalesce live-out registers from predecessors. for (MachineBasicBlock::const_pred_iterator pi = MBB->pred_begin(), pe = MBB->pred_end(); pi != pe; ++pi) { - LiveOutMap::const_iterator fi = LiveOuts.find(*pi); - if (fi == LiveOuts.end()) { - SeenUnknownBackEdge = true; + auto fi = MBBInfos.find(*pi); + assert(fi != MBBInfos.end() && + "Should have pre-allocated MBBInfos for all MBBs"); + LiveReg *Incoming = fi->second.OutRegs; + // Incoming is null if this is a backedge from a BB + // we haven't processed yet + if (Incoming == nullptr) { continue; } - assert(fi->second && "Can't have NULL entries"); for (unsigned rx = 0; rx != NumRegs; ++rx) { // Use the most recent predecessor def for each register. - LiveRegs[rx].Def = std::max(LiveRegs[rx].Def, fi->second[rx].Def); + LiveRegs[rx].Def = std::max(LiveRegs[rx].Def, Incoming[rx].Def); - DomainValue *pdv = resolve(fi->second[rx].Value); + DomainValue *pdv = resolve(Incoming[rx].Value); if (!pdv) continue; if (!LiveRegs[rx].Value) { @@ -432,35 +245,34 @@ void ExeDepsFix::enterBasicBlock(MachineBasicBlock *MBB) { force(rx, pdv->getFirstDomain()); } } - DEBUG(dbgs() << "BB#" << MBB->getNumber() - << (SeenUnknownBackEdge ? ": incomplete\n" : ": all preds known\n")); + DEBUG( + dbgs() << "BB#" << MBB->getNumber() + << (!isBlockDone(MBB) ? ": incomplete\n" : ": all preds known\n")); } -void ExeDepsFix::leaveBasicBlock(MachineBasicBlock *MBB) { +void ExecutionDepsFix::leaveBasicBlock(MachineBasicBlock *MBB) { assert(LiveRegs && "Must enter basic block first."); - // Save live registers at end of MBB - used by enterBasicBlock(). - // Also use LiveOuts as a visited set to detect back-edges. - bool First = LiveOuts.insert(std::make_pair(MBB, LiveRegs)).second; - - if (First) { - // LiveRegs was inserted in LiveOuts. Adjust all defs to be relative to - // the end of this block instead of the beginning. - for (unsigned i = 0, e = NumRegs; i != e; ++i) - LiveRegs[i].Def -= CurInstr; - } else { - // Insertion failed, this must be the second pass. + LiveReg *OldOutRegs = MBBInfos[MBB].OutRegs; + // Save register clearances at end of MBB - used by enterBasicBlock(). + MBBInfos[MBB].OutRegs = LiveRegs; + + // While processing the basic block, we kept `Def` relative to the start + // of the basic block for convenience. However, future use of this information + // only cares about the clearance from the end of the block, so adjust + // everything to be relative to the end of the basic block. + for (unsigned i = 0, e = NumRegs; i != e; ++i) + LiveRegs[i].Def -= CurInstr; + if (OldOutRegs) { + // This must be the second pass. // Release all the DomainValues instead of keeping them. for (unsigned i = 0, e = NumRegs; i != e; ++i) - release(LiveRegs[i].Value); - delete[] LiveRegs; + release(OldOutRegs[i].Value); + delete[] OldOutRegs; } LiveRegs = nullptr; } -void ExeDepsFix::visitInstr(MachineInstr *MI) { - if (MI->isDebugValue()) - return; - +bool ExecutionDepsFix::visitInstr(MachineInstr *MI) { // Update instructions with explicit execution domains. std::pair<uint16_t, uint16_t> DomP = TII->getExecutionDomain(*MI); if (DomP.first) { @@ -470,16 +282,16 @@ void ExeDepsFix::visitInstr(MachineInstr *MI) { visitHardInstr(MI, DomP.first); } - // Process defs to track register ages, and kill values clobbered by generic - // instructions. - processDefs(MI, !DomP.first); + return !DomP.first; } /// \brief Helps avoid false dependencies on undef registers by updating the /// machine instructions' undef operand to use a register that the instruction /// is truly dependent on, or use a register with clearance higher than Pref. -void ExeDepsFix::pickBestRegisterForUndef(MachineInstr *MI, unsigned OpIdx, - unsigned Pref) { +/// Returns true if it was able to find a true dependency, thus not requiring +/// a dependency breaking instruction regardless of clearance. +bool ExecutionDepsFix::pickBestRegisterForUndef(MachineInstr *MI, + unsigned OpIdx, unsigned Pref) { MachineOperand &MO = MI->getOperand(OpIdx); assert(MO.isUndef() && "Expected undef machine operand"); @@ -487,7 +299,7 @@ void ExeDepsFix::pickBestRegisterForUndef(MachineInstr *MI, unsigned OpIdx, // Update only undef operands that are mapped to one register. if (AliasMap[OriginalReg].size() != 1) - return; + return false; // Get the undef operand's register class const TargetRegisterClass *OpRC = @@ -502,7 +314,7 @@ void ExeDepsFix::pickBestRegisterForUndef(MachineInstr *MI, unsigned OpIdx, // We found a true dependency - replace the undef register with the true // dependency. MO.setReg(CurrMO.getReg()); - return; + return true; } // Go over all registers in the register class and find the register with @@ -527,12 +339,14 @@ void ExeDepsFix::pickBestRegisterForUndef(MachineInstr *MI, unsigned OpIdx, // Update the operand if we found a register with better clearance. if (MaxClearanceReg != OriginalReg) MO.setReg(MaxClearanceReg); + + return false; } /// \brief Return true to if it makes sense to break dependence on a partial def /// or undef use. -bool ExeDepsFix::shouldBreakDependence(MachineInstr *MI, unsigned OpIdx, - unsigned Pref) { +bool ExecutionDepsFix::shouldBreakDependence(MachineInstr *MI, unsigned OpIdx, + unsigned Pref) { unsigned reg = MI->getOperand(OpIdx).getReg(); for (int rx : regIndices(reg)) { unsigned Clearance = CurInstr - LiveRegs[rx].Def; @@ -542,14 +356,7 @@ bool ExeDepsFix::shouldBreakDependence(MachineInstr *MI, unsigned OpIdx, DEBUG(dbgs() << ": Break dependency.\n"); continue; } - // The current clearance seems OK, but we may be ignoring a def from a - // back-edge. - if (!SeenUnknownBackEdge || Pref <= unsigned(CurInstr)) { - DEBUG(dbgs() << ": OK .\n"); - return false; - } - // A def from an unprocessed back-edge may make us break this dependency. - DEBUG(dbgs() << ": Wait for back-edge to resolve.\n"); + DEBUG(dbgs() << ": OK .\n"); return false; } return true; @@ -559,16 +366,22 @@ bool ExeDepsFix::shouldBreakDependence(MachineInstr *MI, unsigned OpIdx, // If Kill is set, also kill off DomainValues clobbered by the defs. // // Also break dependencies on partial defs and undef uses. -void ExeDepsFix::processDefs(MachineInstr *MI, bool Kill) { +void ExecutionDepsFix::processDefs(MachineInstr *MI, bool breakDependency, + bool Kill) { assert(!MI->isDebugValue() && "Won't process debug values"); // Break dependence on undef uses. Do this before updating LiveRegs below. unsigned OpNum; - unsigned Pref = TII->getUndefRegClearance(*MI, OpNum, TRI); - if (Pref) { - pickBestRegisterForUndef(MI, OpNum, Pref); - if (shouldBreakDependence(MI, OpNum, Pref)) - UndefReads.push_back(std::make_pair(MI, OpNum)); + if (breakDependency) { + unsigned Pref = TII->getUndefRegClearance(*MI, OpNum, TRI); + if (Pref) { + bool HadTrueDependency = pickBestRegisterForUndef(MI, OpNum, Pref); + // We don't need to bother trying to break a dependency if this + // instruction has a true dependency on that register through another + // operand - we'll have to wait for it to be available regardless. + if (!HadTrueDependency && shouldBreakDependence(MI, OpNum, Pref)) + UndefReads.push_back(std::make_pair(MI, OpNum)); + } } const MCInstrDesc &MCID = MI->getDesc(); for (unsigned i = 0, @@ -584,11 +397,13 @@ void ExeDepsFix::processDefs(MachineInstr *MI, bool Kill) { DEBUG(dbgs() << TRI->getName(RC->getRegister(rx)) << ":\t" << CurInstr << '\t' << *MI); - // Check clearance before partial register updates. - // Call breakDependence before setting LiveRegs[rx].Def. - unsigned Pref = TII->getPartialRegUpdateClearance(*MI, i, TRI); - if (Pref && shouldBreakDependence(MI, i, Pref)) - TII->breakPartialRegDependency(*MI, i, TRI); + if (breakDependency) { + // Check clearance before partial register updates. + // Call breakDependence before setting LiveRegs[rx].Def. + unsigned Pref = TII->getPartialRegUpdateClearance(*MI, i, TRI); + if (Pref && shouldBreakDependence(MI, i, Pref)) + TII->breakPartialRegDependency(*MI, i, TRI); + } // How many instructions since rx was last written? LiveRegs[rx].Def = CurInstr; @@ -607,7 +422,7 @@ void ExeDepsFix::processDefs(MachineInstr *MI, bool Kill) { /// only do it on demand. Note that the occurrence of undefined register reads /// that should be broken is very rare, but when they occur we may have many in /// a single block. -void ExeDepsFix::processUndefReads(MachineBasicBlock *MBB) { +void ExecutionDepsFix::processUndefReads(MachineBasicBlock *MBB) { if (UndefReads.empty()) return; @@ -640,7 +455,7 @@ void ExeDepsFix::processUndefReads(MachineBasicBlock *MBB) { // A hard instruction only works in one domain. All input registers will be // forced into that domain. -void ExeDepsFix::visitHardInstr(MachineInstr *mi, unsigned domain) { +void ExecutionDepsFix::visitHardInstr(MachineInstr *mi, unsigned domain) { // Collapse all uses. for (unsigned i = mi->getDesc().getNumDefs(), e = mi->getDesc().getNumOperands(); i != e; ++i) { @@ -663,7 +478,7 @@ void ExeDepsFix::visitHardInstr(MachineInstr *mi, unsigned domain) { } // A soft instruction can be changed to work in other domains given by mask. -void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) { +void ExecutionDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) { // Bitmask of available domains for this instruction after taking collapsed // operands into account. unsigned available = mask; @@ -774,7 +589,34 @@ void ExeDepsFix::visitSoftInstr(MachineInstr *mi, unsigned mask) { } } -bool ExeDepsFix::runOnMachineFunction(MachineFunction &mf) { +void ExecutionDepsFix::processBasicBlock(MachineBasicBlock *MBB, + bool PrimaryPass) { + enterBasicBlock(MBB); + // If this block is not done, it makes little sense to make any decisions + // based on clearance information. We need to make a second pass anyway, + // and by then we'll have better information, so we can avoid doing the work + // to try and break dependencies now. + bool breakDependency = isBlockDone(MBB); + for (MachineInstr &MI : *MBB) { + if (!MI.isDebugValue()) { + bool Kill = false; + if (PrimaryPass) + Kill = visitInstr(&MI); + processDefs(&MI, breakDependency, Kill); + } + } + if (breakDependency) + processUndefReads(MBB); + leaveBasicBlock(MBB); +} + +bool ExecutionDepsFix::isBlockDone(MachineBasicBlock *MBB) { + return MBBInfos[MBB].PrimaryCompleted && + MBBInfos[MBB].IncomingCompleted == MBBInfos[MBB].PrimaryIncoming && + MBBInfos[MBB].IncomingProcessed == MBB->pred_size(); +} + +bool ExecutionDepsFix::runOnMachineFunction(MachineFunction &mf) { if (skipFunction(*mf.getFunction())) return false; MF = &mf; @@ -810,52 +652,104 @@ bool ExeDepsFix::runOnMachineFunction(MachineFunction &mf) { AliasMap[*AI].push_back(i); } + // Initialize the MMBInfos + for (auto &MBB : mf) { + MBBInfo InitialInfo; + MBBInfos.insert(std::make_pair(&MBB, InitialInfo)); + } + + /* + * We want to visit every instruction in every basic block in order to update + * it's execution domain or break any false dependencies. However, for the + * dependency breaking, we need to know clearances from all predecessors + * (including any backedges). One way to do so would be to do two complete + * passes over all basic blocks/instructions, the first for recording + * clearances, the second to break the dependencies. However, for functions + * without backedges, or functions with a lot of straight-line code, and + * a small loop, that would be a lot of unnecessary work (since only the + * BBs that are part of the loop require two passes). As an example, + * consider the following loop. + * + * + * PH -> A -> B (xmm<Undef> -> xmm<Def>) -> C -> D -> EXIT + * ^ | + * +----------------------------------+ + * + * The iteration order is as follows: + * Naive: PH A B C D A' B' C' D' + * Optimized: PH A B C A' B' C' D + * + * Note that we avoid processing D twice, because we can entirely process + * the predecessors before getting to D. We call a block that is ready + * for its second round of processing `done` (isBlockDone). Once we finish + * processing some block, we update the counters in MBBInfos and re-process + * any successors that are now done. + */ + MachineBasicBlock *Entry = &*MF->begin(); ReversePostOrderTraversal<MachineBasicBlock*> RPOT(Entry); - SmallVector<MachineBasicBlock*, 16> Loops; + SmallVector<MachineBasicBlock *, 4> Workqueue; for (ReversePostOrderTraversal<MachineBasicBlock*>::rpo_iterator MBBI = RPOT.begin(), MBBE = RPOT.end(); MBBI != MBBE; ++MBBI) { MachineBasicBlock *MBB = *MBBI; - enterBasicBlock(MBB); - if (SeenUnknownBackEdge) - Loops.push_back(MBB); - for (MachineInstr &MI : *MBB) - visitInstr(&MI); - processUndefReads(MBB); - leaveBasicBlock(MBB); + // N.B: IncomingProcessed and IncomingCompleted were already updated while + // processing this block's predecessors. + MBBInfos[MBB].PrimaryCompleted = true; + MBBInfos[MBB].PrimaryIncoming = MBBInfos[MBB].IncomingProcessed; + bool Primary = true; + Workqueue.push_back(MBB); + while (!Workqueue.empty()) { + MachineBasicBlock *ActiveMBB = &*Workqueue.back(); + Workqueue.pop_back(); + processBasicBlock(ActiveMBB, Primary); + bool Done = isBlockDone(ActiveMBB); + for (auto *Succ : ActiveMBB->successors()) { + if (!isBlockDone(Succ)) { + if (Primary) { + MBBInfos[Succ].IncomingProcessed++; + } + if (Done) { + MBBInfos[Succ].IncomingCompleted++; + } + if (isBlockDone(Succ)) { + Workqueue.push_back(Succ); + } + } + } + Primary = false; + } } - // Visit all the loop blocks again in order to merge DomainValues from - // back-edges. - for (MachineBasicBlock *MBB : Loops) { - enterBasicBlock(MBB); - for (MachineInstr &MI : *MBB) - if (!MI.isDebugValue()) - processDefs(&MI, false); - processUndefReads(MBB); - leaveBasicBlock(MBB); + // We need to go through again and finalize any blocks that are not done yet. + // This is possible if blocks have dead predecessors, so we didn't visit them + // above. + for (ReversePostOrderTraversal<MachineBasicBlock *>::rpo_iterator + MBBI = RPOT.begin(), + MBBE = RPOT.end(); + MBBI != MBBE; ++MBBI) { + MachineBasicBlock *MBB = *MBBI; + if (!isBlockDone(MBB)) { + processBasicBlock(MBB, false); + // Don't update successors here. We'll get to them anyway through this + // loop. + } } // Clear the LiveOuts vectors and collapse any remaining DomainValues. for (ReversePostOrderTraversal<MachineBasicBlock*>::rpo_iterator MBBI = RPOT.begin(), MBBE = RPOT.end(); MBBI != MBBE; ++MBBI) { - LiveOutMap::const_iterator FI = LiveOuts.find(*MBBI); - if (FI == LiveOuts.end() || !FI->second) + auto FI = MBBInfos.find(*MBBI); + if (FI == MBBInfos.end() || !FI->second.OutRegs) continue; for (unsigned i = 0, e = NumRegs; i != e; ++i) - if (FI->second[i].Value) - release(FI->second[i].Value); - delete[] FI->second; + if (FI->second.OutRegs[i].Value) + release(FI->second.OutRegs[i].Value); + delete[] FI->second.OutRegs; } - LiveOuts.clear(); + MBBInfos.clear(); UndefReads.clear(); Avail.clear(); Allocator.DestroyAll(); return false; } - -FunctionPass * -llvm::createExecutionDependencyFixPass(const TargetRegisterClass *RC) { - return new ExeDepsFix(RC); -} |
