<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Mon, Oct 6, 2014 at 10:09 AM, Benjamin Kramer <span dir="ltr"><<a href="mailto:benny.kra@gmail.com" target="_blank">benny.kra@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class=""><br>
On 06.10.2014, at 18:29, Frédéric Riss <<a href="mailto:friss@apple.com">friss@apple.com</a>> wrote:<br>
<br>
><br>
>> On Oct 6, 2014, at 8:31 AM, Benjamin Kramer <<a href="mailto:benny.kra@googlemail.com">benny.kra@googlemail.com</a>> wrote:<br>
>><br>
>> Author: d0k<br>
>> Date: Mon Oct 6 10:31:04 2014<br>
>> New Revision: 219123<br>
>><br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project?rev=219123&view=rev" target="_blank">http://llvm.org/viewvc/llvm-project?rev=219123&view=rev</a><br>
>> Log:<br>
>> DbgValueHistoryCalculator: Store modified registers in a BitVector instead of std::set.<br>
>><br>
>> And iterate over the smaller map instead of the larger set first. Reduces the time spent in<br>
>> calculateDbgValueHistory by 30-40%.<br>
><br>
> Cool! Do you have a specific testcase where this shows up? how did you measure it? When I last worked on that code, I tried the BitVector approach and it didn’t give me any gain on my specific testcase. I’ll try to run my testcase again.<br>
<br>
</span>This was on a large-ish .c test case with clang -O2 -g under a profiler. This function wasn't particularly hot but std::set always catches my eye ;)<br></blockquote><div><br></div><div>Thanks for the change!</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<br>
- Ben<br>
<div class="HOEnZb"><div class="h5"><br>
><br>
>> Modified:<br>
>> llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp<br>
>><br>
>> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp<br>
>> URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp?rev=219123&r1=219122&r2=219123&view=diff" target="_blank">http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp?rev=219123&r1=219122&r2=219123&view=diff</a><br>
>> ==============================================================================<br>
>> --- llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp (original)<br>
>> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DbgValueHistoryCalculator.cpp Mon Oct 6 10:31:04 2014<br>
>> @@ -8,6 +8,7 @@<br>
>> //===----------------------------------------------------------------------===//<br>
>><br>
>> #include "DbgValueHistoryCalculator.h"<br>
>> +#include "llvm/ADT/BitVector.h"<br>
>> #include "llvm/ADT/SmallVector.h"<br>
>> #include "llvm/CodeGen/MachineBasicBlock.h"<br>
>> #include "llvm/CodeGen/MachineFunction.h"<br>
>> @@ -16,12 +17,10 @@<br>
>> #include "llvm/Target/TargetRegisterInfo.h"<br>
>> #include <algorithm><br>
>> #include <map><br>
>> -#include <set><br>
>> +using namespace llvm;<br>
>><br>
>> #define DEBUG_TYPE "dwarfdebug"<br>
>><br>
>> -namespace llvm {<br>
>> -<br>
>> // \brief If @MI is a DBG_VALUE with debug value described by a<br>
>> // defined register, returns the number of this register.<br>
>> // In the other case, returns 0.<br>
>> @@ -97,6 +96,19 @@ static void addRegDescribedVar(RegDescri<br>
>> VarSet.push_back(Var);<br>
>> }<br>
>><br>
>> +// \brief Terminate the location range for variables described by register at<br>
>> +// @I by inserting @ClobberingInstr to their history.<br>
>> +static void clobberRegisterUses(RegDescribedVarsMap &RegVars,<br>
>> + RegDescribedVarsMap::iterator I,<br>
>> + DbgValueHistoryMap &HistMap,<br>
>> + const MachineInstr &ClobberingInstr) {<br>
>> + // Iterate over all variables described by this register and add this<br>
>> + // instruction to their history, clobbering it.<br>
>> + for (const auto &Var : I->second)<br>
>> + HistMap.endInstrRange(Var, ClobberingInstr);<br>
>> + RegVars.erase(I);<br>
>> +}<br>
>> +<br>
>> // \brief Terminate the location range for variables described by register<br>
>> // @RegNo by inserting @ClobberingInstr to their history.<br>
>> static void clobberRegisterUses(RegDescribedVarsMap &RegVars, unsigned RegNo,<br>
>> @@ -105,11 +117,7 @@ static void clobberRegisterUses(RegDescr<br>
>> const auto &I = RegVars.find(RegNo);<br>
>> if (I == RegVars.end())<br>
>> return;<br>
>> - // Iterate over all variables described by this register and add this<br>
>> - // instruction to their history, clobbering it.<br>
>> - for (const auto &Var : I->second)<br>
>> - HistMap.endInstrRange(Var, ClobberingInstr);<br>
>> - RegVars.erase(I);<br>
>> + clobberRegisterUses(RegVars, I, HistMap, ClobberingInstr);<br>
>> }<br>
>><br>
>> // \brief Collect all registers clobbered by @MI and apply the functor<br>
>> @@ -142,11 +150,12 @@ static const MachineInstr *getFirstEpilo<br>
>> // as the return instruction.<br>
>> DebugLoc LastLoc = LastMI->getDebugLoc();<br>
>> auto Res = LastMI;<br>
>> - for (MachineBasicBlock::const_reverse_iterator I(std::next(LastMI)); I != MBB.rend();<br>
>> - ++I) {<br>
>> + for (MachineBasicBlock::const_reverse_iterator I(std::next(LastMI)),<br>
>> + E = MBB.rend();<br>
>> + I != E; ++I) {<br>
>> if (I->getDebugLoc() != LastLoc)<br>
>> return Res;<br>
>> - Res = std::prev(I.base());<br>
>> + Res = &*I;<br>
>> }<br>
>> // If all instructions have the same debug location, assume whole MBB is<br>
>> // an epilogue.<br>
>> @@ -157,7 +166,7 @@ static const MachineInstr *getFirstEpilo<br>
>> // contents is changed outside of the prologue and epilogue).<br>
>> static void collectChangingRegs(const MachineFunction *MF,<br>
>> const TargetRegisterInfo *TRI,<br>
>> - std::set<unsigned> &Regs) {<br>
>> + BitVector &Regs) {<br>
>> for (const auto &MBB : *MF) {<br>
>> auto FirstEpilogueInst = getFirstEpilogueInst(MBB);<br>
>><br>
>> @@ -165,15 +174,15 @@ static void collectChangingRegs(const Ma<br>
>> if (&MI == FirstEpilogueInst)<br>
>> break;<br>
>> if (!MI.getFlag(MachineInstr::FrameSetup))<br>
>> - applyToClobberedRegisters(MI, TRI, [&](unsigned r) { Regs.insert(r); });<br>
>> + applyToClobberedRegisters(MI, TRI, [&](unsigned r) { Regs.set(r); });<br>
>> }<br>
>> }<br>
>> }<br>
>><br>
>> -void calculateDbgValueHistory(const MachineFunction *MF,<br>
>> - const TargetRegisterInfo *TRI,<br>
>> - DbgValueHistoryMap &Result) {<br>
>> - std::set<unsigned> ChangingRegs;<br>
>> +void llvm::calculateDbgValueHistory(const MachineFunction *MF,<br>
>> + const TargetRegisterInfo *TRI,<br>
>> + DbgValueHistoryMap &Result) {<br>
>> + BitVector ChangingRegs(TRI->getNumRegs());<br>
>> collectChangingRegs(MF, TRI, ChangingRegs);<br>
>><br>
>> RegDescribedVarsMap RegVars;<br>
>> @@ -183,7 +192,7 @@ void calculateDbgValueHistory(const Mach<br>
>> // Not a DBG_VALUE instruction. It may clobber registers which describe<br>
>> // some variables.<br>
>> applyToClobberedRegisters(MI, TRI, [&](unsigned RegNo) {<br>
>> - if (ChangingRegs.count(RegNo))<br>
>> + if (ChangingRegs.test(RegNo))<br>
>> clobberRegisterUses(RegVars, RegNo, Result, MI);<br>
>> });<br>
>> continue;<br>
>> @@ -207,11 +216,12 @@ void calculateDbgValueHistory(const Mach<br>
>> // Make sure locations for register-described variables are valid only<br>
>> // until the end of the basic block (unless it's the last basic block, in<br>
>> // which case let their liveness run off to the end of the function).<br>
>> - if (!MBB.empty() && &MBB != &MF->back()) {<br>
>> - for (unsigned RegNo : ChangingRegs)<br>
>> - clobberRegisterUses(RegVars, RegNo, Result, MBB.back());<br>
>> + if (!MBB.empty() && &MBB != &MF->back()) {<br>
>> + for (auto I = RegVars.begin(), E = RegVars.end(); I != E;) {<br>
>> + auto CurElem = I++; // CurElem can be erased below.<br>
>> + if (ChangingRegs.test(CurElem->first))<br>
>> + clobberRegisterUses(RegVars, CurElem, Result, MBB.back());<br>
>> + }<br>
>> }<br>
>> }<br>
>> }<br>
>> -<br>
>> -}<br>
>><br>
>><br>
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><br>
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</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div dir="ltr">Alexey Samsonov<br><a href="mailto:vonosmas@gmail.com" target="_blank">vonosmas@gmail.com</a></div>
</div></div>