[llvm] r191859 - [llvm-c][Disassembler] Add an option to print latency information in
Quentin Colombet
qcolombet at apple.com
Wed Oct 2 15:07:57 PDT 2013
Author: qcolombet
Date: Wed Oct 2 17:07:57 2013
New Revision: 191859
URL: http://llvm.org/viewvc/llvm-project?rev=191859&view=rev
Log:
[llvm-c][Disassembler] Add an option to print latency information in
disassembled output alongside the instructions.
E.g., on a vector shuffle operation with a memory operand, disassembled
outputs are:
* Without the option:
vpshufd $-0x79, (%rsp), %xmm0
* With the option:
vpshufd $-0x79, (%rsp), %xmm0 ## Latency: 5
The printed latency is extracted from the schedule model available in the
disassembler context. Thus, this option has no effect if there is not a
scheduling model for the target.
This boils down to one may need to specify the CPU string, so that this
option could have an effect.
Note: Latency < 2 are not printed.
This part of <rdar://problem/14687488>.
Modified:
llvm/trunk/include/llvm-c/Disassembler.h
llvm/trunk/lib/MC/MCDisassembler/Disassembler.cpp
llvm/trunk/lib/MC/MCDisassembler/Disassembler.h
Modified: llvm/trunk/include/llvm-c/Disassembler.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm-c/Disassembler.h?rev=191859&r1=191858&r2=191859&view=diff
==============================================================================
--- llvm/trunk/include/llvm-c/Disassembler.h (original)
+++ llvm/trunk/include/llvm-c/Disassembler.h Wed Oct 2 17:07:57 2013
@@ -172,6 +172,8 @@ int LLVMSetDisasmOptions(LLVMDisasmConte
#define LLVMDisassembler_Option_AsmPrinterVariant 4
/* The option to set comment on instructions */
#define LLVMDisassembler_Option_SetInstrComments 8
+ /* The option to print latency information alongside instructions */
+#define LLVMDisassembler_Option_PrintLatency 16
/**
* Dispose of a disassembler context.
Modified: llvm/trunk/lib/MC/MCDisassembler/Disassembler.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCDisassembler/Disassembler.cpp?rev=191859&r1=191858&r2=191859&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCDisassembler/Disassembler.cpp (original)
+++ llvm/trunk/lib/MC/MCDisassembler/Disassembler.cpp Wed Oct 2 17:07:57 2013
@@ -174,6 +174,52 @@ static void emitComments(LLVMDisasmConte
DC->CommentStream.resync();
}
+/// \brief Gets latency information for \p Inst, based on \p DC information.
+/// \return The maximum expected latency over all the definitions or -1
+/// if no information are available.
+static int getLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
+ // Try to compute scheduling information.
+ const MCSubtargetInfo *STI = DC->getSubtargetInfo();
+ const MCSchedModel *SCModel = STI->getSchedModel();
+ const int NoInformationAvailable = -1;
+
+ // Check if we have a scheduling model for instructions.
+ if (!SCModel || !SCModel->hasInstrSchedModel())
+ return NoInformationAvailable;
+
+ // Get the scheduling class of the requested instruction.
+ const MCInstrDesc& Desc = DC->getInstrInfo()->get(Inst.getOpcode());
+ unsigned SCClass = Desc.getSchedClass();
+ const MCSchedClassDesc *SCDesc = SCModel->getSchedClassDesc(SCClass);
+ if (!SCDesc || !SCDesc->isValid())
+ return NoInformationAvailable;
+
+ // Compute output latency.
+ int Latency = 0;
+ for (unsigned DefIdx = 0, DefEnd = SCDesc->NumWriteLatencyEntries;
+ DefIdx != DefEnd; ++DefIdx) {
+ // Lookup the definition's write latency in SubtargetInfo.
+ const MCWriteLatencyEntry *WLEntry = STI->getWriteLatencyEntry(SCDesc,
+ DefIdx);
+ Latency = std::max(Latency, WLEntry->Cycles);
+ }
+
+ return Latency;
+}
+
+
+/// \brief Emits latency information in DC->CommentStream for \p Inst, based
+/// on the information available in \p DC.
+static void emitLatency(LLVMDisasmContext *DC, const MCInst &Inst) {
+ int Latency = getLatency(DC, Inst);
+
+ // Report only interesting latency.
+ if (Latency < 2)
+ return;
+
+ DC->CommentStream << "Latency: " << Latency << '\n';
+}
+
//
// LLVMDisasmInstruction() disassembles a single instruction using the
// disassembler context specified in the parameter DC. The bytes of the
@@ -217,6 +263,9 @@ size_t LLVMDisasmInstruction(LLVMDisasmC
formatted_raw_ostream FormattedOS(OS);
IP->printInst(&Inst, FormattedOS, AnnotationsStr);
+ if (DC->getOptions() & LLVMDisassembler_Option_PrintLatency)
+ emitLatency(DC, Inst);
+
emitComments(DC, FormattedOS);
assert(OutStringSize != 0 && "Output buffer cannot be zero size");
@@ -239,12 +288,14 @@ int LLVMSetDisasmOptions(LLVMDisasmConte
LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
MCInstPrinter *IP = DC->getIP();
IP->setUseMarkup(1);
+ DC->addOptions(LLVMDisassembler_Option_UseMarkup);
Options &= ~LLVMDisassembler_Option_UseMarkup;
}
if (Options & LLVMDisassembler_Option_PrintImmHex){
LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
MCInstPrinter *IP = DC->getIP();
IP->setPrintImmHex(1);
+ DC->addOptions(LLVMDisassembler_Option_PrintImmHex);
Options &= ~LLVMDisassembler_Option_PrintImmHex;
}
if (Options & LLVMDisassembler_Option_AsmPrinterVariant){
@@ -260,6 +311,7 @@ int LLVMSetDisasmOptions(LLVMDisasmConte
AsmPrinterVariant, *MAI, *MII, *MRI, *STI);
if (IP) {
DC->setIP(IP);
+ DC->addOptions(LLVMDisassembler_Option_AsmPrinterVariant);
Options &= ~LLVMDisassembler_Option_AsmPrinterVariant;
}
}
@@ -267,7 +319,13 @@ int LLVMSetDisasmOptions(LLVMDisasmConte
LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
MCInstPrinter *IP = DC->getIP();
IP->setCommentStream(DC->CommentStream);
+ DC->addOptions(LLVMDisassembler_Option_SetInstrComments);
Options &= ~LLVMDisassembler_Option_SetInstrComments;
}
+ if (Options & LLVMDisassembler_Option_PrintLatency) {
+ LLVMDisasmContext *DC = (LLVMDisasmContext *)DCR;
+ DC->addOptions(LLVMDisassembler_Option_PrintLatency);
+ Options &= ~LLVMDisassembler_Option_PrintLatency;
+ }
return (Options == 0);
}
Modified: llvm/trunk/lib/MC/MCDisassembler/Disassembler.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCDisassembler/Disassembler.h?rev=191859&r1=191858&r2=191859&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCDisassembler/Disassembler.h (original)
+++ llvm/trunk/lib/MC/MCDisassembler/Disassembler.h Wed Oct 2 17:07:57 2013
@@ -73,6 +73,8 @@ private:
llvm::OwningPtr<const llvm::MCDisassembler> DisAsm;
// The instruction printer for the target architecture.
llvm::OwningPtr<llvm::MCInstPrinter> IP;
+ // The options used to set up the disassembler.
+ uint64_t Options;
public:
// Comment stream and backing vector.
@@ -90,6 +92,7 @@ public:
MCInstPrinter *iP) : TripleName(tripleName),
DisInfo(disInfo), TagType(tagType), GetOpInfo(getOpInfo),
SymbolLookUp(symbolLookUp), TheTarget(theTarget),
+ Options(0),
CommentStream(CommentsToEmit) {
MAI.reset(mAI);
MRI.reset(mRI);
@@ -114,6 +117,8 @@ public:
const MCSubtargetInfo *getSubtargetInfo() const { return MSI.get(); }
MCInstPrinter *getIP() { return IP.get(); }
void setIP(MCInstPrinter *NewIP) { IP.reset(NewIP); }
+ uint64_t getOptions() const { return Options; }
+ void addOptions(uint64_t Options) { this->Options |= Options; }
};
} // namespace llvm
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