instruction CE_GEP

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1

Hi all,

I have a question with the ”getelemptr” instruction.

E.g.: I have some GEP instructions in my program.

Some look like:

<INST_GEP op0=26 op1=64 op2=429/>

…

<INST_GEP op0=341 op1=64 op2=101 op3=499 op4=0/>

The first instruction above in assembly file:

%tmp60 = getelementptr [512 x i32]* @weights, i32 0, i32 %k.3.ph

Ok, we see it all:

Index of @weights in value list = 26

Index of “i32 0” in value list = 64

Index of “i32 %k.3.ph” in value list = 429

But in the second instructions:

%tmp67.1 = getelementptr [8 x [8 x i32]]* %inter, i32 0, i32 1, i32 %outc.0.reg2mem.0

As the first one, we see:

Index of %inter in value list = 341

Index of “i32 0” in value list = 64

Index of “i32 1” in value list = 101

Index of “i32 %outc.0.reg2mem.0” in value list = 499

è What is the last one, “op4=0” ?

And the index of the second instruction in value list is less than 499.

Thanks for any advice.

Quang

2

The type of a value is only encoded for forward references. Please see the source for the bitcode reader for more information. Here’s a snippet that is useful:

/// getValueTypePair - Read a value/type pair out of the specified record from
/// slot ‘Slot’. Increment Slot past the number of slots used in the record.
/// Return true on failure.
bool getValueTypePair(SmallVector<uint64_t, 64> &Record, unsigned &Slot,
unsigned InstNum, Value *&ResVal) {
if (Slot == Record.size()) return true;
unsigned ValNo = (unsigned)Record[Slot++];
if (ValNo < InstNum) {
// If this is not a forward reference, just return the value we already
// have.
ResVal = getFnValueByID(ValNo, 0);
return ResVal == 0;
} else if (Slot == Record.size()) {
return true;
}

unsigned TypeNo = (unsigned)Record[Slot++];
ResVal = getFnValueByID(ValNo, getTypeByID(TypeNo));
return ResVal == 0;
}

-Chris