[llvm-dev] About "error: instruction expected to be numbered"

Krzysztof Parzyszek via llvm-dev llvm-dev at lists.llvm.org
Tue Jan 22 06:39:24 PST 2019

On 1/22/2019 8:19 AM, Peng Yu via llvm-dev wrote:
> Must the register number be ordered and be without gaps between
> instructions? Is there a way to allow more flexible register
> numbering?

The things in the IR dump with the % prefix are "values" (see Value in 
Value.h). Values may have names, but don't have to. When a value has a 
name, it's printed after the %, so a value with a name "foo" will be 
printed as %foo. Values with names have no restrictions on ordering 
relative to other values.
Values that don't have names will be printed with numbers (e.g. %9), but 
these numbers are not related to names, and they will not become names. 
The numbers are created pretty much out of thin air by the code that 
prints the IR. The flip side is that when the IR is parsed, the numbers 
corresponding to the anonymous values must be sequential, so that you 
cannot have "%5 = ..." followed by "%7 = ...". As you noticed, this 
makes manual editing of the IR somewhat tricky. The easiest thing to do 
is to make sure that all values have names, and to do that you can do 
"opt -S -instnamer < input.ll > output.ll", and all anonymous values in 
input.ll will get names tmp1, tmp2, etc.


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