68 questions
Advice
3
votes
5
replies
177
views
How are loops that modify a state implemented in SSA form?
If I, for example, create my own strlen as such:
unsigned strlen(char *str) {
unsigned len = 0;
while (*str++) len++;
return len;
}
How would this get converted into an SSA form? I've ...
- reputation score 13
1
vote
1
answer
99
views
Superfluous Phi Functions in Self-Loop Converted to SSA
Consider the following statements
10: a = 1
20: b = a
30: a = 2
40: goto 20
This breaks down into two basic blocks: the entry point
# Block 1
10: a = 1
and an infinite loop
Block 2
20: b = a
30: a = ...
- reputation score 321
2
votes
0
answers
247
views
Can't translating out of SSA be more trivial?
I'm reading about how to translate out of SSA form from different sources and I'm having hard time about the necessity of different techniques.
First of all looking at Cytron's SSA paper at section 7 ...
- reputation score 1979
0
votes
1
answer
129
views
How to get method's *ssa.Function
hello i am new to static analysis and try to use golang's SSA package to analyze function code. i want to get a function's or a method's *ssa.Function in the package, get a function's *ssa.Function ...
- reputation score 76
0
votes
1
answer
134
views
Calling Conventions and Register Selection
I've been delving into compiler theory, and how do they really compile source code into machine code. Though, there is something that all papers about register selection seem to ignore, and I'm not ...
- reputation score 97
0
votes
1
answer
81
views
R timeseries 10minutes intervall
I have a large dataset (temp) with measurements every ten minutes over several years. The column "value" also contains NAs.
How can I create a proper timeseries-object? I tried to use the ts ...
- reputation score 1
1
vote
1
answer
714
views
SSA generation using Cytron's algorithm
I'm trying to generate SSA using Cytron's algorithm
Everything seems to work fine but for some test case I'm getting a problem. I have the following loop test example setup:
My problem arises with ...
- reputation score 1979
1
vote
0
answers
184
views
Wrong dominance frontier
My problem is probably misunderstanding of dominance frontier algorithm.
I am implementing SSA form according to this paper: https://c9x.me/compile/bib/ssa.pdf
It seems my algorithm for computing ...
- reputation score 11
0
votes
2
answers
427
views
Do PHI nodes remain in LLVM IR until compilation to binary?
I am new to LLVM and Intermediate Representation (IR), and I am trying to understand how PHI nodes are handled in LLVM IR. I understand that PHI nodes are a fundamental component of SSA (Static Single ...
- reputation score 3706
1
vote
1
answer
393
views
Do phi nodes exist in LLVM IR before the mem2reg optimization pass?
In LLVM IR, phi nodes are a key component of SSA (Static Single Assignment) form and are used to represent control flow in a program. As far as I know the mem2reg optimization pass in LLVM is used to ...
- reputation score 3706
1
vote
0
answers
215
views
What is critical edge spliting used for?
In llvm IR's phi elimination, before adding move instructions to eliminate phi instructions, we need to split the cirtical edge. I don't know what the process of spliting critical edge is used for ...
- reputation score 153
0
votes
1
answer
2k
views
How to eliminate phi instructions in transformed SSA?
I am working on a homework compiler project and I have done the mem2reg pass and got some phi instructions in my LLVM IR.
However, I am confused about how to eliminate the phi nodes (phi destruction). ...
- reputation score 153
2
votes
0
answers
52
views
Can programs in SSA form lead to the construction of cyclic SDG?
Variables in Static Single Assignment (SSA) form transformed programs are only assigned once. This is done by making up a new version of a variable for each variable that is assigned more than once.
...
- reputation score 83
2
votes
1
answer
806
views
Does loop operation with variable assignment violate SSA principle?
I just started to learn LLVM IR and SSA, got a question about the SSA principle.
I found the following code block on the Internet, which seems to violate SSA principle because variables are assigned ...
- reputation score 61
0
votes
1
answer
97
views
Algorithms for repairing ssaa form after modifying the call-flow graph
I'm learning about compiler optimizations on ssa form. One difficulty I'm having is how to retain/repair/reconstruct the ssa form after modifying the structure of the call-flow graph.
Suppose I have ...
- reputation score 20846
