https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105360
Bug ID: 105360
Summary: Inlined lazy parameters / delegate literals, still
emitted
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: d
Assignee: ibuclaw at gdcproject dot org
Reporter: witold.baryluk+gcc at gmail dot com
Target Milestone: ---
```
extern bool g();
extern void f(int n);
void log(lazy int num) {
if (g()) {
const n = num();
f(n);
}
}
void p(int n) {
log(n * 137);
}
```
This should emit the same (or close to the same) as code with no `lazy` (and
num reference changed accordingly) on `log` function. (Because compiler knows
that `num ` is called once, has no side effects, is moderately expensive, etc).
And the code for p is exactly the same - log and `n * 137` fully inlined.
However, the anonymous dgliteral code is still emitted, despite not being
referenced anywhere:
```
pure nothrow @nogc @safe int example.p(int).__dgliteral2(): # < This should
not be in object file
imul eax, DWORD PTR [rdi], 137
ret
```
Rest of the object file is correct and optimal:
```
void example.log(lazy int):
push rbp
push rbx
mov rbp, rdi
mov rbx, rsi
sub rsp, 8
call bool example.g()
test al, al
je .L3
mov rdi, rbp
call rbx
add rsp, 8
pop rbx
pop rbp
mov edi, eax
jmp void example.f(int)
.L3:
add rsp, 8
pop rbx
pop rbp
ret
void example.p(int):
push rbx
mov ebx, edi
call bool example.g()
test al, al
je .L6
imul edi, ebx, 137
pop rbx
jmp void example.f(int)
.L6:
pop rbx
ret
```
gdc
(Compiler-Explorer-Build-gcc-748d46cd049c89a799f99f14547267ebae915af6-binutils-2.36.1)
12.0.1 20220421 (experimental) via godbolt.org
For a code passing reasonably big literals, this can lead to object file code
duplication.
ldc2 shows no such problem.
