dblaikie added a comment.
Ah, so the intent is that this causes these indirect args to be handled the
same way as other arguments at -O0 - placed in an alloca, eg:
struct t1 {
t1(const t1&);
};
void f1(int, int);
void f2(t1 v, int x) {
f1(3, 4);
}
0x00000033: DW_TAG_formal_parameter
DW_AT_location (indexed (0x0) loclist = 0x00000010:
[0x0000000000000000, 0x0000000000000010): DW_OP_breg5
RDI+0
[0x0000000000000010, 0x0000000000000020):
DW_OP_entry_value(DW_OP_reg5 RDI))
DW_AT_name ("v")
...
0x0000003c: DW_TAG_formal_parameter
DW_AT_location (DW_OP_fbreg -4)
DW_AT_name ("x")
...
Though I guess it doesn't change the codegen so that the alloca is used to load
the value like with other values. Maybe it'd be worth changing the codegen to
be more similar in that way? But maybe not. Don't know.
It seems plausible - though the impact on -O0 will be a question - if this
hurts code size/perf too much (there's /some/ line there, but I don't know what
it is), it couldn't go in -O0 and I'm not sure where it'd go. Logically `-Og`
would make sense, but that's `-O1` which runs mem2reg anyway, so would lose the
alloca, which doesn't help...
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D141381/new/
https://reviews.llvm.org/D141381
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