Callsite `DISubprogram` entries are not generated for:
- builtin functions;
- external functions with reserved names (e.g. names starting from "__").
This limitation was added by the commit [1] as a workaround for the
situation described in [2] that triggered the IR verifier error.
The goal of the present commit is to lift this limitation by adjusting
the IR verifier logic.
The logic behind [1] is to avoid the following situation:
- a `DISubprogram` is added for some builtin function;
- there is some location where this builtin is also emitted by a
transformation (w/o debug location);
- the `Verifier::visitCallBase` sees a call to a function with
`DISubprogram` but w/o debug location and emits an error.
Here is an updated example of such situation taken from [2]:
```
extern "C" int memcmp(void *, void *, long);
struct a { int b; int c; int d; };
struct e { int f[1000]; };
bool foo(e g, e &h) {
// DISubprogram for memcmp is created here when [1] is commented out
return memcmp(&g, &h, sizeof(e));
}
bool bar(a &g, a &h) {
// memcmp might be generated here by MergeICmps
return g.b == h.b && g.c == h.c && g.d == h.d;
}
```
This triggers the verifier error when:
- compiled for AArch64:
`clang++ -c -g -Oz -target aarch64-unknown-linux-android21 test.cpp`;
- [1] check is commented out.
Instead of forbidding generation of `DISubprogram` entries as in [1]
one can instead adjust the verifier to additionally check if callee
has a body. Functions w/o bodies cannot be inlined and thus verifier
warning is not necessary.
E.g. `llvm::InlineFunction` requires functions for which
`GlobalValue::isDeclaration() == false`.
[1] 568db780bb7267651a902da8e85bc59fc89aea70
[2] https://bugs.chromium.org/p/chromium/issues/detail?id=1022296
Differential Revision: https://reviews.llvm.org/D136041
This directory contains testcases that the verifier is supposed to detect as
malformed LLVM code. Testcases for situations that the verifier incorrectly
identifies as malformed should go in the test/Assembler directory.
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