524c640090
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
52 lines
2.2 KiB
C
52 lines
2.2 KiB
C
// When entry values are emitted, expect a subprogram for extern decls so that
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// the dwarf generator can describe call site parameters at extern call sites.
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//
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// Initial implementation relied on the 'retainedTypes:' from the corresponding
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// DICompileUnit, so we also ensure that we do not store the extern declaration
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// subprogram into the 'retainedTypes:'.
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//
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// RUN: %clang -g -O2 -target x86_64-none-linux-gnu -S -emit-llvm %s -o - \
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// RUN: | FileCheck %s -check-prefix=DECLS-FOR-EXTERN
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// Similarly, when the debugger tuning is gdb, expect a subprogram for extern
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// decls so that the dwarf generator can describe information needed for tail
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// call frame reconstrution.
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//
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// RUN: %clang -gdwarf-4 -O2 -target x86_64-none-linux-gnu -ggdb -S -emit-llvm %s -o - \
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// RUN: | FileCheck %s -check-prefix=DECLS-FOR-EXTERN
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//
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// Do not emit a subprogram for extern decls when entry values are disabled and
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// the tuning is not set to gdb.
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//
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// RUN: %clang -gdwarf-4 -O2 -target x86_64-none-linux-gnu -gsce -S -emit-llvm %s -o - \
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// RUN: | FileCheck %s -check-prefix=NO-DECLS-FOR-EXTERN
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// DECLS-FOR-EXTERN-NOT: !DICompileUnit({{.*}}retainedTypes: !{{[0-9]+}}
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// DECLS-FOR-EXTERN: [[INT_TYPE:![0-9]+]] = !DIBasicType(name: "int",
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// DECLS-FOR-EXTERN: !DISubprogram(name: "fn1"
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// DECLS-FOR-EXTERN-SAME: type: [[FN1_TYPE:![0-9]+]],
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// DECLS-FOR-EXTERN: [[FN1_TYPE]] = !DISubroutineType(types: [[FN1_TYPES:![0-9]+]])
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// DECLS-FOR-EXTERN: [[FN1_TYPES]] = !{[[X_TYPE:![0-9]+]],
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// DECLS-FOR-EXTERN: [[X_TYPE]] = !DIDerivedType(tag: DW_TAG_typedef, name: "x",
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// DECLS-FOR-EXTERN-SAME: baseType: [[INT_TYPE]])
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// DECLS-FOR-EXTERN: !DISubprogram(name: "memcmp"
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// DECLS-FOR-EXTERN: !DISubprogram(name: "__some_reserved_name"
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// NO-DECLS-FOR-EXTERN-NOT: !DISubprogram(name: "fn1"
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// NO-DECLS-FOR-EXTERN-NOT: !DISubprogram(name: "memcmp"
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// NO-DECLS-FOR-EXTERN-NOT: !DISubprogram(name: "__some_reserved_name"
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typedef int x;
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extern x fn1(int a, int b);
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extern int memcmp(const void *s1, const void *s2, unsigned long n);
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extern void __some_reserved_name(void);
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int fn2 (int *src, int *dst) {
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int x = 4, y = 5;
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int res = fn1(x, y);
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int res2 = memcmp(dst, src, res);
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__some_reserved_name();
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return res + res2;
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}
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