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[CodeGen] Tweak isTriviallyRecursive further 

isTriviallyRecursive is a hack used to bridge a gap between the
expectations that source code assumes and the semantics that LLVM IR can
provide.  Specifically, asm labels on functions are treated as an
explicit name for a GlobalObject in Clang but treated like an
output-processing step in GCC.  Tweak this hack a little further to emit
calls to library functions instead of emitting an incorrect definition.
The definition in question would have available_externally linkage (this
is OK) but result in a call to itself which will either result in an
infinite loop or stack overflow.

This fixes PR23964.

llvm-svn: 241043
This commit is contained in:
David Majnemer 2015-06-30 04:41:18 +00:00
parent 41bb43252b
commit 64b0bdf88a
2 changed files with 8 additions and 6 deletions
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7
clang/lib/CodeGen/CodeGenModule.cpp
View File

@ -1457,12 +1457,7 @@ CodeGenModule::isTriviallyRecursive(const FunctionDecl *FD) {
Name = FD->getName();
}
auto &BI = Context.BuiltinInfo;
unsigned BuiltinID = Context.Idents.get(Name).getBuiltinID();
if (!BuiltinID || !BI.isPredefinedLibFunction(BuiltinID))
return false;
FunctionIsDirectlyRecursive Walker(Name, BI);
FunctionIsDirectlyRecursive Walker(Name, Context.BuiltinInfo);
Walker.TraverseFunctionDecl(const_cast<FunctionDecl*>(FD));
return Walker.Result;
}

7
clang/test/CodeGen/pr9614.c
View File

@ -18,11 +18,16 @@ prefetch(void) {
__builtin_prefetch(0, 0, 1);
}
extern inline __attribute__((__always_inline__, __gnu_inline__)) void *memchr(void *__s, int __c, __SIZE_TYPE__ __n) {
return __builtin_memchr(__s, __c, __n);
}
void f(void) {
foo();
abs(0);
strrchr_foo("", '.');
prefetch();
memchr("", '.', 0);
}
// CHECK-LABEL: define void @f()
@ -30,9 +35,11 @@ void f(void) {
// CHECK: call i32 @abs(i32 0)
// CHECK: call i8* @strrchr(
// CHECK: call void @llvm.prefetch(
// CHECK: call i8* @memchr(
// CHECK: ret void
// CHECK: declare void @foo()
// CHECK: declare i32 @abs(i32
// CHECK: declare i8* @strrchr(i8*, i32)
// CHECK: declare i8* @memchr(
// CHECK: declare void @llvm.prefetch(