From: David Majnemer <david.majnemer@gmail.com>
Date: Tue, 30 Jun 2015 04:41:18 +0000 (+0000)
Subject: [CodeGen] Tweak isTriviallyRecursive further
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=5eeb3a4bfa5fc568d4f3ac51c9c3392f72a4bb17;p=clang

[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.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@241043 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 461f694acb..ea09ba8d4f 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -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;
 }
diff --git a/test/CodeGen/pr9614.c b/test/CodeGen/pr9614.c
index de21dbbb23..63cb5af186 100644
--- a/test/CodeGen/pr9614.c
+++ b/test/CodeGen/pr9614.c
@@ -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(