[CIR] Change default assumption about allowing builtins

clang/lib/CIR/CodeGen/CIRGenExpr.cpp

@@ -1052,7 +1052,8 @@ CIRGenCallee CIRGenFunction::emitDirectCallee(const GlobalDecl &gd) {
 
     bool isPredefinedLibFunction =
         cgm.getASTContext().BuiltinInfo.isPredefinedLibFunction(builtinID);
-    bool hasAttributeNoBuiltin = false;
+    // Assume nobuiltins everywhere until we actually read the attributes.
+    bool hasAttributeNoBuiltin = true;
     assert(!cir::MissingFeatures::attributeNoBuiltin());
 
     // When directing calling an inline builtin, call it through it's mangled

clang/test/CIR/CodeGen/libc.c

@@ -0,0 +1,55 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s
+
+// Note: In the final implementation, we will want these to generate
+//       CIR-specific libc operations. This test is just a placeholder
+//       to make sure we can compile these to normal function calls
+//       until the special handling is implemented.
+
+void *memcpy(void *, const void *, unsigned long);
+void testMemcpy(void *dst, const void *src, unsigned long size) {
+  memcpy(dst, src, size);
+  // CHECK: cir.call @memcpy
+}
+
+void *memmove(void *, const void *, unsigned long);
+void testMemmove(void *src, const void *dst, unsigned long size) {
+  memmove(dst, src, size);
+  // CHECK: cir.call @memmove
+}
+
+void *memset(void *, int, unsigned long);
+void testMemset(void *dst, int val, unsigned long size) {
+  memset(dst, val, size);
+  // CHECK: cir.call @memset
+}
+
+double fabs(double);
+double testFabs(double x) {
+  return fabs(x);
+  // CHECK: cir.call @fabs
+}
+
+float fabsf(float);
+float testFabsf(float x) {
+  return fabsf(x);
+  // CHECK: cir.call @fabsf
+}
+
+int abs(int);
+int testAbs(int x) {
+  return abs(x);
+  // CHECK: cir.call @abs
+}
+
+long labs(long);
+long testLabs(long x) {
+  return labs(x);
+  // CHECK: cir.call @labs
+}
+
+long long llabs(long long);
+long long testLlabs(long long x) {
+  return llabs(x);
+  // CHECK: cir.call @llabs
+}