Un-mangle libc string function names so they can benefit from LLVM optimizations.

sdk/include/cdefs.h

@@ -1,8 +1,7 @@
 // Copyright Microsoft and CHERIoT Contributors.
 // SPDX-License-Identifier: MIT
 
-#ifndef __CDEFS_H__
-#define __CDEFS_H__
+#pragma once
 
 /*
  * Testing against Clang-specific extensions.
@@ -87,14 +86,6 @@ using _Bool = bool;
 #else
 #	define __cheri_libcall __attribute__((cheri_libcall))
 #	define __cheri_callback __attribute__((cheri_ccallback))
-
-/**
- * Define the symbol for the libcall that the compiler will expand the `strlen`
- * builtin to.  This builtin is used internally in libc++ (and possibly in
- * other places) to avoid the namespace pollution from including `string.h` but
- * is either constant folded in the front end or expanded to a libcall.
- */
-unsigned __builtin_strlen(const char *str) __asm__("_Z6strlenPKc");
 #endif
 
 #define offsetof(a, b) __builtin_offsetof(a, b)
@@ -132,4 +123,11 @@ unsigned __builtin_strlen(const char *str) __asm__("_Z6strlenPKc");
 #define CHERIOT_VERSION_TRIPLE(major, minor, patch)                            \
 	((major * 10000) + (minor * 100) + (patch))
 
-#endif // _CDEFS_H_
+/**
+ * Helper for declaring standard library functions that should be exported
+ * as __cheri_libcall, but which should not have their names mangled. This
+ * is needed to enable LLVM optimizations to trigger on standard library
+ * functions.
+ */
+#define CHERIOT_DECLARE_STANDARD_LIBCALL(name, ret, ...)                       \
+	__cheri_libcall ret name(__VA_ARGS__) __asm__(#name);

sdk/include/string.h

@@ -6,27 +6,52 @@
 #include <stddef.h>
 #include <stdint.h>
 
-int __cheri_libcall    memcmp(const void *str1,
-                              const void *str2,
-                              size_t      count) __asm__("memcmp");
-void *__cheri_libcall  memcpy(void       *dest,
-                              const void *src,
-                              size_t      n) __asm__("memcpy");
-void *__cheri_libcall  memset(void *, int, size_t) __asm__("memset");
-void *__cheri_libcall  memmove(void       *dest,
-                               const void *src,
-                               size_t      n) __asm__("memmove");
-void *__cheri_libcall  memchr(const void *, int, size_t);
-void *__cheri_libcall  memrchr(const void *, int, size_t);
-size_t __cheri_libcall strlen(const char *str);
-int __cheri_libcall    strncmp(const char *s1, const char *s2, size_t n);
-char *__cheri_libcall  strncpy(char *dest, const char *src, size_t n);
-int __cheri_libcall    strcmp(const char *s1, const char *s2);
-char *__cheri_libcall  strnstr(const char *haystack,
-                               const char *needle,
-                               size_t      haystackLength);
-char *__cheri_libcall  strchr(const char *s, int c);
-size_t __cheri_libcall strlcpy(char *dest, const char *src, size_t n);
+CHERIOT_DECLARE_STANDARD_LIBCALL(memcmp,
+                                 int,
+                                 const void *str1,
+                                 const void *str2,
+                                 size_t      count)
+CHERIOT_DECLARE_STANDARD_LIBCALL(memcmp,
+                                 int,
+                                 const void *str1,
+                                 const void *str2,
+                                 size_t      count)
+CHERIOT_DECLARE_STANDARD_LIBCALL(memcpy,
+                                 void *,
+                                 void       *dest,
+                                 const void *src,
+                                 size_t      n)
+CHERIOT_DECLARE_STANDARD_LIBCALL(memset, void *, void *, int, size_t)
+CHERIOT_DECLARE_STANDARD_LIBCALL(memmove,
+                                 void *,
+                                 void       *dest,
+                                 const void *src,
+                                 size_t      n)
+CHERIOT_DECLARE_STANDARD_LIBCALL(memchr, void *, const void *, int, size_t)
+CHERIOT_DECLARE_STANDARD_LIBCALL(memrchr, void *, const void *, int, size_t)
+CHERIOT_DECLARE_STANDARD_LIBCALL(strlen, size_t, const char *str)
+CHERIOT_DECLARE_STANDARD_LIBCALL(strncmp,
+                                 int,
+                                 const char *s1,
+                                 const char *s2,
+                                 size_t      n)
+CHERIOT_DECLARE_STANDARD_LIBCALL(strncpy,
+                                 char *,
+                                 char       *dest,
+                                 const char *src,
+                                 size_t      n)
+CHERIOT_DECLARE_STANDARD_LIBCALL(strcmp, int, const char *s1, const char *s2)
+CHERIOT_DECLARE_STANDARD_LIBCALL(strnstr,
+                                 char *,
+                                 const char *haystack,
+                                 const char *needle,
+                                 size_t      haystackLength)
+CHERIOT_DECLARE_STANDARD_LIBCALL(strchr, char *, const char *s, int c)
+CHERIOT_DECLARE_STANDARD_LIBCALL(strlcpy,
+                                 size_t,
+                                 char       *dest,
+                                 const char *src,
+                                 size_t      n)
 
 /**
  * Explicit bzero is a memset variant that the compiler is not permitted to

sdk/lib/atomic/atomic.hh

@@ -9,8 +9,8 @@
  * inserts calls to them.  Declare them using the asm label extension.
  */
 #define DECLARE_ATOMIC_LIBCALL(name, ret, ...)                                 \
-	[[cheri::interrupt_state(disabled)]] __cheri_libcall ret name(             \
-	  __VA_ARGS__) asm(#name);
+	[[cheri::interrupt_state(disabled)]] CHERIOT_DECLARE_STANDARD_LIBCALL(     \
+	  name, ret, __VA_ARGS__)
 
 /**
  * Macro that defines a library function to implement an atomic load for the

sdk/lib/string/strcmp.c

@@ -31,6 +31,7 @@
 
 #include <cdefs.h>
 #include <stddef.h>
+#include <string.h>
 
 /*
  * Compare strings.

sdk/lib/string/strlen.c

@@ -3,6 +3,7 @@
 
 #include <cdefs.h>
 #include <stddef.h>
+#include <string.h>
 
 size_t __cheri_libcall strlen(const char *str)
 {

sdk/lib/string/strncpy.c

@@ -3,6 +3,7 @@
 
 #include <cdefs.h>
 #include <stddef.h>
+#include <string.h>
 
 char *__cheri_libcall strncpy(char *dest, const char *src, size_t n)
 {

tests/allocator-test.cc

@@ -153,7 +153,7 @@ namespace
 
 			free(pStack);
 			free(pGlobal);
-			heap_quarantine_empty();
+			(void)heap_quarantine_empty();
 
 			state = 1;
 
@@ -271,7 +271,7 @@ namespace
 		 * failure we see below isn't because we aren't allowing the revocation
 		 * state machine to advance.
 		 */
-		heap_quarantine_empty();
+		(void)heap_quarantine_empty();
 
 		bool memoryExhausted = false;
 		for (auto &allocation : allocations)