[PATCH] Fix up tree-ssa-strlen.c ICEs (PR tree-optimization/89703)

[Jakub Jelinek]

Hi!

The C FE sadly passes through some really bad prototypes of builtin
functions as "harmless":
          /* Accept "harmless" mismatches in function types such
             as missing qualifiers or pointer vs same size integer
             mismatches.  This is for the ffs and fprintf builtins.
             However, with -Wextra in effect, diagnose return and
             argument types that are incompatible according to
             language rules.  */
In the strlen pass, we'd better have pointers where we expect pointers and
rightly sized integers where we expect integers.  The following patch
ensures that by calling gimple_builtin_call_types_compatible_p against
the builtin_decl_explicit decl.

Furthermore, I've noticed that a bunch of later added builtins that
the strlen pass now handles weren't added to valid_builtin_call, so the
patch adds that too (that is to handle cases where e.g. somebody declares
strncat as pure, or strcmp as const etc.).

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2019-03-13  Jakub Jelinek  <ja...@redhat.com>

        PR tree-optimization/89703
        * tree-ssa-strlen.c (valid_builtin_call): Punt if stmt call types
        aren't compatible also with builtin_decl_explicit.  Check pure
        or non-pure status of BUILT_IN_STR{{,N}CMP,N{LEN,{CAT,CPY}{,_CHK}}}
        and BUILT_IN_STPNCPY{,_CHK}.

        * gcc.c-torture/compile/pr89703-1.c: New test.
        * gcc.c-torture/compile/pr89703-2.c: New test.

--- gcc/tree-ssa-strlen.c.jj    2019-02-26 21:33:38.992826180 +0100
+++ gcc/tree-ssa-strlen.c       2019-03-13 19:53:20.152551962 +0100
@@ -971,12 +971,21 @@ valid_builtin_call (gimple *stmt)
     return false;
 
   tree callee = gimple_call_fndecl (stmt);
+  tree decl = builtin_decl_explicit (DECL_FUNCTION_CODE (callee));
+  if (decl
+      && decl != callee
+      && !gimple_builtin_call_types_compatible_p (stmt, decl))
+    return false;
+
   switch (DECL_FUNCTION_CODE (callee))
     {
     case BUILT_IN_MEMCMP:
     case BUILT_IN_MEMCMP_EQ:
+    case BUILT_IN_STRCMP:
+    case BUILT_IN_STRNCMP:
     case BUILT_IN_STRCHR:
     case BUILT_IN_STRLEN:
+    case BUILT_IN_STRNLEN:
       /* The above functions should be pure.  Punt if they aren't.  */
       if (gimple_vdef (stmt) || gimple_vuse (stmt) == NULL_TREE)
        return false;
@@ -991,10 +1000,16 @@ valid_builtin_call (gimple *stmt)
     case BUILT_IN_MEMSET:
     case BUILT_IN_STPCPY:
     case BUILT_IN_STPCPY_CHK:
+    case BUILT_IN_STPNCPY:
+    case BUILT_IN_STPNCPY_CHK:
     case BUILT_IN_STRCAT:
     case BUILT_IN_STRCAT_CHK:
     case BUILT_IN_STRCPY:
     case BUILT_IN_STRCPY_CHK:
+    case BUILT_IN_STRNCAT:
+    case BUILT_IN_STRNCAT_CHK:
+    case BUILT_IN_STRNCPY:
+    case BUILT_IN_STRNCPY_CHK:
       /* The above functions should be neither const nor pure.  Punt if they
         aren't.  */
       if (gimple_vdef (stmt) == NULL_TREE || gimple_vuse (stmt) == NULL_TREE)
--- gcc/testsuite/gcc.c-torture/compile/pr89703-1.c.jj  2019-03-13 
19:56:10.619785685 +0100
+++ gcc/testsuite/gcc.c-torture/compile/pr89703-1.c     2019-03-13 
19:55:48.490146110 +0100
@@ -0,0 +1,13 @@
+/* PR tree-optimization/89703 */
+
+typedef __SIZE_TYPE__ size_t;
+extern char *strlen (const char *);
+extern char *strnlen (const char *, size_t);
+extern char c[2];
+
+void
+foo (char **q)
+{
+  q[0] = strlen (c);
+  q[1] = strnlen (c, 2);
+}
--- gcc/testsuite/gcc.c-torture/compile/pr89703-2.c.jj  2019-03-13 
19:56:13.495738838 +0100
+++ gcc/testsuite/gcc.c-torture/compile/pr89703-2.c     2019-03-13 
19:55:55.310035032 +0100
@@ -0,0 +1,13 @@
+/* PR tree-optimization/89703 */
+
+typedef __SIZE_TYPE__ size_t;
+extern void *memcpy (void *, const void *, size_t);
+extern char *strlen (const char *);
+extern char c[2];
+
+void
+foo (char **q)
+{
+  memcpy (c, "a", 2);
+  q[0] = strlen (c);
+}

        Jakub