[Bug target/79144] cmpstrnsi optimization breaks glibc

[acsawdey at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79144

--- Comment #2 from acsawdey at gcc dot gnu.org ---
Alan,
  Thanks for jumping in here. What I tried yesterday was this code to try to
get the correct name:

+         const char *id =
+           IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME
+                               (builtin_decl_explicit (BUILT_IN_STRCMP)));
+         if (id == NULL || *id == 0)
+           id = "strcmp";
+         else if (*id == '*')
+           id++;
+         emit_library_call_value (gen_rtx_SYMBOL_REF (Pmode, id),
+                                  target, LCT_NORMAL, GET_MODE (target), 2,
+                                  force_reg (Pmode, XEXP (src1, 0)), Pmode,
+                                  force_reg (Pmode, XEXP (src2, 0)), Pmode);

But this didn't work for reasons I don't quite understand.

The other discussion of this starts here on gcc-patches:

https://gcc.gnu.org/ml/gcc-patches/2017-01/msg00843.html