https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112494
--- Comment #7 from Uroš Bizjak <ubizjak at gmail dot com> ---
It looks to me that gcc_unreachable is problematic in SELECT_CC_MODE. We should
simply return CCmode for all unrecognised RTX:
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 2c80fd8ebf3..5b87361e2e1 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -16469,12 +16504,9 @@ ix86_cc_mode (enum rtx_code code, rtx op0, rtx op1)
return CCNOmode;
else
return CCGCmode;
- /* strcmp pattern do (use flags) and combine may ask us for proper
- mode. */
- case USE:
- return CCmode;
default:
- gcc_unreachable ();
+ /* CCmode should be used in all other cases. */
+ return CCmode;
}
}
Using the above patch, we can also define cmpstrnqi_1 to what it really does:
@@ -22954,9 +22958,8 @@ (define_expand "cmpstrnqi_1"
(const_int 0))
(compare:CC (match_operand 4 "memory_operand")
(match_operand 5 "memory_operand"))
- (const_int 0)))
+ (reg:CC FLAGS_REG)))
(use (match_operand:SI 3 "immediate_operand"))
- (use (reg:CC FLAGS_REG))
(clobber (match_operand 0 "register_operand"))
(clobber (match_operand 1 "register_operand"))
(clobber (match_dup 2))])]
