[Bug target/67391] [SH] Convert clrt addc to normal add insn

[olegendo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67391

Oleg Endo <olegendo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kkojima at gcc dot gnu.org

--- Comment #1 from Oleg Endo <olegendo at gcc dot gnu.org> ---
This seems to be (indirectly) caused by the extra checks added to addsi3 as
part of PR 55212, in particular attachment 33707, and r218999, r219341.

Removing those with:

@@ -2129,11 +2129,6 @@
 {
   if (TARGET_SHMEDIA)
     operands[1] = force_reg (SImode, operands[1]);
-  else if (! arith_operand (operands[2], SImode))
-    {
-      if (reg_overlap_mentioned_p (operands[0], operands[1]))
-       FAIL;
-    }
 })

 (define_insn "addsi3_media"
@@ -2172,10 +2167,7 @@
   [(set (match_operand:SI 0 "arith_reg_dest" "=r,&u")
        (plus:SI (match_operand:SI 1 "arith_operand" "%0,r")
                 (match_operand:SI 2 "arith_or_int_operand" "rI08,rn")))]
-  "TARGET_SH1
-   && ((rtx_equal_p (operands[0], operands[1])
-        && arith_operand (operands[2], SImode))
-       || ! reg_overlap_mentioned_p (operands[0], operands[1]))"
+  "TARGET_SH1"
   "@
        add     %2,%0
        #"
@@ -2190,6 +2182,37 @@
 }
   [(set_attr "type" "arith")])

Removes the suspicious clrt-addc sequence.  The added reg overlap
checks/restrictions also trigger some problems with ifcvt, because it tries to
emit insns that go like

(set (reg:SI 162)
    (ne:SI (reg:SI 147 t)
        (const_int 0 [0])))

(set (reg:SI 162)
     (plus:SI (reg:SI 162) (const_int 2147483647)))

I haven't tested the patch above (with LRA enabled), but on CSiBE it does:
sum:  3347407 -> 3346163    -1244 / -0.037163 %

Kaz, do you have any memory of the extra checks?  Isn't it enough to just
accept the addsi3 pattern as "rC = rA + {rB|imm}" and insert the reg-reg copy
after register allocation via split2, as it's already done?  Why are the reg
overlap checks needed during matching of the patterns?