commit 0f9bb3e7a4aab95fd449f60b5f891ed9a6e5f352
Author: Jeff Law <jlaw@ventanamicro.com>
Date:   Sun Jun 18 11:25:12 2023 -0600

    Fix arc assumption that insns are not re-recognized
    
    Testing the V2 version of Manolis's fold-mem-offsets patch exposed a minor bug
    in the arc backend.
    
    The movsf_insn pattern has constraints which allow storing certain constants
    to memory.  reload/lra will target those alternatives under the right
    circumstances.  However the insn's condition requires that one of the two
    operands must be a register.
    
    Thus if a pass were to force re-recognition of the pattern we can get an
    unrecognized insn failure.
    
    This patch adjusts the conditions to more closely match movsi_insn.  More
    specifically it allows storing a constant into a limited set of memory
    operands (as defined by the Usc constraint).  movqi_insn has the same
    core problem and gets the same solution.
    
    Committed after the tester validated there are not regresisons
    
    gcc/
            * config/arc/arc.md (movqi_insn): Allow certain constants to
            be stored into memory in the pattern's condition.
            (movsf_insn): Similarly.

diff --git a/gcc/config/arc/arc.md b/gcc/config/arc/arc.md
index c51ce173350..1f122d9507f 100644
--- a/gcc/config/arc/arc.md
+++ b/gcc/config/arc/arc.md
@@ -705,6 +705,9 @@ (define_insn "*movqi_insn"
 	(match_operand:QI 1 "move_src_operand"  "rL,rP,q,P,hCm1,cL, I,?Rac,i,?i,T,q,Usd,Ucm,m,?Rac,c,?Rac,Cm3,i"))]
   "register_operand (operands[0], QImode)
    || register_operand (operands[1], QImode)
+   || (CONSTANT_P (operands[1])
+       && (!satisfies_constraint_I (operands[1]) || !optimize_size)
+       && satisfies_constraint_Usc (operands[0]))
    || (satisfies_constraint_Cm3 (operands[1])
        && memory_operand (operands[0], QImode))"
   "@
@@ -1363,7 +1366,10 @@ (define_insn "*movsf_insn"
   [(set (match_operand:SF 0 "move_dest_operand"   "=h,h,   r,r,  q,S,Usc,r,m")
 	(match_operand:SF 1 "move_src_operand"  "hCfZ,E,rCfZ,E,Uts,q,  E,m,r"))]
   "register_operand (operands[0], SFmode)
-   || register_operand (operands[1], SFmode)"
+   || register_operand (operands[1], SFmode)
+   || (CONSTANT_P (operands[1])
+       && (!satisfies_constraint_I (operands[1]) || !optimize_size)
+       && satisfies_constraint_Usc (operands[0]))"
   "@
    mov%?\\t%0,%1
    mov%?\\t%0,%1 ; %A1