[gcc r11-11457] MIPS16: Mark $2/$3 as clobbered if GP is used

[YunQiang Su via Gcc-cvs]

https://gcc.gnu.org/g:1bc4a777b21ae36b116e1842b7c482340ec929ef

commit r11-11457-g1bc4a777b21ae36b116e1842b7c482340ec929ef
Author: YunQiang Su <s...@gcc.gnu.org>
Date:   Wed May 29 02:28:25 2024 +0800

    MIPS16: Mark $2/$3 as clobbered if GP is used
    
    PR Target/84790.
    The gp init sequence
            li      $2,%hi(_gp_disp)
            addiu   $3,$pc,%lo(_gp_disp)
            sll     $2,16
            addu    $2,$3
    is generated directly in `mips_output_function_prologue`, and does
    not appear in the RTL.
    
    So the IRA/IPA passes are not aware that $2/$3 have been clobbered,
    so they may be used for cross (local) function call.
    
    Let's mark $2/$3 clobber both:
      - Just after the UNSPEC_GP RTL of a function;
      - Just after a function call.
    
    Reported-by: Matthias Schiffer <mschif...@universe-factory.net>
    Origin-Patch-by: Felix Fietkau <n...@nbd.name>.
    
    gcc
            * config/mips/mips.c(mips16_gp_pseudo_reg): Mark
            MIPS16_PIC_TEMP and MIPS_PROLOGUE_TEMP clobbered.
            (mips_emit_call_insn): Mark MIPS16_PIC_TEMP and
            MIPS_PROLOGUE_TEMP clobbered if MIPS16 and CALL_CLOBBERED_GP.
    
    (cherry picked from commit 915440eed21de367cb41857afb5273aff5bcb737)

Diff:
---
 gcc/config/mips/mips.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index bb6ff08e94c..3cf09494aec 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -3138,6 +3138,9 @@ mips_emit_call_insn (rtx pattern, rtx orig_addr, rtx 
addr, bool lazy_p)
     {
       rtx post_call_tmp_reg = gen_rtx_REG (word_mode, POST_CALL_TMP_REG);
       clobber_reg (&CALL_INSN_FUNCTION_USAGE (insn), post_call_tmp_reg);
+      clobber_reg (&CALL_INSN_FUNCTION_USAGE (insn), MIPS16_PIC_TEMP);
+      clobber_reg (&CALL_INSN_FUNCTION_USAGE (insn),
+                       MIPS_PROLOGUE_TEMP (word_mode));
     }
 
   return insn;
@@ -3234,7 +3237,13 @@ mips16_gp_pseudo_reg (void)
       rtx set = gen_load_const_gp (cfun->machine->mips16_gp_pseudo_rtx);
       rtx_insn *insn = emit_insn_after (set, scan);
       INSN_LOCATION (insn) = 0;
-
+      /* NewABI support hasn't been implement.  NewABI should generate RTL
+        sequence instead of ASM sequence directly.  */
+      if (mips_current_loadgp_style () == LOADGP_OLDABI)
+       {
+         emit_clobber (MIPS16_PIC_TEMP);
+         emit_clobber (MIPS_PROLOGUE_TEMP (Pmode));
+       }
       pop_topmost_sequence ();
     }