[gcc(refs/vendors/riscv/heads/gcc-13-with-riscv-opts)] RISC-V: Sanitise NEED_EQ_NE_P case with `riscv_emit_int_compare'

[gcc(refs/vendors/riscv/heads/gcc-13-with-riscv-opts)] RISC-V: Sanitise NEED_EQ_NE_P case with `riscv_emit_int_compare'

[Jeff Law]

https://gcc.gnu.org/g:4ac898303c3a0f6e5839eda17bccde2d5fb81911

commit 4ac898303c3a0f6e5839eda17bccde2d5fb81911
Author: Maciej W. Rozycki <macro@embecosm.com>
Date:   Wed Nov 22 01:18:23 2023 +0000

    RISC-V: Sanitise NEED_EQ_NE_P case with `riscv_emit_int_compare'
    
    For the NEED_EQ_NE_P `riscv_emit_int_compare' is documented to only emit
    EQ or NE comparisons against zero, however it does not catch incorrect
    use where a non-equality comparison has been requested and falls through
    to the general case then.  Add a safety guard to catch such a case then.
    
    Arguably the NEED_EQ_NE_P case would best be moved into a function of
    its own, but let's leave it for a separate cleanup.
    
            gcc/
            * config/riscv/riscv.cc (riscv_emit_int_compare): Bail out if
            NEED_EQ_NE_P but the comparison is neither EQ nor NE.
    
    (cherry picked from commit 9f5aa4e210cbcb621ead82f4b56482deaa548c13)

Diff:
---
 gcc/config/riscv/riscv.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 60d3f617395..453c5f17196 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -3808,6 +3808,7 @@ riscv_emit_int_compare (enum rtx_code *code, rtx *op0, rtx *op1,
 	  *op1 = const0_rtx;
 	  return;
 	}
+      gcc_unreachable ();
     }
 
   if (splittable_const_int_operand (*op1, VOIDmode))