Re: [PATCH 3/5] [RISC-V] Generate Zicond instruction for select pattern with condition eq or neq to 0

[Jeff Law via Gcc-patches]

On 7/25/23 11:55, Andreas Schwab wrote:
On Jul 19 2023, Xiao Zeng wrote:

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 38d8eb2fcf5..7e6b24bd232 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -2448,6 +2448,17 @@ riscv_rtx_costs (rtx x, machine_mode mode, int 
outer_code, int opno ATTRIBUTE_UN
          *total = COSTS_N_INSNS (1);
          return true;
        }
+      else if (TARGET_ZICOND && outer_code == SET &&
+               ((GET_CODE (XEXP (x, 1)) == REG && XEXP (x, 2) == const0_rtx) ||
+               (GET_CODE (XEXP (x, 2)) == REG && XEXP (x, 1) == const0_rtx) ||
+               (GET_CODE (XEXP (x, 1)) == REG && GET_CODE (XEXP (x, 2)) &&
+                XEXP (x, 1) == XEXP (XEXP (x, 0), 0)) ||
+               (GET_CODE (XEXP (x, 1)) == REG && GET_CODE (XEXP (x, 2)) &&
+                XEXP (x, 2) == XEXP (XEXP (x, 0), 0))))

Line breaks before the operator, not after.
Also note that && GET_CODE (XEXP (x, 2)) && that appears twice.

That just verifies the code isn't RTX_UNKNOWN which I suspect isn't what 
the author intended.  It probably needs to be adjusted for SUBREGs and 
the pointer equality issues with REGs after reload.

I'll take care of these goofs since the costing ought to be able to move 
forward independently of the improvements Xiao made to generating 
conditional move sequences.

Jeff