The BSWAP operation is not handled in rtx_costs. Add it.
With Zbb, BSWAP for XLEN is a single instruction; for smaller modes,
it will expand into two.
gcc/ChangeLog:
* config/riscv/riscv.c (rtx_costs): Add BSWAP.
---
gcc/config/riscv/riscv.cc | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 32f9ef9ade9..ab6c745c722 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -2562,6 +2562,16 @@ riscv_rtx_costs (rtx x, machine_mode mode, int
outer_code, int opno ATTRIBUTE_UN
*total = riscv_extend_cost (XEXP (x, 0), GET_CODE (x) == ZERO_EXTEND);
return false;
+ case BSWAP:
+ if (TARGET_ZBB)
+ {
+ /* RISC-V only defines rev8 for XLEN, so we will need an extra
+ shift-right instruction for smaller modes. */
+ *total = COSTS_N_INSNS (mode == word_mode ? 1 : 2);
+ return true;
+ }
+ return false;
+
case FLOAT:
case UNSIGNED_FLOAT:
case FIX:
--
2.34.1
