riscv: Fix insn cost calculation

When building riscv32-none-elf with "--enable-checking=yes,rtl", the
following ICE is observed:

  cc1: internal compiler error: RTL check: expected code 'const_int', have 'const_double' in riscv_const_insns, at config/riscv/riscv.cc:1313
  0x843c4d rtl_check_failed_code1(rtx_def const*, rtx_code, char const*, int, char const*)
          /mnt/nvme/dinux/local-workspace/gcc/gcc/rtl.cc:916
  0x8eab61 riscv_const_insns(rtx_def*)
          /mnt/nvme/dinux/local-workspace/gcc/gcc/config/riscv/riscv.cc:1313
  0x15443bb riscv_legitimate_constant_p
          /mnt/nvme/dinux/local-workspace/gcc/gcc/config/riscv/riscv.cc:826
  0xdd3c71 emit_move_insn(rtx_def*, rtx_def*)
          /mnt/nvme/dinux/local-workspace/gcc/gcc/expr.cc:4310
  0x15f28e5 run_const_vector_selftests
          /mnt/nvme/dinux/local-workspace/gcc/gcc/config/riscv/riscv-selftests.cc:285
  0x15f37bd selftest::riscv_run_selftests()
          /mnt/nvme/dinux/local-workspace/gcc/gcc/config/riscv/riscv-selftests.cc:364
  0x1f6fba9 selftest::run_tests()
          /mnt/nvme/dinux/local-workspace/gcc/gcc/selftest-run-tests.cc:111
  0x11d1f39 toplev::run_self_tests()
          /mnt/nvme/dinux/local-workspace/gcc/gcc/toplev.cc:2185

Fix by following the spirit of the adjacent comment, and using the
dedicated riscv_const_insns() function to calculate cost for loading a
constant element.  Infinite recursion is not possible because the first
invocation is on a CONST_VECTOR, whereas the second is on a single
element of the vector (e.g. CONST_INT or CONST_DOUBLE).

Regression tested for riscv32-none-elf. No changes in gcc.sum and
g++.sum.

gcc/ChangeLog:

	* config/riscv/riscv.cc (riscv_const_insns): Recursively call
	for constant element of a vector.

Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 21e7d3b3caaadd6f9a78e8a75ea77b2562a5133b..4ff3758434cbb3ef108e6e813c295306f652dc6e 100644 (file)
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -1310,7 +1310,7 @@ riscv_const_insns (rtx x)
                   a general-purpose register.  This means we need as many
                   insns as it takes to load the constant into the GPR
                   and one vmv.v.x.  */
-               return 1 + riscv_integer_cost (INTVAL (elt));
+               return 1 + riscv_const_insns (elt);
              }
          }