Re: [PATCH] RISC-V: Fix ICE of visiting non-existing block in CFG.

[Jeff Law via Gcc-patches]

On 12/23/22 20:08, juzhe.zh...@rivai.ai wrote:
From: Ju-Zhe Zhong <juzhe.zh...@rivai.ai>

This patch is to fix issue of visiting non-existing block of CFG.
Since blocks index of CFG in GCC are not always contiguous, we will potentially
visit a gap block which is no existing in the current CFG.

This patch can avoid visiting non existing block in CFG.

I noticed such issue in my internal regression of current testsuite
when I change the X86 server machine. This patch fix it:
17:27:15      job(build_and_test_rv32): Increased FAIL List:
17:27:15      job(build_and_test_rv32): FAIL: 
gcc.target/riscv/rvv/vsetvl/vlmax_back_prop-46.c
-O2 -flto -fno-use-linker-plugin -flto-partition=none  (internal compiler 
error: Segmentation fault)

gcc/ChangeLog:

         * config/riscv/riscv-vsetvl.cc 
(pass_vsetvl::compute_global_backward_infos): Change to visit CFG.
         (pass_vsetvl::prune_expressions): Ditto.
The usual way to iterate over the blocks is something like this

basic_block bb
FOR_EACH_BB (bb, cfun)
  {
    do whatever you need on BB
  }

Please use that form as that's what most folks working with GCC are 
already using.

Jeff