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

[Jeff Law <jeffreyalaw@gmail.com>]

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