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

[juzhe . zhong]

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.

---
 gcc/config/riscv/riscv-vsetvl.cc | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/gcc/config/riscv/riscv-vsetvl.cc b/gcc/config/riscv/riscv-vsetvl.cc
index a55b5a1c394..0d66765e09c 100644
--- a/gcc/config/riscv/riscv-vsetvl.cc
+++ b/gcc/config/riscv/riscv-vsetvl.cc
@@ -1962,12 +1962,10 @@ pass_vsetvl::compute_global_backward_infos (void)
   if (dump_file)
     {
       fprintf (dump_file, "\n\nDirty blocks list: ");
-      for (size_t i = 0; i < m_vector_manager->vector_block_infos.length ();
-          i++)
-       {
-         if (m_vector_manager->vector_block_infos[i].reaching_out.dirty_p ())
-           fprintf (dump_file, "%ld ", i);
-       }
+      for (const bb_info *bb : crtl->ssa->bbs ())
+       if (m_vector_manager->vector_block_infos[bb->index ()]
+             .reaching_out.dirty_p ())
+         fprintf (dump_file, "%d ", bb->index ());
       fprintf (dump_file, "\n\n");
     }
 }
@@ -1976,15 +1974,16 @@ pass_vsetvl::compute_global_backward_infos (void)
 void
 pass_vsetvl::prune_expressions (void)
 {
-  for (size_t i = 0; i < m_vector_manager->vector_block_infos.length (); i++)
+  for (const bb_info *bb : crtl->ssa->bbs ())
     {
-      if (m_vector_manager->vector_block_infos[i].local_dem.valid_or_dirty_p 
())
+      if (m_vector_manager->vector_block_infos[bb->index ()]
+           .local_dem.valid_or_dirty_p ())
        m_vector_manager->create_expr (
-         m_vector_manager->vector_block_infos[i].local_dem);
-      if (m_vector_manager->vector_block_infos[i]
+         m_vector_manager->vector_block_infos[bb->index ()].local_dem);
+      if (m_vector_manager->vector_block_infos[bb->index ()]
            .reaching_out.valid_or_dirty_p ())
        m_vector_manager->create_expr (
-         m_vector_manager->vector_block_infos[i].reaching_out);
+         m_vector_manager->vector_block_infos[bb->index ()].reaching_out);
     }
 
   if (dump_file)
-- 
2.36.3