[gcc r12-6836] RISC-V: Do not emit zcisr and zifencei if i-ext is 2.0

[gcc r12-6836] RISC-V: Do not emit zcisr and zifencei if i-ext is 2.0

[Kito Cheng]

https://gcc.gnu.org/g:ca2bbb88f999f4d3cc40e89bc1aba712505dd598

commit r12-6836-gca2bbb88f999f4d3cc40e89bc1aba712505dd598
Author: Kito Cheng <kito.cheng@sifive.com>
Date:   Mon Jan 24 15:46:10 2022 +0800

    RISC-V: Do not emit zcisr and zifencei if i-ext is 2.0
    
    I-ext 2.0 already included zicsr and zifencei, skip that prevent
    confusing binutils.
    
    gcc/ChangeLog
    
            * common/config/riscv/riscv-common.cc (riscv_subset_list::to_string):
            Skip zicsr and zifencei if I-ext is 2.0.

Diff:
---
 gcc/common/config/riscv/riscv-common.cc | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/gcc/common/config/riscv/riscv-common.cc b/gcc/common/config/riscv/riscv-common.cc
index 25f56707d94..a904893b9ed 100644
--- a/gcc/common/config/riscv/riscv-common.cc
+++ b/gcc/common/config/riscv/riscv-common.cc
@@ -488,6 +488,7 @@ riscv_subset_list::to_string (bool version_p) const
 
   bool skip_zifencei = false;
   bool skip_zicsr = false;
+  bool i2p0 = false;
 
   /* For RISC-V ISA version 2.2 or earlier version, zicsr and zifencei is
      included in the base ISA.  */
@@ -497,6 +498,13 @@ riscv_subset_list::to_string (bool version_p) const
       skip_zicsr = true;
     }
 
+  for (subset = m_head; subset != NULL; subset = subset->next)
+    if (subset->name == "i")
+      {
+	i2p0 = subset->major_version == 2 && subset->minor_version == 0;
+	break;
+      }
+
 #ifndef HAVE_AS_MISA_SPEC
   /* Skip since older binutils doesn't recognize zicsr.  */
   skip_zicsr = true;
@@ -509,10 +517,12 @@ riscv_subset_list::to_string (bool version_p) const
 
   for (subset = m_head; subset != NULL; subset = subset->next)
     {
-      if (subset->implied_p && skip_zifencei && subset->name == "zifencei")
+      if (((subset->implied_p && skip_zifencei) || i2p0) &&
+	  subset->name == "zifencei")
 	continue;
 
-      if (subset->implied_p && skip_zicsr && subset->name == "zicsr")
+      if (((subset->implied_p && skip_zicsr) || i2p0) &&
+	  subset->name == "zicsr")
 	continue;
 
       /* For !version_p, we only separate extension with underline for