[binutils-gdb] RISC-V: Imply 'Zicsr' from privileged extensions with CSRs

[binutils-gdb] RISC-V: Imply 'Zicsr' from privileged extensions with CSRs

[Tsukasa OI]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b16e13328b14e2668e2a4355d587368ed040b680

commit b16e13328b14e2668e2a4355d587368ed040b680
Author: Tsukasa OI <research_trasio@irq.a4lg.com>
Date:   Mon Sep 5 08:11:54 2022 +0000

    RISC-V: Imply 'Zicsr' from privileged extensions with CSRs
    
    'H', 'Smstateen', 'Sscofpmf' and 'Sstc' are four privileged extensions with
    their CSR definitions and 'Smepmp' is a privileged extension with additional
    CSR bits.
    
    Volume II: Privileged Architecture of the RISC-V ISA Manual states that the
    privileged architecture requires the 'Zicsr' extension.  However, current
    GNU Binutils has no direct way whether the program has dependency to the
    privileged architecture itself.
    
    As a workaround, we should add implications from privileged extensions that
    either add new CSRs, extend existing CSRs or depends on using CSRs.
    
    This commit adds such implications for existing privileged extensions that
    satisfy this condition.
    
    gas/ChangeLog:
    
            * testsuite/gas/riscv/march-imply-h.d: New test, at least for 'H'.
    
    bfd/ChangeLog:
    
            * elfxx-riscv.c (riscv_implicit_subsets): Add 'Zicsr'
            implicications for privileged extensions 'H', 'Smstateen',
            'Sscofpmf', 'Sstc' and 'Smepmp'.

Diff:
---
 bfd/elfxx-riscv.c                       | 5 +++++
 gas/testsuite/gas/riscv/march-imply-h.d | 6 ++++++
 2 files changed, 11 insertions(+)

diff --git a/bfd/elfxx-riscv.c b/bfd/elfxx-riscv.c
index 1bcc6c0acb4..f0c91cc97f7 100644
--- a/bfd/elfxx-riscv.c
+++ b/bfd/elfxx-riscv.c
@@ -1047,6 +1047,7 @@ static struct riscv_implicit_subset riscv_implicit_subsets[] =
   {"g", "zicsr",	check_implicit_always},
   {"g", "zifencei",	check_implicit_always},
   {"m", "zmmul",	check_implicit_always},
+  {"h", "zicsr",	check_implicit_always},
   {"q", "d",		check_implicit_always},
   {"v", "d",		check_implicit_always},
   {"v", "zve64d",	check_implicit_always},
@@ -1096,6 +1097,10 @@ static struct riscv_implicit_subset riscv_implicit_subsets[] =
   {"zks", "zbkx",	check_implicit_always},
   {"zks", "zksed",	check_implicit_always},
   {"zks", "zksh",	check_implicit_always},
+  {"smepmp", "zicsr",		check_implicit_always},
+  {"smstateen", "zicsr",	check_implicit_always},
+  {"sscofpmf", "zicsr",		check_implicit_always},
+  {"sstc", "zicsr",		check_implicit_always},
   {NULL, NULL, NULL}
 };
 
diff --git a/gas/testsuite/gas/riscv/march-imply-h.d b/gas/testsuite/gas/riscv/march-imply-h.d
new file mode 100644
index 00000000000..04ad9f6c0a5
--- /dev/null
+++ b/gas/testsuite/gas/riscv/march-imply-h.d
@@ -0,0 +1,6 @@
+#as: -march=rv32ih -march-attr -misa-spec=20191213 -mpriv-spec=1.12
+#readelf: -A
+#source: empty.s
+Attribute Section: riscv
+File Attributes
+  Tag_RISCV_arch: "rv32i2p1_h1p0_zicsr2p0"