[PATCH v8 5/7] RISC-V: Print top GP-relative addresses on the disassembler

Tsukasa OI research_trasio@irq.a4lg.com
Sat Aug 27 00:11:02 GMT 2022


This patch makes possible to print the address relative to the global
pointer even if the corresponding symbol is the highest address (0xffffffff
on RV32, 0xffffffff_ffffffff on RV64).

Despite that it is very rare to have GP the highest address, it would be
nice because we enabled highest address printing on regular cases.

opcodes/ChangeLog:

	* riscv-dis.c (struct riscv_private_data): Add `has_gp' to enable
	printing the addresses relative to GP with the highest address.
	(maybe_print_address): Utilize `has_gp'.
	(riscv_disassemble_insn): Likewise.

gas/ChangeLog:

	* testsuite/gas/riscv/dis-addr-topaddr-gp.s: New test for GP-
	relative addressing when GP is the highest address.
	* testsuite/gas/riscv/dis-addr-topaddr-gp-32.d: Likewise.
	* testsuite/gas/riscv/dis-addr-topaddr-gp-64.d: Likewise.
---
 gas/testsuite/gas/riscv/dis-addr-topaddr-gp-32.d | 12 ++++++++++++
 gas/testsuite/gas/riscv/dis-addr-topaddr-gp-64.d | 12 ++++++++++++
 gas/testsuite/gas/riscv/dis-addr-topaddr-gp.s    | 15 +++++++++++++++
 opcodes/riscv-dis.c                              | 11 ++++++++---
 4 files changed, 47 insertions(+), 3 deletions(-)
 create mode 100644 gas/testsuite/gas/riscv/dis-addr-topaddr-gp-32.d
 create mode 100644 gas/testsuite/gas/riscv/dis-addr-topaddr-gp-64.d
 create mode 100644 gas/testsuite/gas/riscv/dis-addr-topaddr-gp.s

diff --git a/gas/testsuite/gas/riscv/dis-addr-topaddr-gp-32.d b/gas/testsuite/gas/riscv/dis-addr-topaddr-gp-32.d
new file mode 100644
index 00000000000..875bfe73189
--- /dev/null
+++ b/gas/testsuite/gas/riscv/dis-addr-topaddr-gp-32.d
@@ -0,0 +1,12 @@
+#as: -march=rv32i
+#source: dis-addr-topaddr-gp.s
+#objdump: -d
+
+.*:     file format elf32-(little|big)riscv
+
+
+Disassembly of section .text:
+
+0+000 <target>:
+[ 	]+[0-9a-f]+:[ 	]+0051a283[ 	]+lw[   	]+t0,5\(gp\) # 4 <addr_rel_gp_pos>
+[ 	]+[0-9a-f]+:[ 	]+ffd1a303[ 	]+lw[   	]+t1,-3\(gp\) # fffffffc <addr_rel_gp_neg>
diff --git a/gas/testsuite/gas/riscv/dis-addr-topaddr-gp-64.d b/gas/testsuite/gas/riscv/dis-addr-topaddr-gp-64.d
new file mode 100644
index 00000000000..5ac4b52b18d
--- /dev/null
+++ b/gas/testsuite/gas/riscv/dis-addr-topaddr-gp-64.d
@@ -0,0 +1,12 @@
+#as: -march=rv64i -defsym rv64=1
+#source: dis-addr-topaddr-gp.s
+#objdump: -d
+
+.*:     file format elf64-(little|big)riscv
+
+
+Disassembly of section .text:
+
+0+000 <target>:
+[ 	]+[0-9a-f]+:[ 	]+0051a283[ 	]+lw[   	]+t0,5\(gp\) # 4 <addr_rel_gp_pos>
+[ 	]+[0-9a-f]+:[ 	]+ffd1a303[ 	]+lw[   	]+t1,-3\(gp\) # fffffffffffffffc <addr_rel_gp_neg>
diff --git a/gas/testsuite/gas/riscv/dis-addr-topaddr-gp.s b/gas/testsuite/gas/riscv/dis-addr-topaddr-gp.s
new file mode 100644
index 00000000000..6ba9fc7a39d
--- /dev/null
+++ b/gas/testsuite/gas/riscv/dis-addr-topaddr-gp.s
@@ -0,0 +1,15 @@
+.ifdef rv64
+topbase = 0xffffffff00000000
+.else
+topbase = 0
+.endif
+
+.set __global_pointer$, topbase + 0xffffffff  # -1
+.set addr_rel_gp_pos,             0x00000004  # +4
+.set addr_rel_gp_neg,   topbase + 0xfffffffc  # -4
+
+target:
+	# Use addresses relative to gp
+	# (gp is the highest address)
+	lw	t0, +5(gp)
+	lw	t1, -3(gp)
diff --git a/opcodes/riscv-dis.c b/opcodes/riscv-dis.c
index 7532c72187d..160cc40f865 100644
--- a/opcodes/riscv-dis.c
+++ b/opcodes/riscv-dis.c
@@ -53,6 +53,7 @@ struct riscv_private_data
   bfd_vma print_addr;
   bfd_vma hi_addr[OP_MASK_RD + 1];
   bool to_print_addr;
+  bool has_gp;
 };
 
 /* Used for mapping symbols.  */
@@ -178,7 +179,7 @@ maybe_print_address (struct riscv_private_data *pd, int base_reg, int offset,
       pd->print_addr = (base_reg != 0 ? pd->hi_addr[base_reg] : 0) + offset;
       pd->hi_addr[base_reg] = -1;
     }
-  else if (base_reg == X_GP && pd->gp != (bfd_vma)-1)
+  else if (base_reg == X_GP && pd->has_gp)
     pd->print_addr = pd->gp + offset;
   else if (base_reg == X_TP || base_reg == 0)
     pd->print_addr = offset;
@@ -603,15 +604,19 @@ riscv_disassemble_insn (bfd_vma memaddr, insn_t word, disassemble_info *info)
       int i;
 
       pd = info->private_data = xcalloc (1, sizeof (struct riscv_private_data));
-      pd->gp = -1;
+      pd->gp = 0;
       pd->print_addr = 0;
       for (i = 0; i < (int)ARRAY_SIZE (pd->hi_addr); i++)
 	pd->hi_addr[i] = -1;
       pd->to_print_addr = false;
+      pd->has_gp = false;
 
       for (i = 0; i < info->symtab_size; i++)
 	if (strcmp (bfd_asymbol_name (info->symtab[i]), RISCV_GP_SYMBOL) == 0)
-	  pd->gp = bfd_asymbol_value (info->symtab[i]);
+	  {
+	    pd->gp = bfd_asymbol_value (info->symtab[i]);
+	    pd->has_gp = true;
+	  }
     }
   else
     pd = info->private_data;
-- 
2.34.1



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