[PATCH] RISC-V: Add string length check for operands in AS

[Li Xu]

The current AS accepts invaild operands due to miss of operands length check.
For example, "e6" is an invalid operand in (vsetvli a0, a1, e6, mf8, tu, ma),
but it's still accepted by assembler. In detail, the condition check "strncmp
(array[i], *s, len) == 0" in arg_lookup function passes with "strncmp ("e64",
"e6", 2)" in the case above. So the generated encoding is same as that of
(vsetvli a0, a1, e64, mf8, tu, ma).
This patch fixes issue above by prompting an error in such case and also adds
a new testcase.

gas/ChangeLog:

        * config/tc-riscv.c (arg_lookup): Add string length check for operands.
        * testsuite/gas/riscv/vector-insns-fail-vsew.d: New testcase for an illegal vsew.
        * testsuite/gas/riscv/vector-insns-fail-vsew.l: Likewise.
        * testsuite/gas/riscv/vector-insns-fail-vsew.s: Likewise.
---
 gas/config/tc-riscv.c                            | 2 +-
 gas/testsuite/gas/riscv/vector-insns-fail-vsew.d | 3 +++
 gas/testsuite/gas/riscv/vector-insns-fail-vsew.l | 3 +++
 gas/testsuite/gas/riscv/vector-insns-fail-vsew.s | 1 +
 4 files changed, 8 insertions(+), 1 deletion(-)
 create mode 100644 gas/testsuite/gas/riscv/vector-insns-fail-vsew.d
 create mode 100644 gas/testsuite/gas/riscv/vector-insns-fail-vsew.l
 create mode 100644 gas/testsuite/gas/riscv/vector-insns-fail-vsew.s

diff --git a/gas/config/tc-riscv.c b/gas/config/tc-riscv.c
index 0682eb35524..b0989e4b124 100644
--- a/gas/config/tc-riscv.c
+++ b/gas/config/tc-riscv.c
@@ -1206,7 +1206,7 @@ arg_lookup (char **s, const char *const *array, size_t size, unsigned *regnop)
     return false;
 
   for (i = 0; i < size; i++)
-    if (array[i] != NULL && strncmp (array[i], *s, len) == 0)
+    if (array[i] != NULL && (strlen(array[i]) == len) && strncmp (array[i], *s, len) == 0)
       {
 	*regnop = i;
 	*s += len;
diff --git a/gas/testsuite/gas/riscv/vector-insns-fail-vsew.d b/gas/testsuite/gas/riscv/vector-insns-fail-vsew.d
new file mode 100644
index 00000000000..c0c81579741
--- /dev/null
+++ b/gas/testsuite/gas/riscv/vector-insns-fail-vsew.d
@@ -0,0 +1,3 @@
+#as: -march=rv32ifv
+#source: vector-insns-fail-vsew.s
+#error_output: vector-insns-fail-vsew.l
diff --git a/gas/testsuite/gas/riscv/vector-insns-fail-vsew.l b/gas/testsuite/gas/riscv/vector-insns-fail-vsew.l
new file mode 100644
index 00000000000..87a2c22a805
--- /dev/null
+++ b/gas/testsuite/gas/riscv/vector-insns-fail-vsew.l
@@ -0,0 +1,3 @@
+.*: Assembler messages:
+.*: Error: instruction vsetvli requires absolute expression
+.*: Error: illegal operands `vsetvli a0,a1,e6,mf8,tu,ma'
diff --git a/gas/testsuite/gas/riscv/vector-insns-fail-vsew.s b/gas/testsuite/gas/riscv/vector-insns-fail-vsew.s
new file mode 100644
index 00000000000..b8f3242406f
--- /dev/null
+++ b/gas/testsuite/gas/riscv/vector-insns-fail-vsew.s
@@ -0,0 +1 @@
+	vsetvli  a0, a1, e6, mf8, tu, ma		# unrecognized vsew
-- 
2.17.1