LoongArch: Enforce 4-byte align for machine instructions

If no alignment is specified in the assembly file, LoongArch will not
perform forced alignment. When this object file (.o) is linked into an
executable, instructions may not be 4-byte aligned, which will
eventually cause instruction fetch errors.

For example, the above issue can occur when generating a shared object
file (.so) with the -nostdlib option.

diff --git a/gas/config/tc-loongarch.c b/gas/config/tc-loongarch.c
index 1eb35f2c75ed0a65122960a47f2a302c1112c8a0..d067318ce2403bff9548b5620bc7a2f661a3c764 100644 (file)
--- a/gas/config/tc-loongarch.c
+++ b/gas/config/tc-loongarch.c
@@ -1432,6 +1432,11 @@ loongarch_assemble_INSNs (char *str, unsigned int expand_from_macro)
       if (*str == '\0')
        break;
 
+      /* LoongArch instructions require 4-byte alignment.  When emitting
+        instructions into any section, record the appropriate section
+        alignment.  */
+      record_alignment (now_seg, 2);
+
       struct loongarch_cl_insn the_one;
       memset (&the_one, 0, sizeof (the_one));
       the_one.name = str;

diff --git a/gas/testsuite/gas/loongarch/insn_align_4.d b/gas/testsuite/gas/loongarch/insn_align_4.d
new file mode 100644 (file)
index 0000000..31a5d35
--- /dev/null
+++ b/gas/testsuite/gas/loongarch/insn_align_4.d
@@ -0,0 +1,7 @@
+#as:
+#readelf: -S
+
+#...
+  \[ [0-9]+\] \.text             PROGBITS         [0-9a-f]{16}  [0-9a-f]{8}
+       [0-9a-f]{16}  [0-9a-f]{16}  AX       0     0     4
+#...

diff --git a/gas/testsuite/gas/loongarch/insn_align_4.s b/gas/testsuite/gas/loongarch/insn_align_4.s
new file mode 100644 (file)
index 0000000..7b4922c
--- /dev/null
+++ b/gas/testsuite/gas/loongarch/insn_align_4.s
@@ -0,0 +1,4 @@
+.type test, @function
+test:
+  jirl $ra, $ra, 0
+.size test, .-test