Trying to compile a certain embedded benchmark with -falign-loops=8
or above fails due to out-of-range references to the literal pool.
This is because arm_reorg doesn't take label alignment into account.
Fixed with the patch below. Tested on arm-linux-gnueabi. I also
tried compiling libav with and without the patch (not using -falign-loops
for either run). As hoped, there were no changes in assembly output.
OK to install?
Richard
gcc/
* config/arm/arm.c (get_label_padding): New function.
(create_fix_barrier, md_reorg): Likewise.
Index: gcc/config/arm/arm.c
===================================================================
--- gcc/config/arm/arm.c 2011-08-11 11:49:18.780977049 +0100
+++ gcc/config/arm/arm.c 2011-08-11 12:14:42.074629364 +0100
@@ -11719,6 +11719,19 @@ get_jump_table_size (rtx insn)
return 0;
}
+/* Return the maximum amount of padding that will be inserted before
+ label LABEL. */
+
+static HOST_WIDE_INT
+get_label_padding (rtx label)
+{
+ HOST_WIDE_INT align, min_insn_size;
+
+ align = 1 << label_to_alignment (label);
+ min_insn_size = TARGET_THUMB ? 2 : 4;
+ return align > min_insn_size ? align - min_insn_size : 0;
+}
+
/* Move a minipool fix MP from its current location to before MAX_MP.
If MAX_MP is NULL, then MP doesn't need moving, but the addressing
constraints may need updating. */
@@ -12265,8 +12278,12 @@ create_fix_barrier (Mfix *fix, HOST_WIDE
within range. */
gcc_assert (GET_CODE (from) != BARRIER);
- /* Count the length of this insn. */
- count += get_attr_length (from);
+ /* Count the length of this insn. This must stay in sync with the
+ code that pushes minipool fixes. */
+ if (LABEL_P (from))
+ count += get_label_padding (from);
+ else
+ count += get_attr_length (from);
/* If there is a jump table, add its length. */
tmp = is_jump_table (from);
@@ -12696,6 +12713,11 @@ arm_reorg (void)
insn = table;
}
}
+ else if (LABEL_P (insn))
+ /* Add the worst-case padding due to alignment. We don't add
+ the _current_ padding because the minipool insertions
+ themselves might change it. */
+ address += get_label_padding (insn);
}
fix = minipool_fix_head;
