bfin-elf started failing in my tester a couple weeks ago. Bisection
pointed to Richi's recent DOM change, but it was pretty clear that was
just exposing a backend issue.
The failure mode was the assembler compiling about an out-of-range
relocation for a pc-relative conditional jump when compiling vfprintf in
newlib.
bfin has multi-sized pc-relative branches and relies on the compiler to
compute lengths and shorten branches. Totally standard. It was pretty
obvious when looking at the assembler listing output for a "-dp"
compiled source. We had an insn with l=2 which was 4 bytes long. Thus
we slightly under-calculated the distance between the conditional branch
and its target and issued a short jump instead of a long jump.
I've never done anything with the bfin port, but this looks to be a very
safe way to address the problem. It's just the first alternative in the
movpdi pattern. It is marked with type "move" which always computes
size 2. AFAICT this pattern+alternative combination is used for moves
between the accumulator registers and should always be 4 bytes long.
So I just explicitly set the length to 4 for that alternative and let
the other alternatives continue to compute their length via the default
mechanisms.
With this patch bfin returns to a working state in my tester.
Committing to the trunk.
Jeff
* config/bfin/bfin.md (movpdi): Fix length for alternative 1.
index 11c7c9ecd24..ac589242413 100644
--- a/gcc/config/bfin/bfin.md
+++ b/gcc/config/bfin/bfin.md
@@ -557,6 +557,7 @@
%0 = %x1; %0 = %w1;
%w0 = %1; %x0 = %1;"
[(set_attr "type" "move,mcst,mcld")
+ (set_attr "length" "4,*,*")
(set_attr "seq_insns" "*,multi,multi")])
(define_insn "load_accumulator"
