[Bug target/72767] New: [avr] Some branches report too small insn length
gjl at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Mon Aug 1 12:32:00 GMT 2016
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=72767
Bug ID: 72767
Summary: [avr] Some branches report too small insn length
Product: gcc
Version: 5.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: gjl at gcc dot gnu.org
Target Milestone: ---
Created attachment 39039
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39039&action=edit
nops.c: C test case
Some branch instructions report too small instruction length which might lead
to problems if other branches crossing the critical ones use a wrong
instruction sequence. Outcome can be "relocation truncted to fit" error from
the linker.
Compile test case with
$ avr-gcc -S -dp -Os -mmcu=atmega16 nops.c
In bra_63 there is (should be "length = 2"):
brne .+2 ; 7 branch [length = 1]
rjmp .L1
In bra_2045 (should be "length = 3"):
brne .+4 ; 7 branch [length = 2]
jmp .L6
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