https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89245
Bug ID: 89245
Summary: [MIPS] v1 is assigned in jalr delay slot for later use
at -Os
Product: gcc
Version: 8.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: i...@mobile-stream.com
Target Milestone: ---
Created attachment 45638
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45638&action=edit
preprocessed LuaJIT-2.1.0-beta3/src/lj_asm.c
command line:
gcc -mips32r2 -mhard-float -fPIC -Os lj_asm.i
generated assembly (asm_href):
lw $2,40($sp)
andi $6,$2,0x1f
$L942:
jalr $25
li $3,-1944125440 # 0xffffffff8c1f0000
lw $4,256($16)
addiu $3,$3,12
where $25 is loaded earlier with the address of emit_tsi.isra.2 (which mangles
$3).
the problem goes away with "-Os -fschedule-insns" (i.e. like at -O2) or "-Os
-fno-schedule-insns2".
"-fno-ipa-sra" changes nothing.
also happens with gcc-6 (codescape-2018.09-03 or debian stretch mipsel) and
gcc-7 (codescape-2018.11-01).
