https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88403
Bug ID: 88403
Summary: [Mips,AArch64] The gcse prevents if-conversion
Product: gcc
Version: 7.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: dragan.mladjeno...@rt-rk.com
Target Milestone: ---
Created attachment 45183
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=45183&action=edit
mark.c
If I compile the marck.c with aarch64-linux-gnu-gcc -O3 or mipsel-linux-gnu-gcc
-mips32r6 -mbranch-cost=5 the inner if does not get transformed to use
conditional moves.
mips32r6 example:
li $13,5000 # 0x1388
$L4:
...
subu $3,$2,$3
bgec $13,$3,$L3
addiu $2,$2,5000
sra $4,$2,31 <-- inserted by gcse
$L3:
muh $2,$2,$9
sra $2,$2,12
subu $2,$4,$2
...
The if-conversion fails because it refuses to speculate both instructions whose
set regs are alive. If I use -fno-gcse or -ftree-loop-if-convert the problem
disappears.
Is there something that can be done here w/o resolving to ftree-loop-if-convert
?
Tried:
mipsel-linux-gnu-gcc --version
mipsel-linux-gnu-gcc-7 (Debian 7.3.0-28) 7.3.0
xgcc --version
xgcc (GCC) 9.0.0 20181203 (experimental)
