https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61551
Bug ID: 61551
Summary: [NEON] alter costs to allow use of post-indexed
addressing modes for VLD{2..4}/VST{2..4}
Product: gcc
Version: 4.10.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: cbaylis at gcc dot gnu.org
CC: ramana.radhakrishnan at arm dot com
Target: arm-unknown-linux-gnueabi
Created attachment 32967
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32967&action=edit
test for NEON addressing modes
The attached test case demonstrates that GCC does not exploit the post-indexed
addressing mode for NEON structure loads and stores: VLDn, VSTn where n>=2.
Generated code for VLD1/VST1 (using desired post-indexed addressing)
test_ld1:
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 0, uses_anonymous_args = 0
@ link register save eliminated.
vld1.8 {d16}, [r0], r1
vst1.8 {d16}, [r0], r1
vld1.8 {d16}, [r0], r1
vst1.8 {d16}, [r0], r1
vld1.8 {d16}, [r0], r1
vst1.8 {d16}, [r0]
bx lr
Generated code for VLD2:
test_ld2:
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 0, uses_anonymous_args = 0
@ link register save eliminated.
adds r3, r0, r1
vld2.8 {d16-d17}, [r0]
adds r0, r3, r1
adds r2, r0, r1
vst2.8 {d16-d17}, [r3]
adds r3, r2, r1
vld2.8 {d16-d17}, [r0]
add r1, r1, r3
vst2.8 {d16-d17}, [r2]
vld2.8 {d16-d17}, [r3]
vst2.8 {d16-d17}, [r1]
bx lr
A proof of concept patch is posted at:
https://gcc.gnu.org/ml/gcc-patches/2014-06/msg01361.html
