[committed] CRIS: Add peephole2 to handle gcc.target/cris/rld-legit1.c for LRA
Checks
Commit Message
The test-case gcc.target/cris/rld-legit1.c is a reduced
test-case that required defining LEGITIMIZE_RELOAD_ADDRESS
to stop the address from being decomposed into several insns
by reload. Valid but suboptimal code was generated.
(Before implementing that hook for CRIS, the same test-case
also exposed a bug in reload, and a fix was committed to
avoid an ICE; see e.g. git r0-71992-gff0d9879ab0f30 and
related commits. But, post-cc0, reload no longer handles
this test-case without LEGITIMIZE_RELOAD_ADDRESS helping and
there'd again an be ICE for CRIS (again: only if
LEGITIMIZE_RELOAD_ADDRESS is disabled). There's a patch to
reload to fix that, at
https://gcc.gnu.org/pipermail/gcc-patches/2023-February/612039.html)
But, LRA also does not handle that test-case gracefully, and
like reload without LEGITIMIZE_RELOAD_ADDRESS for CRIS,
decomposes the address into a suboptimal (but valid)
sequence, about as messy as that from reload, and
gcc.target/cris/rld-legit1.c would regress for LRA. There's
nothing equivalent to LEGITIMIZE_RELOAD_ADDRESS for LRA.
(Stepping through LRA, I can't find an obvious place where
to put such a hook. Granted, I haven't seen this kind of
messy decomposition in other code, so I'm not insisting a
LEGITIMIZE_RELOAD_ADDRESS-like hook is a good idea.)
These new peephole2's are required to not regress
gcc.target/cris/rld-legit1.c with LRA enabled for CRIS.
They don't appear to otherwise make a difference for neither
libgcc, newlib libc, my own at-a-glance tests nor coremark,
for neither LRA nor reload.
* config/cris/cris.md (BW2): New mode-iterator.
(lra_szext_decomposed, lra_szext_decomposed_indirect_with_offset): New
peephole2s.
---
gcc/config/cris/cris.md | 50 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
@@ -183,6 +183,10 @@ (define_mode_iterator SI_ [SI])
(define_mode_iterator WD [SI HI])
(define_mode_iterator BW [HI QI])
+
+; Another "BW" for use where an independent iteration is needed.
+(define_mode_iterator BW2 [HI QI])
+
(define_mode_attr S [(SI "HI") (HI "QI")])
(define_mode_attr s [(SI "hi") (HI "qi")])
(define_mode_attr m [(SI ".d") (HI ".w") (QI ".b")])
@@ -2832,6 +2836,52 @@ (define_peephole2 ; andqu
operands[3] = gen_rtx_ZERO_EXTEND (SImode, op1);
operands[4] = GEN_INT (trunc_int_for_mode (INTVAL (operands[1]), QImode));
})
+
+;; Fix a decomposed szext: fuse it with the memory operand of the
+;; load. This is typically the sign-extension part of a decomposed
+;; "indirect offset" address.
+(define_peephole2 ; lra_szext_decomposed
+ [(parallel
+ [(set (match_operand:BW 0 "register_operand")
+ (match_operand:BW 1 "memory_operand"))
+ (clobber (reg:CC CRIS_CC0_REGNUM))])
+ (parallel
+ [(set (match_operand:SI 2 "register_operand") (szext:SI (match_dup 0)))
+ (clobber (reg:CC CRIS_CC0_REGNUM))])]
+ "REGNO (operands[0]) == REGNO (operands[2])
+ || peep2_reg_dead_p (2, operands[0])"
+ [(parallel
+ [(set (match_dup 2) (szext:SI (match_dup 1)))
+ (clobber (reg:CC CRIS_CC0_REGNUM))])])
+
+;; Re-compose a decomposed "indirect offset" address for a szext
+;; operation. The non-clobbering "addi" is generated by LRA.
+;; This and lra_szext_decomposed is covered by cris/rld-legit1.c.
+(define_peephole2 ; lra_szext_decomposed_indirect_with_offset
+ [(parallel
+ [(set (match_operand:SI 0 "register_operand")
+ (sign_extend:SI (mem:BW (match_operand:SI 1 "register_operand"))))
+ (clobber (reg:CC CRIS_CC0_REGNUM))])
+ (set (match_dup 0)
+ (plus:SI (match_dup 0) (match_operand:SI 2 "register_operand")))
+ (parallel
+ [(set (match_operand:SI 3 "register_operand")
+ (szext:SI (mem:BW2 (match_dup 0))))
+ (clobber (reg:CC CRIS_CC0_REGNUM))])]
+ "(REGNO (operands[0]) == REGNO (operands[3])
+ || peep2_reg_dead_p (3, operands[0]))
+ && (REGNO (operands[0]) == REGNO (operands[1])
+ || peep2_reg_dead_p (3, operands[0]))"
+ [(parallel
+ [(set
+ (match_dup 3)
+ (szext:SI
+ (mem:BW2 (plus:SI (szext:SI (mem:BW (match_dup 1))) (match_dup 2)))))
+ (clobber (reg:CC CRIS_CC0_REGNUM))])])
+
+;; Add operations with similar or same decomposed addresses here, when
+;; encountered - but only when covered by mentioned test-cases for at
+;; least one of the cases generalized in the pattern.
;; Local variables:
;; mode:emacs-lisp