[PATCH V2] RISC-V: Fix RVV_VLMAX

[PATCH V2] RISC-V: Fix RVV_VLMAX

[Juzhe-Zhong]

This patch fixes memory hog found in SPEC2017 wrf benchmark which caused by
RVV_VLMAX since RVV_VLMAX generate brand new rtx by gen_rtx_REG (Pmode, X0_REGNUM)
every time we call RVV_VLMAX, that is, we are always generating garbage and redundant
(reg:DI 0 zero) rtx.

After this patch fix, the memory hog is gone.

Time variable                                   usr           sys          wall           GGC
 machine dep reorg                  :   1.99 (  9%)   0.35 ( 56%)   2.33 ( 10%)   939M ( 80%) [Before this patch]
 machine dep reorg                  :   1.71 (  6%)   0.16 ( 27%)   3.77 (  6%)   659k (  0%) [After this patch]
 
Time variable                                   usr           sys          wall           GGC
 machine dep reorg                  :  75.93 ( 18%)  14.23 ( 88%)  90.15 ( 21%) 33383M ( 95%) [Before this patch]
 machine dep reorg                  :  56.00 ( 14%)   7.92 ( 77%)  63.93 ( 15%)  4361k (  0%) [After this patch]

Test is running. Ok for trunk if I passed the test with no regresion ?

	PR target/113495

gcc/ChangeLog:

	* config/riscv/riscv-protos.h (RVV_VLMAX): Change to regno_reg_rtx[X0_REGNUM].
	(RVV_VUNDEF): Ditto.
	* config/riscv/riscv-vsetvl.cc: Add timevar.

---
 gcc/config/riscv/riscv-protos.h  | 5 ++---
 gcc/config/riscv/riscv-vsetvl.cc | 2 +-
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/gcc/config/riscv/riscv-protos.h b/gcc/config/riscv/riscv-protos.h
index 7853b488838..7fe26fcd939 100644
--- a/gcc/config/riscv/riscv-protos.h
+++ b/gcc/config/riscv/riscv-protos.h
@@ -299,10 +299,9 @@ void riscv_run_selftests (void);
 #endif
 
 namespace riscv_vector {
-#define RVV_VLMAX gen_rtx_REG (Pmode, X0_REGNUM)
+#define RVV_VLMAX regno_reg_rtx[X0_REGNUM]
 #define RVV_VUNDEF(MODE)                                                       \
-  gen_rtx_UNSPEC (MODE, gen_rtvec (1, gen_rtx_REG (SImode, X0_REGNUM)),        \
-		  UNSPEC_VUNDEF)
+  gen_rtx_UNSPEC (MODE, gen_rtvec (1, RVV_VLMAX), UNSPEC_VUNDEF)
 
 /* These flags describe how to pass the operands to a rvv insn pattern.
    e.g.:
diff --git a/gcc/config/riscv/riscv-vsetvl.cc b/gcc/config/riscv/riscv-vsetvl.cc
index 2067073185f..54c85ffb7d5 100644
--- a/gcc/config/riscv/riscv-vsetvl.cc
+++ b/gcc/config/riscv/riscv-vsetvl.cc
@@ -3556,7 +3556,7 @@ const pass_data pass_data_vsetvl = {
   RTL_PASS,	 /* type */
   "vsetvl",	 /* name */
   OPTGROUP_NONE, /* optinfo_flags */
-  TV_NONE,	 /* tv_id */
+  TV_MACH_DEP,	 /* tv_id */
   0,		 /* properties_required */
   0,		 /* properties_provided */
   0,		 /* properties_destroyed */
-- 
2.36.3

Re: [PATCH V2] RISC-V: Fix RVV_VLMAX

[Robin Dapp]

Ah, interesting that this was it.  Thanks for fixing and also
thanks to Andrew for suggesting that fix.

Regards
 Robin