Jennifer Schmitz <jschm...@nvidia.com> writes: > Thanks for the feedback! I updated the patch based on your comments, more > detailed comments inline below. The updated version was bootstrapped and > tested again, no regression. > Best, > Jennifer > > From 89936b7bc2de7a1e4bc55c3a1e8d5e6ac0de579d Mon Sep 17 00:00:00 2001 > From: Jennifer Schmitz <jschm...@nvidia.com> > Date: Wed, 24 Jul 2024 06:13:59 -0700 > Subject: [PATCH] AArch64: Fuse CMP+CSEL and CMP+CSET for -mcpu=neoverse-v2 > > According to the Neoverse V2 Software Optimization Guide (section 4.14), the > instruction pairs CMP+CSEL and CMP+CSET can be fused, which had not been > implemented so far. This patch implements and tests the two fusion pairs. > > The patch was bootstrapped and regtested on aarch64-linux-gnu, no regression. > There was also no non-noise impact on SPEC CPU2017 benchmark. > OK for mainline? > > Signed-off-by: Jennifer Schmitz <jschm...@nvidia.com> > > gcc/ > > * config/aarch64/aarch64.cc (aarch_macro_fusion_pair_p): Implement > fusion logic. > * config/aarch64/aarch64-fusion-pairs.def (cmp+csel): New entry. > (cmp+cset): Likewise. > * config/aarch64/tuning_models/neoversev2.h: Enable logic in > field fusible_ops. > > gcc/testsuite/ > > * gcc.target/aarch64/fuse_cmp_csel.c: New test. > * gcc.target/aarch64/fuse_cmp_cset.c: Likewise. > --- > gcc/config/aarch64/aarch64-fusion-pairs.def | 2 ++ > gcc/config/aarch64/aarch64.cc | 20 +++++++++++ > gcc/config/aarch64/tuning_models/neoversev2.h | 5 ++- > .../gcc.target/aarch64/fuse_cmp_csel.c | 33 +++++++++++++++++++ > .../gcc.target/aarch64/fuse_cmp_cset.c | 31 +++++++++++++++++ > 5 files changed, 90 insertions(+), 1 deletion(-) > create mode 100644 gcc/testsuite/gcc.target/aarch64/fuse_cmp_csel.c > create mode 100644 gcc/testsuite/gcc.target/aarch64/fuse_cmp_cset.c > > diff --git a/gcc/config/aarch64/aarch64-fusion-pairs.def > b/gcc/config/aarch64/aarch64-fusion-pairs.def > index 9a43b0c8065..bf5e85ba8fe 100644 > --- a/gcc/config/aarch64/aarch64-fusion-pairs.def > +++ b/gcc/config/aarch64/aarch64-fusion-pairs.def > @@ -37,5 +37,7 @@ AARCH64_FUSION_PAIR ("aes+aesmc", AES_AESMC) > AARCH64_FUSION_PAIR ("alu+branch", ALU_BRANCH) > AARCH64_FUSION_PAIR ("alu+cbz", ALU_CBZ) > AARCH64_FUSION_PAIR ("addsub_2reg_const1", ADDSUB_2REG_CONST1) > +AARCH64_FUSION_PAIR ("cmp+csel", CMP_CSEL) > +AARCH64_FUSION_PAIR ("cmp+cset", CMP_CSET) > > #undef AARCH64_FUSION_PAIR > diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc > index e0cf382998c..d42c153443e 100644 > --- a/gcc/config/aarch64/aarch64.cc > +++ b/gcc/config/aarch64/aarch64.cc > @@ -27345,6 +27345,26 @@ aarch_macro_fusion_pair_p (rtx_insn *prev, rtx_insn > *curr) > && reg_referenced_p (SET_DEST (prev_set), PATTERN (curr))) > return true; > > + /* Fuse CMP and CSEL/CSET. */ > + if (prev_set && curr_set > + && GET_CODE (SET_SRC (prev_set)) == COMPARE > + && SCALAR_INT_MODE_P (GET_MODE (XEXP (SET_SRC (prev_set), 0))) > + && reg_referenced_p (SET_DEST (prev_set), PATTERN (curr))) > + { > + enum attr_type prev_type = get_attr_type (prev); > + if ((prev_type == TYPE_ALUS_SREG || prev_type == TYPE_ALUS_IMM) > + && (aarch64_fusion_enabled_p (AARCH64_FUSE_CMP_CSEL) > + && GET_CODE (SET_SRC (curr_set)) == IF_THEN_ELSE > + && REG_P (XEXP (SET_SRC (curr_set), 1)) > + && REG_P (XEXP (SET_SRC (curr_set), 2))
Gah, I'd meant to say this in a previous review, but now realise that I forgot. I think these REG_Ps can be relaxed to: && aarch64_reg_or_zero (XEXP (SET_SRC (curr_set), N), VOIDmode) since CSEL can take w/xzr. > + && SCALAR_INT_MODE_P (GET_MODE (XEXP (SET_SRC (curr_set), 1)))) > + || (aarch64_fusion_enabled_p (AARCH64_FUSE_CMP_CSET) > + && GET_RTX_CLASS (GET_CODE (SET_SRC (curr_set))) > + == RTX_COMPARE > + && REG_P (SET_DEST (curr_set)))) > + return true; > + } It looks like there might be a missing pair of brackets here. AFAICT, the current bracketing works out as: if ((prev_type conditions) && (CMP_CSEL conditions) || (CMP_CSET conditions)) and since || binds less tightly than &&, I think the CMP_CSET condition doesn't include the prev_type restriction. Enclosing everything after the first && in an extra set of brackets would fix that. OK with those changes from my POV (no need for another round of review, unless you'd prefer one). Please give others a day or so to comment though. Thanks, Richard > + > /* Fuse flag-setting ALU instructions and conditional branch. */ > if (aarch64_fusion_enabled_p (AARCH64_FUSE_ALU_BRANCH) > && any_condjump_p (curr)) > diff --git a/gcc/config/aarch64/tuning_models/neoversev2.h > b/gcc/config/aarch64/tuning_models/neoversev2.h > index f76e4ef358f..ae99fab22d8 100644 > --- a/gcc/config/aarch64/tuning_models/neoversev2.h > +++ b/gcc/config/aarch64/tuning_models/neoversev2.h > @@ -221,7 +221,10 @@ static const struct tune_params neoversev2_tunings = > 2 /* store_pred. */ > }, /* memmov_cost. */ > 5, /* issue_rate */ > - (AARCH64_FUSE_AES_AESMC | AARCH64_FUSE_CMP_BRANCH), /* fusible_ops */ > + (AARCH64_FUSE_AES_AESMC > + | AARCH64_FUSE_CMP_BRANCH > + | AARCH64_FUSE_CMP_CSEL > + | AARCH64_FUSE_CMP_CSET), /* fusible_ops */ > "32:16", /* function_align. */ > "4", /* jump_align. */ > "32:16", /* loop_align. */ > diff --git a/gcc/testsuite/gcc.target/aarch64/fuse_cmp_csel.c > b/gcc/testsuite/gcc.target/aarch64/fuse_cmp_csel.c > new file mode 100644 > index 00000000000..85f302bab98 > --- /dev/null > +++ b/gcc/testsuite/gcc.target/aarch64/fuse_cmp_csel.c > @@ -0,0 +1,33 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -mcpu=neoverse-v2" } */ > +/* { dg-final { check-function-bodies "**" "" } } */ > + > +/* > +** f1: > +** ... > +** cmp w[0-9]+, w[0-9]+ > +** csel w[0-9]+, w[0-9]+, w[0-9]+, le > +** ret > +*/ > +int f1 (int a, int b, int c) > +{ > + int cmp = a > b; > + int add1 = c + 3; > + int add2 = c + 8; > + return cmp ? add1 : add2; > +} > + > +/* > +** f2: > +** ... > +** cmp x[0-9]+, x[0-9]+ > +** csel x[0-9]+, x[0-9]+, x[0-9]+, le > +** ret > +*/ > +long long f2 (long long a, long long b, long long c) > +{ > + long long cmp = a > b; > + long long add1 = c + 3; > + long long add2 = c + 8; > + return cmp ? add1 : add2; > +} > diff --git a/gcc/testsuite/gcc.target/aarch64/fuse_cmp_cset.c > b/gcc/testsuite/gcc.target/aarch64/fuse_cmp_cset.c > new file mode 100644 > index 00000000000..04f1ce2773b > --- /dev/null > +++ b/gcc/testsuite/gcc.target/aarch64/fuse_cmp_cset.c > @@ -0,0 +1,31 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O2 -mcpu=neoverse-v2" } */ > +/* { dg-final { check-function-bodies "**" "" } } */ > + > +/* > +** f1: > +** cmp w[0-9]+, w[0-9]+ > +** cset w[0-9]+, gt > +** ... > +*/ > +int g; > +int f1 (int a, int b) > +{ > + int cmp = a > b; > + g = cmp + 1; > + return cmp; > +} > + > +/* > +** f2: > +** cmp x[0-9]+, x[0-9]+ > +** cset x[0-9]+, gt > +** ... > +*/ > +long long h; > +long long f2 (long long a, long long b) > +{ > + long long cmp = a > b; > + h = cmp + 1; > + return cmp; > +}