Re: [CI-NOTIFY]: TCWG Bisect tcwg_gnu/gnu-master-aarch64-check_bootstrap - Build # 80 - Successful!

Reported to upstream at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101506 .

-- Maxim Kuvyrkov https://www.linaro.org

On 19 Jul 2021, at 02:30, ci_notify@linaro.org wrote:

Successfully identified regression in *gcc* in CI configuration tcwg_gnu/gnu-master-aarch64-check_bootstrap. So far, this commit has regressed CI configurations:

• tcwg_gnu/gnu-master-aarch64-check_bootstrap

Culprit:

<cut> commit 1dd3f21095858fbfd3e28a149578d5fb67e75f95 Author: Richard Biener <rguenther@suse.de> Date: Tue Jul 13 13:59:15 2021 +0200

Support reduction def re-use for epilogue with different vector size

The following adds support for re-using the vector reduction def from the main loop in vectorized epilogue loops on architectures which use different vector sizes for the epilogue. That's only x86 as far as I am aware.

2021-07-13 Richard Biener rguenther@suse.de

       * tree-vect-loop.c (vect_find_reusable_accumulator): Handle
       vector types where the old vector type has a multiple of
       the new vector type elements.
       (vect_create_partial_epilog): New function, split out from...
       (vect_create_epilog_for_reduction): ... here.
       (vect_transform_cycle_phi): Reduce the re-used accumulator
       to the new vector type.

       * gcc.target/i386/vect-reduc-1.c: New testcase.

</cut>

Results regressed to (for first_bad == 1dd3f21095858fbfd3e28a149578d5fb67e75f95) # reset_artifacts: -10 # build_abe binutils: -2 # build_abe bootstrap: -1 # build_abe dejagnu: 0 # build_abe check_bootstrap -- --set runtestflags=g++.dg/dg.exp --set runtestflags=gcc.target/aarch64/aarch64.exp: 1 # Getting actual results from build directory /home/tcwg-buildslave/workspace/tcwg_gnu_3/artifacts/build-1dd3f21095858fbfd3e28a149578d5fb67e75f95/sumfiles # /home/tcwg-buildslave/workspace/tcwg_gnu_3/artifacts/build-1dd3f21095858fbfd3e28a149578d5fb67e75f95/sumfiles/libstdc++.sum # /home/tcwg-buildslave/workspace/tcwg_gnu_3/artifacts/build-1dd3f21095858fbfd3e28a149578d5fb67e75f95/sumfiles/gfortran.sum # /home/tcwg-buildslave/workspace/tcwg_gnu_3/artifacts/build-1dd3f21095858fbfd3e28a149578d5fb67e75f95/sumfiles/libitm.sum # /home/tcwg-buildslave/workspace/tcwg_gnu_3/artifacts/build-1dd3f21095858fbfd3e28a149578d5fb67e75f95/sumfiles/libgomp.sum # /home/tcwg-buildslave/workspace/tcwg_gnu_3/artifacts/build-1dd3f21095858fbfd3e28a149578d5fb67e75f95/sumfiles/libatomic.sum # /home/tcwg-buildslave/workspace/tcwg_gnu_3/artifacts/build-1dd3f21095858fbfd3e28a149578d5fb67e75f95/sumfiles/g++.sum # /home/tcwg-buildslave/workspace/tcwg_gnu_3/artifacts/build-1dd3f21095858fbfd3e28a149578d5fb67e75f95/sumfiles/gcc.sum # Manifest: gcc-compare-results/contrib/testsuite-management/flaky/gnu-master-aarch64-check_bootstrap.xfail # Getting actual results from build directory base-artifacts/sumfiles # base-artifacts/sumfiles/libstdc++.sum # base-artifacts/sumfiles/gfortran.sum # base-artifacts/sumfiles/libitm.sum # base-artifacts/sumfiles/libgomp.sum # base-artifacts/sumfiles/libatomic.sum # base-artifacts/sumfiles/g++.sum # base-artifacts/sumfiles/gcc.sum # # # Unexpected results in this build (new failures) # === gcc tests === # # Running gcc.target/aarch64/aarch64.exp ... # FAIL: gcc.target/aarch64/vect-fmaxv-fminv-compile.c scan-assembler fminnmv # FAIL: gcc.target/aarch64/vect-fmaxv-fminv-compile.c scan-assembler fmaxnmv # # === Results Summary ===

from (for last_good == a7098d6ef4e4e799dab8ef925c62b199d707694b) # reset_artifacts: -10 # build_abe binutils: -2 # build_abe bootstrap: -1 # build_abe dejagnu: 0 # build_abe check_bootstrap -- --set runtestflags=g++.dg/dg.exp --set runtestflags=gcc.target/aarch64/aarch64.exp: 1

Artifacts of last_good build: https://ci.linaro.org/job/tcwg_gcc-bisect-gnu-master-aarch64-check_bootstrap... Artifacts of first_bad build: https://ci.linaro.org/job/tcwg_gcc-bisect-gnu-master-aarch64-check_bootstrap... Build top page/logs: https://ci.linaro.org/job/tcwg_gcc-bisect-gnu-master-aarch64-check_bootstrap...

Configuration details:

Reproduce builds:

<cut> mkdir investigate-gcc-1dd3f21095858fbfd3e28a149578d5fb67e75f95 cd investigate-gcc-1dd3f21095858fbfd3e28a149578d5fb67e75f95

git clone https://git.linaro.org/toolchain/jenkins-scripts

mkdir -p artifacts/manifests curl -o artifacts/manifests/build-baseline.sh https://ci.linaro.org/job/tcwg_gcc-bisect-gnu-master-aarch64-check_bootstrap... --fail curl -o artifacts/manifests/build-parameters.sh https://ci.linaro.org/job/tcwg_gcc-bisect-gnu-master-aarch64-check_bootstrap... --fail curl -o artifacts/test.sh https://ci.linaro.org/job/tcwg_gcc-bisect-gnu-master-aarch64-check_bootstrap... --fail chmod +x artifacts/test.sh

# Reproduce the baseline build (build all pre-requisites) ./jenkins-scripts/tcwg_gnu-build.sh @@ artifacts/manifests/build-baseline.sh

# Save baseline build state (which is then restored in artifacts/test.sh) rsync -a --del --delete-excluded --exclude bisect/ --exclude artifacts/ --exclude gcc/ ./ ./bisect/baseline/

cd gcc

# Reproduce first_bad build git checkout --detach 1dd3f21095858fbfd3e28a149578d5fb67e75f95 ../artifacts/test.sh

# Reproduce last_good build git checkout --detach a7098d6ef4e4e799dab8ef925c62b199d707694b ../artifacts/test.sh

cd ..

</cut>

History of pending regressions and results: https://git.linaro.org/toolchain/ci/base-artifacts.git/log/?h=linaro-local/c...

Artifacts: https://ci.linaro.org/job/tcwg_gcc-bisect-gnu-master-aarch64-check_bootstrap... Build log: https://ci.linaro.org/job/tcwg_gcc-bisect-gnu-master-aarch64-check_bootstrap...

Full commit (up to 1000 lines):

<cut> commit 1dd3f21095858fbfd3e28a149578d5fb67e75f95 Author: Richard Biener <rguenther@suse.de> Date: Tue Jul 13 13:59:15 2021 +0200

Support reduction def re-use for epilogue with different vector size

The following adds support for re-using the vector reduction def from the main loop in vectorized epilogue loops on architectures which use different vector sizes for the epilogue. That's only x86 as far as I am aware.

2021-07-13 Richard Biener rguenther@suse.de

       * tree-vect-loop.c (vect_find_reusable_accumulator): Handle
       vector types where the old vector type has a multiple of
       the new vector type elements.
       (vect_create_partial_epilog): New function, split out from...
       (vect_create_epilog_for_reduction): ... here.
       (vect_transform_cycle_phi): Reduce the re-used accumulator
       to the new vector type.

       * gcc.target/i386/vect-reduc-1.c: New testcase.

---

gcc/testsuite/gcc.target/i386/vect-reduc-1.c | 17 ++ gcc/tree-vect-loop.c | 227 ++++++++++++++++----------- 2 files changed, 156 insertions(+), 88 deletions(-)

diff --git a/gcc/testsuite/gcc.target/i386/vect-reduc-1.c b/gcc/testsuite/gcc.target/i386/vect-reduc-1.c new file mode 100644 index 00000000000..9ee9ba4e736 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/vect-reduc-1.c @@ -0,0 +1,17 @@ +/* { dg-do compile } */ +/* { dg-options "-O3 -mavx2 -mno-avx512f -fdump-tree-vect-details" } */

+#define N 32 +int foo (int *a, int n) +{

• int sum = 1;
• for (int i = 0; i < 8*N + 4; ++i)
• sum += a[i];
• return sum;

+}

+/* The reduction epilog should be vectorized and the accumulator

• re-used. */

+/* { dg-final { scan-tree-dump "LOOP EPILOGUE VECTORIZED" "vect" } } */ +/* { dg-final { scan-assembler-times "psrl" 2 } } */ +/* { dg-final { scan-assembler-times "padd" 5 } } */ diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c index 8c27d75f889..e9780158a51 100644 --- a/gcc/tree-vect-loop.c +++ b/gcc/tree-vect-loop.c @@ -4896,12 +4896,11 @@ vect_find_reusable_accumulator (loop_vec_info loop_vinfo, accumulator->reduc_info->reduc_scalar_results.begin ())) return false;

• /* For now, only handle the case in which both loops are operating on the

• same vector types.  In future we could reduce wider vectors to narrower
  

• ones as well.  */
  

• /* Handle the case where we can reduce wider vectors to narrower ones. */ tree vectype = STMT_VINFO_VECTYPE (reduc_info); tree old_vectype = TREE_TYPE (accumulator->reduc_input);

• if (!useless_type_conversion_p (old_vectype, vectype))

• if (!constant_multiple_p (TYPE_VECTOR_SUBPARTS (old_vectype),

• 	    TYPE_VECTOR_SUBPARTS (vectype)))
  

  return false;

  /* Non-SLP reductions might apply an adjustment after the reduction

@@ -4935,6 +4934,101 @@ vect_find_reusable_accumulator (loop_vec_info loop_vinfo, return true; }

+/* Reduce the vector VEC_DEF down to VECTYPE with reduction operation

• CODE emitting stmts before GSI. Returns a vector def of VECTYPE. */

+static tree +vect_create_partial_epilog (tree vec_def, tree vectype, enum tree_code code,

• 	    gimple_seq *seq)
  

+{

• unsigned nunits = TYPE_VECTOR_SUBPARTS (TREE_TYPE (vec_def)).to_constant ();
• unsigned nunits1 = TYPE_VECTOR_SUBPARTS (vectype).to_constant ();
• tree stype = TREE_TYPE (vectype);
• tree new_temp = vec_def;
• while (nunits > nunits1)
• {

•  nunits /= 2;
  

•  tree vectype1 = get_related_vectype_for_scalar_type (TYPE_MODE (vectype),
  

• 					   stype, nunits);
  

•  unsigned int bitsize = tree_to_uhwi (TYPE_SIZE (vectype1));
  

•  /* The target has to make sure we support lowpart/highpart
  

• extraction, either via direct vector extract or through
  

• an integer mode punning.  */
  

•  tree dst1, dst2;
  

•  gimple *epilog_stmt;
  

•  if (convert_optab_handler (vec_extract_optab,
  

• 		 TYPE_MODE (TREE_TYPE (new_temp)),
  

• 		 TYPE_MODE (vectype1))
  

•  != CODE_FOR_nothing)
  

• {

•  /* Extract sub-vectors directly once vec_extract becomes
  

•     a conversion optab.  */
  

•  dst1 = make_ssa_name (vectype1);
  

•  epilog_stmt
  

•      = gimple_build_assign (dst1, BIT_FIELD_REF,
  

• 		     build3 (BIT_FIELD_REF, vectype1,
  

• 			     new_temp, TYPE_SIZE (vectype1),
  

• 			     bitsize_int (0)));
  

•  gimple_seq_add_stmt_without_update (seq, epilog_stmt);
  

•  dst2 =  make_ssa_name (vectype1);
  

•  epilog_stmt
  

•      = gimple_build_assign (dst2, BIT_FIELD_REF,
  

• 		     build3 (BIT_FIELD_REF, vectype1,
  

• 			     new_temp, TYPE_SIZE (vectype1),
  

• 			     bitsize_int (bitsize)));
  

•  gimple_seq_add_stmt_without_update (seq, epilog_stmt);
  

• }

•  else
  

• {

•  /* Extract via punning to appropriately sized integer mode
  

•     vector.  */
  

•  tree eltype = build_nonstandard_integer_type (bitsize, 1);
  

•  tree etype = build_vector_type (eltype, 2);
  

•  gcc_assert (convert_optab_handler (vec_extract_optab,
  

• 			     TYPE_MODE (etype),
  

• 			     TYPE_MODE (eltype))
  

•       != CODE_FOR_nothing);
  

•  tree tem = make_ssa_name (etype);
  

•  epilog_stmt = gimple_build_assign (tem, VIEW_CONVERT_EXPR,
  

• 			     build1 (VIEW_CONVERT_EXPR,
  

• 				     etype, new_temp));
  

•  gimple_seq_add_stmt_without_update (seq, epilog_stmt);
  

•  new_temp = tem;
  

•  tem = make_ssa_name (eltype);
  

•  epilog_stmt
  

•      = gimple_build_assign (tem, BIT_FIELD_REF,
  

• 		     build3 (BIT_FIELD_REF, eltype,
  

• 			     new_temp, TYPE_SIZE (eltype),
  

• 			     bitsize_int (0)));
  

•  gimple_seq_add_stmt_without_update (seq, epilog_stmt);
  

•  dst1 = make_ssa_name (vectype1);
  

•  epilog_stmt = gimple_build_assign (dst1, VIEW_CONVERT_EXPR,
  

• 			     build1 (VIEW_CONVERT_EXPR,
  

• 				     vectype1, tem));
  

•  gimple_seq_add_stmt_without_update (seq, epilog_stmt);
  

•  tem = make_ssa_name (eltype);
  

•  epilog_stmt
  

•      = gimple_build_assign (tem, BIT_FIELD_REF,
  

• 		     build3 (BIT_FIELD_REF, eltype,
  

• 			     new_temp, TYPE_SIZE (eltype),
  

• 			     bitsize_int (bitsize)));
  

•  gimple_seq_add_stmt_without_update (seq, epilog_stmt);
  

•  dst2 =  make_ssa_name (vectype1);
  

•  epilog_stmt = gimple_build_assign (dst2, VIEW_CONVERT_EXPR,
  

• 			     build1 (VIEW_CONVERT_EXPR,
  

• 				     vectype1, tem));
  

•  gimple_seq_add_stmt_without_update (seq, epilog_stmt);
  

• }

•  new_temp = make_ssa_name (vectype1);
  

•  epilog_stmt = gimple_build_assign (new_temp, code, dst1, dst2);
  

•  gimple_seq_add_stmt_without_update (seq, epilog_stmt);
  

• }
• return new_temp;

+}

/* Function vect_create_epilog_for_reduction

Create code at the loop-epilog to finalize the result of a reduction @@ -5684,87 +5778,11 @@ vect_create_epilog_for_reduction (loop_vec_info loop_vinfo,

  /* First reduce the vector to the desired vector size we should
do shift reduction on by combining upper and lower halves.  */

•  new_temp = reduc_inputs[0];
  

•  while (nunits > nunits1)
  

• {

•  nunits /= 2;
  

•  vectype1 = get_related_vectype_for_scalar_type (TYPE_MODE (vectype),
  

• 					  stype, nunits);
  

•  unsigned int bitsize = tree_to_uhwi (TYPE_SIZE (vectype1));
  

•  /* The target has to make sure we support lowpart/highpart
  

•     extraction, either via direct vector extract or through
  

•     an integer mode punning.  */
  

•  tree dst1, dst2;
  

•  if (convert_optab_handler (vec_extract_optab,
  

• 		     TYPE_MODE (TREE_TYPE (new_temp)),
  

• 		     TYPE_MODE (vectype1))
  

•      != CODE_FOR_nothing)
  

•    {
  

•      /* Extract sub-vectors directly once vec_extract becomes
  

•  a conversion optab.  */
  

•      dst1 = make_ssa_name (vectype1);
  

•      epilog_stmt
  

•   = gimple_build_assign (dst1, BIT_FIELD_REF,
  

• 			 build3 (BIT_FIELD_REF, vectype1,
  

• 				 new_temp, TYPE_SIZE (vectype1),
  

• 				 bitsize_int (0)));
  

•      gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
  

•      dst2 =  make_ssa_name (vectype1);
  

•      epilog_stmt
  

•   = gimple_build_assign (dst2, BIT_FIELD_REF,
  

• 			 build3 (BIT_FIELD_REF, vectype1,
  

• 				 new_temp, TYPE_SIZE (vectype1),
  

• 				 bitsize_int (bitsize)));
  

•      gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
  

•    }
  

•  else
  

•    {
  

•      /* Extract via punning to appropriately sized integer mode
  

•  vector.  */
  

•      tree eltype = build_nonstandard_integer_type (bitsize, 1);
  

•      tree etype = build_vector_type (eltype, 2);
  

•      gcc_assert (convert_optab_handler (vec_extract_optab,
  

• 				 TYPE_MODE (etype),
  

• 				 TYPE_MODE (eltype))
  

• 	  != CODE_FOR_nothing);
  

•      tree tem = make_ssa_name (etype);
  

•      epilog_stmt = gimple_build_assign (tem, VIEW_CONVERT_EXPR,
  

• 				 build1 (VIEW_CONVERT_EXPR,
  

• 					 etype, new_temp));
  

•      gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
  

•      new_temp = tem;
  

•      tem = make_ssa_name (eltype);
  

•      epilog_stmt
  

•   = gimple_build_assign (tem, BIT_FIELD_REF,
  

• 			 build3 (BIT_FIELD_REF, eltype,
  

• 				 new_temp, TYPE_SIZE (eltype),
  

• 				 bitsize_int (0)));
  

•      gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
  

•      dst1 = make_ssa_name (vectype1);
  

•      epilog_stmt = gimple_build_assign (dst1, VIEW_CONVERT_EXPR,
  

• 				 build1 (VIEW_CONVERT_EXPR,
  

• 					 vectype1, tem));
  

•      gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
  

•      tem = make_ssa_name (eltype);
  

•      epilog_stmt
  

•   = gimple_build_assign (tem, BIT_FIELD_REF,
  

• 			 build3 (BIT_FIELD_REF, eltype,
  

• 				 new_temp, TYPE_SIZE (eltype),
  

• 				 bitsize_int (bitsize)));
  

•      gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
  

•      dst2 =  make_ssa_name (vectype1);
  

•      epilog_stmt = gimple_build_assign (dst2, VIEW_CONVERT_EXPR,
  

• 				 build1 (VIEW_CONVERT_EXPR,
  

• 					 vectype1, tem));
  

•      gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
  

•    }
  

•  new_temp = make_ssa_name (vectype1);
  

•  epilog_stmt = gimple_build_assign (new_temp, code, dst1, dst2);
  

•  gsi_insert_before (&exit_gsi, epilog_stmt, GSI_SAME_STMT);
  

•  reduc_inputs[0] = new_temp;
  

• }

•  gimple_seq stmts = NULL;
  

•  new_temp = vect_create_partial_epilog (reduc_inputs[0], vectype1,
  

• 			     code, &stmts);
  

•  gsi_insert_seq_before (&exit_gsi, stmts, GSI_SAME_STMT);
  

•  reduc_inputs[0] = new_temp;
  
  if (reduce_with_shift && !slp_reduc)
  

  {

@@ -7681,13 +7699,46 @@ vect_transform_cycle_phi (loop_vec_info loop_vinfo,

if (auto *accumulator = reduc_info->reused_accumulator) {

•  tree def = accumulator->reduc_input;
  

•  unsigned int nreduc;
  

•  bool res = constant_multiple_p (TYPE_VECTOR_SUBPARTS (TREE_TYPE (def)),
  

• 		      TYPE_VECTOR_SUBPARTS (vectype_out),
  

• 		      &nreduc);
  

•  gcc_assert (res);
  

•  if (nreduc != 1)
  

• {

•  /* Reduce the single vector to a smaller one.  */
  

•  gimple_seq stmts = NULL;
  

•  def = vect_create_partial_epilog (def, vectype_out,
  

• 			    STMT_VINFO_REDUC_CODE (reduc_info),
  

• 			    &stmts);
  

•  /* Adjust the input so we pick up the partially reduced value
  

•     for the skip edge in vect_create_epilog_for_reduction.  */
  

•  accumulator->reduc_input = def;
  

•  if (loop_vinfo->main_loop_edge)
  

•    {
  

•      /* While we'd like to insert on the edge this will split
  

•  blocks and disturb bookkeeping, we also will eventually
  

•  need this on the skip edge.  Rely on sinking to
  

•  fixup optimal placement and insert in the pred.  */
  

•      gimple_stmt_iterator gsi
  

• = gsi_last_bb (loop_vinfo->main_loop_edge->src);
  

•      /* Insert before a cond that eventually skips the
  

•  epilogue.  */
  

•      if (!gsi_end_p (gsi) && stmt_ends_bb_p (gsi_stmt (gsi)))
  

• gsi_prev (&gsi);
  

•      gsi_insert_seq_after (&gsi, stmts, GSI_CONTINUE_LINKING);
  

•    }
  

•  else
  

•    gsi_insert_seq_on_edge_immediate (loop_preheader_edge (loop),
  

• 			      stmts);
  

• } if (loop_vinfo->main_loop_edge) vec_initial_defs[0]

•  = vect_get_main_loop_result (loop_vinfo, accumulator->reduc_input,
  

•  = vect_get_main_loop_result (loop_vinfo, def,
  	       vec_initial_defs[0]);
  else
  

• vec_initial_defs.safe_push (accumulator->reduc_input);

•  gcc_assert (vec_initial_defs.length () == 1);
  

• vec_initial_defs.safe_push (def); }

  /* Generate the reduction PHIs upfront. */

</cut>