[TCWG CI] Failure after basepoints/gcc-13-3219-g25413fdb2ac: vect: Teach vectorizer how to handle bitfield accesses

[TCWG CI] Failure after basepoints/gcc-13-3219-g25413fdb2ac: vect: Teach vectorizer how to handle bitfield accesses

[ci_notify]

[-- Attachment #1: Type: text/plain, Size: 33775 bytes --]

Failure after basepoints/gcc-13-3219-g25413fdb2ac: vect: Teach vectorizer how to handle bitfield accesses:

Results changed to
-10
# true:
0
# build_abe binutils:
1
# build_abe bootstrap:
# FAILED
# First few build errors in logs:
# 00:06:09 make[3]: [Makefile:1815: armv8l-unknown-linux-gnueabihf/bits/largefile-config.h] Error 1 (ignored)
# 00:29:03 make[3]: [Makefile:1815: armv8l-unknown-linux-gnueabihf/bits/largefile-config.h] Error 1 (ignored)
# 00:31:57 /home/tcwg-buildslave/workspace/tcwg_gnu_11/abe/snapshots/gcc.git~master/gcc/lra.cc:803:1: error: position plus size exceeds size of referenced object in ‘bit_field_ref’
# 00:31:57 /home/tcwg-buildslave/workspace/tcwg_gnu_11/abe/snapshots/gcc.git~master/gcc/lra.cc:803:1: internal compiler error: verify_gimple failed
# 00:31:57 make[3]: *** [Makefile:1147: lra.o] Error 1
# 00:38:17 make[2]: *** [Makefile:5020: all-stage3-gcc] Error 2
# 00:38:17 make[1]: *** [Makefile:25706: stage3-bubble] Error 2
# 00:38:17 make: *** [Makefile:1064: all] Error 2

from
-10
# true:
0
# build_abe binutils:
1
# build_abe bootstrap:
2

THIS IS THE END OF INTERESTING STUFF.  BELOW ARE LINKS TO BUILDS, REPRODUCTION INSTRUCTIONS, AND THE RAW COMMIT.

For latest status see comments in https://linaro.atlassian.net/browse/GNU-692 .
Status of basepoints/gcc-13-3219-g25413fdb2ac commit for tcwg_gcc_bootstrap:
commit 25413fdb2ac24933214123e24ba165026452a6f2
Author: Andre Vieira <andre.simoesdiasvieira@arm.com>
Date:   Tue Oct 11 10:49:27 2022 +0100

    vect: Teach vectorizer how to handle bitfield accesses
    
    gcc/ChangeLog:
    
            * tree-if-conv.cc (if_convertible_loop_p_1): Move ordering of loop bb's from
            here...
            (tree_if_conversion): ... to here.  Also call bitfield lowering when
            appropriate.
            (version_loop_for_if_conversion): Adapt to enable loop versioning when we only
            need to lower bitfields.
            (ifcvt_split_critical_edges): Relax condition of expected loop form as this is
            checked earlier.
            (get_bitfield_rep): New function.
            (lower_bitfield): Likewise.
            (bitfields_to_lower_p): Likewise.
            (need_to_lower_bitfields): New global boolean.
            (need_to_ifcvt): Likewise.
            * tree-vect-data-refs.cc (vect_find_stmt_data_reference): Improve diagnostic
            message.
            * tree-vect-patterns.cc (vect_recog_temp_ssa_var): Add default value for last
            parameter.
            (vect_recog_bitfield_ref_pattern): New.
            (vect_recog_bit_insert_pattern): New.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/vect/vect-bitfield-read-1.c: New test.
            * gcc.dg/vect/vect-bitfield-read-2.c: New test.
            * gcc.dg/vect/vect-bitfield-read-3.c: New test.
            * gcc.dg/vect/vect-bitfield-read-4.c: New test.
            * gcc.dg/vect/vect-bitfield-read-5.c: New test.
            * gcc.dg/vect/vect-bitfield-read-6.c: New test.
            * gcc.dg/vect/vect-bitfield-write-1.c: New test.
            * gcc.dg/vect/vect-bitfield-write-2.c: New test.
            * gcc.dg/vect/vect-bitfield-write-3.c: New test.
            * gcc.dg/vect/vect-bitfield-write-4.c: New test.
            * gcc.dg/vect/vect-bitfield-write-5.c: New test.
* master-arm-bootstrap
** Failure after basepoints/gcc-13-3219-g25413fdb2ac: vect: Teach vectorizer how to handle bitfield accesses:
** https://ci.linaro.org/job/tcwg_gcc_bootstrap-build-master-arm-bootstrap/1603/

Bad  build: https://ci.linaro.org/job/tcwg_gcc_bootstrap-build-master-arm-bootstrap/1603/artifact/artifacts
Good build: https://ci.linaro.org/job/tcwg_gcc_bootstrap-build-master-arm-bootstrap/1602/artifact/artifacts

Reproduce current build:
<cut>
mkdir -p investigate-gcc-25413fdb2ac24933214123e24ba165026452a6f2
cd investigate-gcc-25413fdb2ac24933214123e24ba165026452a6f2

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

# Fetch manifests for bad and good builds
mkdir -p bad/artifacts good/artifacts
curl -o bad/artifacts/manifest.sh https://ci.linaro.org/job/tcwg_gcc_bootstrap-build-master-arm-bootstrap/1603/artifact/artifacts/manifest.sh --fail
curl -o good/artifacts/manifest.sh https://ci.linaro.org/job/tcwg_gcc_bootstrap-build-master-arm-bootstrap/1602/artifact/artifacts/manifest.sh --fail

# Reproduce bad build
(cd bad; ../jenkins-scripts/tcwg_gnu-build.sh ^^ true %%rr[top_artifacts] artifacts)
# Reproduce good build
(cd good; ../jenkins-scripts/tcwg_gnu-build.sh ^^ true %%rr[top_artifacts] artifacts)
</cut>

Full commit (up to 1000 lines):
<cut>
commit 25413fdb2ac24933214123e24ba165026452a6f2
Author: Andre Vieira <andre.simoesdiasvieira@arm.com>
Date:   Tue Oct 11 10:49:27 2022 +0100

    vect: Teach vectorizer how to handle bitfield accesses
    
    gcc/ChangeLog:
    
            * tree-if-conv.cc (if_convertible_loop_p_1): Move ordering of loop bb's from
            here...
            (tree_if_conversion): ... to here.  Also call bitfield lowering when
            appropriate.
            (version_loop_for_if_conversion): Adapt to enable loop versioning when we only
            need to lower bitfields.
            (ifcvt_split_critical_edges): Relax condition of expected loop form as this is
            checked earlier.
            (get_bitfield_rep): New function.
            (lower_bitfield): Likewise.
            (bitfields_to_lower_p): Likewise.
            (need_to_lower_bitfields): New global boolean.
            (need_to_ifcvt): Likewise.
            * tree-vect-data-refs.cc (vect_find_stmt_data_reference): Improve diagnostic
            message.
            * tree-vect-patterns.cc (vect_recog_temp_ssa_var): Add default value for last
            parameter.
            (vect_recog_bitfield_ref_pattern): New.
            (vect_recog_bit_insert_pattern): New.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/vect/vect-bitfield-read-1.c: New test.
            * gcc.dg/vect/vect-bitfield-read-2.c: New test.
            * gcc.dg/vect/vect-bitfield-read-3.c: New test.
            * gcc.dg/vect/vect-bitfield-read-4.c: New test.
            * gcc.dg/vect/vect-bitfield-read-5.c: New test.
            * gcc.dg/vect/vect-bitfield-read-6.c: New test.
            * gcc.dg/vect/vect-bitfield-write-1.c: New test.
            * gcc.dg/vect/vect-bitfield-write-2.c: New test.
            * gcc.dg/vect/vect-bitfield-write-3.c: New test.
            * gcc.dg/vect/vect-bitfield-write-4.c: New test.
            * gcc.dg/vect/vect-bitfield-write-5.c: New test.
---
 gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1.c  |  40 +++
 gcc/testsuite/gcc.dg/vect/vect-bitfield-read-2.c  |  43 +++
 gcc/testsuite/gcc.dg/vect/vect-bitfield-read-3.c  |  44 +++
 gcc/testsuite/gcc.dg/vect/vect-bitfield-read-4.c  |  45 +++
 gcc/testsuite/gcc.dg/vect/vect-bitfield-read-5.c  |  42 +++
 gcc/testsuite/gcc.dg/vect/vect-bitfield-read-6.c  |  42 +++
 gcc/testsuite/gcc.dg/vect/vect-bitfield-write-1.c |  39 +++
 gcc/testsuite/gcc.dg/vect/vect-bitfield-write-2.c |  42 +++
 gcc/testsuite/gcc.dg/vect/vect-bitfield-write-3.c |  43 +++
 gcc/testsuite/gcc.dg/vect/vect-bitfield-write-4.c |  42 +++
 gcc/testsuite/gcc.dg/vect/vect-bitfield-write-5.c |  42 +++
 gcc/tree-if-conv.cc                               | 313 ++++++++++++++++++--
 gcc/tree-vect-data-refs.cc                        |   3 +-
 gcc/tree-vect-patterns.cc                         | 330 +++++++++++++++++++++-
 14 files changed, 1079 insertions(+), 31 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1.c
new file mode 100644
index 00000000000..01cf34fb444
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-1.c
@@ -0,0 +1,40 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s { int i : 31; };
+
+#define ELT0 {0}
+#define ELT1 {1}
+#define ELT2 {2}
+#define ELT3 {3}
+#define N 32
+#define RES 48
+struct s A[N]
+  = { ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3};
+
+int __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    int res = 0;
+    for (int i = 0; i < n; ++i)
+      res += ptr[i].i;
+    return res;
+}
+
+int main (void)
+{
+  check_vect ();
+
+  if (f(&A[0], N) != RES)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-2.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-2.c
new file mode 100644
index 00000000000..1a4a1579c14
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-2.c
@@ -0,0 +1,43 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    unsigned i : 31;
+    char a : 4;
+};
+
+#define N 32
+#define ELT0 {0x7FFFFFFFUL, 0}
+#define ELT1 {0x7FFFFFFFUL, 1}
+#define ELT2 {0x7FFFFFFFUL, 2}
+#define ELT3 {0x7FFFFFFFUL, 3}
+#define RES 48
+struct s A[N]
+  = { ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3};
+
+int __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    int res = 0;
+    for (int i = 0; i < n; ++i)
+      res += ptr[i].a;
+    return res;
+}
+
+int main (void)
+{
+  check_vect ();
+
+  if (f(&A[0], N) != RES)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-3.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-3.c
new file mode 100644
index 00000000000..849f4a017e1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-3.c
@@ -0,0 +1,44 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+#include <stdbool.h>
+
+extern void abort(void);
+
+typedef struct {
+    int  c;
+    int  b;
+    bool a : 1;
+    int  d : 31;
+} struct_t;
+
+#define N 16
+#define ELT_F { 0xFFFFFFFF, 0xFFFFFFFF, 0, 0x7FFFFFFF }
+#define ELT_T { 0xFFFFFFFF, 0xFFFFFFFF, 1, 0x7FFFFFFF }
+
+struct_t vect_false[N] = { ELT_F, ELT_F, ELT_F, ELT_F, ELT_F, ELT_F, ELT_F, ELT_F,
+			   ELT_F, ELT_F, ELT_F, ELT_F, ELT_F, ELT_F, ELT_F, ELT_F  };
+struct_t vect_true[N]  = { ELT_F, ELT_F, ELT_T, ELT_F, ELT_F, ELT_F, ELT_F, ELT_F,
+			   ELT_F, ELT_F, ELT_T, ELT_F, ELT_F, ELT_F, ELT_F, ELT_F  };
+int main (void)
+{
+  unsigned ret = 0;
+  for (unsigned i = 0; i < N; i++)
+  {
+      ret |= vect_false[i].a;
+  }
+  if (ret)
+    abort ();
+
+  for (unsigned i = 0; i < N; i++)
+  {
+      ret |= vect_true[i].a;
+  }
+  if (!ret)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 2 loops" 1 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-4.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-4.c
new file mode 100644
index 00000000000..5bc9c412e96
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-4.c
@@ -0,0 +1,45 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    unsigned i : 31;
+    char x : 2;
+    char a : 4;
+};
+
+#define N 32
+#define ELT0 {0x7FFFFFFFUL, 3, 0}
+#define ELT1 {0x7FFFFFFFUL, 3, 1}
+#define ELT2 {0x7FFFFFFFUL, 3, 2}
+#define ELT3 {0x7FFFFFFFUL, 3, 3}
+#define RES 48
+struct s A[N]
+  = { ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3};
+
+int __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    int res = 0;
+    for (int i = 0; i < n; ++i)
+      res += ptr[i].a;
+    return res;
+}
+
+int main (void)
+{
+  check_vect ();
+
+  if (f(&A[0], N) != RES)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
+
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-5.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-5.c
new file mode 100644
index 00000000000..1dc24d3eded
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-5.c
@@ -0,0 +1,42 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    unsigned a : 23; unsigned b : 9;
+};
+
+#define N 32
+#define ELT0 {0x7FFFFFUL, 0}
+#define ELT1 {0x7FFFFFUL, 1}
+#define ELT2 {0x7FFFFFUL, 2}
+#define ELT3 {0x7FFFFFUL, 3}
+#define RES 48
+struct s A[N]
+  = { ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3};
+
+int __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    int res = 0;
+    for (int i = 0; i < n; ++i)
+      res += ptr[i].b;
+    return res;
+}
+
+int main (void)
+{
+  check_vect ();
+
+  if (f(&A[0], N) != RES)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-6.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-6.c
new file mode 100644
index 00000000000..7d24c299758
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-read-6.c
@@ -0,0 +1,42 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    unsigned a : 23; unsigned b : 8;
+};
+
+#define N 32
+#define ELT0 {0x7FFFFFUL, 0}
+#define ELT1 {0x7FFFFFUL, 1}
+#define ELT2 {0x7FFFFFUL, 2}
+#define ELT3 {0x7FFFFFUL, 3}
+#define RES 48
+struct s A[N]
+  = { ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3,
+      ELT0, ELT1, ELT2, ELT3, ELT0, ELT1, ELT2, ELT3};
+
+int __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    int res = 0;
+    for (int i = 0; i < n; ++i)
+      res += ptr[i].b;
+    return res;
+}
+
+int main (void)
+{
+  check_vect ();
+
+  if (f(&A[0], N) != RES)
+    abort ();
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-1.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-1.c
new file mode 100644
index 00000000000..19683d277b1
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-1.c
@@ -0,0 +1,39 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s { int i : 31; };
+
+#define N 32
+#define V 5
+struct s A[N];
+
+void __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    for (int i = 0; i < n; ++i)
+      ptr[i].i = V;
+}
+
+void __attribute__ ((noipa))
+check_f(struct s *ptr) {
+    for (unsigned i = 0; i < N; ++i)
+      if (ptr[i].i != V)
+	abort ();
+}
+
+int main (void)
+{
+  check_vect ();
+  __builtin_memset (&A[0], 0, sizeof(struct s) * N);
+
+  f(&A[0], N);
+  check_f (&A[0]);
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
+
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-2.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-2.c
new file mode 100644
index 00000000000..d550dd35ab7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-2.c
@@ -0,0 +1,42 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    unsigned i : 31;
+    char a : 4;
+};
+
+#define N 32
+#define V 5
+struct s A[N];
+
+void __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    for (int i = 0; i < n; ++i)
+      ptr[i].a = V;
+}
+
+void __attribute__ ((noipa))
+check_f(struct s *ptr) {
+    for (unsigned i = 0; i < N; ++i)
+      if (ptr[i].a != V)
+	abort ();
+}
+
+int main (void)
+{
+  check_vect ();
+  __builtin_memset (&A[0], 0, sizeof(struct s) * N);
+
+  f(&A[0], N);
+  check_f (&A[0]);
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
+
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-3.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-3.c
new file mode 100644
index 00000000000..3303d2610ff
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-3.c
@@ -0,0 +1,43 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    unsigned i : 31;
+    char x : 2;
+    char a : 4;
+};
+
+#define N 32
+#define V 5
+struct s A[N];
+
+void __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    for (int i = 0; i < n; ++i)
+      ptr[i].a = V;
+}
+
+void __attribute__ ((noipa))
+check_f(struct s *ptr) {
+    for (unsigned i = 0; i < N; ++i)
+      if (ptr[i].a != V)
+	abort ();
+}
+
+int main (void)
+{
+  check_vect ();
+  __builtin_memset (&A[0], 0, sizeof(struct s) * N);
+
+  f(&A[0], N);
+  check_f (&A[0]);
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
+
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-4.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-4.c
new file mode 100644
index 00000000000..fae6ea3557d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-4.c
@@ -0,0 +1,42 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    unsigned b : 23;
+    unsigned a : 9;
+};
+
+#define N 32
+#define V 5
+struct s A[N];
+
+void __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    for (int i = 0; i < n; ++i)
+      ptr[i].a = V;
+}
+
+void __attribute__ ((noipa))
+check_f(struct s *ptr) {
+    for (unsigned i = 0; i < N; ++i)
+      if (ptr[i].a != V)
+	abort ();
+}
+
+int main (void)
+{
+  check_vect ();
+  __builtin_memset (&A[0], 0, sizeof(struct s) * N);
+
+  f(&A[0], N);
+  check_f (&A[0]);
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
+
diff --git a/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-5.c b/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-5.c
new file mode 100644
index 00000000000..99360c2967b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/vect-bitfield-write-5.c
@@ -0,0 +1,42 @@
+/* { dg-require-effective-target vect_int } */
+
+#include <stdarg.h>
+#include "tree-vect.h"
+
+extern void abort(void);
+
+struct s {
+    unsigned b : 23;
+    unsigned a : 8;
+};
+
+#define N 32
+#define V 5
+struct s A[N];
+
+void __attribute__ ((noipa))
+f(struct s *ptr, unsigned n) {
+    for (int i = 0; i < n; ++i)
+      ptr[i].a = V;
+}
+
+void __attribute__ ((noipa))
+check_f(struct s *ptr) {
+    for (unsigned i = 0; i < N; ++i)
+      if (ptr[i].a != V)
+	abort ();
+}
+
+int main (void)
+{
+  check_vect ();
+  __builtin_memset (&A[0], 0, sizeof(struct s) * N);
+
+  f(&A[0], N);
+  check_f (&A[0]);
+
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 1 "vect" } } */
+
diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index bac29fb5574..e468a4659fa 100644
--- a/gcc/tree-if-conv.cc
+++ b/gcc/tree-if-conv.cc
@@ -91,6 +91,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-pass.h"
 #include "ssa.h"
 #include "expmed.h"
+#include "expr.h"
 #include "optabs-query.h"
 #include "gimple-pretty-print.h"
 #include "alias.h"
@@ -123,6 +124,9 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-vectorizer.h"
 #include "tree-eh.h"
 
+/* For lang_hooks.types.type_for_mode.  */
+#include "langhooks.h"
+
 /* Only handle PHIs with no more arguments unless we are asked to by
    simd pragma.  */
 #define MAX_PHI_ARG_NUM \
@@ -145,6 +149,12 @@ static bool need_to_rewrite_undefined;
    before phi_convertible_by_degenerating_args.  */
 static bool any_complicated_phi;
 
+/* True if we have bitfield accesses we can lower.  */
+static bool need_to_lower_bitfields;
+
+/* True if there is any ifcvting to be done.  */
+static bool need_to_ifcvt;
+
 /* Hash for struct innermost_loop_behavior.  It depends on the user to
    free the memory.  */
 
@@ -1411,15 +1421,6 @@ if_convertible_loop_p_1 (class loop *loop, vec<data_reference_p> *refs)
 
   calculate_dominance_info (CDI_DOMINATORS);
 
-  /* Allow statements that can be handled during if-conversion.  */
-  ifc_bbs = get_loop_body_in_if_conv_order (loop);
-  if (!ifc_bbs)
-    {
-      if (dump_file && (dump_flags & TDF_DETAILS))
-	fprintf (dump_file, "Irreducible loop\n");
-      return false;
-    }
-
   for (i = 0; i < loop->num_nodes; i++)
     {
       basic_block bb = ifc_bbs[i];
@@ -2899,18 +2900,22 @@ version_loop_for_if_conversion (class loop *loop, vec<gimple *> *preds)
   class loop *new_loop;
   gimple *g;
   gimple_stmt_iterator gsi;
-  unsigned int save_length;
+  unsigned int save_length = 0;
 
   g = gimple_build_call_internal (IFN_LOOP_VECTORIZED, 2,
 				  build_int_cst (integer_type_node, loop->num),
 				  integer_zero_node);
   gimple_call_set_lhs (g, cond);
 
-  /* Save BB->aux around loop_version as that uses the same field.  */
-  save_length = loop->inner ? loop->inner->num_nodes : loop->num_nodes;
-  void **saved_preds = XALLOCAVEC (void *, save_length);
-  for (unsigned i = 0; i < save_length; i++)
-    saved_preds[i] = ifc_bbs[i]->aux;
+  void **saved_preds = NULL;
+  if (any_complicated_phi || need_to_predicate)
+    {
+      /* Save BB->aux around loop_version as that uses the same field.  */
+      save_length = loop->inner ? loop->inner->num_nodes : loop->num_nodes;
+      saved_preds = XALLOCAVEC (void *, save_length);
+      for (unsigned i = 0; i < save_length; i++)
+	saved_preds[i] = ifc_bbs[i]->aux;
+    }
 
   initialize_original_copy_tables ();
   /* At this point we invalidate porfile confistency until IFN_LOOP_VECTORIZED
@@ -2922,8 +2927,9 @@ version_loop_for_if_conversion (class loop *loop, vec<gimple *> *preds)
 			   profile_probability::always (), true);
   free_original_copy_tables ();
 
-  for (unsigned i = 0; i < save_length; i++)
-    ifc_bbs[i]->aux = saved_preds[i];
+  if (any_complicated_phi || need_to_predicate)
+    for (unsigned i = 0; i < save_length; i++)
+      ifc_bbs[i]->aux = saved_preds[i];
 
   if (new_loop == NULL)
     return NULL;
@@ -2999,7 +3005,7 @@ ifcvt_split_critical_edges (class loop *loop, bool aggressive_if_conv)
   auto_vec<edge> critical_edges;
 
   /* Loop is not well formed.  */
-  if (num <= 2 || loop->inner || !single_exit (loop))
+  if (loop->inner)
     return false;
 
   body = get_loop_body (loop);
@@ -3260,6 +3266,201 @@ ifcvt_hoist_invariants (class loop *loop, edge pe)
   free (body);
 }
 
+/* Returns the DECL_FIELD_BIT_OFFSET of the bitfield accesse in stmt iff its
+   type mode is not BLKmode.  If BITPOS is not NULL it will hold the poly_int64
+   value of the DECL_FIELD_BIT_OFFSET of the bitfield access and STRUCT_EXPR,
+   if not NULL, will hold the tree representing the base struct of this
+   bitfield.  */
+
+static tree
+get_bitfield_rep (gassign *stmt, bool write, tree *bitpos,
+		  tree *struct_expr)
+{
+  tree comp_ref = write ? gimple_assign_lhs (stmt)
+			: gimple_assign_rhs1 (stmt);
+
+  tree field_decl = TREE_OPERAND (comp_ref, 1);
+  tree rep_decl = DECL_BIT_FIELD_REPRESENTATIVE (field_decl);
+
+  /* Bail out if the representative is BLKmode as we will not be able to
+     vectorize this.  */
+  if (TYPE_MODE (TREE_TYPE (rep_decl)) == E_BLKmode)
+    return NULL_TREE;
+
+  /* Bail out if the DECL_SIZE of the field_decl isn't the same as the BF's
+     precision.  */
+  unsigned HOST_WIDE_INT bf_prec
+    = TYPE_PRECISION (TREE_TYPE (gimple_assign_lhs (stmt)));
+  if (compare_tree_int (DECL_SIZE (field_decl), bf_prec) != 0)
+    return NULL_TREE;
+
+  if (struct_expr)
+    *struct_expr = TREE_OPERAND (comp_ref, 0);
+
+  if (bitpos)
+    *bitpos
+      = fold_build2 (MINUS_EXPR, bitsizetype,
+		     DECL_FIELD_BIT_OFFSET (field_decl),
+		     DECL_FIELD_BIT_OFFSET (rep_decl));
+
+  return rep_decl;
+
+}
+
+/* Lowers the bitfield described by DATA.
+   For a write like:
+
+   struct.bf = _1;
+
+   lower to:
+
+   __ifc_1 = struct.<representative>;
+   __ifc_2 = BIT_INSERT_EXPR (__ifc_1, _1, bitpos);
+   struct.<representative> = __ifc_2;
+
+   For a read:
+
+   _1 = struct.bf;
+
+    lower to:
+
+    __ifc_1 = struct.<representative>;
+    _1 =  BIT_FIELD_REF (__ifc_1, bitsize, bitpos);
+
+    where representative is a legal load that contains the bitfield value,
+    bitsize is the size of the bitfield and bitpos the offset to the start of
+    the bitfield within the representative.  */
+
+static void
+lower_bitfield (gassign *stmt, bool write)
+{
+  tree struct_expr;
+  tree bitpos;
+  tree rep_decl = get_bitfield_rep (stmt, write, &bitpos, &struct_expr);
+  tree rep_type = TREE_TYPE (rep_decl);
+  tree bf_type = TREE_TYPE (gimple_assign_lhs (stmt));
+
+  gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    {
+      fprintf (dump_file, "Lowering:\n");
+      print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
+      fprintf (dump_file, "to:\n");
+    }
+
+  /* REP_COMP_REF is a COMPONENT_REF for the representative.  NEW_VAL is it's
+     defining SSA_NAME.  */
+  tree rep_comp_ref = build3 (COMPONENT_REF, rep_type, struct_expr, rep_decl,
+			      NULL_TREE);
+  tree new_val = ifc_temp_var (rep_type, rep_comp_ref, &gsi);
+
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    print_gimple_stmt (dump_file, SSA_NAME_DEF_STMT (new_val), 0, TDF_SLIM);
+
+  if (write)
+    {
+      new_val = ifc_temp_var (rep_type,
+			      build3 (BIT_INSERT_EXPR, rep_type, new_val,
+				      unshare_expr (gimple_assign_rhs1 (stmt)),
+				      bitpos), &gsi);
+
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	print_gimple_stmt (dump_file, SSA_NAME_DEF_STMT (new_val), 0, TDF_SLIM);
+
+      gimple *new_stmt = gimple_build_assign (unshare_expr (rep_comp_ref),
+					      new_val);
+      gimple_move_vops (new_stmt, stmt);
+      gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
+
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	print_gimple_stmt (dump_file, new_stmt, 0, TDF_SLIM);
+    }
+  else
+    {
+      tree bfr = build3 (BIT_FIELD_REF, bf_type, new_val,
+			 build_int_cst (bitsizetype, TYPE_PRECISION (bf_type)),
+			 bitpos);
+      new_val = ifc_temp_var (bf_type, bfr, &gsi);
+
+      gimple *new_stmt = gimple_build_assign (gimple_assign_lhs (stmt),
+					      new_val);
+      gimple_move_vops (new_stmt, stmt);
+      gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
+
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	print_gimple_stmt (dump_file, new_stmt, 0, TDF_SLIM);
+    }
+
+  gsi_remove (&gsi, true);
+}
+
+/* Return TRUE if there are bitfields to lower in this LOOP.  Fill TO_LOWER
+   with data structures representing these bitfields.  */
+
+static bool
+bitfields_to_lower_p (class loop *loop,
+		      vec <gassign *> &reads_to_lower,
+		      vec <gassign *> &writes_to_lower)
+{
+  gimple_stmt_iterator gsi;
+
+  if (dump_file && (dump_flags & TDF_DETAILS))
+    {
+      fprintf (dump_file, "Analyzing loop %d for bitfields:\n", loop->num);
+    }
+
+  for (unsigned i = 0; i < loop->num_nodes; ++i)
+    {
+      basic_block bb = ifc_bbs[i];
+      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+	{
+	  gassign *stmt = dyn_cast<gassign*> (gsi_stmt (gsi));
+	  if (!stmt)
+	    continue;
+
+	  tree op = gimple_assign_lhs (stmt);
+	  bool write = TREE_CODE (op) == COMPONENT_REF;
+
+	  if (!write)
+	    op = gimple_assign_rhs1 (stmt);
+
+	  if (TREE_CODE (op) != COMPONENT_REF)
+	    continue;
+
+	  if (DECL_BIT_FIELD_TYPE (TREE_OPERAND (op, 1)))
+	    {
+	      if (dump_file && (dump_flags & TDF_DETAILS))
+		print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
+
+	      if (!INTEGRAL_TYPE_P (TREE_TYPE (op)))
+		{
+		  if (dump_file && (dump_flags & TDF_DETAILS))
+		    fprintf (dump_file, "\t Bitfield NO OK to lower,"
+					" field type is not Integral.\n");
+		  return false;
+		}
+
+	      if (!get_bitfield_rep (stmt, write, NULL, NULL))
+		{
+		  if (dump_file && (dump_flags & TDF_DETAILS))
+		    fprintf (dump_file, "\t Bitfield NOT OK to lower,"
+					" representative is BLKmode.\n");
+		  return false;
+		}
+
+	      if (dump_file && (dump_flags & TDF_DETAILS))
+		fprintf (dump_file, "\tBitfield OK to lower.\n");
+	      if (write)
+		writes_to_lower.safe_push (stmt);
+	      else
+		reads_to_lower.safe_push (stmt);
+	    }
+	}
+    }
+  return !reads_to_lower.is_empty () || !writes_to_lower.is_empty ();
+}
+
+
 /* If-convert LOOP when it is legal.  For the moment this pass has no
    profitability analysis.  Returns non-zero todo flags when something
    changed.  */
@@ -3270,12 +3471,16 @@ tree_if_conversion (class loop *loop, vec<gimple *> *preds)
   unsigned int todo = 0;
   bool aggressive_if_conv;
   class loop *rloop;
+  auto_vec <gassign *, 4> reads_to_lower;
+  auto_vec <gassign *, 4> writes_to_lower;
   bitmap exit_bbs;
   edge pe;
 
  again:
   rloop = NULL;
   ifc_bbs = NULL;
+  need_to_lower_bitfields = false;
+  need_to_ifcvt = false;
   need_to_predicate = false;
   need_to_rewrite_undefined = false;
   any_complicated_phi = false;
@@ -3291,16 +3496,42 @@ tree_if_conversion (class loop *loop, vec<gimple *> *preds)
 	aggressive_if_conv = true;
     }
 
-  if (!ifcvt_split_critical_edges (loop, aggressive_if_conv))
+  if (!single_exit (loop))
     goto cleanup;
 
-  if (!if_convertible_loop_p (loop)
-      || !dbg_cnt (if_conversion_tree))
+  /* If there are more than two BBs in the loop then there is at least one if
+     to convert.  */
+  if (loop->num_nodes > 2
+      && !ifcvt_split_critical_edges (loop, aggressive_if_conv))
     goto cleanup;
 
-  if ((need_to_predicate || any_complicated_phi)
-      && ((!flag_tree_loop_vectorize && !loop->force_vectorize)
-	  || loop->dont_vectorize))
+  ifc_bbs = get_loop_body_in_if_conv_order (loop);
+  if (!ifc_bbs)
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	fprintf (dump_file, "Irreducible loop\n");
+      goto cleanup;
+    }
+
+  if (loop->num_nodes > 2)
+    {
+      need_to_ifcvt = true;
+
+      if (!if_convertible_loop_p (loop) || !dbg_cnt (if_conversion_tree))
+	goto cleanup;
+
+      if ((need_to_predicate || any_complicated_phi)
+	  && ((!flag_tree_loop_vectorize && !loop->force_vectorize)
+	      || loop->dont_vectorize))
+	goto cleanup;
+    }
+
+  if ((flag_tree_loop_vectorize || loop->force_vectorize)
+      && !loop->dont_vectorize)
+    need_to_lower_bitfields = bitfields_to_lower_p (loop, reads_to_lower,
+						    writes_to_lower);
+
+  if (!need_to_ifcvt && !need_to_lower_bitfields)
     goto cleanup;
 
   /* The edge to insert invariant stmts on.  */
@@ -3311,7 +3542,8 @@ tree_if_conversion (class loop *loop, vec<gimple *> *preds)
      Either version this loop, or if the pattern is right for outer-loop
      vectorization, version the outer loop.  In the latter case we will
      still if-convert the original inner loop.  */
-  if (need_to_predicate
+  if (need_to_lower_bitfields
+      || need_to_predicate
       || any_complicated_phi
       || flag_tree_loop_if_convert != 1)
     {
@@ -3351,10 +3583,31 @@ tree_if_conversion (class loop *loop, vec<gimple *> *preds)
 	pe = single_pred_edge (gimple_bb (preds->last ()));
     }
 
-  /* Now all statements are if-convertible.  Combine all the basic
-     blocks into one huge basic block doing the if-conversion
-     on-the-fly.  */
-  combine_blocks (loop);
+  if (need_to_lower_bitfields)
+    {
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	{
+	  fprintf (dump_file, "-------------------------\n");
+	  fprintf (dump_file, "Start lowering bitfields\n");
+	}
+      while (!reads_to_lower.is_empty ())
+	lower_bitfield (reads_to_lower.pop (), false);
+      while (!writes_to_lower.is_empty ())
+	lower_bitfield (writes_to_lower.pop (), true);
+
+      if (dump_file && (dump_flags & TDF_DETAILS))
+	{
+	  fprintf (dump_file, "Done lowering bitfields\n");
+	  fprintf (dump_file, "-------------------------\n");
+	}
+    }
+  if (need_to_ifcvt)
+    {
+      /* Now all statements are if-convertible.  Combine all the basic
+	 blocks into one huge basic block doing the if-conversion
+	 on-the-fly.  */
+      combine_blocks (loop);
+    }
</cut>