[TCWG CI] 450.soplex grew in size by 2% after gcc: Try to resolve paths in threader without looking further back.

[TCWG CI] 450.soplex grew in size by 2% after gcc: Try to resolve paths in threader without looking further back.

[ci_notify]

After gcc commit f6d012338bf87f427b7420f2f309963c29fe33ba
Author: Aldy Hernandez <aldyh@redhat.com>

    Try to resolve paths in threader without looking further back.

the following benchmarks grew in size by more than 1%:
- 450.soplex grew in size by 2% from 268356 to 272484 bytes

Below reproducer instructions can be used to re-build both "first_bad" and "last_good" cross-toolchains used in this bisection.  Naturally, the scripts will fail when triggerring benchmarking jobs if you don't have access to Linaro TCWG CI.

For your convenience, we have uploaded tarballs with pre-processed source and assembly files at:
- First_bad save-temps: https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_apm-gnu-master-aarch64-spec2k6-Os/7/artifact/artifacts/build-f6d012338bf87f427b7420f2f309963c29fe33ba/save-temps/
- Last_good save-temps: https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_apm-gnu-master-aarch64-spec2k6-Os/7/artifact/artifacts/build-f3dbd3f36d55178d0a9e4431043cbc950524969a/save-temps/
- Baseline save-temps: https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_apm-gnu-master-aarch64-spec2k6-Os/7/artifact/artifacts/build-baseline/save-temps/

Configuration:
- Benchmark: SPEC CPU2006
- Toolchain: GCC + Glibc + GNU Linker
- Version: all components were built from their tip of trunk
- Target: aarch64-linux-gnu
- Compiler flags: -Os
- Hardware: APM Mustang 8x X-Gene1

This benchmarking CI is work-in-progress, and we welcome feedback and suggestions at linaro-toolchain@lists.linaro.org .  In our improvement plans is to add support for SPEC CPU2017 benchmarks and provide "perf report/annotate" data behind these reports.

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

This commit has regressed these CI configurations:
 - tcwg_bmk_gnu_apm/gnu-master-aarch64-spec2k6-Os

First_bad build: https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_apm-gnu-master-aarch64-spec2k6-Os/7/artifact/artifacts/build-f6d012338bf87f427b7420f2f309963c29fe33ba/
Last_good build: https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_apm-gnu-master-aarch64-spec2k6-Os/7/artifact/artifacts/build-f3dbd3f36d55178d0a9e4431043cbc950524969a/
Baseline build: https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_apm-gnu-master-aarch64-spec2k6-Os/7/artifact/artifacts/build-baseline/
Even more details: https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_apm-gnu-master-aarch64-spec2k6-Os/7/artifact/artifacts/

Reproduce builds:
<cut>
mkdir investigate-gcc-f6d012338bf87f427b7420f2f309963c29fe33ba
cd investigate-gcc-f6d012338bf87f427b7420f2f309963c29fe33ba

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

# Fetch manifests and test.sh script
mkdir -p artifacts/manifests
curl -o artifacts/manifests/build-baseline.sh https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_apm-gnu-master-aarch64-spec2k6-Os/7/artifact/artifacts/manifests/build-baseline.sh --fail
curl -o artifacts/manifests/build-parameters.sh https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_apm-gnu-master-aarch64-spec2k6-Os/7/artifact/artifacts/manifests/build-parameters.sh --fail
curl -o artifacts/test.sh https://ci.linaro.org/job/tcwg_bmk_ci_gnu-bisect-tcwg_bmk_apm-gnu-master-aarch64-spec2k6-Os/7/artifact/artifacts/test.sh --fail
chmod +x artifacts/test.sh

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

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

cd gcc

# Reproduce first_bad build
git checkout --detach f6d012338bf87f427b7420f2f309963c29fe33ba
../artifacts/test.sh

# Reproduce last_good build
git checkout --detach f3dbd3f36d55178d0a9e4431043cbc950524969a
../artifacts/test.sh

cd ..
</cut>

Full commit (up to 1000 lines):
<cut>
commit f6d012338bf87f427b7420f2f309963c29fe33ba
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Wed Oct 20 07:29:25 2021 +0200

    Try to resolve paths in threader without looking further back.
    
    Sometimes we can solve a candidate path without having to recurse
    further back.  This can mostly happen in fully resolving mode, because
    we can ask the ranger what the range on entry to the path is, but
    there's no reason this can't always apply.  This one-liner removes
    the fully-resolving restriction.
    
    I'm tickled pink to see how many things we now get quite early
    in the compilation.  I actually had to disable jump threading entirely
    for a few tests because the early threader was catching things
    disturbingly early.  Also, as Richi predicted, I saw a lot of pre-VRP
    cleanups happening.
    
    I was going to commit this as obvious, but I think the test changes
    merit discussion.
    
    We've been playing games with gcc.dg/tree-ssa/ssa-thread-11.c for quite
    some time.  Every time a threading pass gets smarter, we push the
    check further down the pipeline.  We've officially run out of dumb
    threading passes to disable ;-).  In the last year we've gone up from a
    handful of threads, to 34 threads with the current combination of
    options.  I doubt this is testing anything useful anymore, so I've
    removed it.
    
    Similarly for gcc.dg/tree-ssa/ssa-dom-thread-4.c.  We used to thread 3
    jump threads, but they were disallowed because of loop rotation.  Then
    we started catching more jump threads in VRP2 threading so we tested
    there.  With this patch though, we triple the number of threads found
    from 11 to 31.  I believe this test has outlived its usefulness, and
    I've removed it.  Note that even though we have these outrageous
    possibilities for this test, the block copier ultimately chops them
    down (23 survive though).
    
    Tested on x86-64 Linux.
    
    gcc/ChangeLog:
    
            * tree-ssa-threadbackward.c (back_threader::find_paths_to_names):
            Always try to resolve path without looking back.
            * tree-ssa-threadupdate.c (dump_jump_thread): Indidicate whether
            edge is a back edge.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/graphite/scop-dsyr2k-2.c: Adjust for jump threading changes.
            * gcc.dg/graphite/scop-dsyr2k.c: Same.
            * gcc.dg/graphite/scop-dsyrk-2.c: Same.
            * gcc.dg/graphite/scop-dsyrk.c: Same.
            * gcc.dg/tree-ssa/pr20701.c: Same.
            * gcc.dg/tree-ssa/pr20702.c: Same.
            * gcc.dg/tree-ssa/pr21086.c: Same.
            * gcc.dg/tree-ssa/pr25382.c: Same.
            * gcc.dg/tree-ssa/pr58480.c: Same.
            * gcc.dg/tree-ssa/ssa-vrp-thread-1.c: Same.
            * gcc.dg/tree-ssa/vrp08.c: Same.
            * gcc.dg/tree-ssa/vrp55.c: Same.
            * gcc.dg/tree-ssa/ssa-dom-thread-7.c: Same.
            * gcc.dg/tree-ssa/ssa-dom-thread-4.c: Removed.
            * gcc.dg/tree-ssa/ssa-thread-11.c: Removed.
            * gcc.dg/uninit-pr89230-1.c: xfail.
---
 gcc/testsuite/gcc.dg/graphite/scop-dsyr2k-2.c      |  1 +
 gcc/testsuite/gcc.dg/graphite/scop-dsyr2k.c        |  1 +
 gcc/testsuite/gcc.dg/graphite/scop-dsyrk-2.c       |  1 +
 gcc/testsuite/gcc.dg/graphite/scop-dsyrk.c         |  1 +
 gcc/testsuite/gcc.dg/tree-ssa/pr20701.c            |  2 +-
 gcc/testsuite/gcc.dg/tree-ssa/pr20702.c            |  2 +-
 gcc/testsuite/gcc.dg/tree-ssa/pr21086.c            |  2 +-
 gcc/testsuite/gcc.dg/tree-ssa/pr25382.c            |  2 +-
 gcc/testsuite/gcc.dg/tree-ssa/pr58480.c            |  2 +-
 gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-4.c   | 60 ----------------------
 gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c   |  2 +-
 gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-11.c      | 50 ------------------
 .../gcc.dg/tree-ssa/ssa-thread-backedge.c          | 32 ++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/ssa-vrp-thread-1.c   |  4 +-
 gcc/testsuite/gcc.dg/tree-ssa/vrp08.c              |  2 +-
 gcc/testsuite/gcc.dg/tree-ssa/vrp55.c              |  6 +--
 gcc/testsuite/gcc.dg/uninit-pr89230-1.c            |  3 +-
 gcc/tree-ssa-threadbackward.c                      |  4 +-
 gcc/tree-ssa-threadupdate.c                        |  3 ++
 19 files changed, 55 insertions(+), 125 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/graphite/scop-dsyr2k-2.c b/gcc/testsuite/gcc.dg/graphite/scop-dsyr2k-2.c
index 06aa19a8577..42e23fc157e 100644
--- a/gcc/testsuite/gcc.dg/graphite/scop-dsyr2k-2.c
+++ b/gcc/testsuite/gcc.dg/graphite/scop-dsyr2k-2.c
@@ -1,4 +1,5 @@
 /* { dg-require-effective-target size32plus } */
+/* { dg-additional-options "-fno-thread-jumps" } */
 #define NMAX 3000
 
 static double a[NMAX][NMAX], b[NMAX][NMAX], c[NMAX][NMAX];
diff --git a/gcc/testsuite/gcc.dg/graphite/scop-dsyr2k.c b/gcc/testsuite/gcc.dg/graphite/scop-dsyr2k.c
index 41c91b97b57..feb99358ac7 100644
--- a/gcc/testsuite/gcc.dg/graphite/scop-dsyr2k.c
+++ b/gcc/testsuite/gcc.dg/graphite/scop-dsyr2k.c
@@ -1,4 +1,5 @@
 /* { dg-require-effective-target size32plus } */
+/* { dg-additional-options "-fno-thread-jumps" } */
 #define NMAX 3000
 
 static double a[NMAX][NMAX], b[NMAX][NMAX], c[NMAX][NMAX];
diff --git a/gcc/testsuite/gcc.dg/graphite/scop-dsyrk-2.c b/gcc/testsuite/gcc.dg/graphite/scop-dsyrk-2.c
index 5622dce4798..935ade3fb6e 100644
--- a/gcc/testsuite/gcc.dg/graphite/scop-dsyrk-2.c
+++ b/gcc/testsuite/gcc.dg/graphite/scop-dsyrk-2.c
@@ -1,4 +1,5 @@
 /* { dg-require-effective-target size32plus } */
+/* { dg-additional-options "-fno-thread-jumps" } */
 #define NMAX 3000
 #define MEASURE_TIME 1
 
diff --git a/gcc/testsuite/gcc.dg/graphite/scop-dsyrk.c b/gcc/testsuite/gcc.dg/graphite/scop-dsyrk.c
index e01a517be11..5c65e406589 100644
--- a/gcc/testsuite/gcc.dg/graphite/scop-dsyrk.c
+++ b/gcc/testsuite/gcc.dg/graphite/scop-dsyrk.c
@@ -1,4 +1,5 @@
 /* { dg-require-effective-target size32plus } */
+/* { dg-additional-options "-fno-thread-jumps" } */
 #define NMAX 3000
 #define MEASURE_TIME 1
 
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr20701.c b/gcc/testsuite/gcc.dg/tree-ssa/pr20701.c
index 2f914589e32..496c4256733 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr20701.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr20701.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-vrp1 -fno-early-inlining -fdelete-null-pointer-checks" } */
+/* { dg-options "-O2 -fdump-tree-vrp1 -fno-early-inlining -fdelete-null-pointer-checks -fdisable-tree-thread1" } */
 
 typedef struct {
   int code;
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr20702.c b/gcc/testsuite/gcc.dg/tree-ssa/pr20702.c
index c896857748c..81129674d8a 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr20702.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr20702.c
@@ -4,7 +4,7 @@
    immediate successors of the basic block.  */
 
 /* { dg-do compile } */
-/* { dg-options "-O2 -fno-tree-dominator-opts -fdisable-tree-evrp -fdump-tree-vrp1-details -fdelete-null-pointer-checks" } */
+/* { dg-options "-O2 -fno-thread-jumps -fdisable-tree-evrp -fdump-tree-vrp1-details -fdelete-null-pointer-checks" } */
 
 extern void bar (int);
 
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr21086.c b/gcc/testsuite/gcc.dg/tree-ssa/pr21086.c
index aadd53e2237..9b93d39d4e4 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr21086.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr21086.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -fdisable-tree-evrp -fdump-tree-vrp1 -fdump-tree-dce2 -fdelete-null-pointer-checks" } */
+/* { dg-options "-O2 -fno-thread-jumps -fdisable-tree-evrp -fdump-tree-vrp1 -fdump-tree-dce2 -fdelete-null-pointer-checks" } */
 
 int
 foo (int *p)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr25382.c b/gcc/testsuite/gcc.dg/tree-ssa/pr25382.c
index d74765551c2..8634c0a7895 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr25382.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr25382.c
@@ -3,7 +3,7 @@
    Check that VRP now gets ranges from BIT_AND_EXPRs.  */
 
 /* { dg-do compile } */
-/* { dg-options "-O2 -fno-tree-ccp -fdisable-tree-evrp -fdump-tree-vrp1" } */
+/* { dg-options "-O2 -fno-thread-jumps -fno-tree-ccp -fdisable-tree-evrp -fdump-tree-vrp1" } */
 
 int
 foo (int a)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr58480.c b/gcc/testsuite/gcc.dg/tree-ssa/pr58480.c
index 42898e72d4e..f11623b7c6b 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr58480.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr58480.c
@@ -1,5 +1,5 @@
 /* { dg-do compile { target { ! keeps_null_pointer_checks } } } */
-/* { dg-options "-O2 -fdisable-tree-evrp -fdump-tree-vrp1 -fdelete-null-pointer-checks" } */
+/* { dg-options "-O2 -fno-thread-jumps -fdisable-tree-evrp -fdump-tree-vrp1 -fdelete-null-pointer-checks" } */
 
 extern void eliminate (void);
 extern void* f1 (void *a, void *b) __attribute__((nonnull));
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-4.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-4.c
deleted file mode 100644
index 9cd463571c4..00000000000
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-4.c
+++ /dev/null
@@ -1,60 +0,0 @@
-/* { dg-do compile } */ 
-/* { dg-options "-O2 -fdump-tree-vrp-thread2-details -fdump-tree-dom2-details -std=gnu89 --param logical-op-non-short-circuit=1" } */
-struct bitmap_head_def;
-typedef struct bitmap_head_def *bitmap;
-typedef const struct bitmap_head_def *const_bitmap;
-typedef unsigned long BITMAP_WORD;
-typedef struct bitmap_element_def
-{
-  struct bitmap_element_def *next;
-  unsigned int indx;
-} bitmap_element;
-
-
-
-
-
-
-
-
-
-unsigned char
-bitmap_ior_and_compl (bitmap dst, const_bitmap a, const_bitmap b,
-		      const_bitmap kill)
-{
-  unsigned char changed = 0;
-
-  bitmap_element *dst_elt;
-  const bitmap_element *a_elt, *b_elt, *kill_elt, *dst_prev;
-
-  while (a_elt || b_elt)
-    {
-      unsigned char new_element = 0;
-
-      if (b_elt)
-	while (kill_elt && kill_elt->indx < b_elt->indx)
-	  kill_elt = kill_elt->next;
-
-      if (b_elt && kill_elt && kill_elt->indx == b_elt->indx
-	  && (!a_elt || a_elt->indx >= b_elt->indx))
-	{
-	  bitmap_element tmp_elt;
-	  unsigned ix;
-
-	  BITMAP_WORD ior = 0;
-
-	      changed = bitmap_elt_ior (dst, dst_elt, dst_prev,
-					a_elt, &tmp_elt, changed);
-
-	}
-
-    }
-
-
-  return changed;
-}
-/* We used to catch 3 jump threads in vrp-thread1, but they all
-   rotated the loop, so they were disallowed.  This in turn created
-   other opportunities for the other threaders which result in the the
-   post-loop threader (vrp-thread2) catching more.  */
-/* { dg-final { scan-tree-dump-times "Registering jump thread" 5 "vrp-thread2" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c
index 1da00a691c8..ed252b97b24 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-dom-thread-7.c
@@ -1,7 +1,7 @@
 /* { dg-do compile } */
 /* { dg-options "-O2 -fdump-tree-thread1-stats -fdump-tree-thread2-stats -fdump-tree-dom2-stats -fdump-tree-thread3-stats -fdump-tree-dom3-stats -fdump-tree-vrp2-stats -fno-guess-branch-probability" } */
 
-/* { dg-final { scan-tree-dump "Jumps threaded: 12"  "thread3" } } */
+/* { dg-final { scan-tree-dump "Jumps threaded: 11" "thread3" } } */
 /* { dg-final { scan-tree-dump-not "Jumps threaded"  "dom2" } } */
 
 /* aarch64 has the highest CASE_VALUES_THRESHOLD in GCC.  It's high enough
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-11.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-11.c
deleted file mode 100644
index 672a54e07db..00000000000
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-11.c
+++ /dev/null
@@ -1,50 +0,0 @@
-/* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-vrp2-details --param logical-op-non-short-circuit=1" } */
-/* { dg-additional-options "-fdisable-tree-ethread -fdisable-tree-thread1 -fdisable-tree-thread2" } */
-/* { dg-final { scan-tree-dump-not "IRREDUCIBLE_LOOP" "vrp2" } } */
-
-void abort (void);
-typedef struct bitmap_head_def *bitmap;
-typedef const struct bitmap_head_def *const_bitmap;
-typedef struct bitmap_obstack
-{
-  struct bitmap_obstack *next;
-  unsigned int indx;
-}
-bitmap_element;
-typedef struct bitmap_head_def
-{
-  bitmap_element *first;
-}
-bitmap_head;
-static __inline__ unsigned char
-bitmap_elt_ior (bitmap dst, bitmap_element * dst_elt,
-		bitmap_element * dst_prev, const bitmap_element * a_elt,
-		const bitmap_element * b_elt)
-{
-  ((void) (!(a_elt || b_elt) ? abort (), 0 : 0));
-}
-
-unsigned char
-bitmap_ior_and_compl (bitmap dst, const_bitmap a, const_bitmap b,
-		      const_bitmap kill)
-{
-  bitmap_element *dst_elt = dst->first;
-  const bitmap_element *a_elt = a->first;
-  const bitmap_element *b_elt = b->first;
-  const bitmap_element *kill_elt = kill->first;
-  bitmap_element *dst_prev = ((void *) 0);
-  while (a_elt || b_elt)
-    {
-      if (b_elt && kill_elt && kill_elt->indx == b_elt->indx
-	  && (!a_elt || a_elt->indx >= b_elt->indx));
-      else
-	{
-	  bitmap_elt_ior (dst, dst_elt, dst_prev, a_elt, b_elt);
-	  if (a_elt && b_elt && a_elt->indx == b_elt->indx)
-	    ;
-	  else if (a_elt && (!b_elt || a_elt->indx <= b_elt->indx))
-	    a_elt = a_elt->next;
-	}
-    }
-}
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-backedge.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-backedge.c
new file mode 100644
index 00000000000..890a0ee10ec
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-thread-backedge.c
@@ -0,0 +1,32 @@
+// { dg-do compile }
+// { dg-options "-O2 -fdisable-tree-ethread -fdisable-tree-thread1 -fdisable-tree-thread2 -fno-tree-dominator-opts -fdump-tree-thread3-details" }
+
+// Test that we can thread jumps across the backedge of a loop through
+// the switch statement to a particular case.
+//
+// Just in case, we disable all the jump threaders before loop
+// optimizations to make sure we get a clean stab at this.
+
+int foo (unsigned int x, int s)
+{
+  while (s != 999)
+    {
+      switch (s)
+	{
+	case 0:
+	  if (x)
+	    s = 1;
+	  break;
+	case 1:
+	  if (x)
+	    s = 999;
+	  break;
+	default:
+	  break;
+	}
+      x++;
+    }
+  return s;
+}
+
+// { dg-final { scan-tree-dump "Registering jump thread:.*normal \\(back\\)" "thread3" } }
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-vrp-thread-1.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-vrp-thread-1.c
index 86d07ef9bdb..f3ca140bd26 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/ssa-vrp-thread-1.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-vrp-thread-1.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-vrp-thread1-details -fdelete-null-pointer-checks" } */
+/* { dg-options "-O2 -fdump-tree-thread1-details -fdelete-null-pointer-checks" } */
 /* { dg-skip-if "" keeps_null_pointer_checks } */
 
 void oof (void);
@@ -29,5 +29,5 @@ build_omp_regions_1 (basic_block bb, struct omp_region *parent,
 
 /* ARM Cortex-M defined LOGICAL_OP_NON_SHORT_CIRCUIT to false,
    so skip below test.  */
-/* { dg-final { scan-tree-dump-times "Threaded" 1 "vrp-thread1" { target { ! arm_cortex_m } } } } */
+/* { dg-final { scan-tree-dump-times "Registering jump thread" 1 "thread1" { target { ! arm_cortex_m } } } } */
 
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp08.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp08.c
index c2da30b4b68..2c6742b76c7 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/vrp08.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp08.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -fno-tree-fre -fdisable-tree-evrp -fdump-tree-vrp1-details -fdelete-null-pointer-checks" } */
+/* { dg-options "-O2 -fno-tree-fre -fdisable-tree-evrp -fdump-tree-vrp1-details -fdisable-tree-thread1 -fdelete-null-pointer-checks" } */
 
 /* Compile with -fno-tree-fre -O2 to prevent CSEing *p.  */
 int
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp55.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp55.c
index a478a6981ac..0ef57d935e4 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/vrp55.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp55.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-O2 -fdump-tree-vrp-thread1-blocks-vops-details -fdelete-null-pointer-checks" } */
+/* { dg-options "-O2 -fdump-tree-ethread-details -fdelete-null-pointer-checks" } */
 
 void arf (void);
 
@@ -12,6 +12,6 @@ fu (char *p, int x)
     arf ();
 }
 
-/* { dg-final { scan-tree-dump-times "Threaded jump" 1 "vrp-thread1" { target { ! keeps_null_pointer_checks } } } } */
-/* { dg-final { scan-tree-dump-times "Threaded jump" 0 "vrp-thread1" { target {   keeps_null_pointer_checks } } } } */
+/* { dg-final { scan-tree-dump-times "Registering jump thread" 1 "ethread" { target { ! keeps_null_pointer_checks } } } } */
+/* { dg-final { scan-tree-dump-times "Registering jump thread" 0 "ethread" { target {   keeps_null_pointer_checks } } } } */
 
diff --git a/gcc/testsuite/gcc.dg/uninit-pr89230-1.c b/gcc/testsuite/gcc.dg/uninit-pr89230-1.c
index 1c07c4f6d78..dfc87a5b1a0 100644
--- a/gcc/testsuite/gcc.dg/uninit-pr89230-1.c
+++ b/gcc/testsuite/gcc.dg/uninit-pr89230-1.c
@@ -8,7 +8,8 @@ struct S { int i, j; };
 
 int g (void)
 {
-  struct S *p = f (), *q;
+  struct S *p = f ();
+  struct S *q; // { dg-bogus "may be used uninitialized" "uninitialized" { xfail *-*-* } }
 
   if (p->i || !(q = f ()) || p->j != q->i)
    {
diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c
index d94e3b962db..edb396b3d6f 100644
--- a/gcc/tree-ssa-threadbackward.c
+++ b/gcc/tree-ssa-threadbackward.c
@@ -374,8 +374,8 @@ back_threader::find_paths_to_names (basic_block bb, bitmap interesting)
       return false;
     }
 
-  // Try to resolve the path with nothing but ranger knowledge.
-  if (m_resolve && m_path.length () > 1 && maybe_register_path ())
+  // Try to resolve the path without looking back.
+  if (m_path.length () > 1 && maybe_register_path ())
     {
       m_path.pop ();
       m_visited_bbs.remove (bb);
diff --git a/gcc/tree-ssa-threadupdate.c b/gcc/tree-ssa-threadupdate.c
index 8e6f043bb44..8aac733ac25 100644
--- a/gcc/tree-ssa-threadupdate.c
+++ b/gcc/tree-ssa-threadupdate.c
@@ -253,6 +253,9 @@ dump_jump_thread_path (FILE *dump_file,
 	default:
 	  gcc_unreachable ();
 	}
+
+      if ((path[i]->e->flags & EDGE_DFS_BACK) != 0)
+	fprintf (dump_file, " (back)");
     }
   fprintf (dump_file, "; \n");
 }
</cut>
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New failures:
FAIL: gcc.dg/guality/pr36728-4.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  -DPREVENT_OPTIMIZATION line 14 y == 2
FAIL: gcc.dg/guality/pr36728-4.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  -DPREVENT_OPTIMIZATION line 16 y == 2
FAIL: gcc.dg/guality/pr36728-4.c   -O3 -g  -DPREVENT_OPTIMIZATION  line 16 y == 2

New passes: