[gcc r12-4694] Fold all statements in Ranger VRP.

[Andrew Macleod <amacleod@gcc.gnu.org>]

https://gcc.gnu.org/g:cb153222404e2e149aa65a4b3139b09477551203

commit r12-4694-gcb153222404e2e149aa65a4b3139b09477551203
Author: Andrew MacLeod <amacleod@redhat.com>
Date:   Wed Oct 20 13:37:29 2021 -0400

    Fold all statements in Ranger VRP.
    
    Until now, ranger VRP has only simplified statements with ranges.  This patch
    enables us to fold all statements.
    
            gcc/
            * tree-vrp.c (rvrp_folder::fold_stmt): If simplification fails, try
            to fold anyway.
    
            gcc/testsuite/
            * gcc.dg/tree-ssa/vrp98.c: Disable evrp for vrp1 test.
            * gcc.dg/tree-ssa/vrp98-1.c: New. Test for folding in evrp.

Diff:
---
 gcc/testsuite/gcc.dg/tree-ssa/vrp98-1.c | 41 +++++++++++++++++++++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/vrp98.c   |  2 +-
 gcc/tree-vrp.c                          |  5 +++-
 3 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp98-1.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp98-1.c
new file mode 100644
index 00000000000..daa3f073b92
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp98-1.c
@@ -0,0 +1,41 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target int128 } */
+/* { dg-options "-Os -fdump-tree-evrp-details" } */
+
+#include <stdint.h>
+#include <limits.h>
+
+typedef unsigned int word __attribute__((mode(word)));
+typedef unsigned __int128 bigger_than_word;
+
+int
+foo (bigger_than_word a, word b, uint8_t c)
+{
+  /* Must fold use of t1 into use of b, as b is no wider than word_mode. */
+  const uint8_t t1 = b % UCHAR_MAX;
+
+  /* Must NOT fold use of t2 into use of a, as a is wider than word_mode. */
+  const uint8_t t2 = a % UCHAR_MAX;
+
+  /* Must fold use of t3 into use of c, as c is narrower than t3. */
+  const uint32_t t3 = (const uint32_t)(c >> 1);
+
+  uint16_t ret = 0;
+
+  if (t1 == 1)
+    ret = 20;
+  else if (t2 == 2)
+    ret = 30;
+  else if (t3 == 3)
+    ret = 40;
+  /* Th extra condition below is necessary to prevent a prior pass from
+     folding away the cast. Ignored in scan-tree-dump. */
+  else if (t3 == 4)
+    ret = 50;
+
+  return ret;
+}
+
+/* { dg-final { scan-tree-dump "Folded into: if \\(_\[0-9\]+ == 1\\)" "evrp" } } */
+/* { dg-final { scan-tree-dump-not "Folded into: if \\(_\[0-9\]+ == 2\\)" "evrp" } } */
+/* { dg-final { scan-tree-dump "Folded into: if \\(_\[0-9\]+ == 3\\)" "evrp" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp98.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp98.c
index 982f091080c..78d3bbaf499 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/vrp98.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp98.c
@@ -1,6 +1,6 @@
 /* { dg-do compile } */
 /* { dg-require-effective-target int128 } */
-/* { dg-options "-Os -fdump-tree-vrp1-details" } */
+/* { dg-options "-Os -fdisable-tree-evrp -fdump-tree-vrp1-details" } */
 
 #include <stdint.h>
 #include <limits.h>
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index ba7a4efc7c6..a948c524098 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -50,6 +50,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "gimple-range.h"
 #include "gimple-range-path.h"
 #include "value-pointer-equiv.h"
+#include "gimple-fold.h"
 
 /* Set of SSA names found live during the RPO traversal of the function
    for still active basic-blocks.  */
@@ -4381,7 +4382,9 @@ public:
 
   bool fold_stmt (gimple_stmt_iterator *gsi) OVERRIDE
   {
-    return m_simplifier.simplify (gsi);
+    if (m_simplifier.simplify (gsi))
+      return true;
+    return ::fold_stmt (gsi, follow_single_use_edges);
   }
 
 private: