[gcc r13-3052] [PR107130] range-ops: Separate out ffs and popcount optimizations.

[Aldy Hernandez <aldyh@gcc.gnu.org>]

https://gcc.gnu.org/g:f50d103183c551c7f9f9f20efaf2ebbf83d5e99f

commit r13-3052-gf50d103183c551c7f9f9f20efaf2ebbf83d5e99f
Author: Aldy Hernandez <aldyh@redhat.com>
Date:   Mon Oct 3 17:31:32 2022 +0200

    [PR107130] range-ops: Separate out ffs and popcount optimizations.
    
    __builtin_popcount and __builtin_ffs were sharing the same range-ops
    entry, but the nonzero mask optimization is not valid for ffs.
    Separate them out into two entries.
    
            PR tree-optimization/107130
    
    gcc/ChangeLog:
    
            * gimple-range-op.cc (class cfn_popcount): Call op_cfn_ffs.
            (class cfn_ffs): New.
            (gimple_range_op_handler::maybe_builtin_call): Separate out
            CASE_CFN_FFS into its own case.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/tree-ssa/pr107130.c: New test.

Diff:
---
 gcc/gimple-range-op.cc                   | 37 +++++++++++++++++++++++---------
 gcc/testsuite/gcc.dg/tree-ssa/pr107130.c | 19 ++++++++++++++++
 2 files changed, 46 insertions(+), 10 deletions(-)

diff --git a/gcc/gimple-range-op.cc b/gcc/gimple-range-op.cc
index 3a7c9074659..5b71d1cce6d 100644
--- a/gcc/gimple-range-op.cc
+++ b/gcc/gimple-range-op.cc
@@ -387,8 +387,8 @@ cfn_toupper_tolower::fold_range (irange &r, tree type, const irange &lh,
   return true;
 }
 
-// Implement range operator for CFN_BUILT_IN_FFS and CFN_BUILT_IN_POPCOUNT.
-class cfn_popcount : public range_operator
+// Implement range operator for CFN_BUILT_IN_FFS.
+class cfn_ffs : public range_operator
 {
 public:
   using range_operator::fold_range;
@@ -397,14 +397,6 @@ public:
   {
     if (lh.undefined_p ())
       return false;
-    // Calculating the popcount of a singleton is trivial.
-    if (lh.singleton_p ())
-      {
-	wide_int nz = lh.get_nonzero_bits ();
-	wide_int pop = wi::shwi (wi::popcount (nz), TYPE_PRECISION (type));
-	r.set (type, pop, pop);
-	return true;
-      }
     // __builtin_ffs* and __builtin_popcount* return [0, prec].
     int prec = TYPE_PRECISION (lh.type ());
     // If arg is non-zero, then ffs or popcount are non-zero.
@@ -420,6 +412,26 @@ public:
     r.set (build_int_cst (type, mini), build_int_cst (type, maxi));
     return true;
   }
+} op_cfn_ffs;
+
+// Implement range operator for CFN_BUILT_IN_POPCOUNT.
+class cfn_popcount : public cfn_ffs
+{
+public:
+  using range_operator::fold_range;
+  virtual bool fold_range (irange &r, tree type, const irange &lh,
+			   const irange &rh, relation_kind rel) const
+  {
+    // Calculating the popcount of a singleton is trivial.
+    if (lh.singleton_p ())
+      {
+	wide_int nz = lh.get_nonzero_bits ();
+	wide_int pop = wi::shwi (wi::popcount (nz), TYPE_PRECISION (type));
+	r.set (type, pop, pop);
+	return true;
+      }
+    return cfn_ffs::fold_range (r, type, lh, rh, rel);
+  }
 } op_cfn_popcount;
 
 // Implement range operator for CFN_BUILT_IN_CLZ
@@ -734,6 +746,11 @@ gimple_range_op_handler::maybe_builtin_call ()
       break;
 
     CASE_CFN_FFS:
+      m_op1 = gimple_call_arg (call, 0);
+      m_int = &op_cfn_ffs;
+      m_valid = true;
+      break;
+
     CASE_CFN_POPCOUNT:
       m_op1 = gimple_call_arg (call, 0);
       m_int = &op_cfn_popcount;
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr107130.c b/gcc/testsuite/gcc.dg/tree-ssa/pr107130.c
new file mode 100644
index 00000000000..11fb816ad71
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr107130.c
@@ -0,0 +1,19 @@
+// { dg-do compile }
+// { dg-options "-Os -fno-tree-ccp -fno-tree-forwprop -fno-tree-fre -fdump-tree-vrp1" }
+
+static inline int
+foo (int i)
+{
+  return __builtin_ffsl (i);
+}
+
+int
+main (void)
+{
+  int x = foo (41);
+  if (x != 1)
+    __builtin_abort ();
+  return 0;
+}
+
+// { dg-final { scan-tree-dump-not "builtin_abort" "vrp1" } }