From: Aldy Hernandez <aldyh@redhat.com>
Date: Fri, 30 Jun 2023 18:40:02 +0000 (+0200)
Subject: [range-op] Take known set bits into account in popcount [PR107053]
X-Git-Tag: basepoints/gcc-15~7660
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=137fb7077f7711e2e09ee8f82650fe7d93de6a4d;p=thirdparty%2Fgcc.git

[range-op] Take known set bits into account in popcount [PR107053]

This patch teaches popcount about known set bits which are now
available in the irange.

	PR tree-optimization/107053

gcc/ChangeLog:

	* gimple-range-op.cc (cfn_popcount): Use known set bits.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/pr107053.c: New test.
---

diff --git a/gcc/gimple-range-op.cc b/gcc/gimple-range-op.cc
index 72c7b866f90d..67b3c3d015ef 100644
--- a/gcc/gimple-range-op.cc
+++ b/gcc/gimple-range-op.cc
@@ -880,17 +880,20 @@ public:
     if (lh.undefined_p ())
       return false;
     unsigned prec = TYPE_PRECISION (type);
-    wide_int nz = lh.get_nonzero_bits ();
-    wide_int pop = wi::shwi (wi::popcount (nz), prec);
+    irange_bitmask bm = lh.get_bitmask ();
+    wide_int nz = bm.get_nonzero_bits ();
+    wide_int high = wi::shwi (wi::popcount (nz), prec);
     // Calculating the popcount of a singleton is trivial.
     if (lh.singleton_p ())
       {
-	r.set (type, pop, pop);
+	r.set (type, high, high);
 	return true;
       }
     if (cfn_ffs::fold_range (r, type, lh, rh, rel))
       {
-	int_range<2> tmp (type, wi::zero (prec), pop);
+	wide_int known_ones = ~bm.mask () & bm.value ();
+	wide_int low = wi::shwi (wi::popcount (known_ones), prec);
+	int_range<2> tmp (type, low, high);
 	r.intersect (tmp);
 	return true;
       }
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr107053.c b/gcc/testsuite/gcc.dg/tree-ssa/pr107053.c
new file mode 100644
index 000000000000..8195d0f57b4e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr107053.c
@@ -0,0 +1,13 @@
+// { dg-do compile }
+// { dg-options "-O2 -fdump-tree-evrp" }
+
+void link_failure();
+void f(int a)
+{
+    a |= 0x300;
+    int b =  __builtin_popcount(a);
+    if (b < 2)
+        link_failure();
+}
+
+// { dg-final { scan-tree-dump-not "link_failure" "evrp" } }