[I don't know why I keep poking at floats.  I must really like the pain.
Jakub, are you OK with this patch for trunk?]

This is the range-op entry for sin/cos.  It is meant to serve as an
example of what we can do for glibc math functions.  It is by no means
exhaustive, just a stub to restrict the return range from sin/cos to
[-1.0, 1.0] with appropriate smarts of NANs.

As can be seen in the testcase, we see sin() as well as
__builtin_sin() in the IL, and can resolve the resulting range
accordingly.

gcc/ChangeLog:

        * gimple-range-op.cc (class cfn_sincos): New.
        (gimple_range_op_handler::maybe_builtin_call): Add case for sin/cos.

gcc/testsuite/ChangeLog:

        * gcc.dg/tree-ssa/range-sincos.c: New test.
---
 gcc/gimple-range-op.cc                       | 63 ++++++++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/range-sincos.c | 40 +++++++++++++
 2 files changed, 103 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/range-sincos.c

diff --git a/gcc/gimple-range-op.cc b/gcc/gimple-range-op.cc
index 4ca32a7b5d5..36390f2645e 100644
--- a/gcc/gimple-range-op.cc
+++ b/gcc/gimple-range-op.cc
@@ -402,6 +402,60 @@ public:
   }
 } op_cfn_copysign;
 
+class cfn_sincos : public range_operator_float
+{
+public:
+  using range_operator_float::fold_range;
+  using range_operator_float::op1_range;
+  virtual bool fold_range (frange &r, tree type,
+                          const frange &lh, const frange &,
+                          relation_trio) const final override
+  {
+    if (lh.known_isnan () || lh.known_isinf ())
+      {
+       r.set_nan (type);
+       return true;
+      }
+    r.set (type, dconstm1, dconst1);
+    if (!lh.maybe_isnan ())
+      r.clear_nan ();
+    return true;
+  }
+  virtual bool op1_range (frange &r, tree type,
+                         const frange &lhs, const frange &,
+                         relation_trio) const final override
+  {
+    if (!lhs.maybe_isnan ())
+      {
+       // If NAN is not valid result, the input cannot include either
+       // a NAN nor a +-INF.
+       REAL_VALUE_TYPE lb = real_min_representable (type);
+       REAL_VALUE_TYPE ub = real_max_representable (type);
+       r.set (type, lb, ub, nan_state (false, false));
+       return true;
+      }
+    // A known NAN means the input is [-INF,-INF][+INF,+INF] U +-NAN,
+    // which we can't currently represent.
+    if (lhs.known_isnan ())
+      {
+       r.set_varying (type);
+       return true;
+      }
+    // Results outside of [-1.0, +1.0] are impossible.
+    REAL_VALUE_TYPE lb = lhs.lower_bound ();
+    REAL_VALUE_TYPE ub = lhs.upper_bound ();
+    if (real_less (&lb, &dconstm1)
+       || real_less (&dconst1, &ub))
+      {
+       r.set_undefined ();
+       return true;
+      }
+
+    r.set_varying (type);
+    return true;
+  }
+} op_cfn_sincos;
+
 // Implement range operator for CFN_BUILT_IN_TOUPPER and CFN_BUILT_IN_TOLOWER.
 class cfn_toupper_tolower : public range_operator
 {
@@ -880,6 +934,15 @@ gimple_range_op_handler::maybe_builtin_call ()
       m_valid = true;
       break;
 
+    CASE_CFN_SIN:
+    CASE_CFN_SIN_FN:
+    CASE_CFN_COS:
+    CASE_CFN_COS_FN:
+      m_op1 = gimple_call_arg (call, 0);
+      m_float = &op_cfn_sincos;
+      m_valid = true;
+      break;
+
     case CFN_BUILT_IN_TOUPPER:
     case CFN_BUILT_IN_TOLOWER:
       // Only proceed If the argument is compatible with the LHS.
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/range-sincos.c 
b/gcc/testsuite/gcc.dg/tree-ssa/range-sincos.c
new file mode 100644
index 00000000000..50fbac1b68f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/range-sincos.c
@@ -0,0 +1,40 @@
+// { dg-do compile }
+// { dg-options "-O2 -fdump-tree-evrp -fno-thread-jumps" }
+
+#include <math.h>
+
+void use(double);
+void link_error ();
+
+void foo(double x)
+{
+  if (__builtin_isnan (x))
+    __builtin_unreachable();
+  x = sin (x);
+  if (x < -1.0 || x > 1.0)
+    link_error ();
+  use (x);
+}
+
+void bar(double x)
+{
+  if (!__builtin_isnan (sin (x)))
+    {
+      if (__builtin_isnan (x))
+       link_error ();
+      if (__builtin_isinf (x))
+       link_error ();
+    }
+}
+
+void stool (double x)
+{
+  double res1 = sin (x);
+  double res2 = __builtin_sin (x);
+  if (res1 < -1.0 || res2 < -1.0)
+    link_error ();
+  if (res1 > 1.0 || res2 > 1.0)
+    link_error ();
+}
+
+// { dg-final { scan-tree-dump-not "link_error" "evrp" } }
-- 
2.39.2

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