From 3d3470e239e8040f642a8852721b4962b4ed36f2 Mon Sep 17 00:00:00 2001 From: Aldy Hernandez Date: Mon, 9 Nov 2020 20:35:25 +0100 Subject: [PATCH] Normalize VARYING for -fstrict-enums. The problem here is that the representation for VARYING in -fstrict-enums is different between value_range and irange. The helper function irange::normalize_min_max() will normalize to VARYING only if setting the range to the entire domain of the underlying type. That is, [0, 0xff..ff], not the domain as defined by -fstrict-enums. This causes problems because the multi-range version of varying_p() will return true if the range is the domain as defined by -fstrict-enums. Thus, normalize_min_max and varying_p have different concepts of varying for multi-ranges. (BTW, legacy ranges are different because they never look at the extremes of a range to determine varying-ness. They only look at the kind field.) One approach is to change all the code to limit ranges to the domain in the -fstrict-enums world, but this won't work because there are various instances of gimple where the values assigned or compared are beyond the limits of TYPE_{MIN,MAX}_VALUE. One example is the addition of 0xffffffff to represent subtraction. This patch fixes multi-range varying_p() and set_varying() to agree with the normalization code, using the extremes of the underlying type, to represent varying. gcc/ChangeLog: PR tree-optimization/97767 * value-range.cc (dump_bound_with_infinite_markers): Use wi::min_value and wi::max_value. (range_tests_strict_enum): New. (range_tests): Call range_tests_strict_enum. * value-range.h (irange::varying_p): Use wi::min_value and wi::max_value. (irange::set_varying): Same. (irange::normalize_min_max): Remove comment. gcc/testsuite/ChangeLog: * g++.dg/opt/pr97767.C: New test. --- gcc/testsuite/g++.dg/opt/pr97767.C | 10 +++++++ gcc/value-range.cc | 42 ++++++++++++++++++++++++++++-- gcc/value-range.h | 23 +++++++--------- 3 files changed, 60 insertions(+), 15 deletions(-) create mode 100644 gcc/testsuite/g++.dg/opt/pr97767.C diff --git a/gcc/testsuite/g++.dg/opt/pr97767.C b/gcc/testsuite/g++.dg/opt/pr97767.C new file mode 100644 index 00000000000..da0879d0567 --- /dev/null +++ b/gcc/testsuite/g++.dg/opt/pr97767.C @@ -0,0 +1,10 @@ +// { dg-do compile } +// { dg-options "-O -fstrict-enums -ftree-vrp -w" } + +enum { E0 = 0, E1 = 1, E2 = 2 } e; + +int +foo (void) +{ + return __builtin_popcount ((int) e); +} diff --git a/gcc/value-range.cc b/gcc/value-range.cc index 61f7da278d6..f83a824a982 100644 --- a/gcc/value-range.cc +++ b/gcc/value-range.cc @@ -1866,12 +1866,17 @@ static void dump_bound_with_infinite_markers (FILE *file, tree bound) { tree type = TREE_TYPE (bound); + wide_int type_min = wi::min_value (TYPE_PRECISION (type), TYPE_SIGN (type)); + wide_int type_max = wi::max_value (TYPE_PRECISION (type), TYPE_SIGN (type)); + if (INTEGRAL_TYPE_P (type) && !TYPE_UNSIGNED (type) - && vrp_val_is_min (bound) + && TREE_CODE (bound) == INTEGER_CST + && wi::to_wide (bound) == type_min && TYPE_PRECISION (type) != 1) fprintf (file, "-INF"); - else if (vrp_val_is_max (bound) + else if (TREE_CODE (bound) == INTEGER_CST + && wi::to_wide (bound) == type_max && TYPE_PRECISION (type) != 1) fprintf (file, "+INF"); else @@ -2241,6 +2246,38 @@ range_tests_legacy () } } +// Simulate -fstrict-enums where the domain of a type is less than the +// underlying type. + +static void +range_tests_strict_enum () +{ + // The enum can only hold [0, 3]. + tree rtype = copy_node (unsigned_type_node); + TYPE_MIN_VALUE (rtype) = build_int_cstu (rtype, 0); + TYPE_MAX_VALUE (rtype) = build_int_cstu (rtype, 3); + + // Test that even though vr1 covers the strict enum domain ([0, 3]), + // it does not cover the domain of the underlying type. + int_range<1> vr1 (build_int_cstu (rtype, 0), build_int_cstu (rtype, 1)); + int_range<1> vr2 (build_int_cstu (rtype, 2), build_int_cstu (rtype, 3)); + vr1.union_ (vr2); + ASSERT_TRUE (vr1 == int_range<1> (build_int_cstu (rtype, 0), + build_int_cstu (rtype, 3))); + ASSERT_FALSE (vr1.varying_p ()); + + // Test that copying to a multi-range does not change things. + int_range<2> ir1 (vr1); + ASSERT_TRUE (ir1 == vr1); + ASSERT_FALSE (ir1.varying_p ()); + + // The same test as above, but using TYPE_{MIN,MAX}_VALUE instead of [0,3]. + vr1 = int_range<1> (TYPE_MIN_VALUE (rtype), TYPE_MAX_VALUE (rtype)); + ir1 = vr1; + ASSERT_TRUE (ir1 == vr1); + ASSERT_FALSE (ir1.varying_p ()); +} + static void range_tests_misc () { @@ -2442,6 +2479,7 @@ range_tests () range_tests_legacy (); range_tests_irange3 (); range_tests_int_range_max (); + range_tests_strict_enum (); range_tests_misc (); } diff --git a/gcc/value-range.h b/gcc/value-range.h index a483fc802dd..7428c91ea57 100644 --- a/gcc/value-range.h +++ b/gcc/value-range.h @@ -280,12 +280,14 @@ irange::varying_p () const tree l = m_base[0]; tree u = m_base[1]; tree t = TREE_TYPE (l); + unsigned prec = TYPE_PRECISION (t); + signop sign = TYPE_SIGN (t); if (INTEGRAL_TYPE_P (t)) - return l == TYPE_MIN_VALUE (t) && u == TYPE_MAX_VALUE (t); + return (wi::to_wide (l) == wi::min_value (prec, sign) + && wi::to_wide (u) == wi::max_value (prec, sign)); if (POINTER_TYPE_P (t)) - return wi::to_wide (l) == 0 - && wi::to_wide (u) == wi::max_value (TYPE_PRECISION (t), - TYPE_SIGN (t)); + return (wi::to_wide (l) == 0 + && wi::to_wide (u) == wi::max_value (prec, sign)); return true; } @@ -469,8 +471,10 @@ irange::set_varying (tree type) m_num_ranges = 1; if (INTEGRAL_TYPE_P (type)) { - m_base[0] = TYPE_MIN_VALUE (type); - m_base[1] = TYPE_MAX_VALUE (type); + wide_int min = wi::min_value (TYPE_PRECISION (type), TYPE_SIGN (type)); + wide_int max = wi::max_value (TYPE_PRECISION (type), TYPE_SIGN (type)); + m_base[0] = wide_int_to_tree (type, min); + m_base[1] = wide_int_to_tree (type, max); } else if (POINTER_TYPE_P (type)) { @@ -566,13 +570,6 @@ irange::set_zero (tree type) } // Normalize a range to VARYING or UNDEFINED if possible. -// -// Avoid using TYPE_{MIN,MAX}_VALUE because -fstrict-enums can -// restrict those to a subset of what actually fits in the type. -// Instead use the extremes of the type precision which will allow -// compare_range_with_value() to check if a value is inside a range, -// whereas if we used TYPE_*_VAL, said function would just punt upon -// seeing a VARYING. inline void irange::normalize_min_max () -- 2.30.2