mirror of
https://github.com/Z3Prover/z3
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65 lines
2.4 KiB
C++
65 lines
2.4 KiB
C++
/*++
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Copyright (c) 2025 Microsoft Corporation
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--*/
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// Regression tests for floating-point arithmetic encoding and model generation.
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#include "api/z3.h"
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#include "util/debug.h"
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#include <string.h>
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static void run_fp_test(const char * assertion, bool expect_sat) {
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Z3_context ctx = Z3_mk_context(nullptr);
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const char * result = Z3_eval_smtlib2_string(ctx, assertion);
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if (expect_sat) {
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ENSURE(strstr(result, "sat") != nullptr);
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ENSURE(strstr(result, "unsat") == nullptr);
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} else {
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ENSURE(strstr(result, "unsat") != nullptr);
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}
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ENSURE(strstr(result, "invalid") == nullptr);
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Z3_del_context(ctx);
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}
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// Test that fp.to_real produces correct values for denormal floating-point numbers.
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// Regression test for: incorrect model with (_ FloatingPoint 2 24) and fp.to_real.
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// Denormal numbers require subtracting the normalization shift (lz) from the exponent;
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// without this fix, denormals in fp.to_real were ~2^lz times too large.
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static void test_fp_to_real_denormal() {
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// Test 1: the specific denormal from the bug report (fp #b0 #b00 #b00111011011111001011101)
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// has fp.to_real ~= 0.232, which must NOT be > 1.0
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run_fp_test(
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"(set-option :model_validate true)\n"
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"(assert (> (fp.to_real (fp #b0 #b00 #b00111011011111001011101)) 1.0))\n"
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"(check-sat)\n",
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false);
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// Test 2: denormal with leading significand bit = 1, fp.to_real should be 0.5
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// (fp #b0 #b00 #b10000000000000000000000) in (_ FloatingPoint 2 24)
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run_fp_test(
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"(set-option :model_validate true)\n"
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"(assert (= (fp.to_real (fp #b0 #b00 #b10000000000000000000000)) (/ 1.0 2.0)))\n"
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"(check-sat)\n",
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true);
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// Test 3: denormal with significand bit pattern giving fp.to_real = 0.125
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// (fp #b0 #b00 #b00100000000000000000000) in (_ FloatingPoint 2 24)
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run_fp_test(
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"(set-option :model_validate true)\n"
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"(assert (= (fp.to_real (fp #b0 #b00 #b00100000000000000000000)) (/ 1.0 8.0)))\n"
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"(check-sat)\n",
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true);
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// Test 4: a normal value (fp #b0 #b01 #b11111111111111111111111) must be > 1.0
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// This is the maximum finite normal number in (_ FloatingPoint 2 24)
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run_fp_test(
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"(set-option :model_validate true)\n"
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"(assert (> (fp.to_real (fp #b0 #b01 #b11111111111111111111111)) 1.0))\n"
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"(check-sat)\n",
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true);
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}
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void tst_fpa() {
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test_fp_to_real_denormal();
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}
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