[Lldb-commits] [lldb] [LLDB] Fix operators <= and >= returning a wrong result when comparing to a floating point NaN (PR #108060)

Ilia Kuklin via lldb-commits lldb-commits at lists.llvm.org
Tue Sep 10 10:29:38 PDT 2024


https://github.com/kuilpd created https://github.com/llvm/llvm-project/pull/108060

Implement operators `<=` and `>=` to explicitly check the comparison results to be `cmpLessThan` or `cmpEqual` instead of negating the result of `operators<`.

Fixes #85947 

>From 1e83cdfeb7e3a6fba4b190e95dd794723031370d Mon Sep 17 00:00:00 2001
From: Ilia Kuklin <ikuklin at accesssoftek.com>
Date: Tue, 3 Sep 2024 03:08:48 +0500
Subject: [PATCH] Implement operators <= and >= and add a test

---
 lldb/include/lldb/Utility/Scalar.h        |   8 +-
 lldb/source/Utility/Scalar.cpp            |  38 ++++++-
 lldb/test/API/lang/cpp/fpnan/Makefile     |   3 +
 lldb/test/API/lang/cpp/fpnan/TestFPNaN.py | 130 ++++++++++++++++++++++
 lldb/test/API/lang/cpp/fpnan/main.cpp     |   8 ++
 5 files changed, 179 insertions(+), 8 deletions(-)
 create mode 100644 lldb/test/API/lang/cpp/fpnan/Makefile
 create mode 100644 lldb/test/API/lang/cpp/fpnan/TestFPNaN.py
 create mode 100644 lldb/test/API/lang/cpp/fpnan/main.cpp

diff --git a/lldb/include/lldb/Utility/Scalar.h b/lldb/include/lldb/Utility/Scalar.h
index 0d8eba3c9726d5..a8fe7fee3a2b9f 100644
--- a/lldb/include/lldb/Utility/Scalar.h
+++ b/lldb/include/lldb/Utility/Scalar.h
@@ -223,9 +223,9 @@ class Scalar {
   friend bool operator==(Scalar lhs, Scalar rhs);
   friend bool operator!=(const Scalar &lhs, const Scalar &rhs);
   friend bool operator<(Scalar lhs, Scalar rhs);
-  friend bool operator<=(const Scalar &lhs, const Scalar &rhs);
+  friend bool operator<=(Scalar lhs, Scalar rhs);
   friend bool operator>(const Scalar &lhs, const Scalar &rhs);
-  friend bool operator>=(const Scalar &lhs, const Scalar &rhs);
+  friend bool operator>=(Scalar lhs, Scalar rhs);
 };
 
 // Split out the operators into a format where the compiler will be able to
@@ -254,9 +254,9 @@ const Scalar operator>>(const Scalar &lhs, const Scalar &rhs);
 bool operator==(Scalar lhs, Scalar rhs);
 bool operator!=(const Scalar &lhs, const Scalar &rhs);
 bool operator<(Scalar lhs, Scalar rhs);
-bool operator<=(const Scalar &lhs, const Scalar &rhs);
+bool operator<=(Scalar lhs, Scalar rhs);
 bool operator>(const Scalar &lhs, const Scalar &rhs);
-bool operator>=(const Scalar &lhs, const Scalar &rhs);
+bool operator>=(Scalar lhs, Scalar rhs);
 
 llvm::raw_ostream &operator<<(llvm::raw_ostream &os, const Scalar &scalar);
 
diff --git a/lldb/source/Utility/Scalar.cpp b/lldb/source/Utility/Scalar.cpp
index 329f5b6e4b9a5b..bdbd79d375a4f7 100644
--- a/lldb/source/Utility/Scalar.cpp
+++ b/lldb/source/Utility/Scalar.cpp
@@ -893,16 +893,46 @@ bool lldb_private::operator<(Scalar lhs, Scalar rhs) {
   return false;
 }
 
-bool lldb_private::operator<=(const Scalar &lhs, const Scalar &rhs) {
-  return !(rhs < lhs);
+bool lldb_private::operator<=(Scalar lhs, Scalar rhs) {
+  if (lhs.m_type == Scalar::e_void || rhs.m_type == Scalar::e_void)
+    return false;
+
+  llvm::APFloat::cmpResult result;
+  switch (Scalar::PromoteToMaxType(lhs, rhs)) {
+  case Scalar::e_void:
+    break;
+  case Scalar::e_int:
+    return lhs.m_integer <= rhs.m_integer;
+  case Scalar::e_float:
+    result = lhs.m_float.compare(rhs.m_float);
+    if (result == llvm::APFloat::cmpLessThan ||
+        result == llvm::APFloat::cmpEqual)
+      return true;
+  }
+  return false;
 }
 
 bool lldb_private::operator>(const Scalar &lhs, const Scalar &rhs) {
   return rhs < lhs;
 }
 
-bool lldb_private::operator>=(const Scalar &lhs, const Scalar &rhs) {
-  return !(lhs < rhs);
+bool lldb_private::operator>=(Scalar lhs, Scalar rhs) {
+  if (lhs.m_type == Scalar::e_void || rhs.m_type == Scalar::e_void)
+    return false;
+
+  llvm::APFloat::cmpResult result;
+  switch (Scalar::PromoteToMaxType(lhs, rhs)) {
+  case Scalar::e_void:
+    break;
+  case Scalar::e_int:
+    return lhs.m_integer >= rhs.m_integer;
+  case Scalar::e_float:
+    result = lhs.m_float.compare(rhs.m_float);
+    if (result == llvm::APFloat::cmpGreaterThan ||
+        result == llvm::APFloat::cmpEqual)
+      return true;
+  }
+  return false;
 }
 
 bool Scalar::ClearBit(uint32_t bit) {
diff --git a/lldb/test/API/lang/cpp/fpnan/Makefile b/lldb/test/API/lang/cpp/fpnan/Makefile
new file mode 100644
index 00000000000000..99998b20bcb050
--- /dev/null
+++ b/lldb/test/API/lang/cpp/fpnan/Makefile
@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules
diff --git a/lldb/test/API/lang/cpp/fpnan/TestFPNaN.py b/lldb/test/API/lang/cpp/fpnan/TestFPNaN.py
new file mode 100644
index 00000000000000..6093ef91ac1f03
--- /dev/null
+++ b/lldb/test/API/lang/cpp/fpnan/TestFPNaN.py
@@ -0,0 +1,130 @@
+"""
+Test floating point expressions with zero, NaN, dernormalized and infinite
+numbers.
+"""
+
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class FPNaNTestCase(TestBase):
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+        # Find the line number to break inside main().
+        self.line = line_number("main.cpp", "// Set break point at this line.")
+
+    def test(self):
+        self.build()
+        exe = self.getBuildArtifact("a.out")
+        self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
+
+        # Break inside the main.
+        lldbutil.run_break_set_by_file_and_line(
+            self, "main.cpp", self.line, num_expected_locations=1
+        )
+
+        self.runCmd("run", RUN_SUCCEEDED)
+        # Zero and denorm
+        self.expect(
+            "expr +0.0",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["double", "0"],
+        )
+        self.expect(
+            "expr -0.0",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["double", "0"],
+        )
+        self.expect(
+            "expr 0.0 / 0",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["double", "NaN"],
+        )
+        self.expect(
+            "expr 0 / 0.0",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["double", "NaN"],
+        )
+        self.expect(
+            "expr 1 / +0.0",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["double", "+Inf"],
+        )
+        self.expect(
+            "expr 1 / -0.0",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["double", "-Inf"],
+        )
+        self.expect(
+            "expr +0.0 / +0.0 != +0.0 / +0.0",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["bool", "true"],
+        )
+        self.expect(
+            "expr -1.f * 0",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["float", "-0"],
+        )
+        self.expect(
+            "expr 0x0.123p-1",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["double", "0.0355224609375"],
+        )
+        # NaN
+        self.expect(
+            "expr fnan < fnan",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["bool", "false"],
+        )
+        self.expect(
+            "expr fnan <= fnan",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["bool", "false"],
+        )
+        self.expect(
+            "expr fnan > fnan",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["bool", "false"],
+        )
+        self.expect(
+            "expr fnan >= fnan",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["bool", "false"],
+        )
+        self.expect(
+            "expr fnan == fnan",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["bool", "false"],
+        )
+        self.expect(
+            "expr fnan != fnan",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["bool", "true"],
+        )
+        self.expect(
+            "expr 1.0 <= fnan",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["bool", "false"],
+        )
+        self.expect(
+            "expr 1.0f < fnan",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["bool", "false"],
+        )
+        self.expect(
+            "expr 1.0f != fnan",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["bool", "true"],
+        )
+        self.expect(
+            "expr (unsigned int) fdenorm",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["int", "0"],
+        )
+        self.expect(
+            "expr (unsigned int) (1.0f + fdenorm)",
+            VARIABLES_DISPLAYED_CORRECTLY,
+            substrs=["int", "1"],
+        )
diff --git a/lldb/test/API/lang/cpp/fpnan/main.cpp b/lldb/test/API/lang/cpp/fpnan/main.cpp
new file mode 100644
index 00000000000000..8bcfebfaea8e1e
--- /dev/null
+++ b/lldb/test/API/lang/cpp/fpnan/main.cpp
@@ -0,0 +1,8 @@
+#include <limits>
+
+int main() {
+  float fnan = std::numeric_limits<float>::quiet_NaN();
+  float fdenorm = std::numeric_limits<float>::denorm_min();
+
+  // Set break point at this line.
+}



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