[llvm] [ConstantFPRange] Add support for fneg/fabs (PR #162690)

[Yingwei Zheng via llvm-commits]

https://github.com/dtcxzyw updated https://github.com/llvm/llvm-project/pull/162690

>From cc99daaaa7c4398b7cebcae40d8c9fbc2e59105c Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Fri, 10 Oct 2025 00:18:17 +0800
Subject: [PATCH 1/2] [ConstantFPRange] Add support for fneg/fabs

---
 llvm/include/llvm/IR/ConstantFPRange.h    |  6 +++++
 llvm/lib/IR/ConstantFPRange.cpp           | 20 ++++++++++++++
 llvm/unittests/IR/ConstantFPRangeTest.cpp | 33 +++++++++++++++++++++++
 3 files changed, 59 insertions(+)

diff --git a/llvm/include/llvm/IR/ConstantFPRange.h b/llvm/include/llvm/IR/ConstantFPRange.h
index 930c6f98c033f..4a54caa87eaca 100644
--- a/llvm/include/llvm/IR/ConstantFPRange.h
+++ b/llvm/include/llvm/IR/ConstantFPRange.h
@@ -200,6 +200,12 @@ class [[nodiscard]] ConstantFPRange {
   /// with another range.  The resultant range is guaranteed to include the
   /// elements of both sets, but may contain more.
   LLVM_ABI ConstantFPRange unionWith(const ConstantFPRange &CR) const;
+
+  /// Calculate absolute value range.
+  LLVM_ABI ConstantFPRange abs() const;
+
+  /// Calculate range of negated values.
+  LLVM_ABI ConstantFPRange negate() const;
 };
 
 inline raw_ostream &operator<<(raw_ostream &OS, const ConstantFPRange &CR) {
diff --git a/llvm/lib/IR/ConstantFPRange.cpp b/llvm/lib/IR/ConstantFPRange.cpp
index 7509188128524..969af9798bf06 100644
--- a/llvm/lib/IR/ConstantFPRange.cpp
+++ b/llvm/lib/IR/ConstantFPRange.cpp
@@ -391,3 +391,23 @@ ConstantFPRange ConstantFPRange::unionWith(const ConstantFPRange &CR) const {
   return ConstantFPRange(minnum(Lower, CR.Lower), maxnum(Upper, CR.Upper),
                          MayBeQNaN | CR.MayBeQNaN, MayBeSNaN | CR.MayBeSNaN);
 }
+
+ConstantFPRange ConstantFPRange::abs() const {
+  if (isEmptySet())
+    return *this;
+  // Check if the range is all non-negative or all non-positive.
+  if (Lower.isNegative() == Upper.isNegative()) {
+    if (Lower.isNegative())
+      return negate();
+    return *this;
+  }
+  // The range contains both positive and negative values.
+  APFloat NewLower = APFloat::getZero(getSemantics());
+  APFloat NewUpper = maxnum(-Lower, Upper);
+  return ConstantFPRange(std::move(NewLower), std::move(NewUpper), MayBeQNaN,
+                         MayBeSNaN);
+}
+
+ConstantFPRange ConstantFPRange::negate() const {
+  return ConstantFPRange(-Upper, -Lower, MayBeQNaN, MayBeSNaN);
+}
diff --git a/llvm/unittests/IR/ConstantFPRangeTest.cpp b/llvm/unittests/IR/ConstantFPRangeTest.cpp
index 255f62d77b748..1384b68707577 100644
--- a/llvm/unittests/IR/ConstantFPRangeTest.cpp
+++ b/llvm/unittests/IR/ConstantFPRangeTest.cpp
@@ -767,4 +767,37 @@ TEST_F(ConstantFPRangeTest, makeExactFCmpRegion) {
   }
 }
 
+TEST_F(ConstantFPRangeTest, abs) {
+  EXPECT_EQ(Full.abs(),
+            ConstantFPRange(APFloat::getZero(Sem, /*Negative=*/false),
+                            APFloat::getInf(Sem, /*Negative=*/false),
+                            /*MayBeQNaN=*/true,
+                            /*MayBeSNaN=*/true));
+  EXPECT_EQ(Empty.abs(), Empty);
+  EXPECT_EQ(Zero.abs(), PosZero);
+  EXPECT_EQ(PosInf.abs(), PosInf);
+  EXPECT_EQ(NegInf.abs(), PosInf);
+  EXPECT_EQ(Some.abs(), SomePos);
+  EXPECT_EQ(SomeNeg.abs(), SomePos);
+  EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-2.0), APFloat(3.0)).abs(),
+            ConstantFPRange::getNonNaN(APFloat(0.0), APFloat(3.0)));
+  EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-3.0), APFloat(2.0)).abs(),
+            ConstantFPRange::getNonNaN(APFloat(0.0), APFloat(3.0)));
+}
+
+TEST_F(ConstantFPRangeTest, negate) {
+  EXPECT_EQ(Full.negate(), Full);
+  EXPECT_EQ(Empty.negate(), Empty);
+  EXPECT_EQ(Zero.negate(), Zero);
+  EXPECT_EQ(PosInf.negate(), NegInf);
+  EXPECT_EQ(NegInf.negate(), PosInf);
+  EXPECT_EQ(Some.negate(), Some);
+  EXPECT_EQ(SomePos.negate(), SomeNeg);
+  EXPECT_EQ(SomeNeg.negate(), SomePos);
+  EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-2.0), APFloat(3.0)).negate(),
+            ConstantFPRange::getNonNaN(APFloat(-3.0), APFloat(2.0)));
+  EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-3.0), APFloat(2.0)).negate(),
+            ConstantFPRange::getNonNaN(APFloat(-2.0), APFloat(3.0)));
+}
+
 } // anonymous namespace

>From 87869e491e7bbf37850f07f2169fc6cff8c04c7c Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Fri, 10 Oct 2025 00:38:05 +0800
Subject: [PATCH 2/2] [ConstantFPRange] Fix abs(nan)

---
 llvm/lib/IR/ConstantFPRange.cpp           | 2 +-
 llvm/unittests/IR/ConstantFPRangeTest.cpp | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/IR/ConstantFPRange.cpp b/llvm/lib/IR/ConstantFPRange.cpp
index 969af9798bf06..fba6942adfd89 100644
--- a/llvm/lib/IR/ConstantFPRange.cpp
+++ b/llvm/lib/IR/ConstantFPRange.cpp
@@ -393,7 +393,7 @@ ConstantFPRange ConstantFPRange::unionWith(const ConstantFPRange &CR) const {
 }
 
 ConstantFPRange ConstantFPRange::abs() const {
-  if (isEmptySet())
+  if (isNaNOnly())
     return *this;
   // Check if the range is all non-negative or all non-positive.
   if (Lower.isNegative() == Upper.isNegative()) {
diff --git a/llvm/unittests/IR/ConstantFPRangeTest.cpp b/llvm/unittests/IR/ConstantFPRangeTest.cpp
index 1384b68707577..1436f0f2e2559 100644
--- a/llvm/unittests/IR/ConstantFPRangeTest.cpp
+++ b/llvm/unittests/IR/ConstantFPRangeTest.cpp
@@ -779,6 +779,7 @@ TEST_F(ConstantFPRangeTest, abs) {
   EXPECT_EQ(NegInf.abs(), PosInf);
   EXPECT_EQ(Some.abs(), SomePos);
   EXPECT_EQ(SomeNeg.abs(), SomePos);
+  EXPECT_EQ(NaN.abs(), NaN);
   EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-2.0), APFloat(3.0)).abs(),
             ConstantFPRange::getNonNaN(APFloat(0.0), APFloat(3.0)));
   EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-3.0), APFloat(2.0)).abs(),
@@ -794,6 +795,7 @@ TEST_F(ConstantFPRangeTest, negate) {
   EXPECT_EQ(Some.negate(), Some);
   EXPECT_EQ(SomePos.negate(), SomeNeg);
   EXPECT_EQ(SomeNeg.negate(), SomePos);
+  EXPECT_EQ(NaN.negate(), NaN);
   EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-2.0), APFloat(3.0)).negate(),
             ConstantFPRange::getNonNaN(APFloat(-3.0), APFloat(2.0)));
   EXPECT_EQ(ConstantFPRange::getNonNaN(APFloat(-3.0), APFloat(2.0)).negate(),