[llvm] [APFloat][NFC] Add unit test coverage for `getArbitraryFPSemantics` (PR #216501)

[via llvm-commits]

llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-adt

Author: Chinmay Deshpande (chinmaydd)

<details>
<summary>Changes</summary>

`isValidArbitraryFPFormat` and `getArbitraryFPFormatSizeInBits` have unit tests, but `getArbitraryFPSemantics`, the mapping the conversion intrinsics actually lower through, had none. Cover the formats it supports, the valid formats it does not support yet, and invalid format strings, and check that the two tables agree on the size of every format with lowerable semantics.

Also add the missing Float8E5M3FNU case to the `getArbitraryFPFormatSizeInBits` test.

AI disclosure: This PR was generated with the assistance of AI, and I have reviewed it.

---
Full diff: https://github.com/llvm/llvm-project/pull/216501.diff


1 Files Affected:

- (modified) llvm/unittests/ADT/APFloatTest.cpp (+45) 


``````````diff
diff --git a/llvm/unittests/ADT/APFloatTest.cpp b/llvm/unittests/ADT/APFloatTest.cpp
index 4ef2814e1a7b3..0c5103c4b49e4 100644
--- a/llvm/unittests/ADT/APFloatTest.cpp
+++ b/llvm/unittests/ADT/APFloatTest.cpp
@@ -10765,6 +10765,7 @@ TEST(APFloatTest, getArbitraryFPFormatSizeInBits) {
   EXPECT_EQ(8u, APFloat::getArbitraryFPFormatSizeInBits("Float8E4M3B11FNUZ"));
   EXPECT_EQ(8u, APFloat::getArbitraryFPFormatSizeInBits("Float8E3M4"));
   EXPECT_EQ(8u, APFloat::getArbitraryFPFormatSizeInBits("Float8E8M0FNU"));
+  EXPECT_EQ(8u, APFloat::getArbitraryFPFormatSizeInBits("Float8E5M3FNU"));
   EXPECT_EQ(6u, APFloat::getArbitraryFPFormatSizeInBits("Float6E3M2FN"));
   EXPECT_EQ(6u, APFloat::getArbitraryFPFormatSizeInBits("Float6E2M3FN"));
   EXPECT_EQ(4u, APFloat::getArbitraryFPFormatSizeInBits("Float4E2M1FN"));
@@ -10776,6 +10777,50 @@ TEST(APFloatTest, getArbitraryFPFormatSizeInBits) {
   EXPECT_EQ(0u, APFloat::getArbitraryFPFormatSizeInBits("unknown"));
 }
 
+TEST(APFloatTest, getArbitraryFPSemantics) {
+  // Formats that can currently be lowered map to their semantics.
+  EXPECT_EQ(&APFloat::Float8E5M2(),
+            APFloat::getArbitraryFPSemantics("Float8E5M2"));
+  EXPECT_EQ(&APFloat::Float8E4M3FN(),
+            APFloat::getArbitraryFPSemantics("Float8E4M3FN"));
+  EXPECT_EQ(&APFloat::Float6E3M2FN(),
+            APFloat::getArbitraryFPSemantics("Float6E3M2FN"));
+  EXPECT_EQ(&APFloat::Float6E2M3FN(),
+            APFloat::getArbitraryFPSemantics("Float6E2M3FN"));
+  EXPECT_EQ(&APFloat::Float4E2M1FN(),
+            APFloat::getArbitraryFPSemantics("Float4E2M1FN"));
+
+  // Formats that are valid but cannot be lowered yet report no semantics.
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics("Float8E5M2FNUZ"));
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics("Float8E4M3"));
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics("Float8E4M3FNUZ"));
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics("Float8E4M3B11FNUZ"));
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics("Float8E3M4"));
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics("Float8E8M0FNU"));
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics("Float8E5M3FNU"));
+
+  // Invalid formats report no semantics.
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics(""));
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics("Float8"));
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics("float8e5m2"));
+  EXPECT_EQ(nullptr, APFloat::getArbitraryFPSemantics("unknown"));
+}
+
+// The two arbitrary FP format tables must agree: every format with lowerable
+// semantics reports the size of those semantics.
+TEST(APFloatTest, ArbitraryFPSemanticsMatchSizeInBits) {
+  for (StringRef Format :
+       {"Float8E5M2", "Float8E5M2FNUZ", "Float8E4M3", "Float8E4M3FN",
+        "Float8E4M3FNUZ", "Float8E4M3B11FNUZ", "Float8E3M4", "Float8E8M0FNU",
+        "Float8E5M3FNU", "Float6E3M2FN", "Float6E2M3FN", "Float4E2M1FN"}) {
+    ASSERT_TRUE(APFloat::isValidArbitraryFPFormat(Format)) << Format;
+    if (const fltSemantics *Sem = APFloat::getArbitraryFPSemantics(Format))
+      EXPECT_EQ(APFloat::getSizeInBits(*Sem),
+                APFloat::getArbitraryFPFormatSizeInBits(Format))
+          << Format;
+  }
+}
+
 TEST(APFloatTest, DecimalStringPreservesInexactStatus) {
   APFloat F(APFloat::IEEEsingle());
 

``````````

</details>


https://github.com/llvm/llvm-project/pull/216501