[Support] Deprecate one form of support::endian::read (NFC)

[kazutakahirata]

This is a follow-up to #156140, which deprecated one form of write.

We have two forms of read:

template <typename value_type, std::size_t alignment>
[[nodiscard]] inline value_type read(const void *memory, endianness endian)

template <typename value_type, endianness endian, std::size_t alignment>
[[nodiscard]] inline value_type read(const void *memory)

The difference is that endian is a function parameter in the former
but a template parameter in the latter.

This patch streamlines the code by migrating the use of the latter to
the former while deprecating the latter.

[llvmbot]

@llvm/pr-subscribers-llvm-support

@llvm/pr-subscribers-pgo

Author: Kazu Hirata (kazutakahirata)

Changes

This is a follow-up to #156140, which deprecated one form of write.

We have two forms of read:

template <typename value_type, std::size_t alignment>
[[nodiscard]] inline value_type read(const void *memory, endianness endian)

template <typename value_type, endianness endian, std::size_t alignment>
[[nodiscard]] inline value_type read(const void *memory)

The difference is that endian is a function parameter in the former
but a template parameter in the latter.

This patch streamlines the code by migrating the use of the latter to
the former while deprecating the latter.

---

Full diff: https://github.com/llvm/llvm-project/pull/160979.diff

5 Files Affected:

• (modified) llvm/include/llvm/Support/Endian.h (+7-5)
• (modified) llvm/lib/CGData/CodeGenDataReader.cpp (+2-2)
• (modified) llvm/lib/ProfileData/InstrProfReader.cpp (+4-4)
• (modified) llvm/lib/ProfileData/SampleProfReader.cpp (+2-2)
• (modified) llvm/unittests/Support/EndianTest.cpp (+6-7)

diff --git a/llvm/include/llvm/Support/Endian.h b/llvm/include/llvm/Support/Endian.h
index 7eb1d7e8dfe7f..6c86feb78053c 100644
--- a/llvm/include/llvm/Support/Endian.h
+++ b/llvm/include/llvm/Support/Endian.h
@@ -66,7 +66,9 @@ template <typename value_type, std::size_t alignment = unaligned>
 }
 
 template <typename value_type, endianness endian, std::size_t alignment>
-[[nodiscard]] inline value_type read(const void *memory) {
+[[nodiscard]] LLVM_DEPRECATED("Pass endian as a function argument instead",
+                              "read") inline value_type
+    read(const void *memory) {
   return read<value_type, alignment>(memory, endian);
 }
 
@@ -127,7 +129,7 @@ template <typename value_type, endianness endian, std::size_t alignment>
                                                    uint64_t startBit) {
   assert(startBit < 8);
   if (startBit == 0)
-    return read<value_type, endian, alignment>(memory);
+    return read<value_type, alignment>(memory, endian);
   else {
     // Read two values and compose the result from them.
     value_type val[2];
@@ -223,8 +225,8 @@ struct packed_endian_specific_integral {
   explicit packed_endian_specific_integral(value_type val) { *this = val; }
 
   value_type value() const {
-    return endian::read<value_type, endian, alignment>(
-      (const void*)Value.buffer);
+    return endian::read<value_type, alignment>((const void *)Value.buffer,
+                                               endian);
   }
   operator value_type() const { return value(); }
 
@@ -263,7 +265,7 @@ struct packed_endian_specific_integral {
     explicit ref(void *Ptr) : Ptr(Ptr) {}
 
     operator value_type() const {
-      return endian::read<value_type, endian, alignment>(Ptr);
+      return endian::read<value_type, alignment>(Ptr, endian);
     }
 
     void operator=(value_type NewValue) {
diff --git a/llvm/lib/CGData/CodeGenDataReader.cpp b/llvm/lib/CGData/CodeGenDataReader.cpp
index fc59be8df525a..3fd8cfe1a8762 100644
--- a/llvm/lib/CGData/CodeGenDataReader.cpp
+++ b/llvm/lib/CGData/CodeGenDataReader.cpp
@@ -169,8 +169,8 @@ bool IndexedCodeGenDataReader::hasFormat(const MemoryBuffer &DataBuffer) {
   if (DataBuffer.getBufferSize() < sizeof(IndexedCGData::Magic))
     return false;
 
-  uint64_t Magic = endian::read<uint64_t, llvm::endianness::little, aligned>(
-      DataBuffer.getBufferStart());
+  uint64_t Magic = endian::read<uint64_t, aligned>(DataBuffer.getBufferStart(),
+                                                   llvm::endianness::little);
   // Verify that it's magical.
   return Magic == IndexedCGData::Magic;
 }
diff --git a/llvm/lib/ProfileData/InstrProfReader.cpp b/llvm/lib/ProfileData/InstrProfReader.cpp
index 886add7131da2..1da92eafa4b4a 100644
--- a/llvm/lib/ProfileData/InstrProfReader.cpp
+++ b/llvm/lib/ProfileData/InstrProfReader.cpp
@@ -1171,8 +1171,8 @@ bool IndexedInstrProfReader::hasFormat(const MemoryBuffer &DataBuffer) {
 
   if (DataBuffer.getBufferSize() < 8)
     return false;
-  uint64_t Magic = endian::read<uint64_t, llvm::endianness::little, aligned>(
-      DataBuffer.getBufferStart());
+  uint64_t Magic = endian::read<uint64_t, aligned>(DataBuffer.getBufferStart(),
+                                                   llvm::endianness::little);
   // Verify that it's magical.
   return Magic == IndexedInstrProf::Magic;
 }
@@ -1598,8 +1598,8 @@ Error IndexedInstrProfReader::getFunctionBitmap(StringRef FuncName,
         std::memset(W, 0, sizeof(W));
         std::memcpy(W, &BitmapBytes[I], N);
         I += N;
-        return support::endian::read<XTy, llvm::endianness::little,
-                                     support::aligned>(W);
+        return support::endian::read<XTy, support::aligned>(
+            W, llvm::endianness::little);
       },
       Bitmap, Bitmap);
   assert(I == E);
diff --git a/llvm/lib/ProfileData/SampleProfReader.cpp b/llvm/lib/ProfileData/SampleProfReader.cpp
index 81ae792e70b99..766c0814ca067 100644
--- a/llvm/lib/ProfileData/SampleProfReader.cpp
+++ b/llvm/lib/ProfileData/SampleProfReader.cpp
@@ -1290,8 +1290,8 @@ SampleProfileReaderExtBinaryBase::readNameTableSec(bool IsMD5,
     NameTable.reserve(*Size);
     for (size_t I = 0; I < *Size; ++I) {
       using namespace support;
-      uint64_t FID = endian::read<uint64_t, endianness::little, unaligned>(
-          Data + I * sizeof(uint64_t));
+      uint64_t FID = endian::read<uint64_t, unaligned>(
+          Data + I * sizeof(uint64_t), endianness::little);
       NameTable.emplace_back(FunctionId(FID));
     }
     if (!ProfileIsCS)
diff --git a/llvm/unittests/Support/EndianTest.cpp b/llvm/unittests/Support/EndianTest.cpp
index c48b7707b7751..0ee631db74ac1 100644
--- a/llvm/unittests/Support/EndianTest.cpp
+++ b/llvm/unittests/Support/EndianTest.cpp
@@ -24,16 +24,15 @@ TEST(Endian, Read) {
   unsigned char littleval[] = {0x00, 0x04, 0x03, 0x02, 0x01};
   int32_t BigAsHost = 0x00010203;
   EXPECT_EQ(BigAsHost,
-            (endian::read<int32_t, llvm::endianness::big, unaligned>(bigval)));
+            (endian::read<int32_t, unaligned>(bigval, llvm::endianness::big)));
   int32_t LittleAsHost = 0x02030400;
-  EXPECT_EQ(
-      LittleAsHost,
-      (endian::read<int32_t, llvm::endianness::little, unaligned>(littleval)));
+  EXPECT_EQ(LittleAsHost, (endian::read<int32_t, unaligned>(
+                              littleval, llvm::endianness::little)));
 
   EXPECT_EQ(
-      (endian::read<int32_t, llvm::endianness::big, unaligned>(bigval + 1)),
-      (endian::read<int32_t, llvm::endianness::little, unaligned>(littleval +
-                                                                  1)));
+      (endian::read<int32_t, unaligned>(bigval + 1, llvm::endianness::big)),
+      (endian::read<int32_t, unaligned>(littleval + 1,
+                                        llvm::endianness::little)));
 }
 
 TEST(Endian, WriteNext) {