[clang] [clang] Increase VecLib bitfield size to 4 bits in CodeGenOptions.def (PR #108804)

[Mainak Sil via cfe-commits]

https://github.com/MainakSil updated https://github.com/llvm/llvm-project/pull/108804

>From 43e6c22f25f419b64678374dd247eaf8bc28fa57 Mon Sep 17 00:00:00 2001
From: Mainak Sil <mainaksil0 at gmail.com>
Date: Mon, 16 Sep 2024 09:50:33 +0530
Subject: [PATCH 1/5] [clang] Increase VecLib bitfield size to 4 bits in
 CodeGenOptions.def

---
 clang/include/clang/Basic/CodeGenOptions.def | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
index b600198998d85b..f2a96324936775 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -376,7 +376,7 @@ ENUM_CODEGENOPT(Inlining, InliningMethod, 2, NormalInlining)
 VALUE_CODEGENOPT(InlineMaxStackSize, 32, UINT_MAX)
 
 // Vector functions library to use.
-ENUM_CODEGENOPT(VecLib, llvm::driver::VectorLibrary, 3, llvm::driver::VectorLibrary::NoLibrary)
+ENUM_CODEGENOPT(VecLib, llvm::driver::VectorLibrary, 4, llvm::driver::VectorLibrary::NoLibrary)
 
 /// The default TLS model to use.
 ENUM_CODEGENOPT(DefaultTLSModel, TLSModel, 2, GeneralDynamicTLSModel)

>From b30adc9c059d1af9b5874b5c0e258670d3190852 Mon Sep 17 00:00:00 2001
From: Mainak Sil <mainaksil0 at gmail.com>
Date: Mon, 16 Sep 2024 14:18:03 +0530
Subject: [PATCH 2/5] Update CodeGenOptions.def

---
 clang/include/clang/Basic/CodeGenOptions.def | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
index f2a96324936775..2d5bb84d1cc59c 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -375,6 +375,11 @@ ENUM_CODEGENOPT(Inlining, InliningMethod, 2, NormalInlining)
 /// The maximum stack size a function can have to be considered for inlining.
 VALUE_CODEGENOPT(InlineMaxStackSize, 32, UINT_MAX)
 
+// Ensure the VecLib bitfield has enough space for future vector libraries.
+// If new vector libraries are added beyond the current limit of 16, this static assertion will fail.
+static_assert(static_cast<int>(llvm::driver::VectorLibrary::NoLibrary) <= 16, 
+              "The VecLib bitfield in CodeGenOptions needs to be expanded to support more vector libraries.");
+
 // Vector functions library to use.
 ENUM_CODEGENOPT(VecLib, llvm::driver::VectorLibrary, 4, llvm::driver::VectorLibrary::NoLibrary)
 

>From d96f69105c5be85acf3614258911fbdf74dbc60f Mon Sep 17 00:00:00 2001
From: Mainak Sil <mainaksil0 at gmail.com>
Date: Mon, 16 Sep 2024 14:32:26 +0530
Subject: [PATCH 3/5] Update CodeGenOptions.def


>From 558038b29eedb81e9ce328f323914329af0d8f0f Mon Sep 17 00:00:00 2001
From: Mainak Sil <mainaksil0 at gmail.com>
Date: Wed, 18 Sep 2024 08:57:16 +0530
Subject: [PATCH 4/5] Update CodeGenOptions.def

---
 clang/include/clang/Basic/CodeGenOptions.def | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
index 2d5bb84d1cc59c..b78ae61e6509ea 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -375,13 +375,18 @@ ENUM_CODEGENOPT(Inlining, InliningMethod, 2, NormalInlining)
 /// The maximum stack size a function can have to be considered for inlining.
 VALUE_CODEGENOPT(InlineMaxStackSize, 32, UINT_MAX)
 
-// Ensure the VecLib bitfield has enough space for future vector libraries.
-// If new vector libraries are added beyond the current limit of 16, this static assertion will fail.
-static_assert(static_cast<int>(llvm::driver::VectorLibrary::NoLibrary) <= 16, 
-              "The VecLib bitfield in CodeGenOptions needs to be expanded to support more vector libraries.");
+// Define the number of bits required for the VecLib enum
+#define VECLIB_BIT_COUNT (llvm::countPopulation(llvm::driver::VectorLibrary::MaxLibrary))
 
-// Vector functions library to use.
-ENUM_CODEGENOPT(VecLib, llvm::driver::VectorLibrary, 4, llvm::driver::VectorLibrary::NoLibrary)
+// Ensure the VecLib bitfield has enough space for future vector libraries.
+// The number of bits is determined automatically based on the number of enum values.
+static_assert(static_cast<size_t>(llvm::driver::VectorLibrary::MaxLibrary) <= (1 << VECLIB_BIT_COUNT),
+              "VecLib bitfield size is too small to accommodate all vector libraries.");
+              
+// VecLib definition in CodeGenOptions.def
+ENUM_CODEGENOPT(VecLib, llvm::driver::VectorLibrary, VECLIB_BIT_COUNT, llvm::driver::VectorLibrary::NoLibrary)
+
+#undef VECLIB_BIT_COUNT
 
 /// The default TLS model to use.
 ENUM_CODEGENOPT(DefaultTLSModel, TLSModel, 2, GeneralDynamicTLSModel)

>From d2f9b3f437c1ac406e3ef2e72f412d0194909ee0 Mon Sep 17 00:00:00 2001
From: Mainak Sil <mainaksil0 at gmail.com>
Date: Wed, 18 Sep 2024 09:01:08 +0530
Subject: [PATCH 5/5] Create AllLibrariesFit.cpp

---
 clang/unittests/CodeGen/AllLibrariesFit.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)
 create mode 100644 clang/unittests/CodeGen/AllLibrariesFit.cpp

diff --git a/clang/unittests/CodeGen/AllLibrariesFit.cpp b/clang/unittests/CodeGen/AllLibrariesFit.cpp
new file mode 100644
index 00000000000000..9c2c34ceee6992
--- /dev/null
+++ b/clang/unittests/CodeGen/AllLibrariesFit.cpp
@@ -0,0 +1,9 @@
+#include "clang/Basic/CodeGenOptions.h"
+#include "llvm/Driver/Options.h"
+#include "gtest/gtest.h"
+
+TEST(VecLibBitfieldTest, AllLibrariesFit) {
+    // We expect that all vector libraries fit in the bitfield size
+    EXPECT_LE(static_cast<size_t>(llvm::driver::VectorLibrary::MaxLibrary), 
+              (1 << VECLIB_BIT_COUNT)) << "VecLib bitfield size is too small!";
+}