[clang] [llvm] IR: Add Module::getLongDoubleFormat helper (PR #214943)
Matt Arsenault via llvm-commits
llvm-commits at lists.llvm.org
Sat Aug 8 03:30:14 PDT 2026
https://github.com/arsenm updated https://github.com/llvm/llvm-project/pull/214943
>From dd68bacb568ba88c033464363b5bf47894c25e0f Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Fri, 7 Aug 2026 08:54:04 +0200
Subject: [PATCH 1/3] IR: Add Module::getLongDoubleFormat helper
Add a helper function to return the effective long double type
for a module, accounting for the "long-double-type" module flag,
and defaulting to the triple's default.
Co-authored-by: Claude (Claude-Opus-4.8) <noreply at anthropic.com>
---
llvm/include/llvm/IR/Module.h | 12 ++++++++++++
llvm/lib/IR/Module.cpp | 16 ++++++++++++++++
llvm/unittests/IR/ModuleTest.cpp | 24 ++++++++++++++++++++++++
3 files changed, 52 insertions(+)
diff --git a/llvm/include/llvm/IR/Module.h b/llvm/include/llvm/IR/Module.h
index 16dad6ad446fb..53927e96a232e 100644
--- a/llvm/include/llvm/IR/Module.h
+++ b/llvm/include/llvm/IR/Module.h
@@ -1049,6 +1049,18 @@ class LLVM_ABI Module {
void setCodeModel(CodeModel::Model CL);
/// @}
+ /// @}
+ /// @name Utility functions for querying the long double format
+ /// @{
+
+ /// Returns the long double format from the "long-double-type" module flag,
+ /// or the triple default when the flag is absent.
+ LongDoubleFormat getLongDoubleFormat() const;
+
+ /// Set the long double format.
+ void setLongDoubleFormat(LongDoubleFormat Format);
+ /// @}
+
/// @}
/// @name Utility function for querying the floating-point ABI
/// @{
diff --git a/llvm/lib/IR/Module.cpp b/llvm/lib/IR/Module.cpp
index 3dcc9ec5dac3f..2ae76b80ccd57 100644
--- a/llvm/lib/IR/Module.cpp
+++ b/llvm/lib/IR/Module.cpp
@@ -682,6 +682,22 @@ void Module::setCodeModel(CodeModel::Model CL) {
addModuleFlag(ModFlagBehavior::Error, "Code Model", CL);
}
+LongDoubleFormat Module::getLongDoubleFormat() const {
+ if (auto *Val =
+ dyn_cast_or_null<MDString>(getModuleFlag("long-double-type"))) {
+ if (std::optional<LongDoubleFormat> Format =
+ parseLongDoubleFormat(Val->getString()))
+ return *Format;
+ }
+
+ return getTargetTriple().getDefaultLongDoubleFormat();
+}
+
+void Module::setLongDoubleFormat(LongDoubleFormat Format) {
+ addModuleFlag(ModFlagBehavior::Error, "long-double-type",
+ MDString::get(getContext(), getLongDoubleFormatName(Format)));
+}
+
FloatABI::ABIType Module::getFloatABI() const {
if (auto *Val = dyn_cast_or_null<MDString>(getModuleFlag("float-abi")))
return FloatABI::parseABIType(Val->getString()).value_or(FloatABI::Default);
diff --git a/llvm/unittests/IR/ModuleTest.cpp b/llvm/unittests/IR/ModuleTest.cpp
index e8c2ecfb9f3a8..064157a8e2105 100644
--- a/llvm/unittests/IR/ModuleTest.cpp
+++ b/llvm/unittests/IR/ModuleTest.cpp
@@ -103,6 +103,30 @@ TEST(ModuleTest, setModuleFlagInt) {
EXPECT_EQ(Val2, A2->getZExtValue());
}
+TEST(ModuleTest, getLongDoubleFormat) {
+ LLVMContext Context;
+
+ // With no module flag, falls back to the triple's default long double format.
+ Module MX86("x86", Context);
+ MX86.setTargetTriple(Triple("x86_64-unknown-linux-gnu"));
+ EXPECT_EQ(LongDoubleFormat::X87DoubleExtended, MX86.getLongDoubleFormat());
+
+ Module MPPC("ppc", Context);
+ MPPC.setTargetTriple(Triple("powerpc64-unknown-linux-gnu"));
+ EXPECT_EQ(LongDoubleFormat::PPCDoubleDouble, MPPC.getLongDoubleFormat());
+
+ // An explicit module flag overrides the triple default.
+ MX86.setLongDoubleFormat(LongDoubleFormat::IEEEquad);
+ EXPECT_EQ(LongDoubleFormat::IEEEquad, MX86.getLongDoubleFormat());
+
+ // The flag is the string-valued "long-double-type" flag emitted by clang.
+ Module MFlag("flag", Context);
+ MFlag.setTargetTriple(Triple("x86_64-unknown-linux-gnu"));
+ MFlag.addModuleFlag(Module::Error, "long-double-type",
+ MDString::get(Context, "fp128"));
+ EXPECT_EQ(LongDoubleFormat::IEEEquad, MFlag.getLongDoubleFormat());
+}
+
TEST(ModuleTest, setModuleFlagTwoMod) {
LLVMContext Context;
Module MA("MA", Context);
>From ecfb6902ebb878a716d61457d62a992414cf0734 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Sat, 8 Aug 2026 11:34:04 +0200
Subject: [PATCH 2/3] Use helper in clang
---
clang/lib/CodeGen/CodeGenModule.cpp | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 5ed5385c90f26..e17bd72c2f052 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1411,12 +1411,8 @@ void CodeGenModule::Release() {
else if (flt == &llvm::APFloat::IEEEsingle())
Format = llvm::LongDoubleFormat::IEEEsingle;
- if (Format) {
- getModule().addModuleFlag(
- llvm::Module::Error, "long-double-type",
- llvm::MDString::get(VMContext,
- llvm::getLongDoubleFormatName(*Format)));
- }
+ if (Format)
+ getModule().setLongDoubleFormat(*Format);
}
if (getTriple().isOSzOS()) {
>From 9ee9cedaab01cf47756c690e52cbea66182a0169 Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault at amd.com>
Date: Sat, 8 Aug 2026 11:34:25 +0200
Subject: [PATCH 3/3] drop unit test
---
llvm/unittests/IR/ModuleTest.cpp | 24 ------------------------
1 file changed, 24 deletions(-)
diff --git a/llvm/unittests/IR/ModuleTest.cpp b/llvm/unittests/IR/ModuleTest.cpp
index 064157a8e2105..e8c2ecfb9f3a8 100644
--- a/llvm/unittests/IR/ModuleTest.cpp
+++ b/llvm/unittests/IR/ModuleTest.cpp
@@ -103,30 +103,6 @@ TEST(ModuleTest, setModuleFlagInt) {
EXPECT_EQ(Val2, A2->getZExtValue());
}
-TEST(ModuleTest, getLongDoubleFormat) {
- LLVMContext Context;
-
- // With no module flag, falls back to the triple's default long double format.
- Module MX86("x86", Context);
- MX86.setTargetTriple(Triple("x86_64-unknown-linux-gnu"));
- EXPECT_EQ(LongDoubleFormat::X87DoubleExtended, MX86.getLongDoubleFormat());
-
- Module MPPC("ppc", Context);
- MPPC.setTargetTriple(Triple("powerpc64-unknown-linux-gnu"));
- EXPECT_EQ(LongDoubleFormat::PPCDoubleDouble, MPPC.getLongDoubleFormat());
-
- // An explicit module flag overrides the triple default.
- MX86.setLongDoubleFormat(LongDoubleFormat::IEEEquad);
- EXPECT_EQ(LongDoubleFormat::IEEEquad, MX86.getLongDoubleFormat());
-
- // The flag is the string-valued "long-double-type" flag emitted by clang.
- Module MFlag("flag", Context);
- MFlag.setTargetTriple(Triple("x86_64-unknown-linux-gnu"));
- MFlag.addModuleFlag(Module::Error, "long-double-type",
- MDString::get(Context, "fp128"));
- EXPECT_EQ(LongDoubleFormat::IEEEquad, MFlag.getLongDoubleFormat());
-}
-
TEST(ModuleTest, setModuleFlagTwoMod) {
LLVMContext Context;
Module MA("MA", Context);
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