CodeGen: Synthesize "float-abi" module flag from -float-abi

[arsenm]

Avoid annoying test updates when the corresponding TargetOptions
field is removed. Make the -float-abi llc/opt option a lit test
convenience that records the floating-point ABI in the IR,
mirroring how -mcpu/-mattr are recorded as function attributes.

Co-authored-by: Claude (Claude-Opus-4.8) noreply@anthropic.com

[arsenm]

• CodeGen: Remove TargetOptions::FloatABIType #215796
• CodeGen: Synthesize "float-abi" module flag from -float-abi #215795 👈 (View in Graphite)
• CodeGen: Replace Generic FP libcall tests with per-backend coverage #215782
• main

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[llvmorg-github-actions]

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Author: Matt Arsenault (arsenm)

Changes

Avoid annoying test updates when the corresponding TargetOptions
field is removed. Make the -float-abi llc/opt option a lit test
convenience that records the floating-point ABI in the IR,
mirroring how -mcpu/-mattr are recorded as function attributes.

Co-authored-by: Claude (Claude-Opus-4.8) <noreply@anthropic.com>

---

Full diff: https://github.com/llvm/llvm-project/pull/215795.diff

2 Files Affected:

• (modified) llvm/lib/CodeGen/CommandFlags.cpp (+11-1)
• (added) llvm/test/CodeGen/ARM/float-abi-synthesize-flag.ll (+32)

diff --git a/llvm/lib/CodeGen/CommandFlags.cpp b/llvm/lib/CodeGen/CommandFlags.cpp
index 306c0ff7c704b..88987d0bc5558 100644
--- a/llvm/lib/CodeGen/CommandFlags.cpp
+++ b/llvm/lib/CodeGen/CommandFlags.cpp
@@ -270,7 +270,9 @@ codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
   CGBINDOPT(EnableHonorSignDependentRoundingFPMath);
 
   static cl::opt<FloatABI::ABIType> FloatABIForCalls(
-      "float-abi", cl::desc("Choose float ABI type"),
+      "float-abi",
+      cl::desc(
+          "Choose float ABI type (writes the \"float-abi\" IR module flag)"),
       cl::init(FloatABI::Default),
       cl::values(clEnumValN(FloatABI::Default, "default",
                             "Target default float ABI type"),
@@ -774,6 +776,14 @@ void codegen::setFunctionAttributes(Function &F, StringRef CPU,
 
 void codegen::setFunctionAttributes(Module &M, StringRef CPU,
                                     StringRef Features, StringRef TuneCPU) {
+  // Synthesize the "float-abi" module flag from the -float-abi option,
+  FloatABI::ABIType ABI = getFloatABIForCalls();
+  if (ABI != FloatABI::Default && !M.getModuleFlag("float-abi")) {
+    M.addModuleFlag(
+        Module::Error, "float-abi",
+        MDString::get(M.getContext(), FloatABI::getABITypeName(ABI)));
+  }
+
   for (Function &F : M)
     setFunctionAttributes(F, CPU, Features, TuneCPU);
 }
diff --git a/llvm/test/CodeGen/ARM/float-abi-synthesize-flag.ll b/llvm/test/CodeGen/ARM/float-abi-synthesize-flag.ll
new file mode 100644
index 0000000000000..ce4d47d18010f
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/float-abi-synthesize-flag.ll
@@ -0,0 +1,32 @@
+; Check behavior of the -float-abi command-line option; it should
+; synthesize the "float-abi" module flag, unless one is already
+; present
+
+; RUN: split-file %s %t
+
+; -float-abi=hard writes the module flag.
+; RUN: llc -mtriple=armv7-none-eabi -float-abi=hard -stop-after=finalize-isel %t/none.ll -o - | FileCheck %s --check-prefix=HARD
+
+; -float-abi=soft writes the module flag.
+; RUN: llc -mtriple=armv7-none-eabi -float-abi=soft -stop-after=finalize-isel %t/none.ll -o - | FileCheck %s --check-prefix=SOFT
+
+; Without -float-abi, no flag is synthesized.
+; RUN: llc -mtriple=armv7-none-eabi -stop-after=finalize-isel %t/none.ll -o - | FileCheck %s --check-prefix=NONE
+
+; An explicit in-IR flag is not overridden by -float-abi.
+; RUN: llc -mtriple=armv7-none-eabi -float-abi=soft -stop-after=finalize-isel %t/hard.ll -o - | FileCheck %s --check-prefix=HARD
+
+;--- none.ll
+define void @f() {
+  ret void
+}
+; HARD: !{i32 1, !"float-abi", !"hard"}
+; SOFT: !{i32 1, !"float-abi", !"soft"}
+; NONE-NOT: !"float-abi"
+
+;--- hard.ll
+define void @f() {
+  ret void
+}
+!llvm.module.flags = !{!0}
+!0 = !{i32 1, !"float-abi", !"hard"}

[github-actions]

🐧 Linux x64 Test Results

• 202138 tests passed
• 5590 tests skipped

✅ The build succeeded and all tests passed.

[github-actions]

🪟 Windows x64 Test Results

• 139869 tests passed
• 3706 tests skipped

✅ The build succeeded and all tests passed.

[ilovepi]

LGTM.