release/21.x: [Mips] Fix wrong ELF FP ABI info when inline asm was empty (#146457)

[llvmbot]

Backport 778fb76

Requested by: @brad0

[llvmbot]

@llvm/pr-subscribers-backend-mips

Author: None (llvmbot)

Changes

Backport 778fb76

Requested by: @brad0

---

Full diff: https://github.com/llvm/llvm-project/pull/150866.diff

2 Files Affected:

• (modified) llvm/lib/Target/Mips/MipsAsmPrinter.cpp (+6-2)
• (added) llvm/test/CodeGen/Mips/abiflags-soft-float.ll (+12)

diff --git a/llvm/lib/Target/Mips/MipsAsmPrinter.cpp b/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
index 87e06a6d3c08a..2903ff75475cf 100644
--- a/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
+++ b/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
@@ -747,14 +747,18 @@ void MipsAsmPrinter::emitStartOfAsmFile(Module &M) {
     if (FS.empty() && M.size() && F->hasFnAttribute("target-features"))
       FS = F->getFnAttribute("target-features").getValueAsString();
 
+    std::string strFS = FS.str();
+    if (M.size() && F->getFnAttribute("use-soft-float").getValueAsBool())
+      strFS += strFS.empty() ? "+soft-float" : ",+soft-float";
+
     // Compute MIPS architecture attributes based on the default subtarget
     // that we'd have constructed.
     // FIXME: For ifunc related functions we could iterate over and look
     // for a feature string that doesn't match the default one.
     StringRef CPU = MIPS_MC::selectMipsCPU(TT, TM.getTargetCPU());
     const MipsTargetMachine &MTM = static_cast<const MipsTargetMachine &>(TM);
-    const MipsSubtarget STI(TT, CPU, FS, MTM.isLittleEndian(), MTM,
-                            std::nullopt);
+    const MipsSubtarget STI(TT, CPU, StringRef(strFS), MTM.isLittleEndian(),
+                            MTM, std::nullopt);
 
     bool IsABICalls = STI.isABICalls();
     const MipsABIInfo &ABI = MTM.getABI();
diff --git a/llvm/test/CodeGen/Mips/abiflags-soft-float.ll b/llvm/test/CodeGen/Mips/abiflags-soft-float.ll
new file mode 100644
index 0000000000000..01821f2d9b6c6
--- /dev/null
+++ b/llvm/test/CodeGen/Mips/abiflags-soft-float.ll
@@ -0,0 +1,12 @@
+; RUN: llc -filetype=obj -mtriple mipsel-unknown-linux -mcpu=mips32 %s -o tmp.o
+; RUN: llvm-readobj -A tmp.o | FileCheck %s -check-prefix=OBJ
+; RUN: llc -filetype=asm -mtriple mipsel-unknown-linux -mcpu=mips32 %s -o - | \
+; RUN: FileCheck %s -check-prefix=ASM
+
+; OBJ: FP ABI: Soft float
+; ASM: .module	softfloat 
+
+define dso_local void @asm_is_null() "use-soft-float"="true" {
+  call void asm sideeffect "", ""()
+  ret void
+}

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