[llvm] [Mips] Fix wrong ELF FP ABI info when inline asm was empty (PR #146457)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-mips

Author: None (yingopq)

<details>
<summary>Changes</summary>

When Mips process emitStartOfAsmFile and updateABIInfo, it did not know the real value of IsSoftFloat and STI.useSoftFloat(). And when inline asm instruction was empty, Mips did not process asm parser, so it would not do TS.updateABIInfo(STI) again and at this time the value of IsSoftFloat is correct.

Fix #<!-- -->135283.

---
Full diff: https://github.com/llvm/llvm-project/pull/146457.diff


2 Files Affected:

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


``````````diff
diff --git a/llvm/lib/Target/Mips/MipsAsmPrinter.cpp b/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
index 1a3e99ec7f68f..cb2ac3000b717 100644
--- a/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
+++ b/llvm/lib/Target/Mips/MipsAsmPrinter.cpp
@@ -745,14 +745,18 @@ 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
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/146457