[ARM][Clang] Removing lowering of half-precision FP arguments and returns from Clang's CodeGen

Summary:
On the process of moving the argument lowering handling for
half-precision floating point arguments and returns to the backend, this
patch removes the code that was responsible for handling the coercion of
those arguments in Clang's Codegen.

Reviewers: rjmccall, chill, ostannard, dnsampaio

Reviewed By: ostannard

Subscribers: stuij, kristof.beyls, dmgreen, danielkiss, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D81451

3 files changed, 8 insertions, 59 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 78a0ece..8724244 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -3124,20 +3124,6 @@ llvm::Value *CodeGenFunction::EmitCMSEClearRecord(llvm::Value *Src,
   return R;
 }
 
-// Emit code to clear the padding bits when returning or passing as an argument
-// a 16-bit floating-point value.
-llvm::Value *CodeGenFunction::EmitCMSEClearFP16(llvm::Value *Src) {
-  llvm::Type *RetTy = Src->getType();
-  assert(RetTy->isFloatTy() ||
-         (RetTy->isIntegerTy() && RetTy->getIntegerBitWidth() == 32));
-  if (RetTy->isFloatTy()) {
-    llvm::Value *T0 = Builder.CreateBitCast(Src, Builder.getIntNTy(32));
-    llvm::Value *T1 = Builder.CreateAnd(T0, 0xffff, "cmse.clear");
-    return Builder.CreateBitCast(T1, RetTy);
-  }
-  return Builder.CreateAnd(Src, 0xffff, "cmse.clear");
-}
-
 void CodeGenFunction::EmitFunctionEpilog(const CGFunctionInfo &FI,
                                          bool EmitRetDbgLoc,
                                          SourceLocation EndLoc) {
@@ -3307,17 +3293,10 @@ void CodeGenFunction::EmitFunctionEpilog(const CGFunctionInfo &FI,
     if (CurFuncDecl && CurFuncDecl->hasAttr<CmseNSEntryAttr>()) {
       // For certain return types, clear padding bits, as they may reveal
       // sensitive information.
-      const Type *RTy = RetTy.getCanonicalType().getTypePtr();
-      if (RTy->isFloat16Type() || RTy->isHalfType()) {
-        // 16-bit floating-point types are passed in a 32-bit integer or float,
-        // with unspecified upper bits.
-        RV = EmitCMSEClearFP16(RV);
-      } else {
-        // Small struct/union types are passed as integers.
-        auto *ITy = dyn_cast<llvm::IntegerType>(RV->getType());
-        if (ITy != nullptr && isa<RecordType>(RetTy.getCanonicalType()))
-          RV = EmitCMSEClearRecord(RV, ITy, RetTy);
-      }
+      // Small struct/union types are passed as integers.
+      auto *ITy = dyn_cast<llvm::IntegerType>(RV->getType());
+      if (ITy != nullptr && isa<RecordType>(RetTy.getCanonicalType()))
+        RV = EmitCMSEClearRecord(RV, ITy, RetTy);
     }
     EmitReturnValueCheck(RV);
     Ret = Builder.CreateRet(RV);
@@ -4620,17 +4599,10 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
         if (CallInfo.isCmseNSCall()) {
           // For certain parameter types, clear padding bits, as they may reveal
           // sensitive information.
-          const Type *PTy = I->Ty.getCanonicalType().getTypePtr();
-          // 16-bit floating-point types are passed in a 32-bit integer or
-          // float, with unspecified upper bits.
-          if (PTy->isFloat16Type() || PTy->isHalfType()) {
-            Load = EmitCMSEClearFP16(Load);
-          } else {
-            // Small struct/union types are passed as integer arrays.
-            auto *ATy = dyn_cast<llvm::ArrayType>(Load->getType());
-            if (ATy != nullptr && isa<RecordType>(I->Ty.getCanonicalType()))
-              Load = EmitCMSEClearRecord(Load, ATy, I->Ty);
-          }
+          // Small struct/union types are passed as integer arrays.
+          auto *ATy = dyn_cast<llvm::ArrayType>(Load->getType());
+          if (ATy != nullptr && isa<RecordType>(I->Ty.getCanonicalType()))
+            Load = EmitCMSEClearRecord(Load, ATy, I->Ty);
         }
         IRCallArgs[FirstIRArg] = Load;
       }
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 935e855..4296253 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -3923,7 +3923,6 @@ public:
                                    QualType RTy);
   llvm::Value *EmitCMSEClearRecord(llvm::Value *V, llvm::ArrayType *ATy,
                                    QualType RTy);
-  llvm::Value *EmitCMSEClearFP16(llvm::Value *V);
 
   llvm::Value *EmitCommonNeonBuiltinExpr(unsigned BuiltinID,
                                          unsigned LLVMIntrinsic,
diff --git a/clang/lib/CodeGen/TargetInfo.cpp b/clang/lib/CodeGen/TargetInfo.cpp
index 564eb09..44be42aa 100644
--- a/clang/lib/CodeGen/TargetInfo.cpp
+++ b/clang/lib/CodeGen/TargetInfo.cpp
@@ -6265,17 +6265,6 @@ ABIArgInfo ARMABIInfo::classifyArgumentType(QualType Ty, bool isVariadic,
   if (isIllegalVectorType(Ty))
     return coerceIllegalVector(Ty);
 
-  // _Float16 and __fp16 get passed as if it were an int or float, but
-  // with the top 16 bits unspecified. This is not done for OpenCL as it handles
-  // the half type natively, and does not need to interwork with AAPCS code.
-  if ((Ty->isFloat16Type() || Ty->isHalfType()) &&
-      !getContext().getLangOpts().NativeHalfArgsAndReturns) {
-    llvm::Type *ResType = IsAAPCS_VFP ?
-      llvm::Type::getFloatTy(getVMContext()) :
-      llvm::Type::getInt32Ty(getVMContext());
-    return ABIArgInfo::getDirect(ResType);
-  }
-
   // __bf16 gets passed using the bfloat IR type, or using i32 but
   // with the top 16 bits unspecified.
   if (Ty->isBFloat16Type() && IsFloatABISoftFP) {
@@ -6486,17 +6475,6 @@ ABIArgInfo ARMABIInfo::classifyReturnType(QualType RetTy, bool isVariadic,
       return coerceIllegalVector(RetTy);
   }
 
-  // _Float16 and __fp16 get returned as if it were an int or float, but with
-  // the top 16 bits unspecified. This is not done for OpenCL as it handles the
-  // half type natively, and does not need to interwork with AAPCS code.
-  if ((RetTy->isFloat16Type() || RetTy->isHalfType()) &&
-      !getContext().getLangOpts().NativeHalfArgsAndReturns) {
-    llvm::Type *ResType = IsAAPCS_VFP ?
-      llvm::Type::getFloatTy(getVMContext()) :
-      llvm::Type::getInt32Ty(getVMContext());
-    return ABIArgInfo::getDirect(ResType);
-  }
-
   // if we're using the softfp float abi, __bf16 get returned as if it were an
   // int but with the top 16 bits unspecified.
   if (RetTy->isBFloat16Type()) {