Let clang atomic builtins fetch add/sub support floating point types

Recently atomicrmw started to support fadd/fsub:

https://reviews.llvm.org/D53965

However clang atomic builtins fetch add/sub still does not support
emitting atomicrmw fadd/fsub.

This patch adds that.

Reviewed by: John McCall, Artem Belevich, Matt Arsenault, JF Bastien,
James Y Knight, Louis Dionne, Olivier Giroux

Differential Revision: https://reviews.llvm.org/D71726

1 files changed, 26 insertions, 9 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 5b534f8..1d39de7 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -4931,7 +4931,8 @@ ExprResult Sema::BuildAtomicExpr(SourceRange CallRange, SourceRange ExprRange,
   case AtomicExpr::AO__atomic_add_fetch:
   case AtomicExpr::AO__atomic_sub_fetch:
     IsAddSub = true;
-    LLVM_FALLTHROUGH;
+    Form = Arithmetic;
+    break;
   case AtomicExpr::AO__c11_atomic_fetch_and:
   case AtomicExpr::AO__c11_atomic_fetch_or:
   case AtomicExpr::AO__c11_atomic_fetch_xor:
@@ -4946,6 +4947,8 @@ ExprResult Sema::BuildAtomicExpr(SourceRange CallRange, SourceRange ExprRange,
   case AtomicExpr::AO__atomic_or_fetch:
   case AtomicExpr::AO__atomic_xor_fetch:
   case AtomicExpr::AO__atomic_nand_fetch:
+    Form = Arithmetic;
+    break;
   case AtomicExpr::AO__c11_atomic_fetch_min:
   case AtomicExpr::AO__c11_atomic_fetch_max:
   case AtomicExpr::AO__opencl_atomic_fetch_min:
@@ -5038,10 +5041,24 @@ ExprResult Sema::BuildAtomicExpr(SourceRange CallRange, SourceRange ExprRange,
 
   // For an arithmetic operation, the implied arithmetic must be well-formed.
   if (Form == Arithmetic) {
-    // gcc does not enforce these rules for GNU atomics, but we do so for sanity.
-    if (IsAddSub && !ValType->isIntegerType()
-        && !ValType->isPointerType()) {
-      Diag(ExprRange.getBegin(), diag::err_atomic_op_needs_atomic_int_or_ptr)
+    // gcc does not enforce these rules for GNU atomics, but we do so for
+    // sanity.
+    auto IsAllowedValueType = [&](QualType ValType) {
+      if (ValType->isIntegerType())
+        return true;
+      if (ValType->isPointerType())
+        return true;
+      if (!ValType->isFloatingType())
+        return false;
+      // LLVM Parser does not allow atomicrmw with x86_fp80 type.
+      if (ValType->isSpecificBuiltinType(BuiltinType::LongDouble) &&
+          &Context.getTargetInfo().getLongDoubleFormat() ==
+              &llvm::APFloat::x87DoubleExtended())
+        return false;
+      return true;
+    };
+    if (IsAddSub && !IsAllowedValueType(ValType)) {
+      Diag(ExprRange.getBegin(), diag::err_atomic_op_needs_atomic_int_ptr_or_fp)
           << IsC11 << Ptr->getType() << Ptr->getSourceRange();
       return ExprError();
     }
@@ -5168,7 +5185,9 @@ ExprResult Sema::BuildAtomicExpr(SourceRange CallRange, SourceRange ExprRange,
         // passed by address. For the rest, GNU uses by-address and C11 uses
         // by-value.
         assert(Form != Load);
-        if (Form == Init || (Form == Arithmetic && ValType->isIntegerType()))
+        if (Form == Arithmetic && ValType->isPointerType())
+          Ty = Context.getPointerDiffType();
+        else if (Form == Init || Form == Arithmetic)
           Ty = ValType;
         else if (Form == Copy || Form == Xchg) {
           if (IsPassedByAddress) {
@@ -5177,9 +5196,7 @@ ExprResult Sema::BuildAtomicExpr(SourceRange CallRange, SourceRange ExprRange,
                                  ExprRange.getBegin());
           }
           Ty = ByValType;
-        } else if (Form == Arithmetic)
-          Ty = Context.getPointerDiffType();
-        else {
+        } else {
           Expr *ValArg = APIOrderedArgs[i];
           // The value pointer is always dereferenced, a nullptr is undefined.
           CheckNonNullArgument(*this, ValArg, ExprRange.getBegin());