[clang] 52818fd - [Clang][FP16] Add 4 builtins for _Float16

[Phoebe Wang via cfe-commits]

Author: Phoebe Wang
Date: 2022-06-06T09:00:26+08:00
New Revision: 52818fd97f0f2b13d12e66de9f06b9f4cbc0be07

URL: https://github.com/llvm/llvm-project/commit/52818fd97f0f2b13d12e66de9f06b9f4cbc0be07
DIFF: https://github.com/llvm/llvm-project/commit/52818fd97f0f2b13d12e66de9f06b9f4cbc0be07.diff

LOG: [Clang][FP16] Add 4 builtins for _Float16

We are lacking builtins support for `_Float16`. In most cases, we can use other floating-type builtins and truncate them to `_Float16`.
But it's a problem to SNaN, e.g., https://gcc.godbolt.org/z/cqr5nG1jh
This patch adds `__builtin_nansf16` support as well as other 3 ones since they are usually used together.

Reviewed By: LuoYuanke

Differential Revision: https://reviews.llvm.org/D127050

Added: 
    clang/test/CodeGen/builtin_Float16.c

Modified: 
    clang/include/clang/Basic/Builtins.def
    clang/lib/AST/ExprConstant.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Basic/Builtins.def b/clang/include/clang/Basic/Builtins.def
index 6fb6d955557d2..f47e8de806e21 100644
--- a/clang/include/clang/Basic/Builtins.def
+++ b/clang/include/clang/Basic/Builtins.def
@@ -142,10 +142,12 @@ BUILTIN(__builtin_frexpf128, "LLdLLdi*", "Fn")
 BUILTIN(__builtin_huge_val, "d", "nc")
 BUILTIN(__builtin_huge_valf, "f", "nc")
 BUILTIN(__builtin_huge_vall, "Ld", "nc")
+BUILTIN(__builtin_huge_valf16, "x", "nc")
 BUILTIN(__builtin_huge_valf128, "LLd", "nc")
 BUILTIN(__builtin_inf  , "d"   , "nc")
 BUILTIN(__builtin_inff , "f"   , "nc")
 BUILTIN(__builtin_infl , "Ld"  , "nc")
+BUILTIN(__builtin_inff16 , "x"  , "nc")
 BUILTIN(__builtin_inff128 , "LLd"  , "nc")
 BUILTIN(__builtin_labs , "LiLi"  , "Fnc")
 BUILTIN(__builtin_llabs, "LLiLLi", "Fnc")
@@ -160,10 +162,12 @@ BUILTIN(__builtin_modff128, "LLdLLdLLd*", "Fn")
 BUILTIN(__builtin_nan,  "dcC*" , "FnU")
 BUILTIN(__builtin_nanf, "fcC*" , "FnU")
 BUILTIN(__builtin_nanl, "LdcC*", "FnU")
+BUILTIN(__builtin_nanf16, "xcC*", "FnU")
 BUILTIN(__builtin_nanf128, "LLdcC*", "FnU")
 BUILTIN(__builtin_nans,  "dcC*" , "FnU")
 BUILTIN(__builtin_nansf, "fcC*" , "FnU")
 BUILTIN(__builtin_nansl, "LdcC*", "FnU")
+BUILTIN(__builtin_nansf16, "xcC*", "FnU")
 BUILTIN(__builtin_nansf128, "LLdcC*", "FnU")
 BUILTIN(__builtin_powi , "ddi"  , "Fnc")
 BUILTIN(__builtin_powif, "ffi"  , "Fnc")

diff  --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index f679dba44f001..896650e7f4c67 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -13880,10 +13880,12 @@ bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
   case Builtin::BI__builtin_huge_val:
   case Builtin::BI__builtin_huge_valf:
   case Builtin::BI__builtin_huge_vall:
+  case Builtin::BI__builtin_huge_valf16:
   case Builtin::BI__builtin_huge_valf128:
   case Builtin::BI__builtin_inf:
   case Builtin::BI__builtin_inff:
   case Builtin::BI__builtin_infl:
+  case Builtin::BI__builtin_inff16:
   case Builtin::BI__builtin_inff128: {
     const llvm::fltSemantics &Sem =
       Info.Ctx.getFloatTypeSemantics(E->getType());
@@ -13894,6 +13896,7 @@ bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
   case Builtin::BI__builtin_nans:
   case Builtin::BI__builtin_nansf:
   case Builtin::BI__builtin_nansl:
+  case Builtin::BI__builtin_nansf16:
   case Builtin::BI__builtin_nansf128:
     if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
                                true, Result))
@@ -13903,6 +13906,7 @@ bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
   case Builtin::BI__builtin_nan:
   case Builtin::BI__builtin_nanf:
   case Builtin::BI__builtin_nanl:
+  case Builtin::BI__builtin_nanf16:
   case Builtin::BI__builtin_nanf128:
     // If this is __builtin_nan() turn this into a nan, otherwise we
     // can't constant fold it.

diff  --git a/clang/test/CodeGen/builtin_Float16.c b/clang/test/CodeGen/builtin_Float16.c
new file mode 100644
index 0000000000000..099d2ad5697e3
--- /dev/null
+++ b/clang/test/CodeGen/builtin_Float16.c
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -emit-llvm -o - -triple x86_64-linux-pc -target-feature +avx512fp16 %s | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -o - -triple spir-unknown-unknown %s | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -o - -triple armv7a--none-eabi %s | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -o - -triple aarch64-linux-gnu %s | FileCheck %s
+
+void test_float16_builtins(void) {
+  volatile _Float16 res;
+
+  // CHECK: store volatile half 0xH7C00, ptr %res, align 2
+  res = __builtin_huge_valf16();
+  // CHECK: store volatile half 0xH7C00, ptr %res, align 2
+  res = __builtin_inff16();
+  // CHECK: store volatile half 0xH7E00, ptr %res, align 2
+  res = __builtin_nanf16("");
+  // CHECK: store volatile half 0xH7D00, ptr %res, align 2
+  res = __builtin_nansf16("");
+}