https://github.com/Ami-zhang created
https://github.com/llvm/llvm-project/pull/141703
Enable _Float16 for LoongArch target. Additionally, this change fixes incorrect
ABI lowering of _Float16 in the case of structs containing fp16 that are
eligible for passing via GPR+FPR or FPR+FPR. Finally, it also fixes int16 ->
__fp16 conversion code gen, which uses generic LLVM IR rather than
llvm.convert.to.fp16 intrinsics.
>From 537b973a7bab435eb6a569bc1466c7768fae17e6 Mon Sep 17 00:00:00 2001
From: Ami-zhang <zhangli...@loongson.cn>
Date: Thu, 17 Apr 2025 15:59:05 +0800
Subject: [PATCH] [clang][LoongArch] Add support for the _Float16 type
Enable _Float16 for LoongArch target. Additionally, this change
fixes incorrect ABI lowering of _Float16 in the case of structs
containing fp16 that are eligible for passing via GPR+FPR or FPR+FPR.
Finally, it also fixes int16 -> __fp16 conversion code gen, which
uses generic LLVM IR rather than llvm.convert.to.fp16 intrinsics.
---
clang/docs/LanguageExtensions.rst | 1 +
clang/lib/Basic/Targets/LoongArch.h | 3 +
clang/lib/CodeGen/Targets/LoongArch.cpp | 7 +-
clang/test/CodeGen/LoongArch/__fp16-convert.c | 30 ++++++++
clang/test/CodeGen/LoongArch/abi-lp64d.c | 71 +++++++++++++++++++
5 files changed, 108 insertions(+), 4 deletions(-)
create mode 100644 clang/test/CodeGen/LoongArch/__fp16-convert.c
diff --git a/clang/docs/LanguageExtensions.rst
b/clang/docs/LanguageExtensions.rst
index a40dd4d1a1673..088f01a0199e4 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -1001,6 +1001,7 @@ to ``float``; see below for more information on this
emulation.
* X86 (if SSE2 is available; natively if AVX512-FP16 is also available)
* RISC-V (natively if Zfh or Zhinx is available)
* SystemZ (emulated)
+ * LoongArch
* ``__bf16`` is supported on the following targets (currently never natively):
diff --git a/clang/lib/Basic/Targets/LoongArch.h
b/clang/lib/Basic/Targets/LoongArch.h
index 4c7b53abfef9b..8a8c978ab89db 100644
--- a/clang/lib/Basic/Targets/LoongArch.h
+++ b/clang/lib/Basic/Targets/LoongArch.h
@@ -53,6 +53,7 @@ class LLVM_LIBRARY_VISIBILITY LoongArchTargetInfo : public
TargetInfo {
LongDoubleAlign = 128;
LongDoubleFormat = &llvm::APFloat::IEEEquad();
MCountName = "_mcount";
+ HasFloat16 = true;
SuitableAlign = 128;
WCharType = SignedInt;
WIntType = UnsignedInt;
@@ -98,6 +99,8 @@ class LLVM_LIBRARY_VISIBILITY LoongArchTargetInfo : public
TargetInfo {
bool hasBitIntType() const override { return true; }
+ bool useFP16ConversionIntrinsics() const override { return false; }
+
bool handleTargetFeatures(std::vector<std::string> &Features,
DiagnosticsEngine &Diags) override;
diff --git a/clang/lib/CodeGen/Targets/LoongArch.cpp
b/clang/lib/CodeGen/Targets/LoongArch.cpp
index 0f689371a60db..7640f3779816a 100644
--- a/clang/lib/CodeGen/Targets/LoongArch.cpp
+++ b/clang/lib/CodeGen/Targets/LoongArch.cpp
@@ -110,10 +110,9 @@ bool LoongArchABIInfo::detectFARsEligibleStructHelper(
uint64_t Size = getContext().getTypeSize(Ty);
if (IsInt && Size > GRLen)
return false;
- // Can't be eligible if larger than the FP registers. Half precision isn't
- // currently supported on LoongArch and the ABI hasn't been confirmed, so
- // default to the integer ABI in that case.
- if (IsFloat && (Size > FRLen || Size < 32))
+ // Can't be eligible if larger than the FP registers. Handling of half
+ // precision values has been specified in the ABI, so don't block those.
+ if (IsFloat && Size > FRLen)
return false;
// Can't be eligible if an integer type was already found (int+int pairs
// are not eligible).
diff --git a/clang/test/CodeGen/LoongArch/__fp16-convert.c
b/clang/test/CodeGen/LoongArch/__fp16-convert.c
new file mode 100644
index 0000000000000..84ef5de960b47
--- /dev/null
+++ b/clang/test/CodeGen/LoongArch/__fp16-convert.c
@@ -0,0 +1,30 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py
UTC_ARGS: --version 5
+// RUN: %clang_cc1 -triple loongarch64 -emit-llvm %s -o - \
+// RUN: | FileCheck %s
+
+__fp16 y;
+short z;
+// CHECK-LABEL: define dso_local void @bar1(
+// CHECK-SAME: ) #[[ATTR0:[0-9]+]] {
+// CHECK-NEXT: [[ENTRY:.*:]]
+// CHECK-NEXT: [[TMP0:%.*]] = load half, ptr @y, align 2
+// CHECK-NEXT: [[CONV:%.*]] = fpext half [[TMP0]] to float
+// CHECK-NEXT: [[CONV1:%.*]] = fptosi float [[CONV]] to i16
+// CHECK-NEXT: store i16 [[CONV1]], ptr @z, align 2
+// CHECK-NEXT: ret void
+//
+void bar1(){
+ z = y;
+}
+// CHECK-LABEL: define dso_local void @bar2(
+// CHECK-SAME: ) #[[ATTR0]] {
+// CHECK-NEXT: [[ENTRY:.*:]]
+// CHECK-NEXT: [[TMP0:%.*]] = load i16, ptr @z, align 2
+// CHECK-NEXT: [[CONV:%.*]] = sitofp i16 [[TMP0]] to float
+// CHECK-NEXT: [[CONV1:%.*]] = fptrunc float [[CONV]] to half
+// CHECK-NEXT: store half [[CONV1]], ptr @y, align 2
+// CHECK-NEXT: ret void
+//
+void bar2(){
+ y = z;
+}
diff --git a/clang/test/CodeGen/LoongArch/abi-lp64d.c
b/clang/test/CodeGen/LoongArch/abi-lp64d.c
index fc7f1eada586b..9f64cfd662e5f 100644
--- a/clang/test/CodeGen/LoongArch/abi-lp64d.c
+++ b/clang/test/CodeGen/LoongArch/abi-lp64d.c
@@ -48,6 +48,9 @@ unsigned long check_ulong() { return 0; }
// CHECK-LABEL: define{{.*}} i64 @check_ulonglong()
unsigned long long check_ulonglong() { return 0; }
+// CHECK-LABEL: define{{.*}} half @check_float16()
+_Float16 check_float16() { return 0; }
+
// CHECK-LABEL: define{{.*}} float @check_float()
float check_float() { return 0; }
@@ -127,6 +130,14 @@ struct i16x4_s f_i16x4_s(struct i16x4_s x) {
/// available, the value is passed in a GAR; if no GAR is available, the value
/// is passed on the stack.
+struct f16x1_s {
+ __fp16 a;
+};
+
+struct float16x1_s {
+ _Float16 a;
+};
+
struct f32x1_s {
float a;
};
@@ -135,6 +146,16 @@ struct f64x1_s {
double a;
};
+// CHECK-LABEL: define{{.*}} half @f_f16x1_s(half %0)
+struct f16x1_s f_f16x1_s(struct f16x1_s x) {
+ return x;
+}
+
+// CHECK-LABEL: define{{.*}} half @f_float16x1_s(half %0)
+struct float16x1_s f_float16x1_s(struct float16x1_s x) {
+ return x;
+}
+
// CHECK-LABEL: define{{.*}} float @f_f32x1_s(float %0)
struct f32x1_s f_f32x1_s(struct f32x1_s x) {
return x;
@@ -151,10 +172,20 @@ struct f64x1_s f_f64x1_s(struct f64x1_s x) {
/// number of available FAR is less than 2, it’s passed in a GAR, and passed on
/// the stack if no GAR is available.
+struct f16x2_s {
+ __fp16 a;
+ _Float16 b;
+};
+
struct f32x2_s {
float a, b;
};
+// CHECK-LABEL: define{{.*}} { half, half } @f_f16x2_s(half %0, half %1)
+struct f16x2_s f_f16x2_s(struct f16x2_s x) {
+ return x;
+}
+
// CHECK-LABEL: define{{.*}} { float, float } @f_f32x2_s(float %0, float %1)
struct f32x2_s f_f32x2_s(struct f32x2_s x) {
return x;
@@ -165,11 +196,21 @@ struct f32x2_s f_f32x2_s(struct f32x2_s x) {
/// i. Multiple fixed-point members. If there are available GAR, the structure
/// is passed in a GAR, and passed on the stack if no GAR is available.
+struct f16x1_i16x2_s {
+ _Float16 a;
+ int16_t b, c;
+};
+
struct f32x1_i16x2_s {
float a;
int16_t b, c;
};
+// CHECK-LABEL: define{{.*}} i64 @f_f16x1_i16x2_s(i64 %x.coerce)
+struct f16x1_i16x2_s f_f16x1_i16x2_s(struct f16x1_i16x2_s x) {
+ return x;
+}
+
// CHECK-LABEL: define{{.*}} i64 @f_f32x1_i16x2_s(i64 %x.coerce)
struct f32x1_i16x2_s f_f32x1_i16x2_s(struct f32x1_i16x2_s x) {
return x;
@@ -181,11 +222,21 @@ struct f32x1_i16x2_s f_f32x1_i16x2_s(struct f32x1_i16x2_s
x) {
/// but one GAR is available, it’s passed in GAR; If no GAR is available, it’s
/// passed on the stack.
+struct f16x1_i32x1_s {
+ _Float16 a;
+ int32_t b;
+};
+
struct f32x1_i32x1_s {
float a;
int32_t b;
};
+// CHECK-LABEL: define{{.*}} { half, i32 } @f_f16x1_i32x1_s(half %0, i32 %1)
+struct f16x1_i32x1_s f_f16x1_i32x1_s(struct f16x1_i32x1_s x) {
+ return x;
+}
+
// CHECK-LABEL: define{{.*}} { float, i32 } @f_f32x1_i32x1_s(float %0, i32 %1)
struct f32x1_i32x1_s f_f32x1_i32x1_s(struct f32x1_i32x1_s x) {
return x;
@@ -253,6 +304,16 @@ struct f32x4_s f_f32x4_s(struct f32x4_s x) {
return x;
}
+struct f16x5_s {
+ _Float16 a, b, c, d;
+ __fp16 e;
+};
+
+// CHECK-LABEL: define{{.*}} [2 x i64] @f_f16x5_s([2 x i64] %x.coerce)
+struct f16x5_s f_f16x5_s(struct f16x5_s x) {
+ return x;
+}
+
/// ii. The structure with two double members is passed in a pair of available
/// FARs. If no a pair of available FARs, it’s passed in GARs. A structure with
/// one double member and one float member is same.
@@ -312,6 +373,16 @@ struct f32x2_i32x2_s f_f32x2_i32x2_s(struct f32x2_i32x2_s
x) {
return x;
}
+struct f16x4_i32x2_s {
+ _Float16 a, b, c, d;
+ int32_t e, f;
+};
+
+// CHECK-LABEL: define{{.*}} [2 x i64] @f_f16x4_i32x2_s([2 x i64] %x.coerce)
+struct f16x4_i32x2_s f_f16x4_i32x2_s(struct f16x4_i32x2_s x) {
+ return x;
+}
+
/// 3. WOA > 2 × GRLEN
/// a. It’s passed by reference and are replaced in the argument list with the
/// address. If there is an available GAR, the reference is passed in the GAR,
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