https://github.com/wenju-he updated https://github.com/llvm/llvm-project/pull/173821
>From 84478d7b427d32c5b9f24fc1f2b8e1d957563a96 Mon Sep 17 00:00:00 2001 From: Wenju He <[email protected]> Date: Mon, 29 Dec 2025 06:19:00 +0100 Subject: [PATCH 1/2] [Clang] Honor '#pragma STDC FENV_ROUND' in __builtin_store_half/halff Before this change, constrained fptrunc for __builtin_store_half/halff always used round.tonearest, ignoring the active pragma STDC FENV_ROUND. This PR guards builtin emission with CGFPOptionsRAII so the current rounding mode is propagated to the generated constrained intrinsic. --- clang/lib/CodeGen/CGBuiltin.cpp | 1 + ...builtin-store-half-rounding-constrained.cl | 21 +++++++++++++++++++ 2 files changed, 22 insertions(+) create mode 100644 clang/test/CodeGenOpenCL/builtin-store-half-rounding-constrained.cl diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp index d3abf6d2a1f2d..0f9bed130a3b0 100644 --- a/clang/lib/CodeGen/CGBuiltin.cpp +++ b/clang/lib/CodeGen/CGBuiltin.cpp @@ -6199,6 +6199,7 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID, } case Builtin::BI__builtin_store_half: case Builtin::BI__builtin_store_halff: { + CodeGenFunction::CGFPOptionsRAII FPOptsRAII(*this, E); Value *Val = EmitScalarExpr(E->getArg(0)); Address Address = EmitPointerWithAlignment(E->getArg(1)); Value *HalfVal = Builder.CreateFPTrunc(Val, Builder.getHalfTy()); diff --git a/clang/test/CodeGenOpenCL/builtin-store-half-rounding-constrained.cl b/clang/test/CodeGenOpenCL/builtin-store-half-rounding-constrained.cl new file mode 100644 index 0000000000000..a9334d22fe05f --- /dev/null +++ b/clang/test/CodeGenOpenCL/builtin-store-half-rounding-constrained.cl @@ -0,0 +1,21 @@ +// RUN: %clang_cc1 %s -cl-std=cl3.0 -emit-llvm -o - -triple x86_64-unknown-unknown | FileCheck %s + +// CHECK-LABEL: @test_store_float( +// CHECK: [[TMP0:%.*]] = tail call half @llvm.experimental.constrained.fptrunc.f16.f32(float {{.*}}, metadata !"round.upward", metadata !"fpexcept.ignore") +// CHECK-NEXT: store half [[TMP0]], ptr {{.*}}, align 2 +// CHECK-NEXT: ret void +// +__kernel void test_store_float(float foo, __global half* bar) { + #pragma STDC FENV_ROUND FE_UPWARD + __builtin_store_halff(foo, bar); +} + +// CHECK-LABEL: @test_store_double( +// CHECK: [[TMP0:%.*]] = tail call half @llvm.experimental.constrained.fptrunc.f16.f64(double {{.*}}, metadata !"round.downward", metadata !"fpexcept.ignore") +// CHECK-NEXT: store half [[TMP0]], ptr {{.*}}, align 2 +// CHECK-NEXT: ret void +// +__kernel void test_store_double(double foo, __global half* bar) { + #pragma STDC FENV_ROUND FE_DOWNWARD + __builtin_store_half(foo, bar); +} >From 5e6e9e30828888cba97010127e796364c245d238 Mon Sep 17 00:00:00 2001 From: Wenju He <[email protected]> Date: Sun, 4 Jan 2026 05:55:40 +0100 Subject: [PATCH 2/2] add -disable-llvm-passes --- .../builtin-store-half-rounding-constrained.cl | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/clang/test/CodeGenOpenCL/builtin-store-half-rounding-constrained.cl b/clang/test/CodeGenOpenCL/builtin-store-half-rounding-constrained.cl index a9334d22fe05f..ba3b3165e325a 100644 --- a/clang/test/CodeGenOpenCL/builtin-store-half-rounding-constrained.cl +++ b/clang/test/CodeGenOpenCL/builtin-store-half-rounding-constrained.cl @@ -1,7 +1,7 @@ -// RUN: %clang_cc1 %s -cl-std=cl3.0 -emit-llvm -o - -triple x86_64-unknown-unknown | FileCheck %s +// RUN: %clang_cc1 %s -cl-std=cl3.0 -triple x86_64-unknown-unknown -disable-llvm-passes -emit-llvm -o - | FileCheck %s // CHECK-LABEL: @test_store_float( -// CHECK: [[TMP0:%.*]] = tail call half @llvm.experimental.constrained.fptrunc.f16.f32(float {{.*}}, metadata !"round.upward", metadata !"fpexcept.ignore") +// CHECK: [[TMP0:%.*]] = call half @llvm.experimental.constrained.fptrunc.f16.f32(float {{.*}}, metadata !"round.upward", metadata !"fpexcept.ignore") // CHECK-NEXT: store half [[TMP0]], ptr {{.*}}, align 2 // CHECK-NEXT: ret void // @@ -11,7 +11,7 @@ __kernel void test_store_float(float foo, __global half* bar) { } // CHECK-LABEL: @test_store_double( -// CHECK: [[TMP0:%.*]] = tail call half @llvm.experimental.constrained.fptrunc.f16.f64(double {{.*}}, metadata !"round.downward", metadata !"fpexcept.ignore") +// CHECK: [[TMP0:%.*]] = call half @llvm.experimental.constrained.fptrunc.f16.f64(double {{.*}}, metadata !"round.downward", metadata !"fpexcept.ignore") // CHECK-NEXT: store half [[TMP0]], ptr {{.*}}, align 2 // CHECK-NEXT: ret void // _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
