[clang] 9263931 - [SYCL] Assume SYCL device functions are convergent

[Alexey Bader via cfe-commits]

Author: Alexey Bader
Date: 2020-09-29T15:23:50+03:00
New Revision: 9263931fcccdc99000c1de668bea330711333729

URL: https://github.com/llvm/llvm-project/commit/9263931fcccdc99000c1de668bea330711333729
DIFF: https://github.com/llvm/llvm-project/commit/9263931fcccdc99000c1de668bea330711333729.diff

LOG: [SYCL] Assume SYCL device functions are convergent

SYCL device compiler (similar to other SPMD compilers) assumes that
functions are convergent by default to avoid invalid transformations.
This attribute can be removed if compiler can prove that function does
not have convergent operations.

Reviewed By: Naghasan

Differential Revision: https://reviews.llvm.org/D87282

Added: 
    clang/test/CodeGenSYCL/convergent.cpp

Modified: 
    clang/lib/Frontend/CompilerInvocation.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 2d008d8a3fbe..42224339250d 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -2882,7 +2882,8 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
   Opts.Coroutines = Opts.CPlusPlus20 || Args.hasArg(OPT_fcoroutines_ts);
 
   Opts.ConvergentFunctions = Opts.OpenCL || (Opts.CUDA && Opts.CUDAIsDevice) ||
-    Args.hasArg(OPT_fconvergent_functions);
+                             Opts.SYCLIsDevice ||
+                             Args.hasArg(OPT_fconvergent_functions);
 
   Opts.DoubleSquareBracketAttributes =
       Args.hasFlag(OPT_fdouble_square_bracket_attributes,

diff  --git a/clang/test/CodeGenSYCL/convergent.cpp b/clang/test/CodeGenSYCL/convergent.cpp
new file mode 100644
index 000000000000..784fb8976c27
--- /dev/null
+++ b/clang/test/CodeGenSYCL/convergent.cpp
@@ -0,0 +1,20 @@
+// RUN: %clang_cc1 -fsycl -fsycl-is-device -emit-llvm -disable-llvm-passes \
+// RUN:  -triple spir64-unknown-unknown-sycldevice -emit-llvm %s -o - | \
+// RUN:   FileCheck %s
+
+// CHECK-DAG: Function Attrs:
+// CHECK-DAG-SAME: convergent
+// CHECK-DAG-NEXT: define void @_Z3foov
+void foo() {
+  int a = 1;
+}
+
+template <typename Name, typename Func>
+__attribute__((sycl_kernel)) void kernel_single_task(const Func &kernelFunc) {
+  kernelFunc();
+}
+
+int main() {
+  kernel_single_task<class fake_kernel>([] { foo(); });
+  return 0;
+}