[PATCH] D59493: [OpenCL] Generate 'unroll.enable' metadata for __attribute__((opencl_unroll_hint))

[Dmitry Sidorov via Phabricator via cfe-commits]

sidorovd created this revision.
sidorovd added reviewers: Anastasia, yaxunl.
Herald added subscribers: cfe-commits, jdoerfert, dmgreen, zzheng.
Herald added a project: clang.

[OpenCL] Generate 'unroll.enable' metadata for  __attribute__((opencl_unroll_hint))

      

For both !{!"llvm.loop.unroll.enable"} and !{!"llvm.loop.unroll.full"} the unroller
will try to fully unroll a loop unless the trip count is not known at compile time.
In that case for '.full' metadata no unrolling will be processed, while for '.enable'
the loop will be partially unrolled with a heuristically chosen unroll factor.

      

See: docs/LanguageExtensions.rst

      

>From https://www.khronos.org/registry/OpenCL/sdk/2.0/docs/man/xhtml/attributes-loopUnroll.html
----------------------------------------------------------------------------------------------

  __attribute__((opencl_unroll_hint))
  for (int i=0; i<2; i++)
  {
      ...
  }


In the example above, the compiler will determine how much to unroll the loop.
------------------------------------------------------------------------------

Before the patch for  __attribute__((opencl_unroll_hint)) was generated metadata
!{!"llvm.loop.unroll.full"}, which limits ability of loop unroller to decide, how
much to unroll the loop.


Repository:
  rC Clang

https://reviews.llvm.org/D59493

Files:
  lib/CodeGen/CGLoopInfo.cpp
  test/CodeGenOpenCL/unroll-hint.cl


Index: test/CodeGenOpenCL/unroll-hint.cl
===================================================================
--- test/CodeGenOpenCL/unroll-hint.cl
+++ test/CodeGenOpenCL/unroll-hint.cl
@@ -18,12 +18,12 @@
 // CHECK: br label %{{.*}}, !llvm.loop ![[FOR_DISABLE:.*]]
 }
 
-void for_full()
+void for_enable()
 {
-// CHECK-LABEL: for_full
+// CHECK-LABEL: for_enable
     __attribute__((opencl_unroll_hint))
     for( int i = 0; i < 1000; ++i);
-// CHECK: br label %{{.*}}, !llvm.loop ![[FOR_FULL:.*]]
+// CHECK: br label %{{.*}}, !llvm.loop ![[FOR_ENABLE:.*]]
 }
 
 /*** while ***/
@@ -45,13 +45,13 @@
 // CHECK: br label %{{.*}}, !llvm.loop ![[WHILE_DISABLE:.*]]
 }
 
-void while_full()
+void while_enable()
 {
-// CHECK-LABEL: while_full
+// CHECK-LABEL: while_enable
     int i = 1000;
     __attribute__((opencl_unroll_hint))
     while(i-->0);
-// CHECK: br label %{{.*}}, !llvm.loop ![[WHILE_FULL:.*]]
+// CHECK: br label %{{.*}}, !llvm.loop ![[WHILE_ENABLE:.*]]
 }
 
 /*** do ***/
@@ -73,13 +73,13 @@
 // CHECK: br i1 %{{.*}}, label %{{.*}}, label %{{.*}}, !llvm.loop ![[DO_DISABLE:.*]]
 }
 
-void do_full()
+void do_enable()
 {
-// CHECK-LABEL: do_full
+// CHECK-LABEL: do_enable
     int i = 1000;
     __attribute__((opencl_unroll_hint))
     do {} while(i--> 0);
-// CHECK: br i1 %{{.*}}, label %{{.*}}, label %{{.*}}, !llvm.loop ![[DO_FULL:.*]]
+// CHECK: br i1 %{{.*}}, label %{{.*}}, label %{{.*}}, !llvm.loop ![[DO_ENABLE:.*]]
 }
 
 
@@ -87,11 +87,11 @@
 // CHECK: ![[COUNT]]         =  !{!"llvm.loop.unroll.count", i32 8}
 // CHECK: ![[FOR_DISABLE]]   =  distinct !{![[FOR_DISABLE]],  ![[DISABLE:.*]]}
 // CHECK: ![[DISABLE]]       =  !{!"llvm.loop.unroll.disable"}
-// CHECK: ![[FOR_FULL]]      =  distinct !{![[FOR_FULL]],  ![[FULL:.*]]}
-// CHECK: ![[FULL]]          =  !{!"llvm.loop.unroll.full"}
+// CHECK: ![[FOR_ENABLE]]      =  distinct !{![[FOR_ENABLE]],  ![[ENABLE:.*]]}
+// CHECK: ![[ENABLE]]          =  !{!"llvm.loop.unroll.enable"}
 // CHECK: ![[WHILE_COUNT]]   =  distinct !{![[WHILE_COUNT]],    ![[COUNT]]}
 // CHECK: ![[WHILE_DISABLE]] =  distinct !{![[WHILE_DISABLE]],  ![[DISABLE]]}
-// CHECK: ![[WHILE_FULL]]    =  distinct !{![[WHILE_FULL]],     ![[FULL]]}
+// CHECK: ![[WHILE_ENABLE]]    =  distinct !{![[WHILE_ENABLE]],     ![[ENABLE]]}
 // CHECK: ![[DO_COUNT]]      =  distinct !{![[DO_COUNT]],       ![[COUNT]]}
 // CHECK: ![[DO_DISABLE]]    =  distinct !{![[DO_DISABLE]],     ![[DISABLE]]}
-// CHECK: ![[DO_FULL]]       =  distinct !{![[DO_FULL]],        ![[FULL]]}
+// CHECK: ![[DO_ENABLE]]       =  distinct !{![[DO_ENABLE]],        ![[ENABLE]]}
Index: lib/CodeGen/CGLoopInfo.cpp
===================================================================
--- lib/CodeGen/CGLoopInfo.cpp
+++ lib/CodeGen/CGLoopInfo.cpp
@@ -208,13 +208,13 @@
     // Translate opencl_unroll_hint attribute argument to
     // equivalent LoopHintAttr enums.
     // OpenCL v2.0 s6.11.5:
-    // 0 - full unroll (no argument).
+    // 0 - enable unroll (no argument).
     // 1 - disable unroll.
     // other positive integer n - unroll by n.
     if (OpenCLHint) {
       ValueInt = OpenCLHint->getUnrollHint();
       if (ValueInt == 0) {
-        State = LoopHintAttr::Full;
+        State = LoopHintAttr::Enable;
       } else if (ValueInt != 1) {
         Option = LoopHintAttr::UnrollCount;
         State = LoopHintAttr::Numeric;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D59493.191078.patch
Type: text/x-patch
Size: 3350 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20190318/3a535626/attachment-0001.bin>