[PATCH] D53295: [OpenCL] Mark load of block invoke function as invariant

[Yaxun Liu via Phabricator via cfe-commits]

yaxunl created this revision.
yaxunl added reviewers: rjmccall, Anastasia.

  OpenCL v2.0 s6.12.5:
    Block variable declarations are implicitly qualified with const.
  Therefore all block variables must be initialized at declaration time and
  may not be reassigned.
  
  As such, load of block invoke function can be marked as invariant. This is
  to facilitate lowering of indirect function calls resulted from it to
  direct function calls since OpenCL does not require supporting of function
  pointer.


https://reviews.llvm.org/D53295

Files:
  lib/CodeGen/CGBlocks.cpp
  test/CodeGenOpenCL/blocks.cl


Index: test/CodeGenOpenCL/blocks.cl
===================================================================
--- test/CodeGenOpenCL/blocks.cl
+++ test/CodeGenOpenCL/blocks.cl
@@ -98,6 +98,19 @@
   return blockArgFunc(^{return 42;});
 }
 
+// COMMON-LABEL: define {{.*}} @blockInLoopCondition
+// COMMON: %[[INV:.*]] = getelementptr {{.*}}%block.literal, i32 0, i32 2
+// COMMON: load {{.*}}%[[INV]]{{.*}}, !invariant.load
+void blockInLoopCondition(int* res, int tid, int multiplier) {
+  int (^kernelBlock)(int) = ^(int num) {
+    return num * multiplier;
+  };
+  res[tid] = 39;
+  for(int i=0; i<kernelBlock(13); i++) {
+    res[tid]--;
+  }
+}
+
 // CHECK-DEBUG: !DIDerivedType(tag: DW_TAG_member, name: "__size"
 // CHECK-DEBUG: !DIDerivedType(tag: DW_TAG_member, name: "__align"
 
Index: lib/CodeGen/CGBlocks.cpp
===================================================================
--- lib/CodeGen/CGBlocks.cpp
+++ lib/CodeGen/CGBlocks.cpp
@@ -1303,6 +1303,20 @@
   // Load the function.
   llvm::Value *Func = Builder.CreateAlignedLoad(FuncPtr, getPointerAlign());
 
+  // OpenCL v2.0 s6.12.5:
+  //   Block variable declarations are implicitly qualified with const.
+  // Therefore all block variables must be initialized at declaration time and
+  // may not be reassigned.
+  //
+  // As such, load of block invoke function can be marked as invariant. This is
+  // to facilitate lowering of indirect function calls resulted from it to
+  // direct function calls since OpenCL does not require supporting of function
+  // pointer.
+  if (getLangOpts().OpenCL)
+    cast<llvm::LoadInst>(Func)->setMetadata(
+        CGM.getModule().getMDKindID("invariant.load"),
+        llvm::MDNode::get(getLLVMContext(), None));
+
   const FunctionType *FuncTy = FnType->castAs<FunctionType>();
   const CGFunctionInfo &FnInfo =
     CGM.getTypes().arrangeBlockFunctionCall(Args, FuncTy);


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D53295.169729.patch
Type: text/x-patch
Size: 1881 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20181015/69229956/attachment.bin>