Translate llvm.loop.unroll.full metadata (intel#1664)

It can be generated via #pragma clang unroll(full) pragma.
llvm.loop.unroll.full means attempt to do full unroll of the
loop and disable the unrolling if the trip count is not known
at compile time.

Unroll mask to which it was previously mapped doesn't much the
description.

The way the patch represents it in SPIR-V is:
 Unroll mask + PartialCount mask with '1' parameter

This patch also removes some overtesting for unroll metadata.

Signed-off-by: Sidorov, Dmitry <[email protected]>

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@eed0081

Author: MrSidims

llvm-spirv/lib/SPIRV/SPIRVReader.cpp

@@ -690,7 +690,7 @@ void SPIRVToLLVM::setLLVMLoopMetadata(const LoopInstType *LM,
   // i.e. check smaller-numbered bits first.
   // Unroll and UnrollCount loop controls can't be applied simultaneously with
   // DontUnroll loop control.
-  if (LC & LoopControlUnrollMask)
+  if (LC & LoopControlUnrollMask && !(LC & LoopControlPartialCountMask))
     Metadata.push_back(getMetadataFromName("llvm.loop.unroll.enable"));
   else if (LC & LoopControlDontUnrollMask)
     Metadata.push_back(getMetadataFromName("llvm.loop.unroll.disable"));
@@ -728,9 +728,11 @@ void SPIRVToLLVM::setLLVMLoopMetadata(const LoopInstType *LM,
            "Missing loop control parameter!");
   }
   if (LC & LoopControlPartialCountMask && !(LC & LoopControlDontUnrollMask)) {
-    // If unroll factor is set as '1' - disable loop unrolling
-    if (1 == LoopControlParameters[NumParam])
-      Metadata.push_back(getMetadataFromName("llvm.loop.unroll.disable"));
+    // If unroll factor is set as '1' and Unroll mask is applied attempt to do
+    // full unrolling and disable it if the trip count is not known at compile
+    // time.
+    if (1 == LoopControlParameters[NumParam] && (LC & LoopControlUnrollMask))
+      Metadata.push_back(getMetadataFromName("llvm.loop.unroll.full"));
     else
       Metadata.push_back(llvm::MDNode::get(
           *Context,

llvm-spirv/lib/SPIRV/SPIRVWriter.cpp

@@ -1413,8 +1413,18 @@ LLVMToSPIRVBase::getLoopControl(const BranchInst *Branch,
       // appear first.
       if (S == "llvm.loop.unroll.disable")
         LoopControl |= spv::LoopControlDontUnrollMask;
-      else if (S == "llvm.loop.unroll.full" || S == "llvm.loop.unroll.enable")
+      else if (S == "llvm.loop.unroll.enable")
         LoopControl |= spv::LoopControlUnrollMask;
+      // Attempt to do full unroll of the loop and disable unrolling if the trip
+      // count is not known at compile time by setting PartialCount to 1
+      else if (S == "llvm.loop.unroll.full") {
+        LoopControl |= spv::LoopControlUnrollMask;
+        if (BM->isAllowedToUseVersion(VersionNumber::SPIRV_1_4)) {
+          BM->setMinSPIRVVersion(VersionNumber::SPIRV_1_4);
+          ParametersToSort.emplace_back(spv::LoopControlPartialCountMask, 1);
+          LoopControl |= spv::LoopControlPartialCountMask;
+        }
+      }
       // PartialCount must not be used with the DontUnroll bit
       else if (S == "llvm.loop.unroll.count" &&
                !(LoopControl & LoopControlDontUnrollMask)) {

llvm-spirv/test/DebugInfo/DebugControlFlow.cl

@@ -14,11 +14,11 @@
 kernel
 void sample() {
   int arr[10];
-  #pragma clang loop unroll(full)
+  #pragma clang loop unroll(enable)
   for (int i = 0; i < 10; i++)
     arr[i] = 0;
   int j = 0;
-  #pragma clang loop unroll(full)
+  #pragma clang loop unroll(enable)
   do {
     arr[j] = 0;
   } while (j++ < 10);

llvm-spirv/test/DebugInfo/DebugUnstructuredControlFlow.cl

@@ -18,9 +18,9 @@ void sample() {
 // Check that all Line items are retained
 // CHECK-SPIRV: Line [[File:[0-9]+]] 15 0
 // Loop control
-// CHECK-SPIRV: 2 LoopControlINTEL 1
+// CHECK-SPIRV: LoopControlINTEL 257 1
 // CHECK-SPIRV-NEXT: Branch
 
 // CHECK-LLVM: br label %{{.*}}, !dbg !{{[0-9]+}}, !llvm.loop ![[MD:[0-9]+]]
 // CHECK-LLVM: ![[MD]] = distinct !{![[MD]], ![[MD_unroll:[0-9]+]]}
-// CHECK-LLVM: ![[MD_unroll]] = !{!"llvm.loop.unroll.enable"}
+// CHECK-LLVM: ![[MD_unroll]] = !{!"llvm.loop.unroll.full"}