[RISC-V] Use getUnrollThreshold() to get unroll limits

Author: minxuanz

src/coreclr/jit/codegenriscv64.cpp

@@ -2511,7 +2511,7 @@ void CodeGen::genCodeForDivMod(GenTreeOp* tree)
 // Generate code for InitBlk by performing a loop unroll
 // Preconditions:
 //   a) Both the size and fill byte value are integer constants.
-//   b) The size of the struct to initialize is smaller than INITBLK_UNROLL_LIMIT bytes.
+//   b) The size of the struct to initialize is smaller than getUnrollThreshold() bytes.
 void CodeGen::genCodeForInitBlkUnroll(GenTreeBlk* node)
 {
     assert(node->OperIs(GT_STORE_BLK));
@@ -6176,7 +6176,7 @@ void CodeGen::genCodeForIndir(GenTreeIndir* tree)
 //    None
 //
 // Assumption:
-//  The size argument of the CpBlk node is a constant and <= CPBLK_UNROLL_LIMIT bytes.
+//  The size argument of the CpBlk node is a constant and <= getUnrollThreshold() bytes.
 //
 void CodeGen::genCodeForCpBlkUnroll(GenTreeBlk* cpBlkNode)
 {

src/coreclr/jit/compiler.h

@@ -9222,6 +9222,7 @@ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
         // | arm64       |   256  |   128  | ldp/stp (2x128bit)
         // | arm         |    32  |    16  | no SIMD support
         // | loongarch64 |    64  |    32  | no SIMD support
+        // | riscv64     |    64  |    32  | no SIMD support
         //
         // We might want to use a different multiplier for truly hot/cold blocks based on PGO data
         //

src/coreclr/jit/lowerriscv64.cpp

@@ -245,7 +245,8 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
             src = src->AsUnOp()->gtGetOp1();
         }
 
-        if (!blkNode->OperIs(GT_STORE_DYN_BLK) && (size <= INITBLK_UNROLL_LIMIT) && src->OperIs(GT_CNS_INT))
+        if (!blkNode->OperIs(GT_STORE_DYN_BLK) && (size <= comp->getUnrollThreshold(Compiler::UnrollKind::Memset)) && 
+           src->OperIs(GT_CNS_INT))
         {
             blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindUnroll;
 
@@ -300,8 +301,9 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
 
         ClassLayout* layout  = blkNode->GetLayout();
         bool         doCpObj = !blkNode->OperIs(GT_STORE_DYN_BLK) && layout->HasGCPtr();
+        unsigned copyBlockUnrollLimit = comp->getUnrollThreshold(Compiler::UnrollKind::Memcpy);
 
-        if (doCpObj && (size <= CPBLK_UNROLL_LIMIT))
+        if (doCpObj && (size <= copyBlockUnrollLimit))
         {
             // No write barriers are needed on the stack.
             // If the layout contains a byref, then we know it must live on the stack.
@@ -321,7 +323,7 @@ void Lowering::LowerBlockStore(GenTreeBlk* blkNode)
             assert((dstAddr->TypeGet() == TYP_BYREF) || (dstAddr->TypeGet() == TYP_I_IMPL));
             blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindCpObjUnroll;
         }
-        else if (blkNode->OperIs(GT_STORE_BLK) && (size <= CPBLK_UNROLL_LIMIT))
+        else if (blkNode->OperIs(GT_STORE_BLK) && (size <= copyBlockUnrollLimit))
         {
             blkNode->gtBlkOpKind = GenTreeBlk::BlkOpKindUnroll;
 

src/coreclr/jit/targetriscv64.h

@@ -12,8 +12,6 @@
   #define ROUND_FLOAT              0       // Do not round intermed float expression results
   #define CPU_HAS_BYTE_REGS        0
 
-  #define CPBLK_UNROLL_LIMIT       64     // Upper bound to let the code generator to loop unroll CpBlk
-  #define INITBLK_UNROLL_LIMIT     64     // Upper bound to let the code generator to loop unroll InitBlk
 
 #ifdef FEATURE_SIMD
 #pragma error("SIMD Unimplemented yet RISCV64")