[RISC-V] Introduce C extension for Integer Register-Register Operations

src/coreclr/debug/di/module.cpp

@@ -4354,7 +4354,7 @@ HRESULT CordbNativeCode::EnumerateVariableHomes(ICorDebugVariableHomeEnum **ppEn
 
 int CordbNativeCode::GetCallInstructionLength(BYTE *ip, ULONG32 count)
 {
-#if defined(TARGET_ARM)
+#if defined(TARGET_ARM) || defined(TARGET_RISCV64)
     if (Is32BitInstruction(*(WORD*)ip))
         return 4;
     else
@@ -4726,8 +4726,6 @@ int CordbNativeCode::GetCallInstructionLength(BYTE *ip, ULONG32 count)
 
     _ASSERTE(!"Invalid opcode!");
     return -1;
-#elif defined(TARGET_RISCV64)
-    return MAX_INSTRUCTION_LENGTH;
 #else
 #error Platform not implemented
 #endif

src/coreclr/debug/ee/riscv64/walker.cpp

@@ -70,7 +70,7 @@ void NativeWalker::Decode()
 
     LOG((LF_CORDB, LL_INFO100000, "RiscV64Walker::Decode instruction at %p, opcode: %x\n", m_ip, opcode));
 
-    // TODO after "C" Standard Extension support implemented, add C.J, C.JAL, C.JR, C.JALR, C.BEQZ, C.BNEZ
+    // TODO-RISCV64-RVC: after "C" Standard Extension support implemented, add C.J, C.JAL, C.JR, C.JALR, C.BEQZ, C.BNEZ
 
     if ((opcode & 0x7f) == 0x6f) // JAL
     {

src/coreclr/inc/clrnt.h

@@ -470,7 +470,7 @@ RtlpGetFunctionEndAddress (
         FunctionLength = *(PTR_ULONG64)(ImageBase + FunctionLength) & 0x3ffff;
     }
 
-    return FunctionEntry->BeginAddress + 4 * FunctionLength;
+    return FunctionEntry->BeginAddress + 2 * FunctionLength;
 }
 
 #define RUNTIME_FUNCTION__BeginAddress(FunctionEntry)               ((FunctionEntry)->BeginAddress)

src/coreclr/inc/gcinfotypes.h

@@ -803,18 +803,18 @@ struct RISCV64GcInfoEncoding {
     // GC Pointers are 8-bytes aligned
     static inline constexpr int32_t NORMALIZE_STACK_SLOT (int32_t x) { return ((x)>>3); }
     static inline constexpr int32_t DENORMALIZE_STACK_SLOT (int32_t x) { return ((x)<<3); }
-    // All Instructions are 4 bytes long
-    static inline constexpr uint32_t NORMALIZE_CODE_LENGTH (uint32_t x) { return ((x)>>2); }
-    static inline constexpr uint32_t DENORMALIZE_CODE_LENGTH (uint32_t x) { return ((x)<<2); }
+    // All Instructions are 2/4 bytes long
+    static inline constexpr uint32_t NORMALIZE_CODE_LENGTH (uint32_t x) { return ((x)>>1); }
+    static inline constexpr uint32_t DENORMALIZE_CODE_LENGTH (uint32_t x) { return ((x)<<1); }
     // Encode Frame pointer X8 as zero, sp/x2 as 1
     static inline constexpr uint32_t NORMALIZE_STACK_BASE_REGISTER (uint32_t x) { return ((x) == 8 ? 0u : 1u); }
     static inline constexpr uint32_t DENORMALIZE_STACK_BASE_REGISTER (uint32_t x) { return ((x) == 0 ? 8u : 2u); }
     static inline constexpr uint32_t NORMALIZE_SIZE_OF_STACK_AREA (uint32_t x) { return ((x)>>3); }
     static inline constexpr uint32_t DENORMALIZE_SIZE_OF_STACK_AREA (uint32_t x) { return ((x)<<3); }
     static const bool CODE_OFFSETS_NEED_NORMALIZATION = true;
-    // Instructions are 4 bytes long
-    static inline constexpr uint32_t NORMALIZE_CODE_OFFSET (uint32_t x) { return ((x)>>2); }
-    static inline constexpr uint32_t DENORMALIZE_CODE_OFFSET (uint32_t x) { return ((x)<<2); }
+    // Instructions are 2/4 bytes long
+    static inline constexpr uint32_t NORMALIZE_CODE_OFFSET (uint32_t x) { return ((x)>>1); }
+    static inline constexpr uint32_t DENORMALIZE_CODE_OFFSET (uint32_t x) { return ((x)<<1); }
 
     static const int PSP_SYM_STACK_SLOT_ENCBASE = 6;
     static const int GENERICS_INST_CONTEXT_STACK_SLOT_ENCBASE = 6;

src/coreclr/inc/utilcode.h

@@ -101,6 +101,15 @@ inline ResultType ThumbCodeToDataPointer(SourceType pCode)
 
 #endif // TARGET_ARM
 
+#ifdef TARGET_RISCV64
+
+inline bool Is32BitInstruction(WORD opcode)
+{
+    return (opcode & 0b11) == 0b11;
+}
+
+#endif
+
 // Convert from a PCODE to the corresponding PINSTR.  On many architectures this will be the identity function;
 // on ARM, this will mask off the THUMB bit.
 inline TADDR PCODEToPINSTR(PCODE pc)

src/coreclr/jit/codegenriscv64.cpp

@@ -786,6 +786,7 @@ void CodeGen::genZeroInitFrameUsingBlockInit(int untrLclHi, int untrLclLo, regNu
                 GetEmitter()->emitIns_R_R_R(INS_add, EA_PTRSIZE, rEndAddr, rEndAddr, rAddr);
             }
 
+            // TODO-RISCV64-RVC: Remove hardcoded branch offset here
             GetEmitter()->emitIns_R_R_I(INS_sd, EA_PTRSIZE, REG_R0, rAddr, padding);
             GetEmitter()->emitIns_R_R_I(INS_sd, EA_PTRSIZE, REG_R0, rAddr, padding + REGSIZE_BYTES);
             GetEmitter()->emitIns_R_R_I(INS_sd, EA_PTRSIZE, REG_R0, rAddr, padding + 2 * REGSIZE_BYTES);
@@ -1006,10 +1007,11 @@ void CodeGen::genCodeForIncSaturate(GenTree* tree)
     regNumber operandReg = genConsumeReg(operand);
     emitAttr  attr       = emitActualTypeSize(tree);
 
+    BasicBlock* skip = genCreateTempLabel();
     GetEmitter()->emitIns_R_R_I(INS_addi, attr, targetReg, operandReg, 1);
-    // bne targetReg, zero, 2 * 4
-    GetEmitter()->emitIns_R_R_I(INS_bne, attr, targetReg, REG_R0, 8);
+    GetEmitter()->emitIns_J_cond_la(INS_bne, skip, targetReg, REG_R0);
     GetEmitter()->emitIns_R_R(INS_not, attr, targetReg, targetReg);
+    genDefineTempLabel(skip);
 
     genProduceReg(tree);
 }
@@ -1533,6 +1535,8 @@ void CodeGen::genLclHeap(GenTree* tree)
         // and localloc size is a multiple of STACK_ALIGN.
 
         // Loop:
+        BasicBlock* loop = genCreateTempLabel();
+        genDefineTempLabel(loop);
         emit->emitIns_R_R_I(INS_addi, EA_PTRSIZE, REG_SPBASE, REG_SPBASE, -16);
 
         emit->emitIns_R_R_I(INS_sd, EA_PTRSIZE, REG_R0, REG_SPBASE, 8);
@@ -1546,7 +1550,7 @@ void CodeGen::genLclHeap(GenTree* tree)
         emit->emitIns_R_R_I(INS_addi, emitActualTypeSize(type), regCnt, regCnt, -16);
 
         // goto Loop
-        emit->emitIns_R_R_I(INS_bne, EA_PTRSIZE, regCnt, REG_R0, -4 << 2);
+        emit->emitIns_J_cond_la(INS_bne, loop, regCnt, REG_R0);
 
         lastTouchDelta = 0;
     }
@@ -1591,8 +1595,10 @@ void CodeGen::genLclHeap(GenTree* tree)
         emit->emitIns_R_R_R(INS_sub, EA_PTRSIZE, regCnt, REG_SPBASE, regCnt);
 
         // Overflow, set regCnt to lowest possible value
-        emit->emitIns_R_R_I(INS_beq, EA_PTRSIZE, tempReg, REG_R0, 2 << 2);
+        BasicBlock* skip = genCreateTempLabel();
+        emit->emitIns_J_cond_la(INS_beq, skip, tempReg, REG_R0);
         emit->emitIns_R_R(INS_mov, EA_PTRSIZE, regCnt, REG_R0);
+        genDefineTempLabel(skip);
 
         regNumber rPageSize = internalRegisters.GetSingle(tree);
 
@@ -1603,10 +1609,12 @@ void CodeGen::genLclHeap(GenTree* tree)
         emit->emitIns_R_R(INS_mov, EA_PTRSIZE, tempReg, REG_SPBASE);
 
         // tickle the page - this triggers a page fault when on the guard page
+        BasicBlock* loop = genCreateTempLabel();
+        genDefineTempLabel(loop);
         emit->emitIns_R_R_I(INS_lw, EA_4BYTE, REG_R0, tempReg, 0);
         emit->emitIns_R_R_R(INS_sub, EA_4BYTE, tempReg, tempReg, rPageSize);
 
-        emit->emitIns_R_R_I(INS_bgeu, EA_PTRSIZE, tempReg, regCnt, -2 << 2);
+        emit->emitIns_J_cond_la(INS_bgeu, loop, tempReg, regCnt);
 
         // lastTouchDelta is dynamic, and can be up to a page. So if we have outgoing arg space,
         // we're going to assume the worst and probe.
@@ -6522,6 +6530,7 @@ void CodeGen::genJumpToThrowHlpBlk_la(
             params.addr     = helperFunction.addr;
             params.callType = EC_FUNC_TOKEN;
 
+            // TODO-RISCV64-RVC: Remove hardcoded branch offset here
             ssize_t imm = 3 * sizeof(emitter::code_t);
             emit->emitIns_R_R_I(ins, EA_PTRSIZE, reg1, reg2, imm);
         }
@@ -6535,12 +6544,14 @@ void CodeGen::genJumpToThrowHlpBlk_la(
             params.ireg     = REG_DEFAULT_HELPER_CALL_TARGET;
             if (compiler->opts.compReloc)
             {
+                // TODO-RISCV64-RVC: Remove hardcoded branch offset here
                 ssize_t imm = (3 + 1) << 2;
                 emit->emitIns_R_R_I(ins, EA_PTRSIZE, reg1, reg2, imm);
                 emit->emitIns_R_AI(INS_jal, EA_PTR_DSP_RELOC, params.ireg, (ssize_t)pAddr);
             }
             else
             {
+                // TODO-RISCV64-RVC: Remove hardcoded branch offset here
                 ssize_t imm = 9 << 2;
                 emit->emitIns_R_R_I(ins, EA_PTRSIZE, reg1, reg2, imm);
                 // TODO-RISCV64-CQ: In the future we may consider using emitter::emitLoadImmediate instead,