Remove stack probing under sp on Arm in src/coreclr/jit/codegenarm.cpp src/coreclr/jit/codegencommon.cpp

Author: echesakov

src/coreclr/jit/codegenarm.cpp

@@ -1849,28 +1849,22 @@ void CodeGen::genAllocLclFrame(unsigned frameSize, regNumber initReg, bool* pIni
     {
         GetEmitter()->emitIns_R_I(INS_sub, EA_PTRSIZE, REG_SPBASE, frameSize);
     }
-    else if (frameSize < compiler->getVeryLargeFrameSize())
-    {
-        for (target_size_t probeOffset = pageSize; probeOffset <= frameSize; probeOffset += pageSize)
-        {
-            // Generate:
-            //    movw initReg, -probeOffset
-            //    ldr initReg, [SP + initReg]
-
-            instGen_Set_Reg_To_Imm(EA_PTRSIZE, initReg, -(ssize_t)probeOffset);
-            GetEmitter()->emitIns_R_R_R(INS_ldr, EA_PTRSIZE, initReg, REG_SPBASE, initReg);
-        }
-
-        regSet.verifyRegUsed(initReg);
-        *pInitRegZeroed = false; // The initReg does not contain zero
-
-        instGen_Set_Reg_To_Imm(EA_PTRSIZE, initReg, frameSize);
-        compiler->unwindPadding();
-        GetEmitter()->emitIns_R_R_R(INS_sub, EA_PTRSIZE, REG_SPBASE, REG_SPBASE, initReg);
-    }
     else
     {
-        assert(frameSize >= compiler->getVeryLargeFrameSize());
+        // Generate the following code:
+        //
+        //    movw  r4, #frameSize
+        //    sub   r4, sp, r4
+        //    bl    CORINFO_HELP_STACK_PROBE
+        //    mov   sp, r4
+        //
+        // If frameSize can not be encoded by movw immediate this becomes:
+        //
+        //    movw  r4, #frameSizeLo16
+        //    movt  r4, #frameSizeHi16
+        //    sub   r4, sp, r4
+        //    bl    CORINFO_HELP_STACK_PROBE
+        //    mov   sp, r4
 
         genInstrWithConstant(INS_sub, EA_PTRSIZE, REG_STACK_PROBE_HELPER_ARG, REG_SPBASE, frameSize,
                              INS_FLAGS_DONT_CARE, REG_STACK_PROBE_HELPER_ARG);

src/coreclr/jit/codegencommon.cpp

@@ -6632,10 +6632,8 @@ void CodeGen::genFinalizeFrame()
 #endif // TARGET_X86
 
 #ifdef TARGET_ARM
-    // Make sure that callee-saved registers used by call to a stack probing helper generated for very large stack
-    // frames
-    // (see `getVeryLargeFrameSize`) are pushed on stack.
-    if (compiler->compLclFrameSize >= compiler->getVeryLargeFrameSize())
+    // Make sure that callee-saved registers used by call to a stack probing helper generated are pushed on stack.
+    if (compiler->compLclFrameSize >= compiler->eeGetPageSize())
     {
         regSet.rsSetRegsModified(RBM_STACK_PROBE_HELPER_ARG | RBM_STACK_PROBE_HELPER_CALL_TARGET |
                                  RBM_STACK_PROBE_HELPER_TRASH);