For x86/x64, call a stack probe helper for all frame sizes equal or o…

…ver one page (#44664)
dotnet · Nov 19, 2020 · 999785e · 999785e
1 parent 0cb3cfd
commit 999785e
Showing 1 changed file with 14 additions and 35 deletions.
diff --git a/src/coreclr/src/jit/codegenxarch.cpp b/src/coreclr/src/jit/codegenxarch.cpp
@@ -1970,43 +1970,32 @@ void CodeGen::genAllocLclFrame(unsigned frameSize, regNumber initReg, bool* pIni
         return;
     }
 
-    const target_size_t pageSize       = compiler->eeGetPageSize();
-    target_size_t       lastTouchDelta = 0; // What offset from the final SP was the last probe?
+    const target_size_t pageSize = compiler->eeGetPageSize();
 
     if (frameSize == REGSIZE_BYTES)
     {
         // Frame size is the same as register size.
-        inst_RV(INS_push, REG_EAX, TYP_I_IMPL);
+        GetEmitter()->emitIns_R(INS_push, EA_PTRSIZE, REG_EAX);
+        compiler->unwindAllocStack(frameSize);
     }
     else if (frameSize < pageSize)
     {
-        // Frame size is (0x0008..0x1000)
-        inst_RV_IV(INS_sub, REG_SPBASE, frameSize, EA_PTRSIZE);
-        lastTouchDelta = frameSize;
-    }
-    else if (frameSize < compiler->getVeryLargeFrameSize())
-    {
-        lastTouchDelta = frameSize;
-
-        // Frame size is (0x1000..0x3000)
+        GetEmitter()->emitIns_R_I(INS_sub, EA_PTRSIZE, REG_SPBASE, frameSize);
+        compiler->unwindAllocStack(frameSize);
 
-        GetEmitter()->emitIns_AR_R(INS_test, EA_PTRSIZE, REG_EAX, REG_SPBASE, -(int)pageSize);
-        lastTouchDelta -= pageSize;
+        const unsigned lastProbedLocToFinalSp = frameSize;
 
-        if (frameSize >= 0x2000)
+        if (lastProbedLocToFinalSp + STACK_PROBE_BOUNDARY_THRESHOLD_BYTES > pageSize)
         {
-            GetEmitter()->emitIns_AR_R(INS_test, EA_PTRSIZE, REG_EAX, REG_SPBASE, -2 * (int)pageSize);
-            lastTouchDelta -= pageSize;
+            // We haven't probed almost a complete page. If the next action on the stack might subtract from SP
+            // first, before touching the current SP, then we need to probe at the very bottom. This can
+            // happen on x86, for example, when we copy an argument to the stack using a "SUB ESP; REP MOV"
+            // strategy.
+            GetEmitter()->emitIns_R_AR(INS_test, EA_4BYTE, REG_EAX, REG_SPBASE, 0);
         }
-
-        inst_RV_IV(INS_sub, REG_SPBASE, frameSize, EA_PTRSIZE);
-        assert(lastTouchDelta == frameSize % pageSize);
     }
     else
     {
-        // Frame size >= 0x3000
-        assert(frameSize >= compiler->getVeryLargeFrameSize());
-
 #ifdef TARGET_X86
         int spOffset = -(int)frameSize;
 
@@ -2053,24 +2042,14 @@ void CodeGen::genAllocLclFrame(unsigned frameSize, regNumber initReg, bool* pIni
         GetEmitter()->emitIns_R_R(INS_mov, EA_PTRSIZE, REG_SPBASE, REG_STACK_PROBE_HELPER_ARG);
 #endif // !TARGET_X86
 
+        compiler->unwindAllocStack(frameSize);
+
         if (initReg == REG_STACK_PROBE_HELPER_ARG)
         {
             *pInitRegZeroed = false;
         }
     }
 
-    if (lastTouchDelta + STACK_PROBE_BOUNDARY_THRESHOLD_BYTES > pageSize)
-    {
-        // We haven't probed almost a complete page. If the next action on the stack might subtract from SP
-        // first, before touching the current SP, then we do one more probe at the very bottom. This can
-        // happen on x86, for example, when we copy an argument to the stack using a "SUB ESP; REP MOV"
-        // strategy.
-
-        GetEmitter()->emitIns_AR_R(INS_test, EA_PTRSIZE, REG_EAX, REG_SPBASE, 0);
-    }
-
-    compiler->unwindAllocStack(frameSize);
-
 #ifdef USING_SCOPE_INFO
     if (!doubleAlignOrFramePointerUsed())
     {