[PATCH 0/1] MR10921: Draft: vbscript: Fast-path interp_add and var_cmp for pure-integer operands.

[Francis De Brabandere (＠francisdb)]

For-loop counters and conditional comparisons hit VarAdd/VarCmp every
iteration with trivial I2/I4 operands, but the full VARIANT conversion
pipeline (VariantChangeType, locale grab/free in ucrtbase) dominates the
cost. Short-circuit at the call site in interp.c when both operands are
pure VT_I2/VT_I4: compare directly, or add via LONGLONG with native
promotion (I2+I2 -> I4 on overflow, I4+I4 -> R8 on overflow).

Alternative to !10528 
Keeps the optimisation scoped to vbscript callers rather than adding
branches to oleaut32 generic VarAdd/VarCmp.

-- 
https://gitlab.winehq.org/wine/wine/-/merge_requests/10921

[PATCH 1/1] vbscript: Fast-path interp_add and var_cmp for pure-integer operands.

[Francis De Brabandere]

From: Francis De Brabandere <[e-mail]>

For-loop counters and conditional comparisons hit VarAdd/VarCmp every
iteration with trivial I2/I4 operands, but the full VARIANT conversion
pipeline (VariantChangeType, locale grab/free in ucrtbase) dominates the
cost. Short-circuit at the call site in interp.c when both operands are
pure VT_I2/VT_I4: compare directly, or add via LONGLONG with native
promotion (I2+I2 -> I4 on overflow, I4+I4 -> R8 on overflow).

Keeps the optimisation scoped to vbscript callers rather than adding
branches to oleaut32 generic VarAdd/VarCmp.
---
 dlls/vbscript/interp.c | 44 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/dlls/vbscript/interp.c b/dlls/vbscript/interp.c
index ac2bbc64ce6..37c7aefd83b 100644
--- a/dlls/vbscript/interp.c
+++ b/dlls/vbscript/interp.c
@@ -2285,6 +2285,22 @@ static HRESULT var_cmp(exec_ctx_t *ctx, VARIANT *l, VARIANT *r, unsigned flags)
     if(is_unsupported_script_vt(lvt) || is_unsupported_script_vt(rvt))
         return MAKE_VBSERROR(VBSE_INVALID_TYPELIB_VARIABLE);
 
+    /* Fast path: pure-integer comparisons (the dominant case in For-loops and
+     * If-conditions) skip VarCmp's VariantChangeType pipeline. */
+    if(V_VT(l) == VT_I2 && V_VT(r) == VT_I2) {
+        if(V_I2(l) < V_I2(r)) return VARCMP_LT;
+        if(V_I2(l) > V_I2(r)) return VARCMP_GT;
+        return VARCMP_EQ;
+    }
+    if((V_VT(l) == VT_I2 || V_VT(l) == VT_I4) &&
+       (V_VT(r) == VT_I2 || V_VT(r) == VT_I4)) {
+        LONG lv = V_VT(l) == VT_I2 ? V_I2(l) : V_I4(l);
+        LONG rv = V_VT(r) == VT_I2 ? V_I2(r) : V_I4(r);
+        if(lv < rv) return VARCMP_LT;
+        if(lv > rv) return VARCMP_GT;
+        return VARCMP_EQ;
+    }
+
     /* BSTR vs numeric LITERAL: coerce BSTR to a number, parse failure raises
      * type-mismatch (error 13). */
     if((lvt == VT_BSTR && is_numeric_vt(rvt) && r_lit) ||
@@ -2600,7 +2616,33 @@ static HRESULT interp_add(exec_ctx_t *ctx)
 
     hres = stack_pop_val(ctx, &l);
     if(SUCCEEDED(hres)) {
-        hres = VarAdd(l.v, r.v, &v);
+        /* Fast path: pure-integer addition skips VarAdd's VariantChangeType
+         * pipeline. Covers the dominant For-loop counter increment case.
+         * Overflow promotes per native: I2+I2 -> I4, I4+I4 -> R8. */
+        if((V_VT(l.v) == VT_I2 || V_VT(l.v) == VT_I4) &&
+           (V_VT(r.v) == VT_I2 || V_VT(r.v) == VT_I4)) {
+            LONGLONG lv = V_VT(l.v) == VT_I2 ? V_I2(l.v) : V_I4(l.v);
+            LONGLONG rv = V_VT(r.v) == VT_I2 ? V_I2(r.v) : V_I4(r.v);
+            LONGLONG sum = lv + rv;
+
+            if(V_VT(l.v) == VT_I2 && V_VT(r.v) == VT_I2) {
+                if(sum >= SHRT_MIN && sum <= SHRT_MAX) {
+                    V_VT(&v) = VT_I2;
+                    V_I2(&v) = sum;
+                }else {
+                    V_VT(&v) = VT_I4;
+                    V_I4(&v) = sum;
+                }
+            }else if(sum >= LONG_MIN && sum <= LONG_MAX) {
+                V_VT(&v) = VT_I4;
+                V_I4(&v) = sum;
+            }else {
+                V_VT(&v) = VT_R8;
+                V_R8(&v) = sum;
+            }
+        }else {
+            hres = VarAdd(l.v, r.v, &v);
+        }
         release_val(&l);
     }
     release_val(&r);
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10921