JIT: Relax address exposure check for tailcalls (#111397)

jakobbotsch · web-flow · commit d2cdcdd69391 · 2025-01-15T10:15:38.000+01:00
The `lvHasLdAddrOp` based check is conservative: address exposure (as computed in local morph) is much more precise. We can switch to that check only.
diff --git a/src/coreclr/jit/morph.cpp b/src/coreclr/jit/morph.cpp
@@ -5119,11 +5119,6 @@ GenTree* Compiler::fgMorphPotentialTailCall(GenTreeCall* call)
         //
         if (isImplicitOrStressTailCall)
         {
-            if (varDsc->lvHasLdAddrOp && !lvaIsImplicitByRefLocal(varNum))
-            {
-                failTailCall("Local address taken", varNum);
-                return nullptr;
-            }
             if (varDsc->IsAddressExposed())
             {
                 if (lvaIsImplicitByRefLocal(varNum))

Original file line number	Diff line number	Diff line change
`@@ -5119,11 +5119,6 @@ GenTree* Compiler::fgMorphPotentialTailCall(GenTreeCall* call)`
`5119`	`5119`	`//`
`5120`	`5120`	`if (isImplicitOrStressTailCall)`
`5121`	`5121`	`{`
`5122`		`- if (varDsc->lvHasLdAddrOp && !lvaIsImplicitByRefLocal(varNum))`
`5123`		`- {`
`5124`		`- failTailCall("Local address taken", varNum);`
`5125`		`- return nullptr;`
`5126`		`- }`
`5127`	`5122`	`if (varDsc->IsAddressExposed())`
`5128`	`5123`	`{`
`5129`	`5124`	`if (lvaIsImplicitByRefLocal(varNum))`