[GR-65519] In AArch64FarReturnOp, write lr late in case it initially holds sp.

PullRequest: graal/21007

Author: peter-hofer

substratevm/src/com.oracle.svm.core.graal.aarch64/src/com/oracle/svm/core/graal/aarch64/AArch64FarReturnOp.java

@@ -68,20 +68,11 @@ public AArch64FarReturnOp(AllocatableValue result, AllocatableValue sp, Allocata
     public void emitCode(CompilationResultBuilder crb, AArch64MacroAssembler masm) {
         assert sp.getPlatformKind().getSizeInBytes() == FrameAccess.wordSize() && FrameAccess.wordSize() == Long.BYTES : Assertions.errorMessage(sp.getPlatformKind().getSizeInBytes(),
                         FrameAccess.wordSize());
-        /*
-         * Set lr to the new instruction pointer like a regular return does.
-         *
-         * For dispatching an exception into a frame pending deoptimization, we farReturn into a
-         * deopt stub which will do a regular enter and thus push lr. This keeps the stack walkable
-         * and the frame can be recognized as pending deoptimization due to the return address from
-         * lr matching the deopt stub entry point.
-         */
-        masm.mov(64, lr, asRegister(ip));
 
         if (!SubstrateOptions.PreserveFramePointer.getValue() && !fromMethodWithCalleeSavedRegisters) {
             /* No need to restore anything in the frame of the new stack pointer. */
             masm.mov(64, AArch64.sp, asRegister(sp));
-            masm.ret(asRegister(ip));
+            returnTo(asRegister(ip), masm);
         }
 
         /*
@@ -94,7 +85,7 @@ public void emitCode(CompilationResultBuilder crb, AArch64MacroAssembler masm) {
         /*
          * If within the same frame then no additional action is needed.
          */
-        masm.ret(asRegister(ip));
+        returnTo(asRegister(ip), masm);
 
         /*
          * Otherwise we first switch the stack pointer to point to the value of the lowest value
@@ -144,7 +135,20 @@ public void emitCode(CompilationResultBuilder crb, AArch64MacroAssembler masm) {
             }
 
             masm.ldr(64, fp, AArch64Address.createImmediateAddress(64, AArch64Address.AddressingMode.IMMEDIATE_POST_INDEXED, AArch64.sp, minCalleeFrameSize));
-            masm.ret(ipRegister);
+            returnTo(ipRegister, masm);
         }
     }
+
+    private static void returnTo(Register ipRegister, AArch64MacroAssembler masm) {
+        /*
+         * Set lr to the new instruction pointer like a regular return does.
+         *
+         * For dispatching an exception into a frame pending deoptimization, we farReturn into a
+         * deopt stub which will do a regular enter and thus push lr. This keeps the stack walkable
+         * and the frame can be recognized as pending deoptimization due to the return address from
+         * lr matching the deopt stub entry point.
+         */
+        masm.mov(64, lr, ipRegister);
+        masm.ret(lr);
+    }
 }