From 63f21925b3e68d8883dbe4275c2c4dc8865cfbab Mon Sep 17 00:00:00 2001
From: Dmitry Stogov <dmitry@zend.com>
Date: Tue, 20 Sep 2022 00:26:56 +0300
Subject: [PATCH] Avoid useless move

---
 ir_aarch64.dasc | 23 ++++++++++++++---------
 ir_x86.dasc     | 23 ++++++++++++++---------
 2 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/ir_aarch64.dasc b/ir_aarch64.dasc
index 87aad82..756cc37 100644
--- a/ir_aarch64.dasc
+++ b/ir_aarch64.dasc
@@ -4319,8 +4319,13 @@ static int ir_emit_dessa_move(ir_ctx *ctx, uint8_t type, ir_ref from, ir_ref to)
 			ir_emit_load(ctx, type, from_reg, from);
 		}
 		if (to_reg != IR_REG_NONE && (to_reg & IR_REG_SPILL_STORE)) {
-			to_reg &= ~IR_REG_SPILL_STORE;
-			spill_store = 1;
+			if (from_reg != IR_REG_NONE) {
+				/* store directly into spill slot (valid only when to_reg register is not reused) */
+				to_reg = IR_REG_NONE;
+			} else {
+				to_reg &= ~IR_REG_SPILL_STORE;
+				spill_store = 1;
+			}
 		}
 		if (from_reg != IR_REG_NONE && to_reg != IR_REG_NONE) {
 			if (from_reg != to_reg) {
@@ -4347,13 +4352,13 @@ static int ir_emit_dessa_move(ir_ctx *ctx, uint8_t type, ir_ref from, ir_ref to)
 			ir_emit_load(ctx, type, from_reg, from);
 		}
 		if (to_reg != IR_REG_NONE && (to_reg & IR_REG_SPILL_STORE)) {
-#if 1
-			/* store directly into spill slot (valid only when to_reg register is not reused) */
-			to_reg = IR_REG_NONE;
-#else
-			to_reg &= ~IR_REG_SPILL_STORE;
-			spill_store = 1;
-#endif
+			if (from_reg != IR_REG_NONE) {
+				/* store directly into spill slot (valid only when to_reg register is not reused) */
+				to_reg = IR_REG_NONE;
+			} else {
+				to_reg &= ~IR_REG_SPILL_STORE;
+				spill_store = 1;
+			}
 		}
 		if (from_reg != IR_REG_NONE && to_reg != IR_REG_NONE) {
 			if (from_reg != to_reg) {
diff --git a/ir_x86.dasc b/ir_x86.dasc
index 7daf06c..4387dc6 100644
--- a/ir_x86.dasc
+++ b/ir_x86.dasc
@@ -6736,8 +6736,13 @@ static int ir_emit_dessa_move(ir_ctx *ctx, uint8_t type, ir_ref from, ir_ref to)
 			ir_emit_load(ctx, type, from_reg, from);
 		}
 		if (to_reg != IR_REG_NONE && (to_reg & IR_REG_SPILL_STORE)) {
-			to_reg &= ~IR_REG_SPILL_STORE;
-			spill_store = 1;
+			if (from_reg != IR_REG_NONE) {
+				/* store directly into spill slot (valid only when to_reg register is not reused) */
+				to_reg = IR_REG_NONE;
+			} else {
+				to_reg &= ~IR_REG_SPILL_STORE;
+				spill_store = 1;
+			}
 		}
 		if (from_reg != IR_REG_NONE && to_reg != IR_REG_NONE) {
 			if (from_reg != to_reg) {
@@ -6769,13 +6774,13 @@ static int ir_emit_dessa_move(ir_ctx *ctx, uint8_t type, ir_ref from, ir_ref to)
 			ir_emit_load(ctx, type, from_reg, from);
 		}
 		if (to_reg != IR_REG_NONE && (to_reg & IR_REG_SPILL_STORE)) {
-#if 1
-			/* store directly into spill slot (valid only when to_reg register is not reused) */
-			to_reg = IR_REG_NONE;
-#else
-			to_reg &= ~IR_REG_SPILL_STORE;
-			spill_store = 1;
-#endif
+			if (from_reg != IR_REG_NONE) {
+				/* store directly into spill slot (valid only when to_reg register is not reused) */
+				to_reg = IR_REG_NONE;
+			} else {
+				to_reg &= ~IR_REG_SPILL_STORE;
+				spill_store = 1;
+			}
 		}
 		if (from_reg != IR_REG_NONE && to_reg != IR_REG_NONE) {
 			if (from_reg != to_reg) {