From 15f1e94ddd7128f407ada43fd9e4b26d4a8bba8d Mon Sep 17 00:00:00 2001
From: Xi Ruoyao <xry111@xry111.site>
Date: Fri, 4 Nov 2022 01:35:25 +0800
Subject: [PATCH 026/124] LoongArch: fix signed overflow in
 loongarch_emit_int_compare

Signed overflow is an undefined behavior, so we need to prevent it from
happening, instead of "checking" the result.

gcc/ChangeLog:

	* config/loongarch/loongarch.cc (loongarch_emit_int_compare):
	Avoid signed overflow.

Signed-off-by: Peng Fan <fanpeng@loongson.cn>
Signed-off-by: ticat_fp <fanpeng@loongson.cn>
---
 gcc/config/loongarch/loongarch.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
index e9ba3374e..d552b162a 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -4177,10 +4177,13 @@ loongarch_emit_int_compare (enum rtx_code *code, rtx *op0, rtx *op1)
 	      if (!increment && !decrement)
 		continue;
 
+	      if ((increment && rhs == HOST_WIDE_INT_MAX)
+		  || (decrement && rhs == HOST_WIDE_INT_MIN))
+		break;
+
 	      new_rhs = rhs + (increment ? 1 : -1);
 	      if (loongarch_integer_cost (new_rhs)
-		    < loongarch_integer_cost (rhs)
-		  && (rhs < 0) == (new_rhs < 0))
+		    < loongarch_integer_cost (rhs))
 		{
 		  *op1 = GEN_INT (new_rhs);
 		  *code = mag_comparisons[i][increment];
-- 
2.33.0